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水解对乙烯—乙酸乙烯共聚物乳液复合的影响 总被引:3,自引:1,他引:2
乙烯-乙酸乙烯共聚物(EVA)乳液在NaOH作用下进行表面水解处理后,加入甲基丙烯酸甲酯(MMA),在过硫酸铵引发下进行复合反应。对复合乳胶粒的凝胶质量分数的测定、热分析及动态粘弹性的表征表明,随EVA乳胶粒表面水解度的增大,MMA在其表面的接枝率增大,体系的交联程度随之增大,两相相容性得到改善。此外还探讨了复合配比及加入少量丙烯酸对复合体系的影响。 相似文献
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抗水性和抗冻性聚乙酸乙烯酯乳液胶黏剂的制备 总被引:3,自引:0,他引:3
用乙烯-乙酸乙烯酯共聚乳液作为种子进行聚合,制备了抗水性和抗冻性的聚乙酸乙烯酯乳液胶黏剂。研究了乙烯-乙酸乙烯酯共聚物乳液的用量对改进型PVAC乳液的抗冻性、抗水性及表面张力的影响。 相似文献
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文章从悬浮聚合引发剂的选择、分析,介绍了105m3聚合釜使用国产TX23/TX36复合引发剂替代EHP单一引发剂生产PVCSG-7型树脂的情况。采用国产复合引发剂不但解决了悬浮聚合反应后期的超温超压现象,还提高了聚合釜的生产能力,降低了树脂成本,提高了产品在市场上的竞争力。 相似文献
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采用乙酸乙烯酯(VAc)在水中以过硫酸钾(KPS)和亚硫酸氢钠氧化还原体系作为引发剂进行无乳化剂乳液聚合,探讨了引发剂浓度、聚合温度、单体浓度和搅拌速度对聚合速率及转化率的影响。结果表明:当VAc质量分数为30%,KPS:VAc摩尔比为1:2 000,聚合温度10℃,反应时间10 h,搅拌速度80 r/min,时聚合产物聚乙酸乙烯的聚合度达到10 848;当VAc质量分数为35%时,聚合转化率可达到96%,聚合速率与引发剂浓度的0.944次方成正比;当搅拌速度达到200 r/min以上时,搅拌速度对聚合速率以及转化率影的响可以忽略。 相似文献
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Kinetic models for the rate constants of vinyl chloride polymerization in the presence of initiator mixtures were proposed. They may be used to design the initiator recipes for the vinyl chloride polymerization with uniform rate at different temperatures at which various grades of poly(vinyl chloride) will be prepared. 相似文献
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High-molecular weight (HMW) poly(vinyl alcohol) (PVA) was prepared via an emulsifier-free emulsion polymerization of vinyl acetate (VAc) using a redox initiation system in low temperatures, and the subsequent saponification with potassium hydroxide in methanol. The effect of the polymerization conditions on the conversion, molecular weight, and branching degree was investigated. PVA with maximum viscosity-average degree of polymerization (DP) of 8270 could be prepared by saponification of poly(vinyl acetate) (PVAc), with DP of 10,660 obtained at temperature of 10°C, monomer concentration of 30%, potassium persulfate molar ratio to monomer of 1/2000, agitation speed of 160 rpm. The conversion was above 90%. From the emulsifier-free emulsion polymerization of VAc in low temperature, PVAc with HMW and high linearity was effectively prepared, which might be useful for the preparation of high-strength and high-modulus PVA fiber. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
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The free‐radical graft polymerization of vinyl acetate onto nonporous silica particles was studied experimentally. The grafting procedure consisted of surface activation with vinyltrimethoxysilane, followed by free‐radical graft polymerization of vinyl acetate in ethyl acetate with 2,2′‐azobis(2,4‐dimethylpentanenitrile) initiator. Initial monomer concentration was varied from 10 to 40% by volume and the reaction was spanned from 50 to 70°C. The resulting grafted polymer, which was stable over a wide range of pH levels, consisted of polymer chains that are terminally and covalently bonded to the silica substrate. The experimental polymerization rate order, with respect to monomer concentration, ranged from 1.61 to 2.00, consistent with the kinetic order for the high polymerization regime. The corresponding rate order for polymer grafting varied from 1.24 to 1.43. The polymer graft yield increased with both initial monomer concentration and reaction temperature, and the polymer‐grafted surface became more hydrophobic with increasing polymer graft yield. The present study suggests that a denser grafted polymer phase of shorter chains was created upon increasing temperature. On the other hand, both polymer chain length and polymer graft density increased with initial monomer concentration. Atomic force microscopy–determined topology of the polymer‐grafted surface revealed a distribution of surface clusters and surface elevations consistent with the expected broad molecular‐weight distribution for free‐radical polymerization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 300–310, 2003 相似文献
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Poly(vinyl acetate) latices were prepared in the presence of an ammonium persulfate initiator, 10–50 mol of an ethoxylated nonylphenol nonionic emulsifier, and a poly(vinyl alcohol) colloid stabilizer by applying semicontinuous emulsion polymerization (delayed monomer and initiator addition process) in a laboratory scale similar to industrial practice. Two approaches were applied: the molar concentration of the nonionic emulsifier was kept constant and the weight ratios in the polymerization recipe varied or the weight ratios were kept constant. The effects of the change in the ethoxylation degree of the emulsifier to the final latex viscosity, average polymer molecular weight, polymer grafting degree, surface tension of the latex, and the surface free energy of the dried films were investigated. It was determined that the resultant latex viscosity decreases and the viscosity‐average polymer molecular weight increases with increase of the nonionic emulsifier ethoxylation degree. The increase of the ethoxylation degree does not seriously affect the surface tension of the resultant latex or the surface free energy of the dried poly(vinyl acetate) films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 844–851, 2002 相似文献
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The emulsion polymerization of vinyl acetate has been studied using carefully prepared seed lattices. Experiments were carried out in which temperature, particle size and the monomer-polymer ratio could be varied independently. In all cases the polymerization rate was proportional to the initiator concentration raised to the 0.7 power. No new particles were formed. The importance of polymerization in the aqueous phase and changes in the propagation rate coefficient are discussed. 相似文献
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Yu Guan Jingjing Li Leishan Shao Fei Wang Dongyu Dong Yinghan Wang 《Polymer International》2016,65(12):1382-1386
A new redox initiation system, potassium persulfate/N,N‐dimethylethanolamine, was used to initiate traditional radical emulsion polymerization of vinyl acetate at low temperature. Polymers were characterized using gel permeation chromatography, scanning electron microscopy and dynamic light scattering. The results showed that poly(vinyl acetate) with high molar mass and small dispersity (?) was successfully synthesized. © 2016 Society of Chemical Industry 相似文献
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研究了新型过氧化物引发剂过氧化新癸酸 1,1 二甲基-3-羟基丁基酯(Lup 610)在51.3与56.8℃以及过氧化新庚酸叔丁酯(Lup 701)和过氧化新戊酸叔己酯(HPV)在61.8℃单一引发剂引发氯乙烯悬浮聚合动力学,并采用模型计算结果绘制转化率 时间曲线,取与实验数据符合最好的f值作为引发剂的引发效率,求得引发剂Lup 610在51.3与56.8℃的引发效率分别为0.80与0.75,引发剂Lup 701和HPV在61.8℃下的引发效率分别为0.55和0.50。研究了上述引发剂与过氧化二碳酸二(2-乙基己酯)、过氧化新癸酸叔丁酯在各温度下复合引发剂引发氯乙烯悬浮聚合的动力学,与模型值相比较,发现两者能很好吻合。 相似文献