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介绍用红外光谱法测定端羟基聚丁二烯(HTPB)胶粘体系固化度的原理及方法,并对端羟基聚丁二烯胶粘体系固化过程进行监控,分析了一定温度下胶粘体系的固化度与固化时间,以及相同固化时间内胶粘体系的固化度与固化温度之间的数学关系。 相似文献
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耐热芴型环氧树脂的非等温固化动力学 总被引:3,自引:0,他引:3
合成了9,9’-二[4-(2,3环氧丙氧基)苯基]芴,并以4,4’-二氨基二苯砜胺为固化剂,用非等温DSC法研究了其固化动力学,用Flynn-Wall-Ozawa法和Friedman法确定了固化动力学参数,用动力学模拟推测了固化机理函数,并用TGA法对等温固化树脂的耐热性进行了表征。结果表明:双酚芴环氧固化反应的表观活化能约63.86 kJ/mol,扩散因子为3.80×104s-1,反应级数为1.57;固化反应为枝状成核的自催化反应;等温固化后的环氧树脂于400℃开始分解,700℃时残碳率为41.73%。 相似文献
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以有机硅改性丙烯酸环氧单酯为树脂配制了一系列紫外光-热混杂固化体系.通过FTIR表征了光-热固化过程双键和环氧特征吸收峰的变化.研究了不同的稀释剂对光固化和光-热混杂固化膜的凝胶率、吸水率、表面水接触角等性能的影响,并用能谱仪(EDS)测试了固化膜表面硅元素的含量.结果表明:光固化膜的凝胶率低于86.5%,而光-热混杂固化膜的凝胶率在97.0%左右.与丙烯酸环氧单酯光-热固化体系相比,有机硅改性丙烯酸环氧单酯光-热固化膜的表面水接触角有显著提高,由62.53°提高到99.27°,EDS测试也表明有机硅有富集于固化膜表面的特性. 相似文献
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介绍近年来UV/EB固化材料的发展进展,其中包括北美、欧洲、日本的发展概况和重大的新进展:(1)稀释单体和预聚体;(2)水基UV/EB固化;(3)阳离子光固化;(4)辐射固化粉末涂料;(5)复合固化体系;(6)UV固化纳米涂料;(7)光引发剂;(8)计算机直接制版. 相似文献
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Comparative study between core-shell and interpenetrating network structure polyurethane/polyacrylate composite emulsions 总被引:2,自引:0,他引:2
Anionic aqueous polyurethane dispersion was prepared by using carboxyl acid group to make the polyurethane dispersible, and then nanograde core-shell and crosslinked IPN structure polyurethane/polyacrylate composite latex (PUA) were synthesized by soap-free emulsion polymerization method with polyurethane dispersion as seed. FTIR, DSC, dynamic light scattering, TEM, ESCA, TGA, electronic tensile machine were employed to investigate the structures and properties of the composite latex and their polymers. Meanwhile the core-shell composite PUA emulsion and the crosslinked IPN composite PUA emulsion were compared. The results showed that the particle morphology of PUA composite emulsion is inverted core-shell structure with polyacrylate as the core and with polyurethane as the shell. The morphology of the crosslinked PUA emulsion was multi-core structure. The surface in core-shell PUA contains rich PU phase. The phase structure of the crosslinked PUA is more uniform. Three transition temperatures are observed for the core-shell composite PUA, two transitions are observed for the film from the crosslinked PUA. The TGA curves of core-shell PUA and crosslinked PUA exhibit two stages, the first stage corresponds to the thermal decomposition of hard segments in seed polyurethane; the second stage corresponds to the decomposition of soft segments in PUA and decomposition of polyacrylate. With the increase of glycidyl methacrylate (GMA) amounts in PUA composite emulsions, the tensile strength of the PUA films as well as the average diameter of the PUA composite emulsion particles increase, the elongation at break of the PUA films decreases. 相似文献
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Three kinds of UV-curable self-emulsified polyurethane-acrylate (PUA) prepolymer, i.e., conventional, chainextended and grafted PUAs, were prepared. The relatively small particle size of the PUA dispersions indicates that the PUAprepolymers exhibit sufficient aqueous dispersibility. The PUA prepolymers can substantially lower the interfacial tension ofwater. Chain-extended PUA dispersions exhibit pseudoplastic behavior and thixotropy to a greater extent than do theirconventional counterpart. The chain-extended and grafted PUA photocure to higher conversion than do the conventional PUequivalent. The results of DSC measurement suggest that there exists phase mixing between the hard and the soft segmentphases for the PUAs based on PEG 400 that is the comparatively short soft segment in the prepolymer. For the PUAprepolymers based on PEG having higher M_n values, chain-extending and grafting could impede the phase separationbetween the hard and the soft segment domains. The adhesion, impact strength and flexibility of the photocured films were tested. 相似文献
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Surface composition and property of film prepared with aqueous dispersion of polyurethaneurea-acrylate including fluorinated block copolymer 总被引:1,自引:0,他引:1
The aqueous dispersion of polyurethaneurea-acrylate (PUA) including small amount of fluorinated block copolymers containing carboxyl groups (PATF), which can be dissolved in water, was used to make films and the surface properties of these films were examined. The experimental data show that the modified PUA film exhibits a hydrophobic surface property, although the original surface of PUA film is hydrophilic. The surface composition of the modified PUA film was measured by ATR and XPS. The results indicate that there is a concentration gradient of the fluorine groups along the lines of thickness of the modified film and towards the outmost surface layer, resulting from the migration of fluorinated blocks to the air side surface of the modified PUA film during the film formation process. However, the PUA film can not be modified effectively by adding the sodium salt of PATF, since the urethane groups in the system are easy to occupy on the surface of the film. 相似文献
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A carbon dioxide copolymer poly(urethane-amine)(PUA) was blended with poly(propylene carbonate)(PPC) in order to improve the toughness and flexibility of PPC without sacrificing other mechanical properties. Compared with pure PPC, the PPC/PUA blend with 5 wt% PUA loading showed a 400% increase in elongation at break, whilst the corresponding yielding strength remained as high as 33.5 MPa and Young's modulus showed slightly decrease. The intermolecular hydrogen bonding interaction in PPC/PUA blends was comfirmed by FTIR, 2D IR and XPS spectra analysis, and finely dispersed particulate structure of PUA in PPC was observed in the SEM images, which provided good evidence for the toughening mechanism of PPC. 相似文献
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C. Decker K. Moussa T. Bendaikha 《Journal of polymer science. Part A, Polymer chemistry》1991,29(5):739-747
Highly crosslinked aliphatic and aromatic polyurethane-acrylate (PUA) coatings have been obtained by photopolymerization of multifunctional monomers. The discoloration and chemical modifications occurring upon accelerated QUV aging were monitored by UV and IR spectroscopy. The polymers were found to undergo photooxidation and loss of carbamate and phenyl groups, with lower quantum yields (10?3 mol photon?1) than in related linear polymers. Hydroxy-phenyl benzotriazole UV-absorbers have a limited effect on the degradation rate, at the concentration used (0.5%). Hindered amines (HALS) are substantially more effective, especially in aliphatic PUA. A 20-fold increase in the stabilization efficiency was found with the UVA + HALS combination. Aromatic PUA are more difficult to stabilize, because of the strong absorption and photolysis of the phenyl group which yields colored products. Radical-induced oxidation is predominant in aliphatic PUA and develops with long kinetic chains, while in aromatic PUA it competes with direct photolysis. 相似文献
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Lin Gu Xianhong Wang Xuesi Chen Xiaojiang Zhao Fosong Wang 《Journal of polymer science. Part A, Polymer chemistry》2011,49(24):5162-5168
Aliphatic poly(urethane‐amine) (PUA) was synthesized from copolymerization of CO2 and 2‐methylaziridine (MAZ) using Y(CCl3COO)3‐ZnEt2‐glycerine coordination catalyst, the urethane content of PUA was over 80%, and its yield could reach 90%. PUA with molecular weight as high as 31.0 kg/mol was obtained when the copolymerization reaction was carried out in N,N‐dimethylacetamide (DMAc), mainly due to the good solubility of PUA in DMAc. PUA exhibited reversible thermo‐responsive property in deionized water, and the lower critical solution temperature (LCST) was highly sensitive to its urethane content and molecular weight, which was observed in a broad window from 37 to 90 °C. Furthermore, the phase transition behavior could also be controlled by change of pH value. When the pH value of the PUA aqueous solution changed from 9.2 to 13, the LCST value of the solution decreased from 48.4 °C to 30 °C. Therefore, the PUA showed thermo‐ and pH‐ dual responsive performance in water. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
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Paul C. Mengnjoh Harry L. Frisch 《Journal of polymer science. Part A, Polymer chemistry》1989,27(10):3363-3370
Simultaneous full and pseudo- interpenetrating polymer networks of poly(2,6-dimethyl-1,4 phenylene oxide) (PPO) and a poly(urethane acrylate) (PUA) have been synthesized and characterized by differential scanning calorimetry, ultimate mechanical properties, and electron microscopy. No evidence of phase separation was detected in both the full and pseudo- PPO/PUA networks. The networks exhibited a single glass transition temperature at all the compositions studied. A maximum in tensile strength to break was observed at 25 PPO/75 PUA composition by weight percent. 相似文献