Co-reporter:Jiang Gong, Nana Tian, Jie Liu, Kun Yao, Zhiwei Jiang, Xuecheng Chen, Xin Wen, Ewa Mijowska, Tao Tang
Polymer Degradation and Stability 2014 Volume 99() pp:18-26
Publication Date(Web):January 2014
DOI:10.1016/j.polymdegradstab.2013.12.016
A novel combined catalyst of activated carbon (AC) with Ni2O3 was demonstrated to be much more efficient than AC or Ni2O3 alone in enhancing the char yield of polypropylene (PP) and improving its char layer structure, which greatly improved the thermal stability and flame retardancy of PP. The results of X-ray diffraction, field-emission scanning electron microscope and transmission electron microscope revealed that the residual char mainly consisted of carbon nanotubes (CNTs). Thermal gravimetric analyses results indicated that the combination of AC and Ni2O3 dramatically enhanced the thermal stability of PP. The flame retardancy of PP and its composites was studied by cone calorimeter test. The heat release rate and total heat release of the ternary PP/7.5AC–7.5Ni2O3 composite decreased significantly in comparison with those of neat PP. The investigation of the synergetic mechanism showed that in the presence of both AC and Ni2O3, a large amount of CNTs were in situ formed from the degradation products of PP during combustion. This not only reduced the release of flammable degradation products of PP, but also acted as a thermal shield for energy feedback from the flame. In addition, the formation of a network-like structure of AC and Ni2O3 particles in PP matrix favored the formation of a more compacted protective layer, which enhanced the flame retardancy of PP.
Co-reporter:Chaoqun Li;Zhiwei Jiang
Journal of Applied Polymer Science 2014 Volume 131( Issue 16) pp:
Publication Date(Web):
DOI:10.1002/app.40618
ABSTRACT
Nanocomposites composed of organoclay and thermoplastic vulcanizates (TPVs) based on uncompatibilized or compatibilized polypropylene (PP)/ethylene–propylene–diene rubber (EPDM) blends were prepared in this study. The morphology of the nanocomposites was studied with wide-angle X-ray diffraction and transmission electron microscopy, which suggested that the addition of the compatibilizer played a key role in determining the morphology of the composites because of their interaction with the clay surface. Scanning electron microscopy study indicated the changes in the morphology of the rubber particles. Dynamic mechanical analysis was also applied to the analysis of these phenomena. Moreover, for nanocomposites with uncompatibilized PP/EPDM blends as the matrix, the samples showed tensile enhancement compared with neat TPV. Although the addition of the compatibilizer changed tensile properties of the composites in a rather different trend, the tensile modulus increased dramatically when the compatibilizer was added. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40618.
Co-reporter:Jiang Gong, Ran Niu, Nana Tian, Xuecheng Chen, Xin Wen, Jie Liu, Zhaoyan Sun, Ewa Mijowska, Tao Tang
Polymer 2014 Volume 55(Issue 13) pp:2998-3007
Publication Date(Web):13 June 2014
DOI:10.1016/j.polymer.2014.05.006
The combination of fumed silica (SiO2) with carbon black (CB) for improving thermal stability, flame retardancy and mechanical properties of linear low density polyethylene (LLDPE) was investigated. The temperature at the maximum weight loss rate of LLDPE was dramatically increased by 92 °C, and the peak value of heat release rate measured by cone calorimeter was significantly reduced by 80.7%. The improved thermal stability and flame retardancy of LLDPE were partially attributed to the formation of a percolated network structure in LLDPE matrix, and partially to the accelerated oxidation crosslinking reaction of LLDPE or other radicals by CB and SiO2. More importantly, although both SiO2 and CB were used without any pre-treatment, ternary LLDPE nanocomposites showed much higher mechanical properties compared to those of neat LLDPE. This was ascribed to good dispersions of two kinds of nanoparticles and strong matrix-nanoparticle interfacial interactions with LLDPE matrix.
Co-reporter:Haiping Xing, Dong Wan, Jian Qiu, Yanhui Wang, Li Ma, Zhiwei Jiang, Tao Tang
Polymer 2014 Volume 55(Issue 21) pp:5435-5444
Publication Date(Web):9 October 2014
DOI:10.1016/j.polymer.2014.09.005
•The effect of dithiocarbamates on the melt reaction of modified PP is proposed.•The topological structure of the LCBPP depends on the chemical structures of dithiocarbamates.•The proposed mechanism explains the resultant star-like and comb-like topology of the LCBPP.Four dithiocarbamates with different chemical structures (S-Propyl N,N-dipropyldithiocarbamate, S-allyl N,N-dipropyldithiocarbamate, S-Propyl N-pyrrolocarbodithioate and S-allyl N-pyrrolocarbodithioate) were used to adjust the melt radical reaction of polypropylene (PP). The combined effects between activating group Z (N,N-dipropyl and N-pyrrolo) and leaving group R(allyl and propyl) in the dithiocarbamates on melt reaction of PP were studied in the presence of peroxide and trimethylolpropane triacrylate monomer. The results from 1H NMR, FTIR, GPC, rheological measurements and model experiments showed that chemical structures of activating group Z and leaving group R played a key role in the molecular structures and melt properties of modified PP samples. The presence of S-allyl N-pyrrolocarbodithioate with stronger activating group N-pyrrolo and easier leaving group allyl led to the formation of long chain branching structure with more branched points (comb-like topology). The possible reactions in the above systems were also discussed.
Co-reporter:Feng Liu;Dong Wan 唐涛
Chinese Journal of Polymer Science 2014 Volume 32( Issue 1) pp:51-63
Publication Date(Web):2014 January
DOI:10.1007/s10118-014-1370-8
A variety of linear and 3-arm star polyethylene (PE) model polymers covering a wide range of molecular weight are synthesized by the living polymerization of butadiene and the subsequent hydrogenation. Several rheological parameters of these model linear and 3-arm star PE samples are analyzed for detecting the long chain branching (LCB) structure. It is found that the analyses based on zero shear viscosity, vGP plot and flow activation energy are very sensitive to the 3-arm star PEs. The information on the presence of LCB can be obtained with these methods even for low molecular weight samples, which can not be determined by GPC-MALLS. However the information about the LCB structure can not be obtained by the rheological methods alone.
Co-reporter:Jiang Gong, Kun Yao, Jie Liu, Zhiwei Jiang, Xuecheng Chen, Xin Wen, Ewa Mijowska, Nana Tian and Tao Tang
Journal of Materials Chemistry A 2013 vol. 1(Issue 17) pp:5247-5255
Publication Date(Web):26 Feb 2013
DOI:10.1039/C3TA10316A
A one-pot approach was demonstrated to effectively synthesize carbon microspheres through “catalytic carbonization” of commercial chlorinated poly(vinyl chloride) (CPVC) microspheres by Fe2O3 at 700 °C. Without Fe2O3, a “sponge-like” carbon lump was obtained. However, after adding Fe2O3 (even 0.5 g per 100 g CPVC) into CPVC, carbon microspheres with octahedral Fe3O4 microcrystals uniformly embedded on the surface (Fe/CMS) were synthesized. The influence of Fe2O3 on the carbonization of CPVC microspheres was investigated. It was found that Fe2O3 significantly accelerated the dehydrochlorination of CPVC into polyene before the melting of the CPVC microsphere surface. As a result, the microspheres of raw CPVC showed a “shape-duplicate” carbonization behaviour. The resultant Fe/CMS showed high photo-degradation efficiency of Congo red under UV irradiation via a heterogeneous photo-Fenton process with high recyclablity, reusability and long-term stability. This indicated that the resultant Fe/CMS has a potential application in wastewater treatment. Therefore, the initial catalytic substance could be effectively used as a catalyst twice in the carbonization of CPVC microspheres and in the subsequent application of Fe/CMS. More importantly, the strategy of “catalytic carbonization” offers a new potential way to largely convert charring polymers into functional carbon and carbon-based materials with various morphologies.
Co-reporter:Xuecheng Chen, Karolina Wilgosz, Krzysztof Cendrowski, Tao Tang, Paul K. Chu, Ryszard J. Kalenczuk and Ewa Mijowska
Dalton Transactions 2013 vol. 42(Issue 18) pp:6381-6385
Publication Date(Web):08 Jan 2013
DOI:10.1039/C3DT32736A
The synthesis of designed nanostructures is an ultimate target of nanomaterial science. Here, silica spheres with nanoholes have been selectively prepared. Coating the necklace-like structured and magnetic nanoparticles along carbon nanotubes, which is an essential step of the simple synthetic procedure of silica hollow spheres, led to the formation of silica hollow spheres with controllable sized nanoholes in their shell walls. The synthesized hollow spheres with nanoholes would be a good support for loading large molecules, e.g. drugs and proteins.
Co-reporter:Haiying Tan, Donghua Xu, Dong Wan, Yujie Wang, Lu Wang, Jun Zheng, Feng Liu, Li Ma and Tao Tang
Soft Matter 2013 vol. 9(Issue 27) pp:6282-6290
Publication Date(Web):05 Jun 2013
DOI:10.1039/C3SM00103B
The melt viscosity behavior of three-arm and six-arm star polystyrene (SPS)/C60 composites was studied. It was found that the changing trend in the melt viscosity of SPS/C60 composites depended on the molecular weight of the arm chain (Ma) of SPS and the content of C60. When the Ma of SPS was smaller than the critical molecular weight for the entanglement (Mc) of polystyrene (PS), the complex viscosity obtained at 0.05 rad s−1 (η*0.05) of SPS/C60 composites with a low content of C60 was lower than that of pure SPS. When the Ma was larger than the Mc of PS, however, the η*0.05 of the SPS/C60 composites was higher than that of pure SPS. These results were contrary to the previous work on the melt viscosity behavior of linear PS (LPS)/C60 composites (A. Tuteja et al., Macromolecules, 2007, 40, 9427–9434), where the η* at low shear frequencies of LPS/C60 composites was higher than that of pure LPS when the molecular weight (Mw) of LPS was smaller than the Mc of PS, and the η* at low shear frequencies of LPS/C60 was lower than that of pure LPS when the Mw of LPS was larger than the Mc of PS. The possible mechanism behind the melt viscosity behavior of SPS/C60 composites was discussed. It was expected that the topological structure of SPS induced a more heterogeneous dispersion of C60 in the SPS matrix than the dispersion state of C60 in the LPS matrix. When the molecular weight of SPS was different, the contact states between SPS and C60 might also be different, which would make C60 act as a lubricator or barrier, leading to the reduction or increase of the melt viscosity of SPS/C60, respectively.
Co-reporter:Jiang Gong, Jie Liu, Xuecheng Chen, Xin Wen, Zhiwei Jiang, Ewa Mijowska, Yanhui Wang, Tao Tang
Microporous and Mesoporous Materials 2013 Volume 176() pp:31-40
Publication Date(Web):August 2013
DOI:10.1016/j.micromeso.2013.03.039
Highlights•Catalytic carbonization of polystyrene into mesoporous hollow carbon nanospheres (HCNs).•Organically-modified montmorillonite (OMMT) improved the yield and morphology of HCNs.•OMMT affected the cobalt catalyst dispersion and the polystyrene degradation products.•The growth mechanism of mesoporous HCNs was studied.Mesoporous hollow carbon nanospheres (HCNs) were synthesized through the carbonization of polystyrene (PS) under the combined catalysis of organically-modified montmorillonite (OMMT)/cobalt catalyst at 700 °C. The morphology, microstructure, phase structure, textural property and surface composition of the obtained mesoporous HCNs were investigated by field-emission scanning electron microscope, transmission electron microscope (TEM), high-resolution TEM, X-ray diffraction, Raman spectroscopy, N2 sorption and X-ray photoelectron spectroscopy. It was found that OMMT not only promoted the dispersion of cobalt catalyst in the PS matrix but also affected the degradation of PS into light hydrocarbons and aromatics. The lattice oxygen of the cobalt catalyst facilitated the decomposition of light hydrocarbons and aromatics into atomic carbon during the formation of the mesoporous HCNs. A possible mechanism was proposed to explain the growth of mesoporous HCNs through the carbonization of PS under the combined catalysis of OMMT/cobalt catalyst. More importantly, this approach also offers a new potential way to transform waste polymer materials into mesoporous HCNs, which may be used as catalyst supports, adsorbents, storage media and templates for the synthesis of other useful hollow materials.Graphical abstract
Co-reporter:Nana Tian;Xin Wen;Jiang Gong;Li Ma;Jian Xue
Polymers for Advanced Technologies 2013 Volume 24( Issue 7) pp:653-659
Publication Date(Web):
DOI:10.1002/pat.3129
A novel organophosphorus containing spiro and caged bicyclic phosphate, 3,9-Bis-(1-oxo-2,6,7-trioxa-1-phospha-bicyclo[2.2.2]oct-4-ylmethoxy)-2,4,8,10-tetraoxa-3,9-diphospha-spiro[5.5]undecane 3, 9-dioxide (SBCPO), was synthesized and characterized by Fourier transform infrared (FTIR), hydrogen-1 nuclear magnetic resonance (NMR) and phosphorus-31 NMR. The flame retardancy of polypropylene (PP) containing the novel intumescent flame retardant (IFR) based on the combination between SBCPO and melamine (MA) was studied by limiting oxygen index (LOI), UL-94 test and cone calorimeter test. Results indicated that this combination showed the excellent flame retardancy for PP at appropriate proportions (with the total loading of 30 wt. % and SBCPO: MA = 4:1). The value of LOI was as high as 31.6, and the rating in UL94 reached to V-0. Moreover, the HRR and THR of IFR/PP decreased significantly in comparison with that of neat PP. The scanning electron microscopy results indicated that the incorporation of SBCPO could induce the formation of intumescent char layer, which retarded the degradation and combustion process of PP. The thermal oxidative degradation of the PP samples at different temperature was analyzed by FTIR. The thermal stabilities of the composites were further investigated by thermogravimetric analysis. It was found that the amount of residues was increased greatly with the addition of SBCPO that remained in the form of polyaromatic stacks and phosphoric or polyphosphoric acid at the residual chars. Copyright © 2013 John Wiley & Sons, Ltd.
Co-reporter:Dong Wan;Haiping Xing;Zhenjiang Zhang;Yujie Wang;Lu Wang;Yanhui Wang;Zhiwei Jiang
Journal of Applied Polymer Science 2013 Volume 127( Issue 2) pp:1394-1402
Publication Date(Web):
DOI:10.1002/app.38019
Abstract
Effect of different content of C60 on the melt radical reaction between trimethylol propane triacrylate (TMPTA) and polypropylene (PP) was studied by means of Fourier transform infrared, melt torque values, and rheological results. C60 could transfer most of the reactive PP macroradicals to more stable macroradicals at first due to its higher reaction rate with radicals. Therefore, the homopolymerization of TMPTA was restrained to some extent. PP samples containing TMPTA, C60, and 2,5-dimethyl-2,5(tert-butylperoxy) hexane peroxide (DHBP) showed a more obvious influence on increasing the entanglements between PP chains comparing with PP samples containing C60 and DHBP, owing to the synergetic effect between TMPTA and C60 on branching with PP macroradicals. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Xin Wen;Nana Tian;Jiang Gong;Qing Chen;Yanlong Qi;Zhi Liu;Jie Liu;Zhiwei Jiang;Xuecheng Chen
Polymers for Advanced Technologies 2013 Volume 24( Issue 11) pp:971-977
Publication Date(Web):
DOI:10.1002/pat.3172
Nanosized carbon black (CB) was introduced into polypropylene/carbon nanotubes (PP/CNTs) nanocomposites to investigate the effect of multi-component nanofillers on the thermal stability and flammability properties of PP. The obtained ternary nanocomposites displayed dramatically improved thermal stability compared with neat PP and PP/CNTs nanocomposites. Moreover, the flame retardancy of resultant nanocomposites was greatly improved with a significant reduction in peak heat release rate and increase of limited oxygen index value, and it was strongly dependent on the content of CB. This enhanced effect was attributed mainly to the formation of good carbon protective layers by CB and CNTs during combustion. Rheological properties further confirmed that CB played an important role on promoting the formation of crosslink network on the base of PP/CNTs system, which were also responsible for the improved thermal stability and flame retardancy of PP. Copyright © 2013 John Wiley & Sons, Ltd.
Co-reporter:Yichao Lin;Jun Zheng;Feng Liu
Journal of Polymer Science Part A: Polymer Chemistry 2013 Volume 51( Issue 7) pp:1664-1671
Publication Date(Web):
DOI:10.1002/pola.26540
Abstract
A series of graft (co)polymers were synthesized by nucleophilic substitution reaction between iodinated 1,2-polybutadiene (PB-I, backbone) and living polymer lithium (side chains). The coupling reaction between PB-I and living polymers can finish within minutes at room temperature, and high conversion (up to 92%) could be obtained by effectively avoiding side reaction of dimerization when living polymers were capped with 1,1-diphenylethylene. By virtue of living anionic polymerization, backbone length, side chain length, and side chain composition, as well as graft density, were well controlled. Tunable molecular weight of graft (co)polymers with narrow molecular weight distribution can be obtained by changing either the lengths of side chain and backbone, or the graft density. Graft copolymers could also be synthesized with side chains of multicomponent polymers, such as block polymer (polystyrene-b-polybutadiene) and even mixed polymers (polystyrene and polybutadiene) as hetero chains. Thus, based on living anionic polymerization, this work provides a facile way for modular synthesis of graft (co)polymers via nucleophilic substitution reaction between living polymers and polyhalohydrocarbon (PB-I). © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Co-reporter:Dong Wan, Li Ma, Haiping Xing, Lu Wang, Zhenjiang Zhang, Jian Qiu, Guangchun Zhang, Tao Tang
Polymer 2013 Volume 54(Issue 2) pp:639-651
Publication Date(Web):24 January 2013
DOI:10.1016/j.polymer.2012.12.014
Three different heteroaromatic ring derivatives (coagents) were used to adjust the melt radical reaction of polypropylene (PP). From the results of high temperature 1H NMR and high-temperature size-exclusion chromatography (HT-SEC), all the coagents could quickly convert the tertiary PP macroradicals into resonance stabilized macroradicals and effectively restrain the β-scission of PP macroradicals. Long chain branched structures, without significant bimodal distribution of molecular weight, could be introduced into coagents-functionalized PP samples. Effect of chemical structures of heteroaromatic rings and electron-attracting groups on the molecular structures and melt properties of modified PP samples was studied. The possible reactions of coagents-functionalized PP samples in different theoretical molar ratio of coagent to alkoxy radical were also proposed according to the results of 1H NMR, torque curves, rheological measurements and HT-SEC coupled with laser light scattering detector.
Co-reporter:Lu Wang, Hongfan Yang, Haiying Tan, Kun Yao, Jiang Gong, Dong Wan, Jian Qiu, Tao Tang
Polymer 2013 Volume 54(Issue 14) pp:3641-3653
Publication Date(Web):21 June 2013
DOI:10.1016/j.polymer.2013.05.024
Several polypropylene-g-polystyrene (PP-g-PS) and polypropylene-g-poly(n-butyl acrylate) (PP-g-PnBA) graft copolymers with well-defined molecular structures, basing on the same PP-Br precursor, were synthesized via a combination of metallocene-catalyzed polymerization and ATRP. The structure–property relationships of the resultant graft copolymers were systematically investigated. The crystallization temperatures of the obtained PP-g-PS and PP-g-PnBA graft copolymers decreased first and increased then with the enhancement of branch lengths. Compared to PP-Br, the introduction of PS or PnBA branches onto PP backbones both led to increased η0, more pronounced shear-thinning behavior, elevated value of G′ at low shear frequencies, and reduced loss angle. Under the same foaming conditions, the resulting PP-g-PS and PP-g-PnBA foams exhibited closed cell structure, increased cell density, and uniformized cell size distribution compared to the PP-Br foam. The cell density of PP-g-PS foam increased first and decreased then with the enhancement of branch length, and the cell size increased as the branch length increased. However, the cell density of the obtained three PP-g-PnBA foams was almost the same regardless of the PnBA branch length, and the cell size decreased first and increased then with increasing the branch length.
Co-reporter:Jun Zheng;Yichao Lin;Feng Liu;Haiying Tan;Yanhui Wang;Dr. Tao Tang
Chemistry - A European Journal 2013 Volume 19( Issue 2) pp:541-548
Publication Date(Web):
DOI:10.1002/chem.201202942
Abstract
Controlled chain-scission of polybutadiene (PB), polyisoprene, and poly(styrene-co-butadiene), induced by bis(cyclopentadienyl) zirconium hydrochloride (Cp2ZrHCl), was revealed at room temperature. The chain-scission reaction of linear PB was studied by means of GPC, NMR spectroscopy, and MALDI-TOF-MS. It was confirmed that the molecular weights of degraded products were quasi-quantitatively controlled by Cp2ZrHCl loading, irrespective of the starting PB, whereas the microstructure of PB chains was crucial to the scission reaction. The hydrozirconation of model molecules indicated that the existence of an internal double bond in compounds with multiple double bonds was essential for chain cleavage. The chain-cleavage mechanism was proposed to involve hydrozirconation of internal double bonds in PB chains and β-alkyl elimination. Furthermore, metallocene-catalyzed chain-scission by a chain-transfer reaction was developed. It is believed that the reported chain scission offers a promising pathway for end-group functionalization by chain cleavage and presents a new application of Schwartz’s reagent.
Co-reporter:Feng Liu;Hai-ying Tan 唐涛
Chinese Journal of Polymer Science 2013 Volume 31( Issue 12) pp:1647-1659
Publication Date(Web):2013 December
DOI:10.1007/s10118-013-1357-x
Copolymers of 1,3-butadiene and p-methylstyrene (p-MS) were synthesized via anionic polymerization. A benzophenone-potassium complex was added to tune the reactivity ratio of the two monomers, leading to random and gradient composition along the copolymer chain. The overall composition and microstructure could be controlled and well characterized by GPC and 1H-NMR. The p-MS was distributed from gradient to random with increasing the content of the benzophenone-potassium complex, and the 1,2-microstructure in the polybutadiene sequence increased at the same time. The hydrogenation of the copolymer of 1,3-butadiene and p-MS resulted in the corresponding saturated copolymer with welldefined structure and narrow molecular weight distribution.
Co-reporter:Xin Wen, Jiang Gong, Haiou Yu, Zhi Liu, Dong Wan, Jie Liu, Zhiwei Jiang and Tao Tang
Journal of Materials Chemistry A 2012 vol. 22(Issue 37) pp:19974-19980
Publication Date(Web):08 Aug 2012
DOI:10.1039/C2JM33689H
Catalyzing the carbonization of a polymer itself to form a protective carbonaceous layer has attracted tremendous interest in the flame retardancy of polymers, but the efficiency of this strategy was largely limited to polymers containing heteroatoms within their backbone. In this study, a novel type of combined catalyst, consisting of nanosized carbon black (CB) and Ni2O3, was found to efficiently catalyze the carbonization of poly(L-lactide) (PLA) for the first time. The combined catalyst was more efficient than CB or Ni2O3 alone to enhance the char yield of PLA and improve its char layer structure, which greatly improved the flame retardancy of PLA. The catalytic pyrolysis for PLA composites and model carbonization experiments for their degradation products were carried out to investigate the carbonization process of PLA during combustion. The results indicated that the carbonization mechanism was attributed to the combined effect of the combined catalysts: CB catalyzed the degradation of PLA to selectively produce more aldehydes and ketones with lower carbon numbers, then these carbonyl compounds were dehydrogenated (and/or dehydrated) and transferred into carbon products catalyzed by the combination of CB and Ni catalysts.
Co-reporter:Yujie Wang, Xin Wen, Dong Wan, Zhijie Zhang and Tao Tang
Journal of Materials Chemistry A 2012 vol. 22(Issue 9) pp:3930-3938
Publication Date(Web):25 Jan 2012
DOI:10.1039/C1JM14474J
An original and simple method for promoting mobility sensitivity of carbon nanotubes (CNTs) to an external stress field in polypropylene (PP) matrix was developed. In particular, an interfacial melt reaction initiated by free radicals were used as a tool to prepare PP/CNTs nanocomposites. The presence of tetrakis(phenylmethyl)thioperoxydi(carbothioamide) (TBzTD) increased the interfacial reaction between the PP chains and the CNTs. In addition, the grafted TBzTD to PP backbone could form a physical interaction with CNTs via a π–π interaction. In this case, the CNTs were not only well dispersed in the PP matrix during melt-mixing, but also the mobility of dispersed CNTs showed a strong responsive ability to the external stress field in the resultant nanocomposites. As a result, the orientation of CNTs was easily induced in the PP matrix under a weak stress field, such as mold pressing or injection molding. Further research showed that the strong mobility sensitivity of CNTs to an external stress field resulted from a synergistic effect of the physical interaction and chemical linking between CNTs and PP chains. As expected, the toughness of the PP/CNT nanocomposites was dramatically improved when compared with neat PP according to a notched Izod impact test, due to the strong sensitivity of the CNT mobility to an external stress field.
Co-reporter:Yan Liu, Jie Liu, Zhiwei Jiang, Tao Tang
Polymer Degradation and Stability 2012 Volume 97(Issue 3) pp:214-220
Publication Date(Web):March 2012
DOI:10.1016/j.polymdegradstab.2011.12.028
The combination of phenol and potassium hydroxide (KOH) was used to chemically recycle carbon fibre reinforced epoxy resin cured with 4,4′-diaminodiphenylmethane in subcritical water. This combination had a synergistic effect on decomposing this kind of epoxy resin. The main decomposition products from the epoxy resin were identified by means of GC–MS, and a possible free-radical reaction mechanism for the decomposition of epoxy resin is proposed. The recovered carbon fibres were characterized using single fibre tensile tests, scanning electron microscopy and X-ray photoelectron spectroscopy. Compared to virgin carbon fibres after sizing removal, the surface compositions of the recovered carbon fibres had little change and the tensile strength of the recovered carbon fibres was well retained.
Co-reporter:Xin Wen, Yujie Wang, Jiang Gong, Jie Liu, Nana Tian, Yanhui Wang, Zhiwei Jiang, Jian Qiu, Tao Tang
Polymer Degradation and Stability 2012 Volume 97(Issue 5) pp:793-801
Publication Date(Web):May 2012
DOI:10.1016/j.polymdegradstab.2012.01.031
Polypropylene/carbon black (PP/CB) nanocomposites were prepared by melt compounding to investigate the effect of nanofiller loadings on the thermal and flammability properties of PP. The obtained nanocomposites displayed not only dramatically enhanced thermal stability both under nitrogen and in air, but also improved flame retardancy to some extent. Moreover, the higher the loading level of CB, the better was the improved effect. This enhanced mechanism was attributed mainly to trapping of peroxy radicals by CB nanoparticles at elevated temperature to form a gelled-ball crosslinked network, which act as a barrier to both heat and mass transfer. The thermal-oxidation cross-linking reaction was supported by the results of rheological properties, gel measurements and FTIR analysis.
Co-reporter:Dong Wan, Li Ma, Zhenjiang Zhang, Haiping Xing, Lu Wang, Zhiwei Jiang, Guangchun Zhang, Tao Tang
Polymer Degradation and Stability 2012 Volume 97(Issue 1) pp:40-48
Publication Date(Web):January 2012
DOI:10.1016/j.polymdegradstab.2011.10.016
Heteroaromatic ring derivatives with the CC bond conjugated with different five-membered heteroaromatic rings were used to adjust melt reaction of polypropylene (PP). The effect of heteroatoms in the five-membered rings and electron-attracting groups connecting with CC bond on restricting the β-scission of PP macroradicals and promoting the branching reaction between PP and trimethylol propane triacrylate (TMPTA) was studied. From the analysis of the results concerning molecular structures and melt properties, it was found that the electron density of the CC bond determined the reaction rate between PP macroradicals and heteroaromatic ring derivatives. 2-cyano-3-(furan-2-yl)-2-propenoic acid ethyl ester (CFA) and 2-(furan-2-ylmethylene)malononitrile (FN) had CC bonds with lower electron density, therefore they can quickly convert the tertiary PP macroradicals into resonance stabilized macroradicals. As a result, the β-scission of PP macroradicals and the homopolymerisation of TMPTA were restrained to some extent. Modified PP samples containing TMPTA, peroxide and CFA (or FN), which had the lower grafting degree of TMTPA, showed the most obvious change on the relaxation behaviour of polymer chains.
Co-reporter:Yanjie An;Haiping Xing;Yanhui Wang
Journal of Applied Polymer Science 2012 Volume 125( Issue 4) pp:2724-2731
Publication Date(Web):
DOI:10.1002/app.36591
Abstract
Propylene/1-butene copolymer powders were produced through bulk copolymerization of propylene with 1-butene in a 12 m3 polymerization reactor. High melt strength polypropylene (HMSPP) was synthesized by in situ heat induction melt reaction, in which pure propylene/1-butene copolymer powders without any additives were used as a basic resin and trimethylolpropane triacrylate (TMPTA) as a crosslinking agent. The structure and properties of the resultant HMSPP were characterized by means of various measurements. The content of TMPTA strongly influenced the melt strength and melt flow rate (MFR) of HMSPP. With increasing the content of TMPTA, the melt strength of HMSPP increased, and the MFR reduced. In addition, owing to the existence of crosslinking structure, thermal stability and tensile strength of HMSPP were improved compared with pristine propylene/1-butene copolymer. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Haiping Xing, Zhiwei Jiang, Zhenjiang Zhang, Jian Qiu, Yanhui Wang, Li Ma, Tao Tang
Polymer 2012 Volume 53(Issue 4) pp:947-955
Publication Date(Web):17 February 2012
DOI:10.1016/j.polymer.2012.01.004
Co-reporter:Zhenjiang Zhang, Dong Wan, Haiping Xing, Zhijie Zhang, Haiying Tan, Lu Wang, Jun Zheng, Yanjie An, Tao Tang
Polymer 2012 Volume 53(Issue 1) pp:121-129
Publication Date(Web):5 January 2012
DOI:10.1016/j.polymer.2011.11.033
A grafting monomer (p-(3-butenyl)styrene, BS)) containing two carbon–carbon double-bonds with different reactivity was used in melt radical reaction to prepare long chain branched polypropylene (LCB-PP). High-temperature size-exclusion (HT-SEC) coupled with triple detectors, rheometer and NMR were used to characterize the microstructure of the resultant LCB-PP. BS showed double functions in mediating radical reaction, i.e. stabilizing macroradicals and promoting branching reaction. Compared to styrene and divinylbenzene, using BS as a grafting monomer led to the formation of more uniformly distributed LCB structure on the PP backbone. Thus the resultant sample showed strain hardening in extensional flow and had high melt strength.
Co-reporter:Jun Zheng, Feng Liu, Yichao Lin, Zhijie Zhang, Guangchun Zhang, Lu Wang, Yan Liu, and Tao Tang
Macromolecules 2012 Volume 45(Issue 3) pp:1190-1197
Publication Date(Web):January 24, 2012
DOI:10.1021/ma202628p
For the first time, hydrozirconation and halogenolysis of 1,2-polybutadiene (1,2-PBD, by living anionic polymerization) were studied to synthesize reactive polyhalohydrocarbons, which provide a platform for preparing well-defined functional polymers via macromolecular substitution. Hydrozirconation and halogenolysis afforded quite convenience for anti-Markovnikov hydrohalogenation of 1,2-PBD with controllable degree of functionalization. Diverse functional polymers and branched polymers were synthesized after macromolecular substitution reaction with a broad range of commercially available nucleophiles (amines, phenols, alcohols, carbanions, carboxylates, and azide) or macromolecular nucleophiles. NMR and GPC characterizations confirmed high conversion in substitution reaction and narrow molecular weight distribution of the resultant functional polymers, respectively. The methodology utilizing Schwartz’s reagent for hydrozirconation of macromolecules could greatly facilitate the modification of vinyl groups containing polymers with high efficiency.
Co-reporter:Dong Wan;Yujie Wang;Xin Wen;Jian Qiu;Zhiwei Jiang;Haiying Tan
Polymer Engineering & Science 2012 Volume 52( Issue 7) pp:1457-1463
Publication Date(Web):
DOI:10.1002/pen.23091
Abstract
Polypropylene (PP)/C60 nanocomposites with improved interfacial interaction were prepared via in situ melt radical reaction. It was found that the relaxation time of PP/C60 nanocomposites containing peroxide increased due to the reaction between C60 and PP macroradicals and the formation of long chain branched or crosslinking structure. Thermogravimetric analysis (TGA) results showed that the thermal stability of PP/C60 nanocomposites was enhanced. The initial decomposition temperatures and activation energy of PP/C60 nancomposites were strongly influenced by the content of unreacted C60. Because of the improved interfacial interaction, PP/C60 nanocomposites containing peroxide showed obvious increase in tensile strength, Young' modulus, flexural strength, flexural modulus, and impact strength, compared to PP/C60 nanocomposites (without peroxide) containing the same content of C60. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers
Co-reporter:Lu Wang, Dong Wan, Jian Qiu, Tao Tang
Polymer 2012 Volume 53(Issue 21) pp:4737-4757
Publication Date(Web):28 September 2012
DOI:10.1016/j.polymer.2012.08.036
A series of polypropylene-g-poly(ethylene-co-1-butene) graft copolymers (PP-g-EBR) with well-defined long chain branched (LCB) molecular structures, basing on the same PP–BT precursor (PP–BT2), were used to study effects of EBR LCBs on the crystallization and foaming behaviors of PP-g-EBRs. The kinetics results of isothermal and nonisothermal crystallization verify the opposite effects of LCB structure on the crystallization process of PP backbones in PP-g-EBRs: on one hand, the indolent LCB structure can perform the function of heterogeneous nucleation to facilitate the crystallization; on the other hand, the mobility and reptation ability of PP backbones are restrained by the LCB structure, which hinders the crystallization process. Additionally, the fluctuation-assisted nucleation mechanism caused by microphase separation between the EBR rich phase and the PP rich phase may account, to some extent, for the heterogeneous nucleation effect. The PP–BT2 and PP-g-EBRs were foamed by a batch method under the same conditions, using supercritical CO2 as blowing agent. The resulting PP-g-EBR foams exhibited closed cell structure and increased cell density compared to the PP–BT2 foam, attributing to the enhanced melt strength. The cell density of PP-g-EBR foam increased first and decreased then with the LCB level increasing. The influence of LCB level on cell size was somewhat complex. Increasing LCB level, which promoted melt strength and strain hardening behavior of PP-g-EBRs, decreased the cell size and narrowed the cell size distribution. However, large cells were observed in PP-g-EBR foams with relatively high LCB level, which could be ascribed to the larger growing space introduced by the higher content of amorphous EBR LCBs. Moreover, the melting behaviors of PP–BT2 and PP-g-EBRs before and after foaming treatment were compared.Graphical abstract
Co-reporter:Dong Wan, Zhenjiang Zhang, Yujie Wang, Haiping Xing, Zhiwei Jiang and Tao Tang
Soft Matter 2011 vol. 7(Issue 11) pp:5290-5299
Publication Date(Web):19 Apr 2011
DOI:10.1039/C0SM01457E
Polypropylene (PP)/fullerene C60 nanocomposites, in which the interfacial reaction between two components was in situ mediated by peroxide, were prepared by a melt mixing method. Structural characterization showed that the interfacial reaction strongly affected the microstructures of PP/C60 nanocomposites at different scales, such as improving the dispersion state of C60 nanoparticles and forming long chain branched structures in which C60 acts as a branching point. This was ascribed to the ability of C60 (as a reactive nanoparticle) for preferentially trapping carbon-centred macroradicals of PP to in situ form long chain branched structures of PP on the surface of C60 during melt mixing. As a result, the shear-responsive sensitivity of the nanocomposite melts in low shear frequency regions was dramatically enhanced compared to parent PP and the nanocomposites without interfacial reaction. The nanocomposites also showed high melt strength. In addition, the transition from the melt state to solid state (crystallization process) occurred at higher temperature after the interfacial reaction between PP and C60 took place.
Co-reporter:Zhenjiang Zhang, Dong Wan, Yanjie An, Feng Liu, Haiping Xing, Lu Wang, Zhiwei Jiang, Tao Tang
Polymer Degradation and Stability 2011 Volume 96(Issue 4) pp:653-659
Publication Date(Web):April 2011
DOI:10.1016/j.polymdegradstab.2010.12.010
The effects of zinc dithiocarbamates on degradation and branching of polypropylene (PP) were studied during melt radical modification using a tri-functional monomer (trimethylol propane triacrylate (TMPTA)). High-temperature size-exclusion chromatography (HT-SEC) coupled with differential refractive index detector (DRI), light scattering detector (LSD) and viscometer detector (VD) and rotational rheometry were used to analyse the microstructure of modified PP samples. The chemical structure of the N-substituted group showed an important influence in controlling the evolution of PP microstructure during melt radical reaction. The chain cleavage of PP was controlled in the presence of zinc N, N-dimethyldithiocarbamate (ZDMC), and a substantial long chain branched (LCB) fraction was formed. Without co-agent, the molecular weight of PP decreased measurably, and only a minor LCB fraction was formed. Importantly, considerable amounts of highly branched (microgel and hyperbranched) structures were formed in this case.
Co-reporter:Jie Liu, Zhiwei Jiang, Haiou Yu, Tao Tang
Polymer Degradation and Stability 2011 Volume 96(Issue 10) pp:1711-1719
Publication Date(Web):October 2011
DOI:10.1016/j.polymdegradstab.2011.08.008
A two-stage reaction process was used to convert polypropylene (PP) into multi-walled carbon nanotubes (MWCNTs) and hydrogen-rich gas. The proposed process consisted of two stages: catalytic pyrolysis of PP over HZSM-5 zeolite in a screw kiln reactor and the subsequent catalytic decomposition of pyrolysis gases over a nickel catalysts in a moving-bed reactor for producing MWCNTs and hydrogen. The resultant gas mainly consisted of hydrogen and methane. SEM and TEM images revealed that carbon products in the moving-bed reactor were in the form of MWCNTs. XRD and TGA characterization indicated that high decomposition temperature resulted in the formation of more highly crystalline nanotubes. The influence of pyrolysis temperature (550–750 °C) and decomposition temperature (500–800 °C) on the performances of the two-stage reaction system were investigated. The MWCNT yield and hydrogen concentration increased with an increase in the decomposition temperature and reached a maximum at 700 °C. With increasing pyrolysis temperature the yield of pyrolysis gas increased while the liquid yield decreased. The yield of MWCNTs in the moving-bed reactor was determined by both the quantity and quality of the pyrolysis gas.
Co-reporter:Haiou Yu, Jie Liu, Xin Wen, Zhiwei Jiang, Yujie Wang, Lu Wang, Jun Zheng, Shaoyun Fu, Tao Tang
Polymer 2011 Volume 52(Issue 21) pp:4891-4898
Publication Date(Web):29 September 2011
DOI:10.1016/j.polymer.2011.08.013
Molybdenum-phenolic resin (Mo-PR) was grafted onto the surface of multi-walled carbon nanotubes (MWCNTs) to obtain modified MWCNTs (CNT-PR). Compared to epoxy resin, epoxy resin/CNT-PR nanocomposites showed the improvements in flame retardancy and mechanical properties. Structural characterization showed that the grafted Mo-PR improved the dispersion of MWCNTs in epoxy resin and enhanced the interfacial interaction between CNT-PR and epoxy resin. On the other hand, the grafted Mo-PR could show high char yield during the process of combustion. Thus the flame retardancy of nanocomposites was improved, especially for the heat release rate and total smoke production. Furthermore, the combination of CNT-PR with melamine dramatically promoted the LOI value and the level of UL-94 rating.
Co-reporter:Lu Wang, Dong Wan, Zhenjiang Zhang, Feng Liu, Haiping Xing, Yanhui Wang, and Tao Tang
Macromolecules 2011 Volume 44(Issue 11) pp:4167-4179
Publication Date(Web):May 9, 2011
DOI:10.1021/ma200604y
A series of polypropylene-g-poly(ethylene-co-1-butene) (PP-g-EBR) graft copolymers with well-defined long chain branched (LCB) molecular structures were synthesized via the combination of coordination polymerization and anionic polymerization. The structure–property relationships of PP-g-EBR were systematically investigated. The structural information was clarified by characterization of 1H NMR and SEC equipped with triple detectors. The DMA measurements demonstrated that the amorphous EBR branches were miscible with the PP backbones. The melt behavior of the PP-g-EBRs was studied with small-amplitude dynamic rheological measurements. Increasing branch length and branch density both led to increased zero-shear viscosity, more pronounced shear-thinning behavior, elevated value of storage modulus at low shear frequencies, more significant upshift deviation from linear behavior in the Han plot, and reduced loss angle. Comparatively, branch length contributed more to the improvement of rheological properties than branch density did. Interestingly, DSC results showed that the crystallization temperature of PP-g-EBR increased with the enhancement of branch length and branch density; however, when the LCB level exceeded a certain degree, further increasing the LCB level would reduce the crystallization temperature.
Co-reporter:Xiaohua Du, Haiou Yu, Zhe Wang, Tao Tang
Polymer Degradation and Stability 2010 Volume 95(Issue 4) pp:587-592
Publication Date(Web):April 2010
DOI:10.1016/j.polymdegradstab.2009.12.009
Two organoclays, octadecylammonium modified montmorillonite (COM) and an anionic surfactant modified montmorillonite (AOM), were used to prepare acrylonitrile–butadiene–styrene (ABS)/clay composites. The flammability of these composites was evaluated by cone calorimetry. COM enhanced the flame retardancy of ABS/COM composite due to the catalysis by acidic sites originating from COM. Interestingly, AOM presented a similar flame retardancy to ABS/AOM composite, although AOM did not form the acidic sites. The morphology observation showed that the dispersion degree of AOM in ABS resin was lower than that of COM, which was also confirmed by the rheological properties of ABS composites. The investigations on the surface of the residue after cone calorimeter tests showed that the better flame retardancy of ABS/AOM composite was mainly due to the special structure of AOM.
Co-reporter:Shiyun Li;Hui Chen;Dongmei Cui;Jianzhong Li;Zhenjiang Zhang;Yanhui Wang
Polymer Composites 2010 Volume 31( Issue 3) pp:507-515
Publication Date(Web):
DOI:10.1002/pc.20831
Abstract
Multi-walled carbon nanotubes (MWCNTs)/polyethylene (PE) nanocomposites were prepared via in situ polymerization with MWCNTs supported Bis- (cyclopentadienyl) zirconium dichloride (Cp2ZrCl2) catalyst. X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope (FESEM) results implied that Cp2ZrCl2 catalyst was immobilized in the surface of the MWCNTs supports via a bridge of methylaluminoxane (MAO). The efficient dispersion of MWCNTs in PE matrix and the strong compressive forces associated with PE on the MWCNTs were demonstrated by means of transmission electron microscope (TEM), FESEM and Raman spectra. With introducing 0.2 wt% MWCNTs, both the tensile strength and elongation of MWCNTs/PE nanocomposite were improved by factors of 1.6 (from 29 to 45 MPa) and 1.5 (from 909% to 1360%) comparing with the pure PE, respectively. Morphology observation of fractured surface revealed that the PE firmly adhered to the nanotubes, which was responsible for the significant improvement of the mechanical properties of nanocomposites. Thermal stabilities of the nanocomposites were significantly improved. In addition, the MWCNTs/PE nanocomposites showed very high ultraviolet (UV) shielding property, which could increase photooxidative stability of the PE. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Co-reporter:Xiaohua Du;Zhenjiang Zhang;Haiou Yu;Dong Wan;Haiping Xing
Journal of Applied Polymer Science 2010 Volume 115( Issue 2) pp:1105-1112
Publication Date(Web):
DOI:10.1002/app.31143
Abstract
A covalently functionalized organoclay was synthesized successfully through a condensation reaction of SiOH groups on the edge of montmorillonite (MMT) with acryloyl chloride followed by modification with hexadecyltrimethylammonium bromide (CTAB) via an ion-exchange reaction. Fourier transform infrared confirmed that CC groups had been grafted to MMT sheets. Wide-angle X-ray diffraction measurements showed that CTAB had intercalated into MMT interlayers. The content of bonded acryloyl chloride was 2.42 wt % in the functionalized organoclay according to thermogravimetric analysis. Polypropylene (PP) nanocomposites were prepared by melt mixing. Rheological measurements and morphology observations confirmed that PP nanocomposites containing the organoclay bearing CC groups exhibited improved interfacial interaction between PP chains and MMT sheets. Thus, the PP nanocomposites showed not only higher storage modulus and complex viscosity values at low frequencies but also enhanced mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Yanjie An;Zhenjiang Zhang;Yanhui Wang;Jian Qiu
Journal of Applied Polymer Science 2010 Volume 116( Issue 3) pp:1739-1746
Publication Date(Web):
DOI:10.1002/app.31610
Abstract
High melt strength polypropylene (HMSPP) was prepared by in situ heat induction reaction, in which pure polypropylene (PP) powders without any additives was used as basic resin, and low density polyethylene (LDPE) and trimethylolpropane triacrylate (TMPTA) were added as blending resin and as crosslinking agent, respectively. Microstructure of the obtained HMSPP (PP/LDPE/TMPTA blends) was characterized by FTIR, Wide-angle X-ray diffraction (WAXD), and testing of gel content. The effect of LDPE content on melt strength and melt flow rate of HMSPP were investigated. When the content of LDPE was 40 wt %, the melt strength of the HMSPP was above 16 CN, which was much higher than those of pure PP powder (2.6 CN) and PP/LDPE blends without TMPTA (6.1 CN). Moreover, thermal behavior and mechanical properties of the HMSPP were also investigated. The results showed that the thermal stability and impact strength of HMSPP were greatly improved. In addition, HMSPP possessed good processing performance and good foaming properties. The foams produced by HMSPP showed uniform, closed, and independent cells. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Changyi Ren;Xiaohua Du;Li Ma;Yanhui Wang
Journal of Applied Polymer Science 2010 Volume 117( Issue 3) pp:1646-1657
Publication Date(Web):
DOI:10.1002/app.32040
Abstract
Effect of polymerizable montmorillonites (P-MMTs) on the morphology of polyethylene/montmorillonites (PE/MMTs) nanocomposites during filling polymerization was studied. The microstructure analysis showed that the P-MMTs were more exfoliatable than nonpolymerizable MMTs in the preparation of PE/MMTs nanocomposites. By examining the influence of the polymerization condition on the microstructure of the resultant nanocomposites, it was confirmed that the shear force formed by the mechanical stirring was the driving force of the exfoliation dispersion of MMT sheets during the filling polymerization. Comparatively, the shear force on MMT sheets might be increased due to strong interaction between PE chains linked to the surface of P-MMTs and the solvents molecules, which is the reason that polymerizable clay is more exfoliatable than nonpolymerizable clay. The copolymerization between polymerizable modifier and ethylene was confirmed by NMR measurements. Furthermore, the morphology of the resultant nanocomposites was influenced by the concentration of the dispersed P-MMTs. The degree of exfoliation of the resultant nanocomposites at a relatively low concentration was higher than that at a high concentration. This is because of the multiscale organization of the organoclay dispersed in the organic medium. High exfoliation degree of MMTs and improved interaction between PE matrix and P-MMTs in PE/P-MMTs nanocomposites led to significant improvements in mechanical properties and barrier properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Wen-xi Cheng 唐涛
Chinese Journal of Polymer Science 2010 Volume 28( Issue 1) pp:
Publication Date(Web):2010 January
DOI:10.1007/s10118-010-8204-0
Mesoporous silica (MS), 3-aminopropyltriethoxysilane (APTES) modified mesoporous silica (AMS), bis(3-trimethoxysilylpropyl)amine modified mesoporous silica (BAMS) and APTES modified solid spherical silica (AS) were prepared and used to immobilize metallocene catalysts for ethylene polymerization. Gel permeation chromatography results showed that polyethylenes (PEs) catalyzed by AMS (or BAMS) supported metallocene catalysts at the molar ratios of Al/Zr = 100, 300 and 500 were of bimodal molecular weight distribution (BMWD); while PEs catalyzed by the above catalysts at the molar ratios of Al/Zr ≥ 800 were of monomodal molecular weight distribution (MMWD). However, MS (or AS) supported metallocene catalysts could only produce PEs with MMWD in spite of the molar ratio of Al/Zr. It was because that AMS (or BAMS) supported catalysts possessed two active sites for ethylene polymerization at low molar ratios of Al/Zr due to the combination effects of mesopore geometrical constraint and amino groups of the supports, which was confirmed by X-ray photoelectron spectroscopy. This brings forward a novel and easy method for the synthesis of polyolefin with BMWD.
Co-reporter:Haiou Yu, Zhenjiang Zhang, Zhe Wang, Zhiwei Jiang, Jie Liu, Lu Wang, Dong Wan and Tao Tang
The Journal of Physical Chemistry C 2010 Volume 114(Issue 31) pp:13226-13233
Publication Date(Web):July 16, 2010
DOI:10.1021/jp104216r
Chlorinated carbon nanotubes (CNT-Cl) and its combination with Ni2O3 were used to prepare polypropylene (PP) composites via melt mixing. The cone calorimetry and TGA results showed that both the flame retardancy and the thermal stability of the composites containing CNT-Cl were better than the samples containing unchlorinated CNTs. NMR measurements confirmed that CNT-Cl could react with the double bond of degradation products at high temperature. Furthermore, the role of CNT-Cl in the combination between CNT-Cl and Ni2O3 was investigated by carbonization experiments and rheology measurements. The results demonstrated that CNT-Cl could significantly promote the carbonization of degradation products of PP catalyzed by nickel catalyst during combustion. In contrast, the combination between unchlorinated CNTs and Ni2O3 could not promote the carbonization of degradation products of PP compared to the case containing Ni2O3 alone. This was attributed to Cl radicals releasing from CNT-Cl, which worked as a catalyst to accelerate dehydrogenation−aromatization of degradation products of PP and promoted the carbonization of degradation products catalyzed by nickel catalyst.
Co-reporter:Zhenjiang Zhang, Haiping Xing, Jian Qiu, Zhiwei Jiang, Haiou Yu, Xiaohua Du, Yanhui Wang, Li Ma, Tao Tang
Polymer 2010 Volume 51(Issue 7) pp:1593-1598
Publication Date(Web):24 March 2010
DOI:10.1016/j.polymer.2010.01.063
Effect of copper N,N-dimethyldithiocarbamate (CDD) on melt reactions during preparing long chain branched polypropylenes (LCB-PP) via free radical grafting was studied. The structure and rheological properties of the modified PPs were characterized. The results showed that CDD could efficiently control two side reactions, i.e. degradation of PP backbone and homopolymerization of multifunctional monomer (trimethylol propane triacrylate (TMPTA)) in the presence of peroxide. Meanwhile the addition of CDD also increased the efficiency of forming LCB structure. The reaction between CDD and active free radicals (carbon centered and alkoxy species) led to forming in situ dithiocarbamate radicals, which cannot attack PP backbone and are weaker initiator for TMPTA. The resultant dithiocarbamate radicals could react with the PP macroradicals and the acrylic radicals reversibly, which prolong the life time of PP macroradical and increase the reaction probability between macroradicals. The obtained LCB-PP showed high melt strength.
Co-reporter:Changyi Ren, Xiaohua Du, Li Ma, Yanhui Wang, Jun Zheng, Tao Tang
Polymer 2010 Volume 51(Issue 15) pp:3416-3424
Publication Date(Web):8 July 2010
DOI:10.1016/j.polymer.2010.05.041
A new type of multifunctional ammonium modifier with carbonyl group and vinyl group was synthesized to prepare multifunctional montmorillonites (F-MMTs), which were used as multifunctional catalyst supports for in situ ethylene polymerization. High loading of metallocene catalyst in the galleries of F-MMT had been achieved due to the presence of carbonyl group in the multifunctional modifier. XRD profiles and TEM images showed that polyethylene/montmorillonite (PE/F-MMT) nanocomposites with exfoliated structure could be synthesized using the intercalated catalyst described above, even when the content of MMT was very high (more than 15.1 wt%). The as-produced PE/F-MMTs nanocomposites were composed of flower-like particles with a diameter of about 5 μm. A thermal stable monoclinic phase was observed in PE/F-MMT nanocomposites. Comparatively, the resultant PE/F-MMT nanocomposites showed low gas permeability. Interfacial interaction between PE matrix and F-MMT was enhanced due to the chemical linking between the two components via copolymerization of ethylene with vinyl group of F-MMT. Thus the resultant PE/F-MMT nanocomposites showed good structural stability.
Co-reporter:Xiaoyu Meng;Zhe Wang;Xiaohua Du;Yanhui Wang
Journal of Applied Polymer Science 2009 Volume 113( Issue 1) pp:678-684
Publication Date(Web):
DOI:10.1002/app.29964
Abstract
This work is focused on the factors influencing the intercalation of maleated polypropylene (PPMA) into organically modified montmorillonite (OMMT). Two kinds of PPMA were used to explore the optimal candidate for effective intercalation into OMMT. The grafting degree of maleic anhydride and the viscosity of PPMA have effects on the diffusion of polymer molecules. Moreover, the loading level of surfactant was varied to optimize the modification of montmorillonite because the appropriate loading level can provide a balance between interlayer distance and steric hindrance. The kind of surfactant changes the interaction between OMMT and PPMA, and accordingly the intercalation of PPMA is different, resulting in the discrepancy of the intercalation of PPMA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Changyi Ren, Zhiyong Jiang, Xiaohua Du, Yongfeng Men and Tao Tang
The Journal of Physical Chemistry B 2009 Volume 113(Issue 43) pp:14118-14127
Publication Date(Web):September 29, 2009
DOI:10.1021/jp9063164
Deformation behavior of polyethylene/modified montmorillonites with polymerizable surfactant (PE/P-MMT) nanocomposite with strong interfacial interaction was studied by means of morphology observation and X-ray scattering measurements. The orientation of PE chains was accompanied by the orientation of well-dispersed MMT platelets due to the presence of strong interfacial interaction, and both of the orientations were parallel to the deformation direction. The high degree of orientation of MMT platelets and PE chains resulted from the synergistic movement of PE matrix and MMTs, which originated from the presence of a network-like structure. Meanwhile, the existence of MMT platelets with good mobility during deformation and strong interfacial interaction with PE matrix could further improve the break energy of material by restraining the initiation and growth of cavities during deformation. In contrast, PE/MMT nanocomposite with no strong interfacial interaction and poor dispersed state of MMT sheets showed the weaker orientation of both PE chains and MMT platelets, and a strong cavitation during deformation.
Co-reporter:Zhe Wang, Xiaoyu Meng, Jianzhong Li, Xiaohua Du, Shiyun Li, Zhiwei Jiang and Tao Tang
The Journal of Physical Chemistry C 2009 Volume 113(Issue 19) pp:8058-8064
Publication Date(Web):2017-2-22
DOI:10.1021/jp811260p
A simple novel method for preparing multiwalled carbon nanotubes/montmorillonite (MWNTs/MMT) hybrids has been established through mixing pristine MWNTs in MMT aqueous dispersion. The principle of this method is based on the formation of stable dispersion containing both MWNTs and MMT in water, which results from strong interaction between MWNTs and MMT platelets. Sedimentation experiments, measurements of ζ potential, and Raman spectra have been used to confirm the presence of strong interaction between MWNTs and MMT sheets. The morphology observation for the dried MWNTs/MMT hybrids shows that the obtained hybrids are homogeneous, in which MWNTs exist as the state of single nanotubes that are absorbed on the surface and edge of MMT sheets. In addition, poly(ethylene oxide) (PEO) nanocomposites containing both MWNTs and MMTs are prepared by using this method. An obvious synergistic effect of MMT sheets and MWNTs in improving mechanical properties of PEO matrix has been observed.
Co-reporter:Haiou Yu, Jie Liu, Zhe Wang, Zhiwei Jiang and Tao Tang
The Journal of Physical Chemistry C 2009 Volume 113(Issue 30) pp:13092-13097
Publication Date(Web):July 6, 2009
DOI:10.1021/jp902081e
Effects of multiwalled carbon nanotubes (MWCNTs) and Ni2O3 on the flame retardancy of linear low density polyethylene (LLDPE) have been studied. A combination of MWCNTs and Ni2O3 showed a synergistic effect in improving the flame retardancy of LLDPE compared with LLDPE composites containing MWCNTs or Ni2O3 alone. As a result, the peak value of heat release rate measured by cone calorimeter was obviously decreased in the LLDPE/MWCNTs/Ni2O3 composites. According to the results from rheological tests, carbonization experiments, and structural characterization of residual char, the improved flame retardancy was partially attributed to the formation of a networklike structure due to the good dispersion of MWCNTs in LLDPE matrix, and partially to the carbonization of degradation products of LLDPE catalyzed by Ni catalyst originated from Ni2O3. More importantly, both viscoelastic characteristics and catalytic carbonization behavior of LLDPE/MWCNTs/Ni2O3 composites acted in concert to result in a synergistic effect in improving the flame retardancy. Although both MWCNTs and Ni2O3 were not organically modified, LLDPE composites incorporating both the fillers showed higher mechanical properties compared with those of pure LLDPE.
Co-reporter:Haiou Yu, Zhiwei Jiang, Jeffrey W. Gilman, Takashi Kashiwagi, Jie Liu, Rongjun Song, Tao Tang
Polymer 2009 50(26) pp: 6252-6258
Publication Date(Web):
DOI:10.1016/j.polymer.2009.10.068
Co-reporter:Zhe Wang, Xiaohua Du, Haiou Yu, Zhiwei Jiang, Jie Liu, Tao Tang
Polymer 2009 50(24) pp: 5794-5802
Publication Date(Web):
DOI:10.1016/j.polymer.2009.09.077
Co-reporter:Xiaoyu Meng, Zhe Wang, Haiou Yu, Xiaohua Du, Shiyun Li, Yanhui Wang, Zhiwei Jiang, Qiaoyi Wang, Tao Tang
Polymer 2009 50(16) pp: 3997-4006
Publication Date(Web):
DOI:10.1016/j.polymer.2009.06.042
Co-reporter:Rongjun Song;Zhiwei Jiang;Haiou Yu;Jie Liu;Zhijun Zhang;Qingwen Wang
Macromolecular Rapid Communications 2008 Volume 29( Issue 10) pp:789-793
Publication Date(Web):
DOI:10.1002/marc.200800088
Co-reporter:Xiaoyu Meng, Xiaohua Du, Zhe Wang, Wuguo Bi, Tao Tang
Composites Science and Technology 2008 Volume 68(7–8) pp:1815-1821
Publication Date(Web):June 2008
DOI:10.1016/j.compscitech.2008.01.012
Cloisite 30B (30B) was melt-mixed with two kinds of thermoplastic polyurethane (TPU) with different molecular weights to discern the roles of molecular diffusion and shear in the exfoliation process. The higher level of exfoliation was achieved in TPU matrix with higher molecular weight due to the appropriate viscosity. In order to have an insight into the mechanism of exfoliation, the degree of dispersion and exfoliation of 30B was characterized by wide angle X-ray diffraction and transmission electron microscopy. The layers of 30B were exfoliated via a slippage process, which was also observed in polyamide 12 nanocomposites recently. Shear played a dominating role in the process of exfoliation. The effect of morphology on rheological and mechanical properties was investigated, thus improving our understanding of TPU nanocomposites processing and optimization.
Co-reporter:Yanjie An;Zhenjiang Zhang;Wuguo Bi;Yanhui Wang
Journal of Applied Polymer Science 2008 Volume 110( Issue 6) pp:3727-3732
Publication Date(Web):
DOI:10.1002/app.28975
Abstract
High melt strength polypropylene (HMSPP) was synthesized by in situ heat induction reaction, in which pure polypropylene (PP) powders without any additives were used as a basic resin and vinyl trimethoxysilane (VTMS) as a grafting and crosslinking agent. The grafting reaction of VTMS with PP was confirmed by FTIR. The structure and properties of HMSPP were characterized by means of various measurements. The content of grafted silane played a key role on the melt strength and melt flow rate (MFR) of HMSPP. With increasing the content of grafted silane, the melt strength of HMSPP increased, and the MFR reduced. In addition, due to the existence of crosslinking structure, the thermal stability and tensile strength of HMSPP were improved compared with PP. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Jianzhong Li;Min Li;Shiyun Li;Liya Shi;Changyi Ren;Dongmei Cui;Yanhui Wang
Journal of Polymer Science Part A: Polymer Chemistry 2008 Volume 46( Issue 4) pp:1240-1248
Publication Date(Web):
DOI:10.1002/pola.22465
Abstract
A novel catalyst system based on nickel(II) tetraphenylporphyrin (Ni(II)TPP) and methylaluminoxane for styrene polymerization was developed. This catalyst system has a high thermal stability and show fairly good activity. The obtained polystyrene (PS) was isotactic-rich atactic polymer by 13C NMR analysis, and its molecular weight distribution was rather narrow (Mw/Mn ≈ 1.6, by GPC analysis). ESR revealed that Ni(II)TPP π cation radicals were formed in the polymerization and could remain in the resulting PS stably. The mechanism of the polymerization was discussed and a special coordination mechanism was proposed. The PS product containing Ni(II)TPP π cation radicals can be used as a potential functional material. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1240–1248, 2008
Co-reporter:Zhiwei Jiang, Rongjun Song, Wuguo Bi, Jun Lu, Tao Tang
Carbon 2007 Volume 45(Issue 2) pp:449-458
Publication Date(Web):February 2007
DOI:10.1016/j.carbon.2006.08.012
Multi-walled carbon nanotubes (MWCNTs) were efficiently synthesized by catalytic combustion of polypropylene (PP) using nickel compounds (such as Ni2O3, NiO, Ni(OH)2 and NiCO3 · 2Ni(OH)2) as catalysts in the presence of organic-modified montmorillonite (OMMT) at 630–830 °C. Morphologies of the sample undergoing different combustion times were observed to investigate actual process producing MWCNTs by this method. The obtained MWCNTs were characterized by X-ray diffraction (XRD), transmission electron microscope and Raman spectroscopy. The yield of MWCNTs was affected by the composition of PP mixtures with OMMT and nickel compounds and the combustion temperature. The proton acidic sites from the degraded OMMT layers due to the Hoffman reaction of the modifiers at high temperature played an important role in the catalytic degradation of PP to supply carbon sources that are easy to be catalyzed by nickel catalyst for the growth of MWCNTs. The XRD measurements demonstrated that the nickel compounds were in situ reduced into the Ni(0) state with the aid of hydrogen gas and/or hydrocarbons in the degradation products of PP, and the Ni(0) was really the active site for the growth of MWCNTs. The combination of nickel compounds with OMMT was a key factor to efficiently synthesize MWCNTs via catalytic combustion of PP.
Co-reporter:Wenxi Cheng, Zhe Wang, Changyi Ren, Hui Chen, Tao Tang
Materials Letters 2007 Volume 61(14–15) pp:3193-3196
Publication Date(Web):June 2007
DOI:10.1016/j.matlet.2006.11.022
SiO2/polyacrylamide (PAM) composite was prepared via the polymerization of acrylamide in the presence of silica sol in water/hexane emulsion, and pure SiO2 was also prepared without the use of acrylamide in the same way. Field emission scanning electron micrographs (FESEM) showed that PAM covered the silica nanoparticles to form SiO2/PAM nanospheres, which loosely agglomerated to form SiO2/PAM secondary particles, while SiO2 secondary particles were made up of tightly agglomerated silica nanoparticles. Metallocene catalyst was then immobilized over SiO2 and SiO2/PAM respectively to prepare supported metallocene catalyst for ethylene polymerization. Transmission electron micrographs (TEM) showed that support particles broke up to smaller particles and even nanoparticles in polyethylene (PE) matrix when the support particles were the fragile SiO2/PAM secondary particles, which shows a novel way to prepare silica/polyacrylamide/polyethylene nanocomposite.
Co-reporter:Rongjun Song;Zhe Wang;Baoyan Zhang;Xiaoyu Meng
Journal of Applied Polymer Science 2007 Volume 106(Issue 5) pp:3488-3494
Publication Date(Web):22 AUG 2007
DOI:10.1002/app.27033
The degradation and flame retardancy of polypropylene/organically modified montmorillonite (PP/OMMT) nanocomposite were studied by means of gas chromatography-mass spectrometry and cone calorimeter. The catalysis of hydrogen proton containing montmorillonite (H-MMT) derived from thermal decomposition of (alkyl) ammonium in the OMMT on degradation of PP strongly influence carbonization behavior of PP and then flame retardancy. Brønsted acid sites on the H-MMT could catalyze degradation reaction of PP via cationic mechanism, which leads to the formation of char during combustion of PP via hydride transfer reaction. A continuous carbonaceous MMT-rich char on the surface of the burned residues, which work as a protective barrier to heat and mass transfer, results from the homogeneous dispersion of OMMT in the PP matrix and appropriate char produced. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:Liya Shi;Wuguo Bi;Hui Chen
Journal of Polymer Science Part A: Polymer Chemistry 2007 Volume 45(Issue 19) pp:4477-4486
Publication Date(Web):17 AUG 2007
DOI:10.1002/pola.22218
The bifunctional comonomer 4-(3-butenyl) styrene was used to synthesize crosslinked polystyrene microspheres (c-PS) with pendant butenyl groups on their surface via suspension copolymerization. Polyethylene chains were grafted onto the surface of c-PS microspheres (PS-g-PE) via ethylene copolymerizing with the pendant butenyl group on the surface of the c-PS microspheres under the catalysis of metallocene catalyst. The composition and morphology of the PS-g-PE microspheres were characterized by means of Fourier transform infrared spectroscopy, Fourier transform Raman spectroscopy, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy. It is possible to control the content of PE grafted onto the surface of c-PS microspheres by varying the polymerization time or the initial quantity of pendant butenyl group on the surface of c-PS microspheres. Investigation on the morphology and crystallization behavior of grafted PE chains showed that different surface patterns could be formed under various crystallization conditions. Moreover, the crystallization temperature of PE chains grafted on the surface of c-PS microspheres was 6 °C higher than that of pure PE. The c-PS microspheres decorated by PE chains had a better compatibility with PE matrix. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4477–4486, 2007
Co-reporter:Rongjun Song;Zhiwei Jiang;Wuguo Bi;Wenxi Cheng Dr.;Jun Lu Dr.;Baotong Huang
Chemistry - A European Journal 2007 Volume 13(Issue 11) pp:
Publication Date(Web):2 JAN 2007
DOI:10.1002/chem.200601018
The effects of both organically modified montmorillonite (OMMT) and Ni2O3 on the carbonization of polypropylene (PP) during pyrolysis were investigated. The results from TEM and Raman spectroscopy showed that the carbonized products of PP were mainly multiwalled carbon nanotubes (MWNTs). Surprisingly, a combination of OMMT and Ni2O3 led to high-yield formation of MWNTs. X-ray powder diffraction (XRD) and GC–MS were used to investigate the mechanism of this combination for the high-yield formation of MWNTs from PP. Brønsted acid sites were created in degraded OMMT layers by thermal decomposition of the modifiers. The resultant carbenium ions play an important role in the carbonization of PP and the formation of MWNTs. The degradation of PP was induced by the presence of carbenium ions to form predominantly products with lower carbon numbers that could be easily catalyzed by the nickel catalyst for the growth of MWNTs. Furthermore, carbenium ions are active intermediates that promote the growth of MWNTs from the degradation products with higher carbon numbers through hydride-transfer reactions. The XRD measurements showed that Ni2O3 was reduced into metallic nickel (Ni) in situ to afford the active sites for the growth of MWNTs.
Co-reporter:Shiyun Li;Hui Chen;Wuguo Bi;Jianjun Zhou;Jianzhong Li;Yanhui Wang;Wenxi Cheng;Meiye Li;Lin Li
Journal of Polymer Science Part A: Polymer Chemistry 2007 Volume 45(Issue 23) pp:5459-5469
Publication Date(Web):19 OCT 2007
DOI:10.1002/pola.22290
Polyethylene (PE) chains grafted onto the sidewalls of SWCNTs (SWCNT-g-PE) were successfully synthesized via ethylene copolymerization with functionalized single-walled carbon nanotubes (f-SWCNTs) catalyzed by rac-(en)(THInd)2ZrCl2/MAO. Here f-SWCNTs, in which α-alkene groups were chemically linked on the sidewalls of SWCNTs, were synthesized by Prato reaction. The composition and microstructure of SWCNT-g-PE were characterized by means of 1H NMR, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analyses (TGA), field-emission scanning electron microscope (FESEM), and transmission electron microscope (TEM). Nanosized cable-like structure was formed in the SWCNT-g-PE, in which the PE formed a tubular shell and several SWCNTs bundles existed as core. The formation of the above morphology in the SWCNT-g-PE resulted from successfully grafting of PE chains onto the surface of SWCNTs via copolymerization. The grown PE chains grafted onto the sidewall of the f-SWCNTs promoted the exfoliation of the mass nanotubes. Comparing with pure PE, the physical mixture of PE/f-SWCNTs and in situ PE/SWCNTs mixture, thermal stability, and mechanical properties of SWCNT-g-PE were higher because of the chemical bonding between the f-SWCNTs and PE chains. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5459–5469, 2007
Co-reporter:Rongjun Song;Baoyan Zhang;Baotong Huang
Journal of Applied Polymer Science 2006 Volume 102(Issue 6) pp:5988-5993
Publication Date(Web):28 SEP 2006
DOI:10.1002/app.25178
Supported nickel catalyst (Ni-Cat) was used as a catalyst to improve the flame retardancy of intumescent flame-retardants (IFR) systems based on ammonium polyphosphate and pentaerythritol (PETOL) in polypropylene (PP) matrix. Limited oxygen index (LOI), UL-94 rating, and thermogravimetric analysis were used to characterize the flame retardancy and thermal stability of the PP systems, and field emission scanning electron microscopy (FE-SEM) and Fourier transformed infrared spectroscopy (FTIR) were used to analyze the microstructure and composition of the chars formed during measuring LOI value and after combustion at 800°C. The catalytic effect of Ni-Cat was shown in an increase of LOI, a change in the char microstructure, and improvement of the thermal stability in the PP systems, which result from the synergistic effect of Ni-Cat and IFR. The results from FE-SEM and FTIR spectra of the char can explain how this synergistic effect happened. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5988–5993, 2006
Co-reporter:Wenxi Cheng, Zunshi Zhou, Wei Miao, Hui Chen, Baotong Huang, Tao Tang
Materials Letters 2006 Volume 60(Issue 15) pp:1843-1846
Publication Date(Web):July 2006
DOI:10.1016/j.matlet.2005.12.032
Organic mesoporous silicas (OMSs) were synthesized in the presence of urea via one-pot synthesis method, in which tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethoxysilica (APTES) were used as the silica resources, non-ionic surfactant was used as the template. XRD results showed that the average periodic mesopore sizes of OMSs in the presence of urea were larger than those in the absence of urea. It was also found that the pore sizes of the products in the presence of urea distributed more narrowly than those in the absence of urea, and the contents of organosiloxane incorporated into OMSs, the pore wall thicknesses, the pore volumes and the surface areas of the products all increased with the use of urea. This shows a novel way to synthesize high regular and periodic organic mesoporous silicas.
Co-reporter:Xuecheng Chen;Yaping Ding
Polymer International 2005 Volume 54(Issue 6) pp:
Publication Date(Web):15 FEB 2005
DOI:10.1002/pi.1787
Nickel formate was used as a catalyst to improve the flame-retardancy of intumescent systems based on ammonium polyphosphate (APP) and pentaerythritol (petol) in polypropylene (PP). Limited oxygen index (LOI), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to characterize the fire-retardancy and thermal stability of the PP system and the microstructure of the burned residue. The catalytic effect was shown in an increase in LOI, and a change in the residue microstructure and the thermal stability of the PP system. LOI increased with the concentration of the catalyst in the range 0.1–5 wt% of the composition until a maximum was reached. At higher concentration of the catalyst a decrease in the LOI was observed. Copyright © 2005 Society of Chemical Industry
Co-reporter:Tao Tang ;Xuecheng Chen;Xiaoyu Meng;Hui Chen Dr.;Yaping Ding
Angewandte Chemie International Edition 2005 Volume 44(Issue 10) pp:
Publication Date(Web):28 JAN 2005
DOI:10.1002/anie.200461506
New for old: A novel catalytic combustion method to synthesize multiwalled carbon nanotubes (MWNTs, see SEM image) in situ in high yields from polypropylene as the carbon source in the presence of an organic-modified clay and a supported nickel catalyst is reported. The method allows new high-value MWNTs to be created from used polypropylene in an energy-saving and environmentally friendly process.
Co-reporter:Tao Tang ;Xuecheng Chen;Xiaoyu Meng;Hui Chen Dr.;Yaping Ding
Angewandte Chemie 2005 Volume 117(Issue 10) pp:
Publication Date(Web):28 JAN 2005
DOI:10.1002/ange.200461506
Aus alt mach neu: Eine neuartige Methode zur katalytischen Verbrennung von Polypropylen liefert hohe Ausbeuten an mehrwandigen Kohlenstoffnanoröhren (MWNTs, siehe Rasterelektronenmikroskopie-Bild) in Gegenwart eines mit organischen Gruppen modifizierten Tones und eines immobilisierten Nickelkatalysators. Der umweltverträgliche Prozess wandelt gebrauchtes Polypropylen in hochwertige MWNTs um.
Co-reporter:Yongxin Qin, Tao Tang and Zhongfu Zhao
Chemical Communications 2004 (Issue 2) pp:222-223
Publication Date(Web):28 Nov 2003
DOI:10.1039/B311548H
Polyethylene–polystyrene blends were synthesized by in situ ethylene polymerization with polystyrene porous beads supported metallocene; the influence of fragmenting support beads on the morphology and the mechanical performance of the blends was investigated.
Co-reporter:Liangming Wei, Tao Tang, Baotong Huang
Microporous and Mesoporous Materials 2004 Volume 67(2–3) pp:175-179
Publication Date(Web):6 February 2004
DOI:10.1016/j.micromeso.2003.11.002
A new class of organic–inorganic hybrid porous clay heterostructures (HPCHs) have been prepared through the surfactant-directed assembly of organosilica in the galleries of montmorillonite. The reaction involved hydrolysis and condensation of phenyltriethoxysilane and tetraethoxysilane in the presence of intragallery surfactant templates (dodecylame and cetyltrimethylammonium ion). The surfactant templates were removed from the pores by solvent-extraction. The products were characterized by X-ray diffraction (XRD), N2 adsorption, solid-state 29Si and 13C NMR, and FTIR. XRD patterns indicated a regular interstratification of the clay layers for HPCHs. Depending on loading of phenyl groups, HPCHs had BET surface areas of 390–771 m2 g−1, pore volumes of 0.3–0.59 cm3 g−1, and the framework pore sizes in the supermicropore to small mesopore range (1.2–2.6 nm). HPCHs were hydrophobic and acidic.
Co-reporter:Liangming Wei;Baotong Huang
Journal of Polymer Science Part A: Polymer Chemistry 2004 Volume 42(Issue 4) pp:941-949
Publication Date(Web):6 JAN 2004
DOI:10.1002/pola.11053
A novel approach to the preparation of polyethylene (PE) nanocomposites, with montmorillonite/silica hybrid (MT-Si) supported catalyst, was developed. MT-Si was prepared by depositing silica nanoparticles between galleries of the MT. A common zirconocene catalyst [bis(cyclopentadienyl)zirconium dichloride/methylaluminoxane] was fixed on the MT-Si surface by a simple method. After ethylene polymerization, two classes of nanofillers (clay layers and silica nanoparticles) were dispersed concurrently in the PE matrix and PE/clay–silica nanocomposites were obtained. Exfoliation of the clay layers and dispersion of the silica nanoparticles were examined with transmission electron microscopy. Physical properties of the nanocomposites were characterized by tensile tests, dynamic mechanical analysis, and DSC. The nanocomposites with a low nanofiller loading (<10 wt %) exhibited good mechanical properties. The nanocomposite powder produced with the supported catalyst had a granular morphology and a high bulk density, typical of a heterogeneous catalyst system. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 941–949, 2004
Co-reporter:Dongmei Cui;Wuguo Bi;Jianhua Cheng;Wenqi Chen;Baotong Huang
Journal of Polymer Science Part A: Polymer Chemistry 2003 Volume 41(Issue 17) pp:2667-2675
Publication Date(Web):22 JUL 2003
DOI:10.1002/pola.10814
Divalent samarocene complex [(C5H9C5H4)2Sm(tetrahydrofuran)2] was prepared and characterized and used to catalyze the ring-opening polymerization of L-lactide (L-LA) and copolymerization of L-LA with caprolactone (CL). Several factors affecting monomer conversion and molecular weight of polymer, such as polymerization time, temperature, monomer/catalyst ratio, and solvent, were examined. The results indicated that polymerization was rapid, with monomer conversions reaching 100% within 1 h, and the conformation of L-LA was retained. The structure of the block copolymer of CL/L-LA was characterized by NMR and differential scanning calorimetry. The morphological changes during crystallization of poly(caprolactone) (PCL)-b-P(L-LA) copolymer were monitored with real-time hot-stage atomic force microscopy (AFM). The effect of temperature on the morphological change and crystallization behavior of PCL-b-P(L-LA) copolymer was demonstrated through AFM observation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2667–2675, 2003
Co-reporter:Chengbin Liu;Zhongfu Zhao;Baotong Huang
Journal of Polymer Science Part A: Polymer Chemistry 2002 Volume 40(Issue 11) pp:1892-1898
Publication Date(Web):22 APR 2002
DOI:10.1002/pola.10265
Ethylene polymerization was carried out with zirconocene catalysts supported on montmorillonite (or functionalized montmorillonite). The functionalized montmorillonite was from simple ion exchange of [CH3O2CCH2NH3]+ (MeGlyH+) ions with interlamellar cations of layered montmorillonites. The functionalized montmorillonites [high-purity montmorillonite (MMT)-MeGlyH+] had larger interlayer spacing (12.69 Å) than montmorillonites without treatment (9.65 Å). The zirconocene catalyst system [Cp2ZrCl2/methylaluminoxane (MAO)/MMT-MeGlyH+] had much higher Zr loading and higher activities than those of other zirconocene catalyst systems (Cp2ZrCl2/MMT, Cp2ZrCl2/MMT-MeGlyH+, Cp2ZrCl2/MAO/MMT, [Cp2ZrCl]+[BF4]/MMT, [Cp2ZrCl]+[BF4]−/MMT-MeGlyH+, [Cp2ZrCl]+[BF4]−/MAO/MMT-MeGlyH+, and [Cp2ZrCl]+[BF4]−/MAO/MMT). The polyethylenes with good bulk density were obtained from the catalyst systems, particularly (Cp2ZrCl2/MAO/MMT-MeGlyH+). MeGlyH+ and MAO seemed to play important roles for preparation of the supported zirconocenes and polymerization of ethylene. The difference in Zr loading and catalytic activity among the supported zirconocene catalysts is discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1892–1898, 2002
Co-reporter:Jiang Gong, Kun Yao, Jie Liu, Zhiwei Jiang, Xuecheng Chen, Xin Wen, Ewa Mijowska, Nana Tian and Tao Tang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 17) pp:NaN5255-5255
Publication Date(Web):2013/02/26
DOI:10.1039/C3TA10316A
A one-pot approach was demonstrated to effectively synthesize carbon microspheres through “catalytic carbonization” of commercial chlorinated poly(vinyl chloride) (CPVC) microspheres by Fe2O3 at 700 °C. Without Fe2O3, a “sponge-like” carbon lump was obtained. However, after adding Fe2O3 (even 0.5 g per 100 g CPVC) into CPVC, carbon microspheres with octahedral Fe3O4 microcrystals uniformly embedded on the surface (Fe/CMS) were synthesized. The influence of Fe2O3 on the carbonization of CPVC microspheres was investigated. It was found that Fe2O3 significantly accelerated the dehydrochlorination of CPVC into polyene before the melting of the CPVC microsphere surface. As a result, the microspheres of raw CPVC showed a “shape-duplicate” carbonization behaviour. The resultant Fe/CMS showed high photo-degradation efficiency of Congo red under UV irradiation via a heterogeneous photo-Fenton process with high recyclablity, reusability and long-term stability. This indicated that the resultant Fe/CMS has a potential application in wastewater treatment. Therefore, the initial catalytic substance could be effectively used as a catalyst twice in the carbonization of CPVC microspheres and in the subsequent application of Fe/CMS. More importantly, the strategy of “catalytic carbonization” offers a new potential way to largely convert charring polymers into functional carbon and carbon-based materials with various morphologies.
Co-reporter:Yujie Wang, Xin Wen, Dong Wan, Zhijie Zhang and Tao Tang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 9) pp:
Publication Date(Web):
DOI:10.1039/C1JM14474J
Co-reporter:Xin Wen, Jiang Gong, Haiou Yu, Zhi Liu, Dong Wan, Jie Liu, Zhiwei Jiang and Tao Tang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 37) pp:NaN19980-19980
Publication Date(Web):2012/08/08
DOI:10.1039/C2JM33689H
Catalyzing the carbonization of a polymer itself to form a protective carbonaceous layer has attracted tremendous interest in the flame retardancy of polymers, but the efficiency of this strategy was largely limited to polymers containing heteroatoms within their backbone. In this study, a novel type of combined catalyst, consisting of nanosized carbon black (CB) and Ni2O3, was found to efficiently catalyze the carbonization of poly(L-lactide) (PLA) for the first time. The combined catalyst was more efficient than CB or Ni2O3 alone to enhance the char yield of PLA and improve its char layer structure, which greatly improved the flame retardancy of PLA. The catalytic pyrolysis for PLA composites and model carbonization experiments for their degradation products were carried out to investigate the carbonization process of PLA during combustion. The results indicated that the carbonization mechanism was attributed to the combined effect of the combined catalysts: CB catalyzed the degradation of PLA to selectively produce more aldehydes and ketones with lower carbon numbers, then these carbonyl compounds were dehydrogenated (and/or dehydrated) and transferred into carbon products catalyzed by the combination of CB and Ni catalysts.
Co-reporter:Xuecheng Chen, Karolina Wilgosz, Krzysztof Cendrowski, Tao Tang, Paul K. Chu, Ryszard J. Kalenczuk and Ewa Mijowska
Dalton Transactions 2013 - vol. 42(Issue 18) pp:NaN6385-6385
Publication Date(Web):2013/01/08
DOI:10.1039/C3DT32736A
The synthesis of designed nanostructures is an ultimate target of nanomaterial science. Here, silica spheres with nanoholes have been selectively prepared. Coating the necklace-like structured and magnetic nanoparticles along carbon nanotubes, which is an essential step of the simple synthetic procedure of silica hollow spheres, led to the formation of silica hollow spheres with controllable sized nanoholes in their shell walls. The synthesized hollow spheres with nanoholes would be a good support for loading large molecules, e.g. drugs and proteins.
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