摘要
利用HAAKE密炼机对比研究了甲基丙烯酸缩水甘油酯(GMA)、甲基丙烯酸羟丙酯(HPMA)、甲基丙烯酸羟乙酯(HEMA)、甲基丙烯酸乙酯(EMA)、甲基丙烯酸甲酯(MMA)以及丙烯酸羟乙酯(HEA)等具有不同分子结构的丙烯酸酯类单体对线性低密度聚乙烯(LLDPE)的接枝反应.通过对不同温度下不同反应时间的产物接枝率的测定,发现丙烯酸酯类单体接枝聚烯烃过程中均存在解聚现象.开始发生解聚现象的温度,也即解聚温度(ceiling temperature,Tc),与单体分子结构有关.讨论了位阻效应和特殊基团(如羟基等)相互作用对解聚温度的影响,并通过丙烯酸酯类单体的溶液聚合反应确认了不同丙烯酸酯类单体的解聚温度范围.讨论了添加苯乙烯(St)作为助单体对不同丙烯酸酯类单体接枝率的影响,并结合Q-e法则和竞聚率对其进行了解释.
The melt grafting of acrylates onto LLDPE was investigated for monomers of GMA,HPMA,HEMA, EMA,MMA and HEA by Haake mixer. It is found that, the depolymerization would occur during the melt grafting process for the grafted acrylate oligomer chains when the temperature was higher than the ceiling temperature （To） of the grafted acrylate polymers, which induced the decrease in the grafting ratio of the acrylates. To varied with different molecular structures of acrylate monomers. The influence of the steric hindrance and the special interactions between monomers was discussed. For the monomers with hydroxyl groups （ GMA, HPMA, HEMA, HEA） , the larger the steric hindrance is, the lower the reaction heat, which results in the lower ceiling temperature. The monomers of MMA and EMA have no hydroxyl groups, so the reaction heat is much lower, which results in the relatively low ceiling temperature than that with hydroxyl groups. The order of the ceiling temperatures was finally suggested ： To （HEA） 〉 Tc （HEMA） 〉 To （HPMA） To （GMA） 〉 Tc （EMA,MMA）. The solution polymerization in dichlorobenzene of the acrylate monomers was carried out respectively and the ceiling temperature ranges of different acrylate monomers were identified, which agreed well with the results of melt grafting. The styrene （St） was added as co-monomer to assist the grafting of acrylate monomers onto LLDPE,and the effect could be predicted by the Q-e rule. The grafting ratio of GMA,HPMA,MMA and EMA could be improved by adding St because they can copolymerize with St well and the depolymerization in melt grafting could be depressed even at high temperatures.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2012年第11期1349-1354,共6页
Acta Polymerica Sinica
基金
国家自然科学基金(基金号51073088)资助项目
关键词
丙烯酸酯
聚烯烃
接枝
解聚
Q-e法则
Acrylate, Polyolefin, Melt grafting, Depolymerization, Q-e rule
