水解VAE/苯丙乳液共混体系研究

乙烯－醋酸乙类共聚物（ＶＡＥ）乳液碱催化水解与苯乙烯－丙烯酸丁酯共聚物（ＰＢＡ－Ｓｉ）乳液共混改性,考察共混体系稳定性及流变性能,以ＴＥＭ及ＤＳＣ表征共混乳胶膜的形态结构及共混相容性,研究ＶＡＥ乳液的不同水解程度及不同配比对共混乳胶膜力学性能的影响。     

水解对乙烯—乙酸乙烯共聚物乳液复合的影响：Ⅰ.EVA／BA复合体系

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,加入丙烯酸丁酯（ＢＡ）,在过硫酸铵引发下进行复合反应,通过对复合乳胶粒的形态表征及胶膜的凝胶质量分数的测定、热分析及动态粘度弹性表征,表明随ＥＶＡ乳胶粒的表面水解程度的增大,ＢＡ在胶粒表面的接枝率增大,体系的交联程度也增大,两相体系的相容性得到改善。     

水解EVA乳液与甲苯二异氰酸酯交联反应研究

乙烯－醋酸乙烯共聚物（ＥＶＡ）乳液经碱催化水解与甲苯－２，４－二异氰酸酯（ＴＤＩ）进行交联反应而改性。ＥＶＡ乳液水解程度为３％，反应温度为３０℃，反应时间为１ｈ的条件下有较高的转化率。ＴＤＩ用量与ＥＶＡ水解程度有关，以红外光谱，透射电子显微镜表征水解反应、交联反应及乳胶粒结构形态，。     

水解对乙烯－乙酸乙烯共聚物乳液复合的影响Ⅲ.复合乳液的性能

对水解处理后的乙烯－乙酸乙烯共聚物（ＥＶＡ）乳液与丙烯酸丁酯、甲基丙烯酸丁酯的复合乳液的性能进行了表征。结果表明,复合单体的水解处理后的ＥＶＡ乳胶粒表面的接枝状况对复合乳液的稳定性及其胶膜的而水性和力学性能有较大影响,热处理对胶膜性能的影响与复合单体的ＥＶＡ乳胶粒表面的接枝状况有关。     

水解对乙烯—乙酸乙烯共聚物乳液复合的影响

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。     

马丁—侯状态方程向固相发展

ＭＨ－８１状态方程式经过进一步改进后，其使用范围可扩展到固相。在该方程中增加了三个常数，Ａ６、Ｂ７和ｂｓ后变为：Ｐ＝ＲＴ／Ｖ－ｂ＋Ａ２＋Ｂ２Ｔ＋Ｃ２ｅ－５．４７５Ｔ／Ｔｃ／（Ｖ－ｂ）＾２＋Ａ３＋Ｂ３Ｔ＋Ｃ３ｅ－５．４７５Ｔ／Ｔｃ／（Ｖ－ｂ）＾３＋Ａ４＋Ｂ４Ｔ／（Ｖ－ｂ）＾４＋Ｂ５Ｔ／（Ｖ－ｂ）＾５＋Ａ６／（Ｖ－ｂｓ）＾６＋Ｂ７Ｔ／（Ｖ－ｂ）＾７改进后的状态方程对于一般物质，如二氧化碳、氩、甲烷及氮     

马丁－侯状态方程向固相发展

ＭＨ－８１状态方程式经过进一步改进后，其使用范围可扩展到固相。在该方程中增加了三个常数，Ａ６、Ｂ７和ｂｓ后变为：Ｐ＝ＲＴＶ－ｂ＋Ａ２＋Ｂ２Ｔ＋Ｃ２ｅ－５．４７５ＴＴｃ（Ｖ－ｂ）２＋Ａ３＋Ｂ３Ｔ＋Ｃ３ｅ－５．４７５ＴＴｃ（Ｖ－ｂ）３＋Ａ４＋Ｂ４Ｔ（Ｖ－ｂ）４＋Ｂ５Ｔ（Ｖ－ｂ）５＋Ａ６（Ｖ－ｂｓ）６＋Ｂ７Ｔ（Ｖ－ｂｓ）７改进后的状态方程对于一般物质，如二氧化碳、氩、甲烷及氮等，在三相点到临界点温度、计算的饱和液相、汽相摩尔体积与文献值的偏差基本上保持ＭＨ－８１方程的准确度，而固相摩尔体积的偏差在几千大气压下也在１０％左右，一般压力不太高时都在５％以内，需要增加的输入信息仅三相点（Ｐｔ，Ｔｔ）下的Ｖｓｔ数据。     

核—壳型丙烯酸乳液压敏胶聚合工艺的研究

以ＶＡＥ乳液为核,以ＢＡ－ＶＡｃ－ＨＥＭＡ等混合单体为壳,采用核－壳乳液聚合工艺研制出一种新型丙烯酸乳液压敏胶,讨论了核,壳,乳化剂,引发剂,聚合温度等因素对压敏胶性能的影响,ＶＡＥ用量１２．５％,ＢＡ：ＶＡｃ：ＨＥＭＡ：ＡＡ＝８．７：１．２：０．３：０．１,使用过硫酸铵加ＮＨ４Ｓ２Ｏ８－ＮａＨＳＯ３氧化还原体系为引发剂,制得的压敏胶性能优良。     

VAE—松香乳液共混体系研究

共混后松香粒子变形并吸附在 Ｖ Ａ Ｅ 胶粒表面，其分布均匀性受 Ｖ Ａ Ｅ 水解程度影响。讨论了共混体系的流变性能、稳定性以及胶膜的力学性能。发现 ｍ（ Ｖ Ａ Ｅ）∶ｍ（ 松香乳液） ＝ ９０∶１０ 时胶膜的力学性能最好     

E/VAC与马来酸酐反应挤出接枝的研究

用同向双螺杆挤出机进行Ｅ／ＶＡＣ熔融接枝ＭＡＨ的反应。考察了单体、引发剂用量和加工条件对接枝率及熔体流动速率的影响。结果表明,在Ｅ／ＶＡＣ接枝ＭＡＨ的反应中,接枝率随着ＤＣＰ用量、ＭＡＨ用量以及螺杆转速的增加出现峰值,较佳的实验配方为Ｅ／ＶＡＣ：ＭＡＨ：ＤＣＰ＝１００：２：０．２。接枝反应对Ｅ／ＶＡＣ的流动性有很大影响,接枝物的熔体流动速率随ＤＣＰ用量的增加而下降。     

Thermal degradation of EVA and EBA—A comparison. I. Volatile decomposition products

This is the first in a series of papers in which structural changes during thermal degradation of ethylene-vinyl acetate (EVA) and ethylene-butyl acrylate (EBA) copolymers are compared. EVA, containing 11.4 mol% vinyl acetate (VA) and EBA, containing 5.4 mol% butyl acrylate (BA), were pyrolyzed at 280°C in nitrogen for 30 min. In another series of pyrolysis, EVA containing 1.2, 2.2, and 11.4 mol% VA were treated at 150–190°C for 3 h. The volatile decomposition products were collected in cooled traps respectively gas bags and then analysed with GC-MS and ion-chromatography. EVA is rather labile. The main volatile decomposition product is acetic acid. A linear decomposition rate was found already at the lowest investigated pyrolysis temperature, 150°C. After 30 min at 280°C every 15th of the acetate side groups had been eliminated. EBA is much more stable to pyrolysis. Thirty minutes at 280°C resulted in a decomposition of one out of 1500 BA groups. Butene is the main volatile decomposition product. Ester pyrolysis is supposed to account for the degradation of both types of polymers. The big difference in reactivity is presumably due to conformational differences. The ester pyrolysis mechanism will result in random unsaturations in EVA and carboxylic groups in EBA. To a minor extent acetaldehyde is formed when EVA is degraded. According to the mechanisms suggested, carbonyl groups remain in the main chain. Contrary to what is reported for poly(butyl acrylate), no alcohol was formed when pyrolysing EBA. This indicates that adjacent acrylate groups are needed for alcohol formation. For both types of polymer, scissions of the main chain results in hydrocarbon fragments mainly. In addition, acrylate containing fragments are observed when EBA is degraded. EVA, however, does not give any acetate-containing fragments.     

丙烯酸丁酯合成方法的改进

丙烯酸与正丁醇在浓硫酸催化作用下 ,减压蒸馏合成丙烯酸丁酯。由于丙烯酸丁酯沸点较高 ,在常压下蒸馏易发生自身聚合反应而影响产率 ,所以采用减压蒸馏以降低其沸点。为阻止聚合反应的发生 ,在减压蒸馏同时加入适量的阻聚剂 ,使减压蒸馏顺利进行。影响产率的另一个重要因素是最佳的原料配比 ,适当的酯化时间 ,控制粗酯酸度。通过大量实验证明 ,当丙烯酸含量大于 98%时 ,正丁酸与丙烯酸的质量比采用 1.15 ,酯化时间为 4h ,粗酯含量可达到 97.7%。阻聚剂常选用对苯二酚或对甲氧基苯酚 ,后者价格较贵 ,选用前者为佳。用量为粗酯量的 0 .1%效果比较理想。使用对苯二酚为阻聚剂时要注意洗涤阶段的粗酯碱洗之前先水洗 ,因为对苯二酚极易氧化变色 ,遇到碱性物质立即变成黄色物质 ,会严重影响产物的质量及产率。     

水性丙烯酸酯共聚物EVA表面处理剂的合成

采用乳液聚合法合成丙烯酸酯EVA表面处理剂,研究丙烯酸、丙烯酸丁酯、醋酸乙烯酯、丙烯腈和甲基丙烯酸缩水甘油酯等单体对丙烯酸酯EVA表面处理剂乳液性能的影响。所制备的丙烯酸酯EVA表面处理剂对交联程度低的EVA发泡鞋底具有良好的处理效果。     

Thermal degradation of EVA and EBA—A comparison. III. Molecular weight changes

This is the third in a series of papers in which the thermal degradation of ethylene-vinyl acetate (EVA) and ethylene-butyl acrylate (EBA) copolymers are compared. The EBA samples contained 0.8, 1.6, and 5.4 mol % butyl acrylate (BA), respectively, and the EVA samples 1.2 and 6.7 mol % vinyl acetate (VA). The samples were heated in nitrogen in a tubular oven at 285–390°C, for 6–120 min. The molecular weight distribution (MWD), long chain branching, and gel content were analyzed with size exclusion chromatography (SEC). The columns were connected to refractive index, viscometric, and light scattering detectors. EVA gave a pronounced molecular enlargement at all degradation temperatures. In EVA-6.7, gel was formed at all degradation levels, whereas the low content sample, EVA-1.2, did not form any visible amount of gel. The strong tendency to molecular enlargement is due to allyl radicals formed after thermal deacetylation and the formation of internal double bonds. These macroradicals will combine or, less frequently, add to double bonds. The EBA copolymers show a more polyethylenelike degradation behavior. At 285°C molecular enlargement dominates, but already at 333°C a net reduction in molecular size is observed. At high temperatures, ester pyrolysis of the BA groups give carboxylic groups and anhydrides. Alkaline treatment will not give any appreciable change in MWD, showing that the anhydride formation is mainly intramolecular. The chain scission increases with the BA content. This is probably due to β-cleavage of tertiary macroradicals formed in the chain at the acrylate or carboxylic side groups.     

Thermal degradation of EVA and EBA—A comparison. II. Changes in unsaturation and side group structure

This is the second in a series of papers in which the thermal degradation of ethylene-vinyl acetate (EVA) and ethylene-butyl acrylate (EBA) copolymers are compared. The EBA samples contain 0.8, 1.6, and 5.4 mol % butyl acrylate (BA), respectively, and the EVA samples 1.2 and 6.7 mol % vinyl acetate (VA). The samples were heated in nitrogen in a tubular oven at 285, 333, 350, 370 and 390°C for 6–120 min. The samples were analyzed with IR, NMR, gravimetry, and titration of carboxylic groups. The EVA samples were rapidly degraded by deacetylation, which was complete after about 30 min at 333°C. A linear relation between the loss of acetate groups and the formation of trans double bonds was found. A small amount of keto groups and traces of lactones were also observed. The data confirm the previously proposed mechanisms for deacetylation and the formation of acetaldehyde. A mechanism for lactone formation is suggested. The deacetylation rate is increasing with the VA content, presumably because of an increased amount of block sequences and an enhanced acid catalytic effect. The acrylate sidegroups are much more stable than the acetate groups, and are similar in stability to the main hydrocarbon chain. The BA decomposition results in carboxylic and anhydride groups. Decarboxylation also occur and increases with the thermal treatment. In LDPE and EBA the increase in unsaturation is small and mainly due to vinyl end groups formed via β-cleavage or disproportionation. In EVA the formation of vinyl end groups is suppressed.     

明胶上接枝丙烯酸丁酯的研究——Ⅰ.反应机理及动力学

在明胶上接枝丙烯酸丁酯是以硝酸铈铵为引发剂在水介质中进行的。本文讨论了接枝反应机理,提出了反应速度方程式,并以所得试验数据进行了印证。根据试验结果求出了接枝共聚、均聚和总聚合反应的表观活化能。此外,为了进一步弄清反应机理,还对反应过程中铈离子消失速率的规律进行了探讨。     

丙烯酸丁酯/VAE互穿聚合物乳液的研究

以互穿聚合物网络(IPN)方法合成丙烯酸丁酯与VAE共聚物乳液。研究了乳化剂、交联剂、溶胀时间、反应时间等条件对转化率的影响。以红外光谱、透射电子显微镜表征互穿共聚物乳胶膜的微观结构。通过吸水性及乳胶膜对水接触角的测定，证明其耐水性较VAE乳胶膜明显增强。。YEM照片表明互穿聚合物胶粒形态结构较VAE乳胶粒发生了明显变化。     

溶液聚合制备丙烯酸酯橡胶的研究

采用溶液聚合方法,通过改变聚合条件研究丙烯酸酯橡胶聚合转化率随反应时间变化的关系。提高温度有利于聚合速率的提高,但同时会导致单体最终转化率的降低;改变引发剂过氧化苯甲酰（BPO）含量发现,BPO浓度提高聚合反应速率加快,单体转化率差别不大;丙烯酸丁酯（BA）分别与丙烯酸乙酯（EA）、丙烯酸甲酯（MA）共聚,聚合反应速率有所提高,聚合转化率略有降低;改变丙烯酸丁酯与丙烯酸甲酯共聚组成发现,MA作为共聚单体加快了聚合反应速率,对转化率影响不大。     

竹原纤维与丙烯酸酯接枝物的结构与性能研究

以Ce4+引发丙烯酸甲酯(MA)、丙烯酸乙酯(EA)、丙烯酸丁酯(BA)与竹原纤维进行接枝聚合,用ATR、SEM、XRD和TG等手段表征接枝纤维的结构。接枝后纤维强度和初始模量下降,断裂伸长和柔顺性提高;耐酸、耐碱能力随接枝率的增加而提高,热稳定性提高,回潮率下降。接枝单体对纤维的改性效果顺序为BA>EA>MA。     

Miscibility and mechanical properties of poly(styrene-co-4-vinylpyridine) and poly(butyl acrylate-co-acrylic acid) ionomer blends

The miscibility of polystyrene with poly(butyl acrylate) is very poor. Ionic interactions have been utilized recently as miscibility enhancers. In this paper, dynamic mechanical studies indicate that ion pair–ion pair interactions can be utilized to achieve miscibility in blends of polystyrene and poly(butyl acrylate). The styrenes contain 0–15mol% quaternary ammonium salt of 4-vinylpyridine, while the butyl acrylates contain 0–15mol% potassium acrylate groups. The miscibility increases with increase of ion content. When the ion content exceeds 11mol%, the polymers can be completely miscible. The mechanical properties of the ionomers and their blends were also studied. The results indicate that the tensile strength of ionomer blends is higher than that of corresponding poly(butyl acrylate-co-potassium acrylate)s (PBA-AA-K). The elongation at break of ionomer blends is higher than that of the corresponding poly(styrene-co-N-methyl-4-vinylpyridinium iodide) (PS-4VP-Q). © 1998 SCI.