Co-reporter:Shan Li, Hao Li, Zheng Li, Heng Zhou, Ying Guo, Fenghua Chen, Tong Zhao
Polymer 2017 Volume 120(Volume 120) pp:
Publication Date(Web):30 June 2017
DOI:10.1016/j.polymer.2017.05.063
•A novel couple agent was synthesized, and used to link phenolic and polysiloxane.•Co-continuous structure in tens of nanometers was first obtained in this system.•Enhanced oxidation resistance and higher residual weight was achieved in hybrid.Co-continuous structure with tens of nanometers was obtained in polysiloxane modified phenolic resin by using of a novel couple agent. The couple agent was synthesized through addition reaction between resorcinol and isocyanatopropyltrimethoxysilane; then, it was introduced into the mixture of silane monomers, phenol and formaldehyde solution, in situ coupled the silane and phenolic during the polymerization reaction, and hybrid resin was obtained. Structure of the couple agent and hybrid resin was characterized by FTIR and NMR measurements. Through varying the amount of the couple agent, different morphology was obtained. The co-continuous structure of the cured hybrid with relatively higher amount of couple agent was confirmed by TEM and AFM observation, with the periodic length being about 50–65 nm. The oxidation resistance of the hybrid resin was greatly enhanced, the residual weight after oxidation at 1000 °C was much higher than that of pure phenolic resin.Download high-res image (287KB)Download full-size image
Co-reporter:Han Yu;Li Ye;Tuzi Zhang;Heng Zhou
RSC Advances (2011-Present) 2017 vol. 7(Issue 25) pp:15265-15271
Publication Date(Web):2017/03/06
DOI:10.1039/C6RA27187A
A novel synthetic method to prepare N-doped TiO2 catalysts was studied, by which a stable and homogeneous liquid polymeric precursor was produced, thus the catalysts can be loaded on suitable substrates, making catalysts facilely separated from waste water. The doping ratios and annealing temperatures were optimized by testing photodegradation of the products to methyl orange. To improve the Brunauer–Emmett–Teller surface areas of the catalyst, PEG was grafted to the structure of precursor polymer, by which an increase of 55% in BET surface areas and 20% in the photodegradation efficiencies was achieved. The crystalline phase was measured by X-ray diffraction and structural parameters were calculated by Xpert Highscores. FESEM and HRTEM pictures showed that the average particle size of the nitrogen doped and PEG modified catalyst reached to only 5 nm. X-ray photoelectron spectroscopy showed that nitrogen dope mode was interstitial. Using quartz fabrics as substrate, the loaded catalysts were facilely recycled and reused by 15 times without decay in photodegradation efficiency.
Co-reporter:Zheng Li;Yue Han;Ying Guo;Shuangshuang Xu;Fenghua Chen;Li Ye;Zhenhua Luo;Xiang Liu;Heng Zhou
RSC Advances (2011-Present) 2017 vol. 7(Issue 72) pp:45818-45823
Publication Date(Web):2017/09/22
DOI:10.1039/C7RA07181G
A porous covalent triazine-based framework (CTF) was prepared by a two-step strategy, where p-toluenesulfonic acid monohydrate (TsOH·H2O) was used as a catalyst. The porosity and gas storage capacity of the as-obtained framework was evaluated. In addition, the evolution of the chemical structure during the two stages was studied. Crystallite size was calculated to study the formation of the framework; the evolution of internal porosity has been discussed based on the results obtained. In the first step, a triazine-based polymer was formed at relatively low temperatures, and limited crystallites were developed. However, in the second step, a treatment at higher temperatures performed in an open system resulted in the purification of the chemical structure; furthermore, CTF lamellae with an improved ordered stacking developed, resulting in a dramatic increase in internal porosity.
Co-reporter:Shan Li, Fenghua Chen, Boxing Zhang, Zhenhua Luo, Hao Li, Tong Zhao
Polymer Degradation and Stability 2016 Volume 133() pp:321-329
Publication Date(Web):November 2016
DOI:10.1016/j.polymdegradstab.2016.07.020
Phenolic resin modified with silicon and boron (SNBA) was prepared by a simple two-step method: silane was firstly grafted onto phenolic resin, with silicon modified phenolic resin (SN) obtained; and then boric acid was introduced into SN. Boric acid, acting as a curing agent, catalyzed the self-polymerization of the silane in SN, and induced phase separation in the cured SNBA systems. Thermal stability was evaluated by thermogravimetric analysis (TGA). In air, the maximum decomposition rate (Dmax) decreased about 2%/min and the residual weight at 900 °C (R900) increased 16.7% after the introduction of boron and silicon. Oxyacetylene flame ablation also confirmed the improved ablative properties of the hybrids. The flame retardancy was studied by cone calorimeter. The total heat release (THR), the total smoke produce (TSP) and the rate of mass loss (RML) were decreased after the modification. The structure of the oxidized resin was characterized to study the mechanism of the improved thermal stability and flame retardancy. The oxide compounds of silicon and boron were formed during high temperature oxidation, which consumed some oxygen and hindered the permeation of heat and oxygen, protecting the matrix from thermal oxidation.
Co-reporter:Shan Li, Yue Han, Fenghua Chen, Zhenhua Luo, Hao Li, Tong Zhao
Polymer Degradation and Stability 2016 Volume 124() pp:68-76
Publication Date(Web):February 2016
DOI:10.1016/j.polymdegradstab.2015.12.010
In order to improve the thermal properties of the phenolic resin, silane with different degree of polymerization was introduced into phenolic resin by controllable reactions. Silicone phenolic resin was first synthesized via esterification reaction between methyltrimethoxysilane and novolac phenolic resin; then the degree of self-polymerization of silane was controlled by the hydrolyzation reaction. The designed structure of the hybrids was confirmed by Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (1H-NMR and 29Si-NMR), and curing of the hybrids was performed to obtain samples for microstructure observation and anti-oxidation evaluation. In situ self-polymerization of the silane during both the hydrolyzation and the curing processes led to phase separation in the cured hybrids, and the size of the phase structure increased with the increase of self-polymerization degree of the silane. Thermogravimetric analysis and high-temperature oxidation test were performed, and silane introduction was found to be beneficial to the enhancement of both thermal stability and oxidation resistance. Anti-oxidation mechanisms for the phenolic resin modified with silanes at different polymerization degree were compared and discussed.
Co-reporter:Yue Han, Shan Li, Fenghua Chen, Tong Zhao
Materials Today Communications 2016 Volume 6() pp:56-68
Publication Date(Web):March 2016
DOI:10.1016/j.mtcomm.2015.12.002
Carbon nanotube/carbon (CNT/C) composites derived from entangled CNT network and different precursors, phenolic or pitch, were fabricated in this work. Multi-step mechanical stretching, repeated polymer infiltration pyrolysis and graphitization were subsequently performed for the preparation. CNT alignment was accomplished in CNT/C derived from both phenolic and pitch precursors, while aligned carbon matrix could be only found in CNT/pitch derived CNT/C composites. Such phenomenon provided direct evidence for the promoting effect of CNT alignment on the graphitization of the carbon matrix. Mechanisms for the stretching induced alignment and the formation of aligned carbon matrix were proposed and discussed. The planar configuration of pitch molecules and its Pi–Pi stacking with CNT walls were considered beneficial for the stress induced graphitization, thus the carbon matrix could be aligned along the CNT walls. Based on the tensile and electrical conductivity measurements, we believed that CNT alignment dominated both mechanical and conducting performances of cured (stabilized) and carbonized CNT/C composites; while the alignment of carbon matrix played the decisive role in graphitized CNT/C. In addition, the carbonized composites could exhibit tensile strength as high as 1.2 GPa, while the electrical conductivity of graphitized samples was in the scale of 105 S/m.
Co-reporter:Li Ye, Kaikai Ge, Wenfeng Qiu, Weijian Han, Tong Zhao
Materials Letters 2015 Volume 141() pp:210-213
Publication Date(Web):15 February 2015
DOI:10.1016/j.matlet.2014.11.076
•Mesoporous SiC/ZrC/C ultra-thin composite ceramic fibers were prepared.•The microstructure and phase transition during pyrolysis process was investigated.•The composite fibers have a high crystalline quality and well element distribution.SiC/ZrC/C ultra-thin composite fibers were fabricated by high-temperature pyrolysis treatment of as-electrospun fibers from polycarbosilane and polyzirconoxane blend solution. The phase transition during pyrolysis process was investigated and the results revealed that polycarbosilane was converted to amorphous SiC and extra carbon, while polyzirconoxane was converted to t-ZrO2 at 1200 °C. Then, amorphous SiC was converted to cubic SiC and extra carbon from polycarbosilane served as carbon source for the carbothermal formation of cubic ZrC at 1600 °C. Meanwhile, the carbon oxide generated during the carbothermal reduction process led the ceramic fibers to form mesoporous structure. The obtained mesoporous fibers are highly crystalline SiC/ZrC/C ternary composite fibers.
Co-reporter:Zibin Guo, Zhe Liu, Li Ye, Kaikai Ge, Tong Zhao
Materials Letters 2015 Volume 142() pp:49-51
Publication Date(Web):1 March 2015
DOI:10.1016/j.matlet.2014.11.068
•Lignin-phenol-formaldehyde resin (LPF) was synthesized by using lignin as partial substitution of phenol in phenol-formaldehyde resin.•The carbon fibers were obtained by using LPF resin as carbon precursor and BN preceramic polymer as a cross-linking agent.•LPF derived carbon fibers exhibited good dimensional and thermal stability.Lignin-phenol-formaldehyde resin (LPF) derived submicron carbon fibers were successfully prepared by using LPF which was synthesized by using lignin as partial substitution of phenol in phenol-formaldehyde resin as precursor. The carbon fibers were obtained through electrospinning the LPF/polyvinylpyrrolidone (PVP)/dimethylformamide (DMF) solution followed by successive stabilization with BN preceramic polymer and carbonization processes. The chemical structure of LPF resin was studied by Fourier transform infrared spectroscopy (FTIR) and the morphology properties of carbon fibers were studied by scanning electron microscopy (SEM). The results showed that stabilized by immerging in BN precursor solution and then stabilized at 250 °C in the air, the morphology generated during the electrospinning processing was successfully retained throughout the stabilization and carbonization processes. LPF derived carbon fibers exhibited homogeneous diameter distribution and smooth surface.
Co-reporter:Ying Guo;Yue Han;Feng Liu;Heng Zhou;Fenghua Chen
Journal of Applied Polymer Science 2015 Volume 132( Issue 46) pp:
Publication Date(Web):
DOI:10.1002/app.42791
ABSTRACT
In this study, novel fluorinated bismaleimide (BMI) resins were prepared by the copolymerization of 2,2′-bis[4-(4-maleimidephenoxy)phenyl]hexafluoropropane (6FBMP) and diallyl hexafluorobisphenol A (6FDABPA) to enhance their dielectric properties. The dielectric properties of the resins were investigated in the frequency range 7–18 GHz through a cavity method. Through the incorporation of a hexafluoroisopropyl group with the polymer chain, the dielectric constant (ε) was effectively decreased because of the small dipole and the low polarizability of the carbon-fluorine (CF) bonds. The 6FBMP/6FDABPA resin possessed excellent dielectric properties, with ε being 2.88 and the dielectric loss being 0.009 at 10 GHz and 25°C. In comparison with the 4,4′-bismaleimidodiphenylmethane (BDM)/2,2′-diallyl bisphenol A (DABPA) resin, the glass-transition temperature (Tg) of 6FBMP/6FDABPA decreased. The flexible ether group in the long chain of 6FBMP was considered to disrupt chain packing and cause a decreased crosslinking density and a lower Tg. 6FBMP/6FDABPA showed a similar thermal decomposition temperature and good thermal properties like the BDM/DABPA resin, whereas the impact strength of the 6FBMP/6FDABPA resin was almost 1.6 times higher than that of the BDM/DABPA resin. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42791.
Co-reporter:Shan Li, Fenghua Chen, Yue Han, Heng Zhou, Hao Li, Tong Zhao
Materials Chemistry and Physics 2015 Volume 165() pp:25-33
Publication Date(Web):1 September 2015
DOI:10.1016/j.matchemphys.2015.07.054
•Hybrid resin containing phenolic resin and silicone intermediate was prepared.•The morphology evolution mechanism of the hybrid during curing was discussed.•Thermal stability of the cured hybrids was improved.In this paper, hybrids containing novolac phenolic resin (NR) and silicone intermediate (SI) were investigated. Compatibility between the two components was enhanced by modifying NR with a coupling agent, γ-(2,3-epoxypropoxy) propyltrimethoxysilane (KH560). SI with silanol groups was synthesized by the hydrolysis of phenyltrimethoxysilane and dimethyldimethoxysilane. Different amount of SI was blended with modified NR, and the corresponding yellow transparent samples were obtained and used for the subsequent curing and microscopic observation. SI-rich nanoparticles were found to be evenly dispersed in the initial sample and further coarsened to nano- and micro-particles. The size and amount of the particles increased with the SI loading. The morphology evolution mechanism was discussed based on microscopic observation and chemical reaction processes. Thermal stability of the cured hybrids was characterized by thermalgravimetric analysis. Temperatures at 5% and 10% mass loss and residual weight at 900 °C were found to increase with the SI loading. Furthermore, carbon retention after high temperature oxidation was also increased.
Co-reporter:Yue Han, Heng Zhou, Shan Li, Li Ye, Fenghua Chen, Yuanchao Li, Tong Zhao
Surface and Coatings Technology 2015 Volume 276() pp:502-506
Publication Date(Web):25 August 2015
DOI:10.1016/j.surfcoat.2015.06.024
•A facile strategy for coating carbon nanotubes with aluminium nitride was developed.•The strategy involved gradual sedimentation and ceramization of the precursor.•The oxidation resistance of the product was significantly improved.•The coating mechanism was proposed and verified.Carbon nanotubes (CNTs) were coated by aluminium nitride (AlN) via a simple gradual sedimentation and ceramization route. Following a designed sequence, CNTs were coated with aluminium-containing precursor and carbon source, which were dissolved in a mixed solution of isopropanol and toluene; the subsequent pyrolysis and carbothermal nitridation generated AlN layer onto the CNT surface. The coating thickness was tunable from 1 to 2 nm, while maintaining defect free. Thermogravimetric analysis revealed that the onset oxidizing temperature of the product delayed from 525 to 707 °C, and more than 90% CNTs survived the oxidation. Furthermore, the coating mechanism was proposed and verified.
Co-reporter:Tao Cai, Wen-Feng Qiu, Dan Liu, Wei-Jian Han, Li Ye, Ai-Jun Zhao and Tong Zhao
Dalton Transactions 2013 vol. 42(Issue 12) pp:4285-4290
Publication Date(Web):12 Dec 2012
DOI:10.1039/C2DT32428H
Soluble organometallic polymers containing zirconium and silicon were synthesized by a salt metathesis reaction. The molecular weight of the polymers was measured by GPC and the corresponding structures were identified by 13C NMR and FT-IR. After heat treatment of the polymers under argon at 1400 °C for 2 h, ZrC/SiC composites with different molar ratios of crystalline phases were obtained and characterized by XRD, elemental analysis, SEM and Raman spectroscopy. The crystalline size of the composites was approximately 100 nm–200 nm and the elements were well distributed at the different sites in the ceramics. The Raman results indicated that the ceramic residue could be considered as ZrC/SiC/C ternary composites.
Co-reporter:Zibin Guo;Hao Li;Weijian Han
Journal of Applied Polymer Science 2013 Volume 128( Issue 5) pp:3356-3364
Publication Date(Web):
DOI:10.1002/app.38441
Abstract
To improve the thermal stability of phenolic resins, silicon- and boron-containing phenolic resin (SBPR) was synthesized from novolac-type phenolic resin using polyborosilazane (PBSZ) as curing agent, which can react with novolac resin at room temperature. The curing mechanism was studied by Fourier Transform infrared spectroscopy. The thermal and morphological properties of SBPR were studied by thermogravimetric analysis (TG) and scanning electron microscopy (SEM) respectively. TG results showed that the thermal properties of SBPR were much better than the corresponding novolac resin cured with hexamethylenetetramine, both for the initial decomposition temperatures (Td) and residual weight at 900°C. The SEM and EDX results showed that the SBPR hybrids after oxidation were covered with SiO2 glass coatings, which improved the thermo-oxidative resistance of SBPR. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Guangzhu Li;Zhenhua Luo;Weijian Han;Yongming Luo;Caihong Xu
Journal of Applied Polymer Science 2013 Volume 130( Issue 5) pp:3794-3799
Publication Date(Web):
DOI:10.1002/app.39642
ABSTRACT
A serial of addition-curable hybrid resins for resin matrix of advanced composites are prepared by thermal prepolymerization between acetylene-functional benzoxazine(BZ) and polyvinylsilazane(PSN) with various weight ratios. Processing capability of BZ-PSN resin is investigated by measuring viscosity. Cure behavior is investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectra. Thermal property of cured BZ-PSN resin is investigated by Thermogravimetric analysis (TGA) and Dynamic mechanical analysis (DMA). BZ-PSN resin shows a low viscosity of 40–180 mPa·s between 60 and 90°C, and maintains the low viscosity for 6 h, indicating that the resin is suitable for resin transfer molding (RTM) process to fabricate composites. DSC results show that BZ-PSN resin can be cured completely at about 250°C without adding any other curing additives. FT-IR shows the reaction between BZ and PSN take place. TGA shows that thermal stability of cured BZ-PSN resin is increased with the content of polyvinylsilazane increasing both in nitrogen and in air. DMA shows cured hybrid resins have excellent thermal properties. The excellent processability and thermal properties suggest that BZ-PSN resin is a promising candidate for resin matrix of advanced composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3794–3799, 2013
Co-reporter:Kaikai Ge, Li Ye, Weijian Han, Yue Han, Caihong Xu, Tong Zhao
Materials Letters 2013 Volume 112() pp:124-128
Publication Date(Web):1 December 2013
DOI:10.1016/j.matlet.2013.08.122
Co-reporter:Li Ye;Wenfeng Qiu;Hao Li;Aijun Zhao
Journal of Sol-Gel Science and Technology 2013 Volume 65( Issue 2) pp:150-159
Publication Date(Web):2013 February
DOI:10.1007/s10971-012-2919-z
Zr-containing organic aerogels were synthesized by ligand substitution reaction of polyzirconoxone and 2, 4-dihydroxybenzoic acid, followed by polymerization with formaldehyde, and then supercritical drying using CO2. After carbonization and carbothermal reduction under an argon atmosphere, ZrCO/C composite aerogels with controllable zirconium content (47.8–78.6 wt%) were obtained. The carbothermal reduction was substantially completed at 1,500 °C, and the obtained ZrCO/C composite aerogels exhibit low oxygen contents (9.4–6.7 wt%) and high surface areas (589–147 m2/g). Pore morphologies of the ZrCO/C composite aerogels were investigated in detail by nitrogen sorption measurements, scanning electron microscopy and its associated energy-dispersive X-ray microanalysis measurements. The results show that the aerogels are composed of carbon framework and Zr-conglomerations, and the surface area of aerogel is severely affected by its zirconium content. The presence of reductive ZrC crystals can greatly enhance the oxidation resistance ability of amorphous carbon framework and prevent collapse.
Co-reporter:Weijian Han;Li Ye;Jidong Hu
Journal of Applied Polymer Science 2012 Volume 123( Issue 3) pp:1384-1391
Publication Date(Web):
DOI:10.1002/app.33567
Abstract
A new kind of acetylene terminated silazanes, N-(3-acetylenephenyl)-diorganosilazanes (abbreviated as APSZs) with three kind of substituents, were synthesized by the aminolysis of dichlorosilane with 3-aminophenylacetylene (3-APA). Structure of APSZs was confirmed by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR). Thermal behavior of the cured silazanes was determined by thermogravimetry analysis (TGA), revealing that cured silazanes exhibited high temperature resistance. The ceramic yields of APSZ-Me2, APSZ-MeVi, and APSZ-Ph2 at 1000°C under nitrogen were 77.6, 81.9, and 68.7%, respectively. The peak separation of derivative thermogravimetric data was employed to evaluate the three major regions of the thermolysis, and the kinetic parameters of thermolysis were calculated by the method of Kissinger from dynamic thermogravimetric measurement in nitrogen atmosphere at several different heating rates. Influence of substituents on the thermal behavior of cured silazanes in each separated region was discussed. The results showed that the vinyl derivative exhibit higher thermal stability than methyl and phenyl derivatives due to the high decomposition activation energy and small pendant group. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Yuntao Li, Weijian Han, Hao Li, Jingbo Zhao, Tong Zhao
Materials Letters 2012 Volume 68() pp:101-103
Publication Date(Web):1 February 2012
DOI:10.1016/j.matlet.2011.10.060
ZrB2/ZrC/SiC precursors were prepared in a one-pot reaction of polyzirconoxanesal with boric acid and poly(methylsilylene)ethynylene. The pyrolysis of the precursors at 1400 °C in argon led to formation of the nano-crystalline ZrB2/ZrC/SiC ceramics. The ceramics were characterized by inductively coupled plasma (ICP), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the ceramics were mainly composed of zirconium diboride, zirconium carbide and β-silicon carbide phases. The average size of the ZrB2, ZrC and SiC grains was approximately 100 nm. Elemental analysis showed that the molar ratio of crystal phases was ZrB2/ZrC/SiC = 2/1.35/1, and the total weight ratio of zirconium, boride and silicon was above 81% in the ceramics. The presence of SiC obviously restrained the oxidation of ZrC and ZrB2 at 1000 °C.Highlights► ZrB2/ZrC/SiC ceramic was prepared in one-pot method from liquid precursors. ► The average size of the ZrB2, ZrC and SiC grains was approximately 100 nm. ► Presence of SiC obviously restrained th e oxidation of ZrC and ZrB2 at 1000 °C.
Co-reporter:Zhihong Ji, Li Ye, Xueyu Tao, Hao Li, Wenfeng Qiu, Tao Cai, Yanbin Jiang, Tong Zhao
Materials Letters 2012 Volume 71() pp:88-90
Publication Date(Web):15 March 2012
DOI:10.1016/j.matlet.2011.11.020
Using phenolic resoles and zirconium citrate as carbon and zirconium precursors, respectively, and triblock PEO–PPO–PEO copolymers of Pluronic F127 as templates, followed by carbonization under Ar atmosphere, ordered mesoporous ZrO2/C nanocomposite has been successfully fabricated. After magnesiothermic reduction at rather low temperature (700 °C), ZrC/C nanocomposite with high surface area (344 m2/g) and narrow pore-size distribution was obtained. Thermogravimetric measurements under air show that the collapse temperature improved from 400 °C to 480 °C for the ZrO2/C sample and the ZrC/C sample, which illustrates that the presence of reductive ZrC nanocystals can greatly enhance the oxidation resistance ability of carbon frameworks and prevent collapse.
Co-reporter:Wei Jian Han, Li Ye, Ji Dong Hu, Tong Zhao
Chinese Chemical Letters 2011 Volume 22(Issue 2) pp:139-142
Publication Date(Web):February 2011
DOI:10.1016/j.cclet.2010.10.001
Novel acetylene terminated silazane compounds, with three types of substituent, were synthesized by the aminolysis of dichlorosilane with 3-aminophenylacetylene (3-APA). Thermal property of the compounds is studied by thermogravimetry analysis (TGA). It shows that the acetylene terminated silazane has high temperature resistance. The char yield at 1000 °C is 77.6, 81.9 and 68.7 wt% for methyl, vinyl, and phenyl substituted silazane, respectively. The pyrolysis kinetics of the silazane is investigated by non-isothermal thermogravimetric measurement. The pyrolysis undergoes three stages, which is resolved by PEAKFIT. The kinetic parameters are calculated by the Kissinger method. The role of functionalities on the thermal resistance is discussed. The vinyl-silazane exhibits higher thermal stability because of higher cross-linking density.
Co-reporter:Zhihong Ji, Weijian Han, Li Ye, Yanbin Jiang, Hao Li, Tong Zhao
Materials Letters 2011 Volume 65(Issue 2) pp:185-187
Publication Date(Web):31 January 2011
DOI:10.1016/j.matlet.2010.09.060
Ordered mesoporous silicon carbide with a high specific surface area was prepared using poly(methlysilylene)ethynylene by utilizing mesoporous silica SBA-15 as a template which was etched off after pyrolysis in an argon atmosphere. The obtained sample is mainly composed of randomly oriented β-SiC crystallites, and it exhibits an ordered mesoporous structure, a high surface area of 511 m2/g, a large pore volume of 0.61 cm3/g, and narrow pore-size distributions of 4 nm. The rough surface and high order of the material that result from the strong interconnections of the SiC products are the main reasons for such high surface areas. The mesoporous ceramics have stability even after re-treatment at 900 °C for 2 h under an air atmosphere.
Co-reporter:Ming Yang;Song Shi;Mingcun Wang;Zhenhua Luo;Wenfeng Qiu;Yuhui Wang;Zhihai Feng
Polymers for Advanced Technologies 2011 Volume 22( Issue 11) pp:1471-1477
Publication Date(Web):
DOI:10.1002/pat.1630
Abstract
A novel hydroxyl-ethynyl-arene (HEA) resin was synthesized via Aldol condensation and Sonogashira reaction. The structure of the obtained resin was confirmed by the techniques of mass spectroscopy (MS), gel permeation chromatography (GPC), proton nuclear magnetic resonance spectroscopy (1H-NMR), Fourier transform infrared spectroscopy, (FT-IR) and elemental analysis (EA). Differential scanning calorimetry (DSC) results showed an exotherm at the temperature range of 187°C–245°C, attributable to crosslinking reaction of the acetylene groups. After thermal cure, the obtained cured resin possessed excellent thermal stability. Thermal gravimetric analysis (TGA) in nitrogen showed the Td5 (temperature of 5% weight loss) was about 400°C, and the char yield in nitrogen was about 78% at 900°C. The laminate composite of HEA resin was prepared and its mechanical and thermal properties were determined. The usefulness of the HEA resin as matrix for ablative composite was evaluated. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Xueyu Tao;Wenfeng Qiu;Hao Li
Polymers for Advanced Technologies 2010 Volume 21( Issue 4) pp:300-304
Publication Date(Web):
DOI:10.1002/pat.1664
Abstract
A novel preceramic polymer, polyzirconoxanesal (PZS), was synthesized efficiently by one-pot protocol. The PZS polymer was characterized by the techniques of Fourier transform infrared spectra (FTIR), nuclear magnetic resonance (1H-NMR and 13C-NMR) and gel permeation chromatography (GPC). The precursor exhibited excellent solubility and rheology for the processing of ceramic matrix fiber composites. Pyrolytic conversion of the preceramic polymer was studied by means of thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM) and element analysis. It is suggested that the polymer decomposed completely at 600°C and nanosized ZrC is formed at 1300°C for 2 hr in argon atmosphere with a yield of 68.5%. To the best of our knowledge, this is the lowest temperature reported in the literatures for preparing ZrC ceramics from preceramic polymers. The obtained ZrC particles exhibit spherical morphology with size ranged in 20–100 nm. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Feng Liu;Jinge Liu
Journal of Applied Polymer Science 2010 Volume 115( Issue 5) pp:3103-3109
Publication Date(Web):
DOI:10.1002/app.31174
Abstract
Novel thermosetting monomers possessing both maleimide and propargyl groups were first designed and synthesized. The monomers included N-(2-propargyloxyphenyl) maleimide (2-PPM), N-(3-propargyloxyphenyl) maleimide (3-PPM), and N-(4-propargyloxyphenyl) maleimide (4-PPM), and their structures were confirmed with Fourier transform infrared (FTIR) spectroscopy, 1H-NMR, and elemental analysis. The cure behaviors of these monomers were characterized with differential scanning calorimetry and FTIR spectroscopy, and the results indicated that the monomers had a broader processing window than normal bismaleimide (BMI) resins. The thermal properties of the cured monomers were characterized with thermogravimetric analysis and dynamic mechanical analysis. The 5% mass loss temperatures of the cured monomers were high (ca. 400°C), and the glass-transition temperatures of cured 2-PPM, 3-PPM, and 4-PPM were 386, 373, and 387°C, respectively, which were much higher than those of typical commercial blended BMI resins. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Ming Yang;Song Shi;Mingcun Wang;Yuhui Wang;Zhenhua Luo;Zhihai Feng
Journal of Applied Polymer Science 2010 Volume 117( Issue 2) pp:714-719
Publication Date(Web):
DOI:10.1002/app.31237
Abstract
A novel silicon-containing resin (ESA resin) was successfully synthesized by the condensation reaction of lithium arylacetylide with chlorosilane in high yields. The resin was characterized by the techniques of FTIR, 1H-NMR, 29Si-NMR, and gel permeation chromatography. Thermal cure process was monitored by DSC and FTIR methods. This resin could melt at around 100°C and thermally cured at 200–250°C with low exothermal enthalpy. Owing to the high aryl groups containing and the complete crosslinking of ethynyl groups, the cured ESA resin exhibited excellent thermal stability and high char yield. The decomposition temperature of the cured resin was at 510°C, and the residue yield at 900°C was 82.9% in N2. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Wei Jian Han, Ji Dong Hu, Li Ye, Song Shi, Xue Yu Tao, Tong Zhao
Chinese Chemical Letters 2010 Volume 21(Issue 11) pp:1299-1302
Publication Date(Web):November 2010
DOI:10.1016/j.cclet.2010.06.008
Oligo(methylsilylene)-ethynylene polymer with crosslinkable ethynyl unit in the main chain was synthesized by condensation of α,ω-dicholorooligo(methylsilane) with dilithioacetylene. The as-synthesized polymer was characterized by GPC, FT-IR and NMR. The results showed ethynyl group was successfully introduced to the polymer main chain. The ceramic yield was dramatically increased by the cross-polymerization of ethynyl group, and the excess silicon of PMS was compensated. Near-stoichiometric (C/Si = 1.17) and partial crystallization β-SiC monoliths were obtained by pressureless pyrolysing PSPA at 1200 °C in a high yield (73.6 wt%).
Co-reporter:Xue Yu Tao, Wen Feng Qiu, Hao Li, Tong Zhao
Chinese Chemical Letters 2010 Volume 21(Issue 5) pp:620-623
Publication Date(Web):May 2010
DOI:10.1016/j.cclet.2010.01.002
A new polymer, polyzirconoxanesal (PZS), is synthesized from the reaction of zirconium oxychloride octahydrate (ZrOCl2·8H2O) with acetylacetone (Hacac) and salicyl alcohol (SA) by one-pot protocol. The polymer is soluble in common organic solvents, such as ethanol, methanol, acetone, tetrahydrofuran and chloroform, and exhibits rheology with viscosity of 100–300 mpa s at 25 °C. These properties are suitable for uses in fabrication of ceramic matrix fiber composites. Pyrolysis of this polymer at 1300 °C in argon provides nanosized ZrC with spherical morphology and size of 20–100 nm.
Co-reporter:Zhihong Ji, Shuguang Liang, Yanbin Jiang, Hao Li, Zhimin Liu, Tong Zhao
Carbon 2009 Volume 47(Issue 9) pp:2194-2199
Publication Date(Web):August 2009
DOI:10.1016/j.carbon.2009.04.001
A Ru-containing ordered mesoporous carbon with a high specific surface area of 2186 m2/g was synthesized through evaporation-induced multi-constituent co-assembly method, wherein soluble resol polymer is used as the carbon precursor, silicate oligomers as the inorganic precursor, triblock copolymer as the template, and RuCl3 · 3H2O as the Ru precursor. The resultant sample was characterized by X-ray diffraction, nitrogen sorption, transmission electron microscopy and scanning electron microscopy. The results showed that the carbon material exhibited highly ordered mesoporous structure, and the ruthenium particles with sizes of ∼2 nm were uniformly distributed in the carbon matrix. The sample was used to catalyze benzene hydrogenation, which displayed high efficiency for this reaction.
Co-reporter:Mingcun Wang, Ming Yang, Tong Zhao, Jian Pei
European Polymer Journal 2008 Volume 44(Issue 3) pp:842-848
Publication Date(Web):March 2008
DOI:10.1016/j.eurpolymj.2008.01.002
Novel phenolic resins with high ethynyl contents were realized via azo coupling reaction between phenol units and diazonium of 3-ethynylaniline. If Novolac and high-ortho Novolac resins were used as the starting materials directly, the ratio of ethynyl groups to phenolic rings was ca 70%; while the ratio was 100% for the resin from Friedel–Craft polycondensation of 4-(3-ethynylphenyl)salicyl alcohol. All the resins were readily soluble in acetone and ethanol, and meltable at temperatures below 100 °C. The resins underwent thermal addition-type cure with a broad exotherm of around 140–280 °C, and the starting curing temperature showed a downward drift with increase in the ethynyl content. The thermal properties of the cured resins, determined from thermogravimetric analysis (TGA), were considerably superior to those of Novolac- and Resole-type phenolic resins. The initial decomposition temperatures were at ca 400 °C, and the anaerobic carbon yields were ca 80% for all the resins.
Co-reporter:Wanwan Li;Feng Liu;Liuhe Wei
Journal of Applied Polymer Science 2008 Volume 107( Issue 1) pp:554-561
Publication Date(Web):
DOI:10.1002/app.26300
Abstract
The curing behavior of polydimethylsiloxane-modified allylated novolac/4,4′-bismaleimidodiphenylmethane resin (PDMS-modified AN/BDM) was investigated by using Fourier transform infrared spectrometry (FTIR) and differential scanning calorimetry. The results of FTIR confirmed that the curing reactions of the PDMS-modified AN/BDM resins, including “Ene” reaction and Diels–Alder reaction between allyl groups and maleimide groups, should be similar to those of the parent allylated novolac/4,4′-bismaleimidodiphenylmethane (AN/BDM) resin. The results of dynamic DSC showed that the total curing enthalpy of the PDMS-modified AN/BDM resins was lower than that of the parent resin. Incorporation of polydimethylsiloxane (PDMS) into the backbone of the allylated novolac (AN) resin favored the Claisen rearrangement reaction of allyl groups. The isothermal DSC method was used to study the kinetics of the curing process. The experimental data for the parent AN/BDM resin and the PDMS-modified AN/BDM resins exhibited an nth-order behavior. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Zhenhua Luo;Liuhe Wei;Wanwan Li;Feng Liu
Journal of Applied Polymer Science 2008 Volume 109( Issue 1) pp:525-529
Publication Date(Web):
DOI:10.1002/app.28090
Abstract
An isothermal differential scanning calorimetry (DSC) study on the cure kinetics was performed on N-(3-acetylenephenyl)maleimide (3-APMI) monomer to determine a suitable cure model. The 3-APMI monomer reported in our prior article was a novel aromatic maleimide monomer with an acetylene terminal that would be an ideal candidate for heat-resistant composites. The isothermal DSC study was carried out in the temperature range 150–200°C. Although the cure temperatures were different, the shapes of the conversion curves were similar, and all of the cure reactions could be described by an nth-order kinetic model. In particular, the cure reaction at the initial stage was a first-order kinetic reaction. The cure kinetic parameters of the 3-APMI monomer, including the reaction model, activation energy, and frequency factor, were determined. This information was very useful for defining the process parameters, final properties, and quality control of the cured 3-APMI monomer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Zhenhua Luo, Liuhe Wei, Feng Liu, Tong Zhao
European Polymer Journal 2007 Volume 43(Issue 8) pp:3461-3470
Publication Date(Web):August 2007
DOI:10.1016/j.eurpolymj.2007.05.005
N-(3-acetylenephenyl)maleimide (3-APMI), was synthesized by reacting 3-aminophenylacetylene (3-APA) with maleic anhydride by the usual two-step procedure that included ring-opening addition to give maleamic acid, followed by cyclodehydration to maleimide. Structure of the monomer was confirmed by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), elemental analysis (EA) and mass spectrum (MS). Thermal cure of the monomer was investigated by differential scanning calorimetry (DSC) and FTIR, then processing parameters and cure kinetics parameters were determined. The results showed that the monomer possesses excellent reactivity, whose cure peak temperature was 197.9 °C and cure reaction was almost complete after 4 h cure at 200 °C. Thermal properties of the cured monomer were determined by dynamic mechanical analysis (DMA) and the results show that glass transition temperature (represented by onset temperature of storage modulus) is high up to 460 °C. The results of thermogravimetry analysis (TGA) reveal that the cured monomer possessed excellent thermal stability, whose 10% weight loss temperature (T10%) is 515.6 °C and char yield at 800 °C is 59.1%. All these characteristics make the 3-APMI monomer be an ideal candidate for matrix of thermo-resistant composites.
Co-reporter:Wanwan Li;Feng Liu;Liuhe Wei
Journal of Applied Polymer Science 2007 Volume 104(Issue 6) pp:3903-3908
Publication Date(Web):27 MAR 2007
DOI:10.1002/app.26051
Allylated novolac/4,4′-bismaleimidodiphenylmethane resin (AN/BDM) had been modified with well-defined inorganic building blocks-polyhedral oligomeric silsesquioxane (POSS). Octamaleimidophenyl polyhedral silsesquioxane (OMPS) was used as the cocuring reagent of the AN/BDM resin to prepare POSS-modified AN/BDM resin, and POSS content was between 0 and 17.8 wt %. The curing reaction of the POSS-modified AN/BDM resin was monitored by means of Fourier transform infrared spectroscopy (FTIR), and the results revealed that maleimide groups on OMPS molecule could undergothe curing reaction between allyl groups and maleimide groups. Therefore, the crosslinked network containing POSS was formed. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to study the morphology of the cured POSS-modified AN/BDM resins. The homogeneous dispersion of POSS cages in AN/BDM matrices was evidenced. Thermogravimetric analysis (TGA) indicated that incorporation of POSS into AN/BDM crosslinked network led to enhanced thermal stability. The improved thermal stability could be ascribed to higher crosslink density and inorganic nature of POSS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3903–3908, 2007
Co-reporter:Zhen-hua Luo;Liu-he Wei;Feng Liu
Polymer Composites 2007 Volume 28(Issue 2) pp:180-185
Publication Date(Web):28 FEB 2007
DOI:10.1002/pc.20280
A series of allyl-functional novolac resin with various allylation degree, from 32.4 to 114.6%, were synthesized and then blended reactively with 4,4′-bismaleimide biphenyl methane (BMI) at a weight ratio of 2.50:1 to get BMI-modified allyl-functional novolac (BMAN) resins. BMAN resins were used as matrix resin to fabricate BMAN/Silica cloth composites by compression molding process. Heat-resistant properties of the composites were evaluated by means of dynamic mechanical analysis. The results indicated that thermal resistance of the composites increased as allylation degree of BMAN resins increased. Mechanical properties of the composites, including interlaminar shear strength (ILSS) and flexural strength at room temperature and 300°C, were determined, and the results showed that with increase in allylation degree of matrices the ILSS and flexural strength values of composites at room temperature decreased, but the values of ILSS and flexural strength at 300°C increased. Scanning electron microscope morphology analysis of fracture surface for composites revealed that tough interphase was responsible for the better mechanical properties of the composites based on lower allylation degree resins. POLYM. COMPOS., 28:180–185, 2007. © 2007 Society of Plastics Engineers
Co-reporter:Zhenhua Luo;Liuhe Wei;Feng Liu
Journal of Applied Polymer Science 2007 Volume 104(Issue 5) pp:2822-2829
Publication Date(Web):28 FEB 2007
DOI:10.1002/app.25706
A series of allyl-functional novolac (AN) resins with various allylation degree, from 32.4 to 114.6%, were synthesized and blended reactively with 4,4′-bismaleimide biphenyl methane (BMI) at a weight ratio of 2.50 : 1 to get BMI-modified and allyl-functional novolac (BMAN) resins. Structural characteristics of the resins were determined by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1HNMR) techniques. Processing properties of BMAN resin system was evaluated by solubility, rheology, and thermal gelation, and the results show that processing properties of BMAN resins were excellent and could be tailored by changing allylation degree of AN resins. Differential scanning calorimetry (DSC) was used to evaluate cure reactivity of BMAN resin system, and the results reveal that the resins with higher allylation degree possessed better cure reactivity. Thermal properties were evaluated by means of dynamic mechanical analysis (DMA) and thermogravimetry analysis (TGA) techniques. The results reveal that with increase in allylation degree of resins the thermal stability of BMAN resins increased because of increase in crosslinking density, but char-yields of the above resins at 800°C decreased in turn. Understanding of the relationship between allylation degree and properties of the resins would be useful to direct the design of material to meet different requirements of applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:Yanbin Jiang;Dujin Wang
Journal of Applied Polymer Science 2007 Volume 104(Issue 5) pp:2799-2806
Publication Date(Web):27 FEB 2007
DOI:10.1002/app.25962
Microcapsules with phenolic resin (PFR) shell and n-hexadecane (HD) core were prepared by controlled precipitation of the polymer from droplets of oil-in-water emulsion, followed by a heat-curing process. The droplets of the oil phase are composed of a polymer (PFR), a good solvent (ethyl acetate), and a poor solvent (HD) for the polymer. Removal of the good solvent from the droplets leads to the formation of microcapsules with the poor solvent encapsulated by the polymer. The microstructure, morphology, and phase-change property as well as thermal stability of the microcapsules were systematically characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimety (DSC), and thermogravimetric analysis (TGA). The phase-change microcapsules exhibit smooth and perfect structure, and the shell thickness is a constant fraction of the capsule radius. The initial weight loss temperature of the microcapsules was determined to be 330°C in N2 and 255°C in air, respectively, while that of the bulk HD is only about 120°C both in air and N2 atmospheres. The weight loss mechanism of the microcapsules in different atmosphere is not the same, changing from the pyrolysis temperature of the core material in N2 to the evaporation of core material caused by the fracture of shell material in air. The melting point of HD in microcapsules is slightly lower than that of bulk HD, and a supercooling was observed upon crystallization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:Ming-Cun Wang
Journal of Applied Polymer Science 2007 Volume 105(Issue 5) pp:2939-2946
Publication Date(Web):16 MAY 2007
DOI:10.1002/app.26465
Novel binary blends of polyarylacetylene (PAA resin) with propargyl-novoalc resin (PN resin) was prepared. The miscibility, processing capability, and thermal properties of the blends were investigated. The evaluation of the blends as matrice for thermostructural composites was also studied. The blends were highly miscible. In comparison to PAA resin, the blends exhibited remarkably improved processability suitable to various process techniques (especially resin transfer molding, RTM). By dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), it was revealed that the cured blends possessed high thermal stability. The blend with 1/2 PN content was evaluated as matrices. The high temperature mechanical properties of silica laminates were compared favorably with those of conventional phenolic laminate. When compared with pure PAA laminate, the blend matrix laminate exhibited improved mechanical properties at both ambient temperature and high temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:Wanwan Li, Feng Liu, Liuhe Wei, Tong Zhao
European Polymer Journal 2006 Volume 42(Issue 3) pp:580-592
Publication Date(Web):March 2006
DOI:10.1016/j.eurpolymj.2005.08.015
Polydimethylsiloxane was incorporated into the backbone of allylated novolac (AN) to improve the toughness of allylated novolac/4,4′-bismaleimidodiphenylmethane(AN/BDM). Polydimethylsiloxane–modified allylated novolac (PDMS–AN) was synthesized via the hydrosilylation reaction between the terminal Si–H groups of α,ω-hydrogen functional dimethylsiloxane oligomer (PDMS) and the allyl groups of allylated novolac resin (AN). The blend of PDMS–AN and 4,4′-bismaleimidodiphenylmethane (BDM) could undergo co-cure reaction at elevated temperatures, and the co-cure system was denoted PDMS–AN/BDM. PDMS–AN was characterized by Fourier transfer infrared (FTIR) spectroscopy, 1H and 29Si nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The curing behavior of PDMS–AN/BDM was evaluated by differential scanning calorimetry (DSC). The morphology of the cured resins was examined by scanning electron microscope (SEM) and dynamic mechanical analysis (DMA). The effects of the content and number-average molecular weight of the incorporated PDMS on the mechanical and thermal properties of PDMS–AN/BDM were investigated. The results indicated that the incorporation of PDMS could improve the impact toughness of AN/BDM.
Co-reporter:Mingcun Wang;Liuhe Wei
Journal of Applied Polymer Science 2006 Volume 99(Issue 3) pp:1010-1017
Publication Date(Web):18 NOV 2005
DOI:10.1002/app.22592
In this article, propargyl functionalized novolac resins (PN resins), with varying propargyl contents and varying molecular weights, were synthesized conveniently. The structural characteristics were determined by 1HNMR and FTIR methods. Thermal cure studies revealed that the uncatalyzed thermal cure was remarkably affected by propargyl extent, while it was hardly affected by molecular weight. The processability of the as-prepared PN resins was excellent as matrix of composite materials. The cure mechanism was complicated; postcure at high temperature was required to achieve entire crosslink formation. Both dynamic mechanical analysis and thermogravimetric analysis showed that the cured PN resins had substantially improved thermal mechanical properties and thermal stability in comparison to conventional cured phenolics. High propargyl extent was preferred for high thermal stability. The results show that PN resin is one of the ideal candidates for advanced composites matrices in thermostructural and ablative applications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1010–1017, 2006
Co-reporter:Feng Liu;Liuhe Wei;Wanwan Li
Journal of Applied Polymer Science 2006 Volume 102(Issue 5) pp:4207-4212
Publication Date(Web):28 SEP 2006
DOI:10.1002/app.24633
A new propargyl-functional resin, propargyl ether bisphenol A novolac (PBPN), was synthesized, and the structure of PBPN were characterized using 1H NMR and FTIR spectra. The PBPN was blended with 4,4′-bismaleimide diphenyl methane (BDM) at different molar ratio to obtain the blends. Differential scanning calorimetry (DSC) was used to characterize the cure behavior of PBPN and the blends. Thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) were performed, respectively, to evaluate thermal stability and dynamic mechanical properties of the cured resins. The results indicate that the PBPN presented better cure and thermal properties than do traditional propargyl resins; furthermore, the cure behavior and thermal properties of PBPN could be improved remarkably by blending with BDM. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4207–4212, 2006
Co-reporter:Feng Liu;Wanwan Li;Liuhe Wei
Journal of Applied Polymer Science 2006 Volume 102(Issue 4) pp:3610-3615
Publication Date(Web):29 AUG 2006
DOI:10.1002/app.24015
Bis propargyl ether bisphenol A (PBPA) was synthesized and blended with 4,4′-bismaleimide diphenyl methane (BDM) at different molar ratios. The cure behavior of the blend resins was measured by DSC and FTIR spectra. The results indicated that the onset cure temperatures of the blend resins were about 20–30°C lower than that of pure PBPA, and the cure exothermic enthalpy of the resins also significantly reduced from 1320 (PBPA) to 493 J/g (PBPA–BDM (1.0:2.0)). The thermal stabilities and dynamic mechanical properties of the cured resins were characterized by TGA and DMA, respectively. The thermal stability of the resins improved markedly with the increase in BDM content, and the glass transition temperature increased from 306°C for PBPA–BDM (1.0:0.5) to 358°C for PBPA–BDM (1.0:2.0). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3610–3615, 2006
Co-reporter:Mingcun Wang, Liuhe Wei, Tong Zhao
European Polymer Journal 2005 Volume 41(Issue 5) pp:903-912
Publication Date(Web):May 2005
DOI:10.1016/j.eurpolymj.2004.11.036
By the incorporation of propargyl and methylol groups on to novolac backbone, a series of addition-curable phenolic resins and condensation–addition dual-cure type phenolic resins (novolac modified by propargyl groups referred as PN, and novolac modified by propargyl and methylol groups simultaneously referred as MPN) were synthesized. The processing characteristics, thermal cure and catalytic cure behavior for both resins were investigated mainly by means of viscosity measurement and non-isothermal differential scanning calorimetry (DSC) techniques. The effect of propargyl and methylol content of PN and MPN, the molecular weight and the configuration of the parent novolac, on the processing and cure behavior was studied in details. Processing parameters and curing kinetic parameters were obtained. Both resins exhibit excellent processing properties. Thermal cure of PN resins possessed one cure mechanism and that of MPN resins possessed two cure mechanisms according to DSC analysis. The dual-cure-type mechanism made MPN resins superior to PN resins in terms of a mild and controllable cure process. Compared with thermal cure, catalytic cure of PN resins showed lower initiation temperature and cure temperature by about 60 °C. These novel resins have a bright prospect of application as matrix for thermal–structural composite materials.
Co-reporter:Hongsheng Wang;Yunzhao Yu
Journal of Applied Polymer Science 2005 Volume 96(Issue 2) pp:466-474
Publication Date(Web):15 FEB 2005
DOI:10.1002/app.20955
Sodium montmorillonite (Na–MMT) was swollen with protonated p-phenylenediamine, and the latter was converted to maleamic acid. Intercalation of the swelling agents was confirmed by FTIR, XRD, and TGA data. Exfoliation of the organoclay took place easily in the melt of the Bismaleimide-modified allylated novolac resin. It is remarkable that, as a result of layer delamination, introduction of 2 phr organoclay MAA–MMT brought in a rise in steady shear viscosity for over two orders of magnitude at low shear rates. Major improvement in thermal stability, flexural strength, and modulus was achieved by incorporation of the exfoliated clay layers, in contrast to the composite using pristine Na–MMT as reinforcement. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 466–474, 2005
Co-reporter:Yuan Yao;Yunzhao Yu
Journal of Applied Polymer Science 2005 Volume 97(Issue 2) pp:443-448
Publication Date(Web):26 APR 2005
DOI:10.1002/app.21671
Thermosetting resin systems with very high glass-transition temperatures were formulated on the basis of bismaleimide and allylated novolac (BMAN). When the allylation degree of the novolac resin was high enough, the bismaleimide (BMI) proportion was not critical to the heat resistance of the cured resin. The BMAN15 resin with a high allylation degree and a low BMI proportion was appropriate for resin-transfer molding. Composites of BMAN15, with quartz woven cloth as reinforcement showed good strength and modulus retention rates at 350°C. The curing of the BMAN15 resin was illustrated by Fourier transform infrared and differential scanning calorietry studies. It turned out that allyl groups participated via ene reaction and the Diels–Alder reaction, as the maleimide groups did, forming a densely crosslinked structure in the cured resin. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 443–448, 2005
Co-reporter:Tao Cai, Wen-Feng Qiu, Dan Liu, Wei-Jian Han, Li Ye, Ai-Jun Zhao and Tong Zhao
Dalton Transactions 2013 - vol. 42(Issue 12) pp:NaN4290-4290
Publication Date(Web):2012/12/12
DOI:10.1039/C2DT32428H
Soluble organometallic polymers containing zirconium and silicon were synthesized by a salt metathesis reaction. The molecular weight of the polymers was measured by GPC and the corresponding structures were identified by 13C NMR and FT-IR. After heat treatment of the polymers under argon at 1400 °C for 2 h, ZrC/SiC composites with different molar ratios of crystalline phases were obtained and characterized by XRD, elemental analysis, SEM and Raman spectroscopy. The crystalline size of the composites was approximately 100 nm–200 nm and the elements were well distributed at the different sites in the ceramics. The Raman results indicated that the ceramic residue could be considered as ZrC/SiC/C ternary composites.
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