乙烯基硅烷/苯乙烯接枝聚丙烯的结晶和力学性能

研究了乙烯基硅烷（VS）和苯乙烯（St）双单体接枝聚丙烯（PP-g-VS/St）的结晶性能和力学性能。结果表明，长支链的引入使PP-g-VS/St的结晶峰值温度和熔融峰值温度相对于线形等规聚丙烯（iPP）分别提高了10、2 ℃，且球晶得到了细化; PP-g-VS/St在10 ℃/min的降温速率下结晶产生的晶型为α晶型与少量γ晶型的混合物；在注塑条件下结晶产生的晶型为α晶型与β晶型的混合物; 利用莫志深法研究PP-g-VS/St的非等温结晶动力学过程发现，在结晶的早期和后期，长支链对PP-g-VS/St的结晶分别起到了加速成核和阻碍生长两种相反的作用；相对于iPP，PP-g-VS/St的拉伸强度、弯曲模量和冲击强度分别提高了29 %、40 %和453 %。

Crystallization Behaviors and Mechanical Properties of Polypropylene Grafted by Vinyl Silane/Styrene

The crystallization behavior of and the mechanical properties of long chain branching polypropylene(LCBPP-g-VS/St) grafted by vinyl silane and styrene were investigated in this paper. The results indicated that the crystallization peak temperature and the melting peak temperature of PP-g-VS/St increased 10℃ and 2℃ respectively, and the spherulite size of PP-g-VS/St dramatically decreased based on neat LCBPP. Furthermore, the crystallites of PP-g-VS/St composed of γ and α forms when the cooling rate was 10℃/min，while the crystal of PP-g-VS/St composed of α and β form when the polymer crystallized on the injection-molding condition. The non-isothermal crystallization kinetics of PP-g-VS/St indicated that the LCB structure acted as a heterogeneous nucleating agent at the beginning of crystallization and hindered the crystal growth in the latter stage. Compared to virgin iPP, the tensile strength, flexural modulus and impact strength of PP-g-VS/St increased by 28%, 40% and 453%, respectively.