Co-reporter:Zhongzhu Ma, Cheng Li, Hong Fan, Jintao Wan, Yingwu Luo, and Bo-Geng Li
Industrial & Engineering Chemistry Research November 29, 2017 Volume 56(Issue 47) pp:14089-14089
Publication Date(Web):November 7, 2017
DOI:10.1021/acs.iecr.7b04029
To develop biobased polyurethanes (PUs) via a less hazardous, nonisocyanate route, herein we synthesize a series of biobased polyhydroxyurethanes (PHUs) by reacting a new biobased cyclocarbonate (derived from renewable diphenolic acid and carbon dioxide) with ethylenediamine (EDA), diethylenetriamine (DETA), and isophoronediamine (IPDA), corresponding to PHU-EDA, PHU-DETA, and PHU-IPDA, respectively. Their molecular structures are identified from 1H NMR and FTIR analyses. Gel permeation chromatography (GPC) analysis shows that the molecular weights of these PHUs grow to as high as 5 kDa in a short reaction time (4 h) at a relatively low reaction temperature (80 °C). Subsequently, the solvent-borne (in acetone) coatings of these PHUs are successfully fabricated with diglycidyl ether of bisphenol A as the cross-linker. The cured PHU coatings on aluminum panels show the high pencil hardness (up to 4 H), adhesive force (up to grade 1), glass transition as high as 116 °C, and initial thermal degradation temperature up to 190 °C. Furthermore, we realize the good dispersion of these PHUs in water by introducing chemically bonded carboxylic anions into the molecular backbone to form a stable aqueous emulsion with well-controlled particle sizes and further demonstrate its application in a water-borne PHU coating with good mechanical and thermal properties. Overall, we develop a facile yet effective method to prepare sustainable, biobased PHUs based on diphenolic acid and carbon dioxide via a safer, greener nonisocyanate route and furthermore demonstrated their use as solvent-borne coatings and greener water-borne coatings of reduced environmental impact.
Co-reporter:Jintao Wan, Cheng Li, Hong Fan, and Bo-Geng Li
Industrial & Engineering Chemistry Research May 3, 2017 Volume 56(Issue 17) pp:4938-4938
Publication Date(Web):April 10, 2017
DOI:10.1021/acs.iecr.7b00610
Aliphatic diamines and polyamines are long used as important curing agents for epoxy resins, especially in room-temperature-cure epoxy coatings and adhesives due to their high reactivity and low cost. Herein we systematically evaluate our newly developed liquid branched aliphatic polyamine, N,N,N′,N′-tetra(3-aminopropyl)-1,6-diaminohexane (TADH), as the curing agent for bisphenol A epoxy (DGEBA), emphasizing the isothermal cure reaction, network structure, and mechanical properties. The isothermal curing reaction of DGEBA/TADH at 40, 50 60, and 70 °C is autocatalytic, and we adequately simulate the curing kinetic rate with the extended autocatalytic Kamal model. Further isoconversional kinetic analysis reveals that the effective activation energy changes dramatically as the reaction proceeds, especially for the diffusion-controlled stage due to the chemical vitrification (Tg∞(DSC) = 119 °C). Compared to DGEBA/1,6-diaminohexane (a starting material of TADH), a dynamic mechanical analysis illustrates that the cured DGEBA/TADH network features three relaxations and shows the increased storage modulus (up to 54 °C), α and β transition temperatures, and activation energy of the α relaxation. Also, DGEBA/TADH shows enhanced mechanical properties: flexural strength (∼95 MPa), flexural modulus (∼2440 MPa), and shear strength (∼8 MPa), with good processing ability (gel time of 130–150 min at 25 °C). Due to these merits, TADH may be suitable to be used in epoxy systems, highlighting its good promise in adhesive applications.
Co-reporter:Cheng Li, Deqi Zhang, Linbo Wu, Hong Fan, Deyi Wang, and Bo-Geng Li
Industrial & Engineering Chemistry Research June 28, 2017 Volume 56(Issue 25) pp:7120-7120
Publication Date(Web):April 24, 2017
DOI:10.1021/acs.iecr.7b01279
Restricted by their molecular structure defects, poly(methylphenylsiloxanes) usually exhibit a relatively low thermal stability, thus limiting their application in high-temperature areas. In this paper, we introduce a cost-effective synthesis method to prepare poly(methylphenylsiloxanes) (PPMS-M) with methyl–phenyl mixed cyclic monomers as raw materials. The molecular structure characterization shows that PPMS-M contain abundant phenyl groups, and the phenylsiloxane units are evenly distributed among methylsiloxane segments. The thermal degradation kinetics are systematically studied with the Flynn–Wall–Ozawa method. It shows that PPMS-M exhibits much higher degradation activation energy than ordinary poly(methylphenylsiloxanes) (PPMS-PD) does, which is prepared by 2,4,6-trimethyl-2,4,6-triphenylcyclotrisiloxane (P3) and octamethylcyclotetrasiloxane (D4). The thermogravimetry–Fourier transform infrared characterization shows that the degradation process of the phenyl group in PPMS-M occurs at temperatures of 100–200 °C higher than those for PPMS-PD. PPMS-M exhibits good thermal stability and a low glass transition temperature. Our method would be applied to cost-effective synthesis of other high-performance functional polysiloxanes.
Co-reporter:Jun Cao, Hong Fan, Bo-Geng Li, Shiping Zhu
Polymer 2017 Volume 124(Volume 124) pp:
Publication Date(Web):25 August 2017
DOI:10.1016/j.polymer.2017.07.056
•Two kinds of epoxy group containing Double-Decker Silsesquioxanes were synthesized.•theThe effects of DDSQs in the curing of DGEBA/33DDS were studied with changing effective activity energy.•The performance of epoxy resin with different DDSQ loading ratios was studied, including thermal and mechanical properties.In this paper, we synthesized two types of epoxy group containing POSS derivatives: mono and poly Double-Decker Silsesquioxanes (mono DDSQ and poly DDSQ). The performance of epoxy resin with different DDSQ loading ratios was investigated, including curing kinetics, thermal, mechanical and surface properties. Both mono and poly DDSQ significantly improved thermal and mechanical properties of the epoxy thermosets. The mono DDSQ showed more flexible structure and toughened the epoxy resin better, while the branched poly DDSQ exhibited better thermal resistance. In addition, the DDSQ altered surface of the epoxy resin from hydrophilic to hydrophobic.Download high-res image (166KB)Download full-size image
Co-reporter:Cheng Li, Jintao Wan, Ye-Tang Pan, Peng-Cheng Zhao, Hong Fan, and De-Yi Wang
ACS Sustainable Chemistry & Engineering 2016 Volume 4(Issue 6) pp:3113
Publication Date(Web):April 14, 2016
DOI:10.1021/acssuschemeng.6b00134
With wide application of natural fibers in polymer composites, improvements in their flame retardancy, water absorption, and electrical resistance become an urgent need. To this end, 4.5 wt % of layered double hydroxide (LDH) is introduced into sisal fiber reinforced biobased silicone modified phenolic composites. The modified composites optimally shows 60% reduction in total heat release (20.2 MJ/m2) compared to the composites without LDH. In addition, the biobased silicone modifier TDS is incorporated into phenolic resins (SPF), to further reduce water absorption rate to 6 wt %, and increase volume electrical resistance up to 4.6 × 1016 Ω m. The SPF-SF-SDBSLDH exhibits a high impact strength of 4.2 kJ/m2, over 50% higher than the unmodified PF-SF composites. The SEM observations show that the SPF composites exhibit better interfacial interaction with sisal fiber than normal phenolic (PF) composites. All these flame retardant, impact strength and electrical resistance properties are compatible with the requirement for applications as molding compounds. Our research provides a cost-effective method to improve the performance of this sustainable natural-fiber reinforced composites with novel and low cost biobased silicone modifier and LDHs. These high performance composites are promising for applications in high technology areas such as the microelectric industry and lightweight automotives.Keywords: Biobased silicone; Electrical resistance; Flame retardancy; Layered double hydroxide; Phenolic composites; Sisal fiber; Water absorption rate
Co-reporter:Cheng Li, Zhongzhu Ma, Xianwei Zhang, Hong Fan, Jintao Wan
Thermochimica Acta 2016 Volume 639() pp:53-65
Publication Date(Web):10 September 2016
DOI:10.1016/j.tca.2016.07.011
•A biobased silicon modifier (TDS) is used to modify phenolic resin (SPF).•The SPF exhibits a much higher weight-average molecular weight than PF.•The isoconversional method is applied describing their nonisothermal curing reaction.•The relationship between activation energy and conversion rates are acquired.A silicone-modified phenolic resin (SPF) is synthesized by in-situ polymerization of 4,4′-(1,5-dipropyl-3,3-diphenyl-1,1,5,5-tetramethyltrisiloxane)bis-2-methoxyphenol(TDS), phenol and formaldehyde. The curing reaction and kinetics of SPF with hexamethylenetetramine (HMTA) are studied using a differential scanning calorimeter (DSC) in terms of the model-fitting and isoconversional methods. The results are described by Šesták-Berggren model precisely. The reaction kinetics show that the nonisothermal curing reaction of SPF/HMTA is autocatalytic, and is more affected by diffusion controlled process than PF/HMTA at high conversion stage. The isothermal conversion is predicted by using the model-free Vyazovkin method, exhibiting good agreement with experimental data. This study provide a method to understand how the silicone modifier affect the affect the curing behaviors of phenolic resins.
Co-reporter:Zhen Jin, Hong Fan, Bo-Geng Li, Shiping Zhu
Polymer 2016 Volume 83() pp:20-26
Publication Date(Web):28 January 2016
DOI:10.1016/j.polymer.2015.11.058
•Designed and synthesized a novel type of low-oxophilicity siloxane-containing olefinic macromonomer, OO7.•Demonstrated copolymerizability of OO7 macromonomer with ethylene by vanadium catalyst and prepared poly(ethylene-co-OO7).•Demonstrated that OO7 incorporation in PE significantly benefits PE chain flexibility with Tg between −74.3 to −64.0 °C.•Demonstrated that poly(ethylene-co-OO7) is an excellent lubricant for HDPE, adding 10% resulted in 44% increase in MFR.This paper reported the synthesis of a novel type of octyltetramethyldisiloxane-containing olefinic macromonomer (1-oct(7-en)yl-3-octyl-1,1,3,3-tetramethyldisiloxane or OO7), the copolymerization of OO7 with ethylene by vanadium catalyst, the evaluation of poly(ethylene-co-OO7) as additive on the flow, mechanical and thermal properties of polyethylene. The novel siloxane-containing comonomer OO7 was synthesized by a two-step hydrosilylation route, with only one oxygen atom in the molecule. The comonomer had low oxophilicity and hence could be readily copolymerized with ethylene by VCl3(THF)3 catalyst with a high activity of 14 kg/mmolV·h at the comonomer feed of 160 mmol/L. The OO7 incorporation reached to 4.9 mol%. The reactivity ratios were: rE = 41.6, rOO7 = 0.021 and rE•rOO7 = 0.87, which indicated a tendency of random copolymerization. DSC analysis revealed that the glass transition temperatures (Tg) of poly(ethylene-co-OO7) were in the range between −74.3 °C to −64.0 °C, lower than that of a LLDPE control sample of the similar composition. The melting endotherm of poly(ethylene-co-OO7) was broadened and shifted to a lower temperature range with increase of the OO7 content. Adding 10% poly(ethylene-co-OO7) as lubricant to HDPE increased 44% melt flow rate (MFR) of the blend. However, the mechanical and thermal properties of the blends were not adversely affected, compared to HDPE.
Co-reporter:Cheng Li, Jintao Wan, Ehsan Naderi Kalali, Hong Fan and De-Yi Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 7) pp:3471-3479
Publication Date(Web):19 Dec 2014
DOI:10.1039/C4TA05740F
Aiming to develop a multi-functional flame retardant for epoxy resins, a novel bio-based eugenol derivative containing silicon and phosphorus [((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(2-methoxy-4,1-phenylene)bis(phenylphosphonochloridate), SIEPDP] was synthesized, and was further used to modify Mg–Al layered double hydroxide (SIEPDP-LDH). This modified SIEPDP-LDH was used as a novel nanoflame-retardant for bisphenol epoxy resins and compared with unmodified pristine LDH. X-ray diffraction (XRD) analysis justified that intercalation of SIEPDP into LDH increased the interlayer distance to 2.95 nm. Morphological analysis (XRD and TEM) revealed that the SIEPDP-LDH was dispersed well in the epoxy matrix in a partially exfoliated manner. Results from the cone calorimeter tests showed that even a low loading of SIEPDP-LDH into epoxy resin led to a significant decrease in heat release rate and total heat release compared to unmodified LDH/epoxy composites. More interestingly, SIEPDP-LDH/epoxy's UL-94 classification passed V-0 with only 8 wt% loading. Moreover, the addition of SIEPDP-LDH enabled the increase in the impact strength and modulus of the cured epoxy. These data indicated that SIEPDP-LDH could serve as not only a nanoflame retardant but a good reinforcing agent as well.
Co-reporter:Yufen Jin, Qun Pu, and Hong Fan
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 14) pp:7552
Publication Date(Web):March 27, 2015
DOI:10.1021/am5088743
In this work, silicone softener (PTSO–PEG) was synthesized, with piperazine terminated polydimethylsiloxane (PTSO) and epoxy terminated polyethylene glycol (EPEG) as raw materials. Chemical structure of PTSO–PEG was characterized by 1H NMR, FTIR, GPC, and TGA. Its application on cotton fabrics was studied. Morphologies of silicone modified surfaces on cotton fabrics and silicon wafers were investigated by SEM and AFM, respectively. The morphology images indicated that PTSO–PEG treated surface was macroscopically smooth and microscopically rough. Performance properties of silicone treated cotton fabrics, including hydrophilicity, whiteness, and softness, were tested. The results showed that PTSO–PEG treated cotton fabrics expressed better whiteness and hydrophilicity than traditional amino silicone treated sample. The piperazine and hydrophilic polyether groups on PTSO–PEG molecules disturbed the continuous and orderly arrangement of Si–CH3 groups, giving the cotton a hydrophilic and rough surface. This work provided a cost-effective and environmental method to synthesize and apply high performance silicone softener.Keywords: hydrophilicity; morphology; piperazine; silicone softener; whiteness;
Co-reporter:Yi Wang, Hong Fan, Suyun Jie, Bo-Geng Li
Inorganic Chemistry Communications 2014 Volume 41() pp:68-71
Publication Date(Web):March 2014
DOI:10.1016/j.inoche.2014.01.005
Co-reporter:Yanyan Zhang;Bo-Geng Li
Journal of Applied Polymer Science 2014 Volume 131( Issue 22) pp:
Publication Date(Web):
DOI:10.1002/app.41114
ABSTRACT
Advance polyamide-6-b-polydimethylsiloxane (PA6-b-PDMS) multiblock copolymers were first synthesized via the polymerization in bulk. Binary carboxyl terminated PA6 was served as the hard segment and PDMS modified with hexamethylene diisocyanate (PDMS-NCO) was the soft segment. A series of PA6-b-PDMS copolymers based on different content and length of soft segments were obtained. Interestingly, Differential scanning calorimetry (DSC) studies revealed no obvious change in melting temperature after introducing PDMS segments to copolymers. The high melting temperatures indicated these copolymers possess potential applications in automotive industry that require high continuous use temperatures. DSC and transmission electron microscopy studies both demonstrated increasing the length and the content of the soft segment contributed to increasing of the degree of microphase separation. However, the improvement of thermal stability resulting from PDMS segments was also observed by thermo gravimetric analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41114.
Co-reporter:Caina Min;Qun Pu;Liu Yang
Journal of Applied Polymer Science 2014 Volume 131( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/app.40186
ABSTRACT
A novel polysiloxane bearing dodecyl and epoxy side groups (DESO) was synthesized as an intermediate through hydrosilylation of polymethylhydrosiloxane with allyl glycidyl ether and 1-dodecene. Then, dodecyl/piperazine functional polysiloxane (DPSO) was prepared through the reaction of N-aminoethylpiperazine with DESO. The chemical structure of DPSO was characterized with FTIR and 1H-NMR spectroscopy and its application performance on cotton fabrics was studied. DPSO with dodecyl side groups gifted the treated fabrics with good wettability and whiteness compared with piperazine functional polysiloxane, while with a slightly reduced softness as well as thickening handle. Film morphology, orientation, and performance on cotton substrates of DPSO were investigated by scanning electron microscope, atomic force microscopy, X-ray photoelectron microscope, and so on. Affected by the dodecyl side groups, DPSO formed relatively hydrophilic, macroscopically smooth but actually uneven films with many dodecyl side chain pillars on the treated substrate surfaces. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40186.
Co-reporter:Jun Cao, Jijiang Hu, Hong Fan, Jintao Wan, Bogeng Li
Thermochimica Acta 2014 Volume 593() pp:30-36
Publication Date(Web):10 October 2014
DOI:10.1016/j.tca.2014.06.014
•A novel silicone–phenyl contained aliphatic polyamine was first time employed as the curing agent of epoxy resin.•The non-isothermal curing kinetics of DGEBA/PSPA was investigated with DSC.•The isoconversional method was used to analyze the effective activation of the curing reaction.•Thermo gravimetric analysis showed the cured DGEBA/PSPA was thermally stable up to 380 °C.A novel type of silicone–phenyl contained aliphatic polyamine (PSPA) was originally synthesized and employed as the curing agent for bisphenol A epoxy resin (DGEBA). The non-isothermal curing behavior of DGEBA/PSPA was systematically characterized with differential scanning calorimetry (DSC), showing that the reaction exothermic peak temperature increased with the increasing heating rate. The isoconversional Vyazovkin method was used to analyze the curing kinetics, giving the effective activation energy Eα. The Eα rapidly decreased at the initial curing stage, after which it kept stable and decreased quickly to the end. In addition, thermo gravimetric analysis (TGA) showed that the cured DGEBA/PSPA network was thermally stable up to 380 °C.
Co-reporter:Yi Wang 范宏;Su-yun Jie;Bo-geng Li
Chinese Journal of Polymer Science 2014 Volume 32( Issue 7) pp:854-863
Publication Date(Web):2014 July
DOI:10.1007/s10118-014-1470-5
This contribution reports ethylene polymerization behavior of titanium complexes incorporating bis(phenoxyimine) ligands. Six phenoxy-imine Ti(IV) complexes {6-R1-2-[CH=N(2,6-difluoro-3,5-diR2-4-R3Ph)]C6H3O}2TiCl2 (1: R1 = H, R2 = H, R3 = H; 2: R1 = H, R2 = H, R3 = 4-vinylphenyl; 3: R1 = CH3, R2 = H, R3 = H; 4: R1 = CH3, R2 = H, R3 = 4-vinylphenyl; 5: R1 = CH3, R2 = F, R3 = H; 6: R1 = CH3, R2 = F, R3 = 4-vinylphenyl) have been synthesized and evaluated for ethylene polymerization using dried MAO (simplified as DMAO) as cocatalyst. An obvious catalytic heterogeneity of Cat 2 (Complex 2/DMAO) towards ethylene polymerization was observed, which was illustrated by decreased activity, multimodal molecular weight distribution and partially improved particle morphology comparing with Cat 1. Moreover, Cat 3 exhibits “living” characteristics in the process under certain conditions (25 °C, less than 20 min). Otherwise, the moderate to high ethylene polymerization activity of ca. 105–106 g PE/(mol Ti·h) and high molecular weight (Mw = 105–106) of polyethylene can be obtained by changing the skeleton structure of these complexes.
Co-reporter:Cheng Li, Hong Fan, De-Yi Wang, Jijiang Hu, Jintao Wan, Bogeng Li
Composites Science and Technology 2013 Volume 87() pp:189-195
Publication Date(Web):18 October 2013
DOI:10.1016/j.compscitech.2013.08.016
4,4′-(1,3-Dipropyl-tetramethyldisiloxane)bis-2-methoxyphenol (SIE), a novel silicone-contained biphenol type monomer, is synthesized from eugenol and 1,1,3,3-tetramethyldisiloxane, and used to modify phenolic novolac through copolymerization with phenol and formaldehyde to yield SIE-modified resins (SPNs). Then, the SPNs are used as resin matrix, while surface-treated chopped sisal fiber is used as the reinforced filler to produce the novel phenolic molding composites. Eugenol and sisal are biobased renewable materials. Due to modification of SIE, the ultimate composites expressed excellent electrical resistance, low water absorption and high thermal stability compared to the normal composites. Our work provides a facile and effective way to prepare the silicone modified, biofiber-reinforced phenolic composites with improved water resistance and electric property.
Co-reporter:Weifeng Liu, Song Guo, Zhiyang Bu, Hong Fan, Wen-Jun Wang, Bo-Geng Li
European Polymer Journal 2013 Volume 49(Issue 7) pp:1823-1831
Publication Date(Web):July 2013
DOI:10.1016/j.eurpolymj.2013.04.008
•Molecular weight controllable bimodal polyethylene was synthesized using a fluorinated FI–Ti catalyst and ZnEt2.•ZnEt2 was a useful molecular weight regulator.•The high molecular weight fraction could be controlled via altering the living polymerization time.•The low fraction could be controlled via varying the Zn/Ti ratio.Molecular weight controllable bimodal polyethylene was synthesized by adding ZnEt2 during ethylene living polymerization with the fluorinated FI–Ti catalyst system, bis[N-(3-methylsalicylidene)-2,3,4,5,6-pentafluoroanilinato] TiCl2/dMAO. The presented FI–Ti catalyst system was demonstrated to perform good living feature. High molecular weight polyethylene with narrow polydispersity was obtained in the absence of ZnEt2. ZnEt2 was found to be a useful molecular weight regulator in this catalyst system. Increasing the Zn/Ti ratio led to a monotonic decrease in the molecular weight. The stagewise process allowed for a facile control on the molecular weight of bimodal polyethylene in a wide range: the molecular weight of high fraction could be controlled via altering the living polymerization time, the molecular weight of low fraction could be controlled via varying the Zn/Ti ratio. This method shows a new application for the living coordination polymerization technique.
Co-reporter:Jintao Wan, Cheng Li, Zhi-Yang Bu, Hong Fan, Bo-Geng Li
Materials Chemistry and Physics 2013 Volume 138(Issue 1) pp:303-312
Publication Date(Web):15 February 2013
DOI:10.1016/j.matchemphys.2012.11.060
Acrylonitrile-modified aliphatic amine adducts are often used as curing agents for room-temperature epoxy formulations (coatings, adhesives, sealants, castings, etc.), yet the curing reaction and properties of resultant epoxy systems still remain less fundamentally understood. Herein we systematically investigate our newly-developed acrylonitrile-modified multifunctional polyamine curing agent for bisphenol A epoxy resin (DGEBA): an acrylonitrile-capped poly(propyleneimine) dendrimer (PAN4). The impact of the molecular structure of PAN4 and a controlled poly(propyleneimine) dendrimer (1.0GPPI) on the curing reactivity, reaction mechanisms, thermal stability, viscoelastic response and mechanical properties of the epoxy systems are highlighted. Differential scanning calorimetry (DSC) confirms DGEBA/PAN4 shows markedly lower reactivity and reaction exotherm than DGEBA/1.0GPPI, and the model-free isoconversional kinetic analysis reveals that DGEBA/PAN4 has the generally lower reaction activation energy. To be quantitative, the progress of the isothermal cure is predicted from the dynamic cure by using the Vyazovkin equation. The isothermal kinetic prediction shows that DGEBA/PAN4 requires about 10 times longer time to achieve the same conversion than DGEBA/1.0GPPI, which agrees with the experimentally observed much longer gel time of DGEBA/PAN4. Subsequently, dynamic mechanical analysis shows that PAN4 results in the cured epoxy network with the lower β- and glass-relaxation temperatures, crosslink density, relaxation activation energy, enthalpy, entropy, but the higher damping near room temperature than 1.0GPPI. Finally, thermogravimetric analysis (TGA) demonstrates cured DGEBA/PAN4 is thermally stable up to 200 °C, and mechanical property tests substantiate that PAN4 endows the cured epoxy with much higher impact and adhesion strengths than 1.0GPPI. Our data can provide a deeper insight into acrylonitrile-modified aliphatic amine curing agents from the two good model compounds (PAN4 and 1.0GPPI).Highlights► We compare the isoconversional curing kinetics of DGEBA/1.0GPPI and DGEBA/PAN4. ► Acrylonitrile-capped PAN4 is much lower reactive than controlled 1.0GPPI. ► TG analysis shows the two cured epoxy systems are thermally stable up to 200 °C. ► DMA results reveal the viscoelastic response of the two cured networks differs greatly. ► PAN4 greatly improves the shear, impact strengths and processability of the epoxy.
Co-reporter:Song Guo;Suyun Jie;Jianxiu Weng;Weifeng Liu ;Bo-Geng Li
Journal of Applied Polymer Science 2013 Volume 129( Issue 4) pp:1971-1977
Publication Date(Web):
DOI:10.1002/app.38901
Abstract
Two new FI complexes, bis[N-(3-allylsalicylidene)-pentafluoroanilinato]titanium(IV) dichloride (AFI) and bis[N-(3-propylsalicylidene)-pentafluoroanilinato]titanium(IV) dichloride (PFI) were designed and synthesized as catalysts for living polymerization of ethylene. The two complexes were characterized by elemental analysis, spectroscopy and X-ray single diffraction. The catalysts were evaluated in ethylene polymerization under atmospheric pressure. It was found that both catalysts exhibited high activity and good livingness. The effects of temperature and dMAO/Ti molar ratio on the polymerization behavior of AFI were studied in detail. Elevating temperature increased self-immobilization of the AFI catalyst, which broadened the polymer molecular weight distribution. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Cheng Li, Zhiyang Bu, Jianping Sun, Hong Fan, Jintao Wan, Bogeng Li
Thermochimica Acta 2013 Volume 557() pp:77-86
Publication Date(Web):10 April 2013
DOI:10.1016/j.tca.2013.01.004
The molecular structure of phenolic novolacs plays an important role in their processing, properties and applications, yet its exact influences on the cure and thermal decomposition remain insufficiently understood. Herein two type of novolacs are prepared: high-ortho novolacs (HOPF) with high ortho–para ratio, and ordinary novolacs (NPF). Their cure behavior with hexamethylenetetramine (HMTA) investigated using DSC and TGA. The DSC analysis confirmed that HOPF/HMTA exhibited higher reactivity than NPF/HMTA. The model-free isoconversional analysis with the Vyazovkin method HOPF/HMTA has the higher effective activation energy than NPF/HMTA at the first stage, but lower in the latter stage. The isothermal cure is reasonably predicted. Moreover, the model-fitting kinetics using Málek method reveals the autocatalytic reaction mechanisms and yields the curing rate equation which can well predict the non-isothermal cure. Furthermore, TGA reveals the network structures of cured HOPE and NPF moderately affect the thermal decomposition process.Highlights► The nonisothermal curing kinetics of HOPF/HMTA and NPF/HMTA are systematically investigated and compared. ► The model-free isoconversional method is applied to untangle the curing mechanisms. ► The nonisothermal curing reaction of HOPF/HMTA were successfully simulated.
Co-reporter:Cheng Li, Chunmiao Zuo, Hong Fan, Mingxin Yu, Bogeng Li
Thermochimica Acta 2012 Volume 545() pp:75-81
Publication Date(Web):10 October 2012
DOI:10.1016/j.tca.2012.06.031
An interesting silicone-contained aliphatic polyamine, 1,3-bis(2-aminoethylaminomethyl) tetramethyldisiloxane (SFA), was originally employed as the curing agent for bisphenol A epoxy resin (DGEBA). The non-isothermal curing reaction of DGEBA/SFA was systematically investigated. Differential scanning calorimetry (DSC) showed that reaction exothermic peak temperature was systematically increased with increasing the heating rate, but the reaction exotherm changed slightly within 460–488 J/g. The isoconversional Vyazovkin method was used to analyze the curing kinetic schemes, yielding the effective activation energy Eα. The Eα rapidly decreased at the initial cure stage, after which it kept stable until curing completion. In addition, thermogravimetric analysis (TGA) showed that the cured DGEBA/SFA network was thermally stable up to 340 °C.Highlights► A novel silicone-contained aliphatic polyamine (SFA) was first time employed as the curing agent for bisphenol A epoxy resin. ► The non-isothermal curing kinetics of DGEBA/SFA was systematically investigated by differential scanning calorimetry. ► The isoconversional method was used to analyze the curing kinetic schemes, yielding the effective activation energy Eα. ► The obtained Eα–α correlation demonstrated Eα rapidly decreased at the initial cure stage, after which it changed little with α up to the completion. ► Thermogravimetric analysis showed that the cured DGEBA/SFA network was thermally stable up to 340 °C.
Co-reporter:Jintao Wan, Cheng Li, Hong Fan, Zhi-Yang Bu, Bo-Geng Li
Thermochimica Acta 2012 Volume 544() pp:99-104
Publication Date(Web):20 September 2012
DOI:10.1016/j.tca.2012.06.023
Star-branched polymers have being captured much research interest, yet impacts of the star-chain branching on the crystallization still need further elucidating. We originally report a comparative study of the isothermal crystallization kinetics of a star-branched DPA-11 and a linear nylon-11 (PA-11). Differential scanning calorimetry (DSC) confirms DPA-11 crystallizes at a much slower rate than PA-11. The kinetic analysis demonstrates the Avrami equation can generally well predict relative crystallinity X, and DPA-11 exhibits the higher Avrami exponents. The Hoffman–Lauritzen spherulitic growth analysis demonstrates DPA-11 has the decreased G0 and Kg values, accounting for the appreciably lowered spherulitic growth rate. More interestingly, the advanced isoconversional (Vyazovkin) method reveals DPA-11 always manifests the higher activation energy than PA-11, and once X exceeding 0.85 the activation energy of DPA-11 rises sharply, whereas that of PA-11 tends to decrease.Graphical abstractHighlights► Isothermal crystallization of a star-branched DPA-11 and a linear PA-11 are compared. ► DPA-11 exhibits the much lower crystallization rate than PA-11. ► The Vyazovkin method shows that DPA-11 always has the higher activation energy EX. ► The star branching of DPA-11 causes the sharp rise in EX during a high crystallinity range. ► The secondary crystallization of DPA-11 seems suppressed by the star-chain branching.
Co-reporter:Cheng Li, Hong Fan, Jijiang Hu, Bogeng Li
Thermochimica Acta 2012 Volume 549() pp:132-139
Publication Date(Web):10 December 2012
DOI:10.1016/j.tca.2012.09.008
A multifunctional silicone-contained aliphatic polyamine, 1,3-bis(2-aminoethylaminomethyl) tetramethyldisiloxane (SFA), was originally employed to cure bisphenol A epoxy resin (DGEBA) isothermally, and the curing reaction of DGEBA–SFA was systematically investigated by DSC measurement at 55, 60, 65 and 70 °C. The model fitting kinetic analysis confirmed that the reaction rate could be well simulated with an autocatalytic Kamal model up to the onset of the diffusion control stage. Taking the diffusion effects into account, the extended Kamal model was applied to fit the experimental reaction rate, with an excellent agreement throughout whole reaction process. The multi-frequency dynamic mechanical analysis shows that the cured DGEBA–SFA appears in a β relaxation in low temperature and an α relaxation in higher temperature interval (>80 °C). The relaxation activation energies for α and β relaxations are 70.1 and 287.6 kJ/mol, respectively.Highlights► A novel silicone-contained aliphatic polyamine (SFA) was employed as the curing agent for bisphenol A epoxy resin. ► The isothermal curing kinetics of DGEBA/SFA was systematically investigated by differential scanning calorimetry. ► The extended Kamal model was successfully applied in describing the cure reaction of DGEBA–SFA precisely in the entire conversion range. ► The DMA test shows β transition (at low temperature) and α relaxation (at high temperature). The α relaxation expresses much higher activation energy in comparison with other DGEBA/polyamine systems.
Co-reporter:Jintao Wan, Zhi-Yang Bu, Cun-Jin Xu, Bo-Geng Li, Hong Fan
Thermochimica Acta 2011 Volume 519(1–2) pp:72-82
Publication Date(Web):20 May 2011
DOI:10.1016/j.tca.2011.02.038
Novel butyl-glycidylether-modified poly(propyleneimine) dendrimers (PPIs) are prepared by reacting butyl glycidylether with PPI, which turn out to be able to cure bisphenol-A epoxy resin to an acceptable reaction extent. The nonisothermal reactions, dynamic mechanical properties and thermal stabilities of their cured epoxy resin are comparatively investigated with DSC, DMA and TGA, respectively. The model-fitting kinetic study demonstrates that Šesták–Berggren model can generally well simulate the reaction rates, and the isoconversional kinetic analysis with the Vyazovkin method indicates the curing agents, particularly their setric hindrance and the number of the –OH groups attached, greatly affect reaction kinetic schemes. Increasing the number of the BGE substituents attached to PPIs decreases the reactivity, glass- and beta-relaxation temperatures and thermal stability of the resulting epoxy systems, yet the intensity and width of the glass relaxation increase. This work offers a unique way of preparing modified-aliphatic-polyamine curing agents, and provides an opportunity to better learn about the amine-adduct curing agents which are widely used in room-temperature-cure epoxy coatings and adhesives from these good model compounds.Graphical abstractHighlights► Butyl-glycidylether-modified poly(propylene imine) dendrimers are successfully prepared. ► They, as novel hardeners, have high reactivity and can well cure epoxy resin nonisothermally. ► The Šesták–Berggren model can generally well simulate the epoxy reaction rates. ► The model-free isoconversional kinetic analysis are performed with the Vyazovkin method. ► Influences of the hardeners on curing behaviors and thermal properties of the epoxy are revealed.
Co-reporter:Jintao Wan, Zhi-Yang Bu, Cun-Jin Xu, Hong Fan, Bo-Geng Li
Thermochimica Acta 2011 Volume 525(1–2) pp:31-39
Publication Date(Web):20 October 2011
DOI:10.1016/j.tca.2011.07.018
This paper reports the original work on the nonisothermal curing reaction of bisphenol A epoxy resin (DGEBA) and N,N,N′,N′,N′′-penta(3-aminopropyl)-diethylenetriamine (PADT). The nonisothermal reaction kinetics of DGEBA/PADT is systematically investigated using dynamic DSC with the model-fitting and advanced model-free isoconversional methods. The high reaction heats (115–118 kJ/mol) indicate that PADT can efficiently cure DGEBA, and the reaction activation energy is 55.4 kJ/mol. The further reaction kinetic analysis with the Málek method discloses the autocatalytic characteristic, and the Šesták–Berggren model is able to well simulate the reaction rate. Furthermore, the dependence of the effective activation energy on conversion is established from the model-free kinetic analysis with the Vyazovkin method, from which the reaction mechanisms are discussed in detail. Additionally, the isothermal conversion predication from the nonisothermal data is accomplished using the two methods, respectively, with an acceptable match obtained.Graphical abstractHighlights► Nonisothermal cure reaction of DGEBA/PADT is examined with DSC. ► Model-fitting and advanced model-free isoconversional methods are used to the curing kinetic analysis. ► Reaction rate equation is established with the Málek method. ► Effective activation energy determined from the Vyazovkin method is interpreted in detail. ► Isothermal conversion prediction from the nonisothermal data is accomplished.
Co-reporter:Jintao Wan, Zhi-Yang Bu, Cheng Li, Hong Fan, Bo-Geng Li
Thermochimica Acta 2011 Volume 524(1–2) pp:117-127
Publication Date(Web):20 September 2011
DOI:10.1016/j.tca.2011.07.002
A novel dendritic nylon-11, DPA-11, is prepared from the melting copolycondensation of 11-aminoundecanoic acid and the 2nd generation poly(propyleneimine) dendrimer as the dendritic unit, with its melting, glass-transition and nonisothermal crystallization behaviors highlighted. DPA-11 is characterized using FTIR, TGA, WXRD and DSC. The results show that PDA-11 has excellent thermal stability, at room temperature its δ′-form crystal is predominant, and the dual melting processes and glass transition occur during the heating. The subsequent crystallization kinetic analysis with JMA, Ozawa and Mo methods demonstrates the mechanisms and crystallizability changing with the relative crystallinity, α, especially, during the primary and secondary crystallization stages. Moreover, applying the Vyazovkin method yields the dependence of the effective activation energy on crystallinity, from which the crystallization mechanisms are discussed in detail. Then the equilibrium melting temperature is determined, being 200.9 °C. Furthermore, the spherulitic growth analysis with the extended Hoffman–Lauritzen method produces the Regime I/II transition temperature of 158° C.Graphical abstractHighlights► A novel dendritic nylon-11 (DPA-11) is prepared and characterized using FTIR, TGA, WXRD, and DSC. ► The melting, glass relaxation and nonisothermal crystallization kinetics of DPA-11 is systematically studied by comparing with linear nylon-11. ►The isothermal crystallization kinetics of DPA-11 is analyzed using a number of classic methods (JMA, Ozawa, Mo and Vyazovkin). ► The equilibrium melting point of DPA-11 is determined from the Hoffman–Weeks method. ►The spherulitic growth of DPA-11 is examined using the extended Hoffman-Lauritzen method.
Co-reporter:Jintao Wan, Bo-Geng Li, Hong Fan, Zhi-Yang Bu, Cun-Jin Xu
Thermochimica Acta 2010 Volume 511(1–2) pp:51-58
Publication Date(Web):20 November 2010
DOI:10.1016/j.tca.2010.07.024
N,N,N′,N′-tetra(3-aminopropyl)-1,6-diaminohexane (TADH), a nonlinear multifunctional polyamine, was prepared and employed as a novel hardener for diglycidyl ether of bisphenol A (DGEBA). Nonisothermal reactions of DGEBA/TADH were systematically investigated with differential scanning calorimetry (DSC). According to the Málek method, the two-parameter Šesták–Berggren model was selected to simulate the reaction rate with a good match achieved, and a correlation of effective activation energies Eα with fractional conversion α was determined with the mode-free isoconversional Vyazovkin method. As α rose, Eα reduced quickly from ∼65 to 57 kJ/mol up to α ≈ 15%, then decreased slowly to ∼50 kJ/mol till α ≈ 75%, and finally dropped to ∼30 kJ/mol at full conversion. In addition, analysis of thermal stability of the cured DGEBA/TADH with thermogravimetric analysis (TGA) revealed that it possessed quite good thermal stability and increased residual char content at 600 °C in nitrogen. Furthermore, dynamic mechanical analysis (DMA) of the DGEBA/TADH network showed its relaxations were characterized by localized motions of hydroxyl ether segments (β relaxation) and cooperative motions of whole network chains (glass relaxation) at different temperature regions.
Co-reporter:Jintao Wan, Songsong Wang, Cheng Li, Dapeng Zhou, Jianguo Chen, Zheng Liu, Liqiong Yu, Hong Fan, Bo-Geng Li
Thermochimica Acta (20 February 2012) Volume 530() pp:32-41
Publication Date(Web):20 February 2012
DOI:10.1016/j.tca.2011.11.032
Co-reporter:Cheng Li, Jintao Wan, Ehsan Naderi Kalali, Hong Fan and De-Yi Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 7) pp:NaN3479-3479
Publication Date(Web):2014/12/19
DOI:10.1039/C4TA05740F
Aiming to develop a multi-functional flame retardant for epoxy resins, a novel bio-based eugenol derivative containing silicon and phosphorus [((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(2-methoxy-4,1-phenylene)bis(phenylphosphonochloridate), SIEPDP] was synthesized, and was further used to modify Mg–Al layered double hydroxide (SIEPDP-LDH). This modified SIEPDP-LDH was used as a novel nanoflame-retardant for bisphenol epoxy resins and compared with unmodified pristine LDH. X-ray diffraction (XRD) analysis justified that intercalation of SIEPDP into LDH increased the interlayer distance to 2.95 nm. Morphological analysis (XRD and TEM) revealed that the SIEPDP-LDH was dispersed well in the epoxy matrix in a partially exfoliated manner. Results from the cone calorimeter tests showed that even a low loading of SIEPDP-LDH into epoxy resin led to a significant decrease in heat release rate and total heat release compared to unmodified LDH/epoxy composites. More interestingly, SIEPDP-LDH/epoxy's UL-94 classification passed V-0 with only 8 wt% loading. Moreover, the addition of SIEPDP-LDH enabled the increase in the impact strength and modulus of the cured epoxy. These data indicated that SIEPDP-LDH could serve as not only a nanoflame retardant but a good reinforcing agent as well.
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