非离子型可聚合聚氨酯/苯乙烯的超浓乳液聚合

研究了以非离子型可聚合聚氨酯(PUAG)和苯乙烯(St)为混合单体的超浓乳液聚合, 并且考察了n(NCO)/n(OH)摩尔比、复合乳化剂体系质量浓度E]、不同乳化剂的种类、引发剂质量浓度I]、单体体积分数(或分散相体积分数, 也称内相比Φ)、聚合温度等因素对聚合稳定性、动力学的影响. 同时结合光相关光谱(PCS)测定了聚合物乳胶粒子大小和粒径分布, 用透射电子显微镜(TEM)观察了粒子形态, 结果表明: 当n(NCO)/n(OH)＝2∶1, T＝328 K, Φ＝80.39%, I]＝0.8% g/g (PUAG-St), E]＝0.22 g/mL H₂O, m(MS-1)/m(CA)＝2∶1, PVA＝0.01 g/mL H₂O时, 超浓乳液不仅有较好的聚合稳定性和较快的聚合速率, 而且粒径小分布均匀. 同时, 在此条件下的表观动力学表达式和表观活化能分别确定为R_p＝kI]^0.50E]^0.73M]^0.54和 E_a＝29.7 kJ/mol. 热失重分析(TGA)进一步表明: 调节PUAG的含量可以达到对聚苯乙烯的改性, 提高聚苯乙烯的热稳定性.

Concentrated Emulsion Polymerization of Nonionic Polymerizable Polyurethane/Styrene

The concentrated emulsion polymerization using nonionic polymerizable polyurethane (PUAG)/ styrene (St) as mixture monomers was studied. The effects of NCO/OH molar ratio, composite emulsifier concentration, different emulsifiers, initiator concentration, volume fraction of the monomer phase (Φ) and temperature on the polymerization stability and kinetics of the concentrated emulsion were investigated. The morphology of polymer particles, the average size and distribution of the latex particles were analyzed by transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS), respectively. The conditions for polymerization with a higher stability, higher polymerization rate, small particle size and homogeneous particle size distribution were as follows: n(NCO)/n(OH)＝2∶1, T＝328 K, Φ＝80.39%, I]＝0.8% g/g (PUAG-St), E]＝0.22 g/mL H₂O, m(MS-1)/m(CA)＝2∶1, PVA＝0.01 g/mL H₂O. The apparent polymerization kinetics and activation energy were found to be R_p＝k I]^0.50E]^0.73M]^0.54 and E_a＝29.7 kJ/mol, respectively. Thermogravimetry analysis (TGA) result indicates that the stability of polystyrene may be promoted by adding appropriate amount of PUAG.