【作者】 杜中杰；

【导师】 励杭泉；

【作者基本信息】 北京化工大学 ， 材料学， 2002， 博士

【摘要】 浓乳液是指分散相体积分数大于74％的乳液，浓乳液聚合方法是制备增容化高分子合金的一种新方法。研究浓乳液聚合过程自增容的反应机理对了解浓乳液乳胶粒间的界面反应及建立共混物的制备、增容新方法都有重要意义。本论文旨在建立浓乳液聚合过程反应自增容的模型，逐步验证，查明自增容反应机理，并研究聚合过程中各参数对增容效果的影响。 浓乳液中乳胶粒(分散相)的体积分数一旦高于74％，乳胶粒便相互挤压在一起，失去了活动性，体积分数进一步提高时，乳胶粒就不再呈球状，而被挤压成多面体状。体积分数越高，界面／体积比越高，这种情况特别有利于界面或乳胶粒外缘的反应。 针对浓乳液体系中乳胶粒界面／体积比高和紧密堆积的特点，本论文采用浓乳液聚合方法，通过在浓乳液乳胶粒界面上设计不同类型的反应原位生成某种形式的聚合物，以此为增容剂实现对乳胶粒内部生成的两均聚物的增容。本论文根据浓乳液乳胶粒界面上的反应类型，研究了四种不同的浓乳液方法聚合过程自增容机理。(ⅰ) 浓乳液扩散自增容反应机理：首先将两种单体分别制成浓乳液，部分预聚后通过机械搅拌将两组浓乳液均匀混合，此后将混合浓乳液直接完成聚合。在后续的聚合过程中，两种聚合物分别在各自的乳胶粒中生成，与此同时，某种形式的增容剂在乳胶粒外缘或界面上生成，这样便实现了共混体系的增容。因为该过程是两种单体通过在乳胶粒界面上的相互扩散原位生成准嵌段共聚物而增容，因此称为浓乳液扩散自增容；(ⅱ)浓乳液微交联反应自增容反应机理：同样制备两种单体的浓乳液，与上述反应机理不同的是在浓乳液反应体系中添加一种双亲性(亲水／亲油)的大分子单体，该大分子单体均匀分布于乳胶粒界面间，在聚合过程中，它起到了一种“架桥”的作用，将乳胶粒间不同的分子链段联接起来，在乳胶粒的外缘或界面层上生成了接枝或交联聚合物，该聚合物即原位生成的增容剂。(ⅲ)浓乳液官能团化自增容反应机理：在两浓乳液体系中分别引入反应性的官能团，将两部分预聚后的浓乳液混合后， 北京化工大学博士学位论文在乳胶粒界面层上不同分子链上的官能团就会反应，生成接枝或交联共聚物，以此为增容剂实现共混体系的增容;(iv)浓乳液种子接枝方法自增容反应机理:首先通过普通乳液聚合方法制备高分子合金中作为分散相的种子，然后向其中滴加高分子合金中连续相的单体，配置成浓乳液。浓乳液体系中分散相体积分数高，超过74%，这就保证了浓乳液乳胶粒必然将所有的种子包容，而且浓乳液体系是由连续相的液膜分割开的紧密堆积在一起的乳胶粒，使得作为橡胶相的种子能够均匀分布于乳胶粒内部。被溶胀的橡胶相种子与浓乳液单体界面之间会产生接枝聚合物，从而实现两相之间的增容化。 按照上述四种浓乳液反应自增容机理，分别以聚苯乙烯/聚丙烯睛、聚苯乙烯/聚丙烯酸丁酷、聚苯乙烯/聚甲基丙烯酸丁酷体系为研究模板，制备了各自增容化的高分子合金。浓乳液扩散自增容方法制备的聚苯乙烯/聚丙烯睛高分子合金的测试结果表明，增容体系中存在准嵌段共聚物，浓乳液预聚转化率越高，乳胶粒界面上生成的准嵌段共聚物也越多;在此基础上，将浓乳液扩散自增容方法引入到聚苯乙烯/聚丙烯酸丁酷体系中，探讨了合金的增容效果与试样冲击韧性的关系，最终得出，浓乳液的预聚转化率是控制准嵌段共聚物的组成及含量的关键因素，在实验范围内，当预聚转化率为12.0%时，PS/PBA合金的相容性最好，试样的冲击强度最高，达到4.OZKJ/m，。浓乳液微交联反应自增容方法制备的聚苯乙烯/聚甲基丙烯酸丁酷高分子合金，其增容效果通过动态热力学分析、扫描电镜照片和透射电镜照片分别进行了验证，冲击强度值和剪切应力一剪切速率关系曲线分别表征了试样的冲击韧性和加工性能，研究了大分子单体用量与合金相容性的关系。结果表明，聚乙烯醇二甲基丙烯酸酷大分子单体的用量在0.050%左右时，PS/PBMA高分子合金的相容性最好。浓乳液官能团化反应自增容方法是通过乳胶粒间官能团之间的反应而增容，研究过程中分别将甲基丙烯酸和甲基丙烯酸缩水甘油酷单体引入到各自的浓乳液体系中，利用异种乳胶粒间梭基与环氧基团之间的反应分别制备了聚苯乙烯/聚甲基丙烯酸丁酷、聚苯乙烯/聚丙烯酸丁醋高分子合金。结果表明，在实验范围内，随着反应体系中官能团含量的增加，接枝或交联共聚物的含量也随之增加，高分子合金的相容性也相应得到提高。扫描电镜照片也表明了高分子合金的相容性随官能团含量增加而提高的变化规律。高分子合金冲击强度的实验结果表明，官能团含量的增加，有利于合金冲击强度的提高。这也验证了在乳胶粒界面上生成的接枝 第H页北京化工大学博士学位论文二二二二二二二二二二二二二二二二或交联共聚物降低了两相间的界面张力，提高了两相间的相容性。浓乳液种子接枝方法制备的高分子合金中，作为分散相的种子是聚丙烯酸丁酷，而连续相是聚苯乙烯，实验过程中研究了丙烯酸丁酷含量、聚丙烯酸丁醋种子粒径以及接枝聚合温度等因素更多还原

【Abstract】 Self-compatibilization is a novel method for preparing compatibilized polymer blends via concentrated emulsion polymerization. In this method, two partially polymerized concentrated emulsions are mechanically mixed, and then they are subjected to complete polymerization. Some compatibilizers are generated at the interfaces between the two kinds of cells, which compatibilize the homopolymers generated simultaneously inside the cells. In particular, when a rigid polymer was blended in this manner with a flexible one, tough materials were obtained. SELF-COMPATIBILIZATION VIA DIFFUSION OF CONCENTRATED EMULSIONSTwo concentrated emulsions of styrene (St) and butyl acrylate (BA) in water were prepared respectively. Each system contains a small amount of initiator in the dispersed phase. This kind of emulsion has a large volume fraction of the dispersed phase (as large as 0.99). After the two concentrated emulsions were partially polymerized, they were mixed mechanically and subjected to complete polymerization. Subsequently reactions between the interfaces of different cells occurred. During the latter diffusion polymerization, a kind of pseudo-block copolymer was generated which constituted the compatibilizers of the blend systems. Fourier transform infrared spectra (FTIR), Dynamic mechanical thermal analysis (DMTA), Rheometric testing, Scanning electron microscope (SEM) and Transmission electron microscope (TEM) were employed to characterize the compatibilization of the polymer blends. The results showed that the blend materials thus obtained possessed excellent compatibilization. SELF-COMPATIBILIZATION VIA BRIDGING BY MACROMONOMERIn this case, a macromonomer - Poly (ethylene glycol) dimethacrylate (PEGD) was employed as the precursor of a compatibilizer that can bridge the polystyreneand poly (butyl methacrylate). As in the preceding section, two concentrated emulsions in water were prepared first. In each of the concentrated emulsions, the continuous phase was a mixture containing SDS solution and PEGD (or introduced after mixing of the partially polymerized concentrated emulsion). The partial polymerization of the two concentrated emulsions was conducted and mixed mechanically after a 22.5% conversion was reached. Because of the vinyl groups at each of its ends, the PEGD copolymerized with styrene and butyl methacrylate in different cells, and thus some copolymers or networks containing both polystyrene and poly (butyl methacrylate) were formed. Such copolymers or networks constituted compatibilizers between polystyrene and poly (butyl methacrylate). The compatibility of the blends thus prepared was characterized by curves of dynamical mechanic mechanical thermal analysis (DMTA), Scanning electron microscope (SEM) and Transmission electron microscope (TEM). The impact properties and rheological curves of the blends showed excellent toughness and processability for base materials respectively. One can conclude that a macromonomer content of 0.025wt% to 0.050wt% provides the optimum benefit for the compatibilization of PS/PBMA blends.SELF-COMPATTOILIZATION VIA FUNCITONALLZED CONCENTRATED EMULSIONSTwo "functionalized" concentrated emulsions in water were prepared separately, one from a weakly polymerized mixture of styrene (St) and a small amount of acrylic acid (AA) and the other from a mixture of butyl methacrylate (or butyl acrylate) and a small amount of glycidyl methacrylate (GMA). After the two concentrated emulsions were polymerized partially, they were mixed and subjected to complete polymerization. During the latter polymerization, reactions between the carboxyl groups of the AA moieties of the St/AA copolymer and the glycidyl groups of the GMA-containing copolymer occurred, and copolymers and crosslinked structures were generated that constituted the compatibilizers of the system. The blend materials thus obtained possessed excellent toughness compared to those without functional groups.SELF-COMPATIBILIZATION VIA GRAFTING IN A CONCENTRATED EMULSIONA novel polymerization procedure, the concentra更多还原