低相对分子质量反-1,4-聚异戊二烯蜡的分级与表征

Classification and characterization of low relative molecular mass trans-1,4-polyisoprene wax

以负载型TiCl4/MgCl2 -Al(i-Bu) 3 为催化剂 ,1 48MPa氢气为相对分子质量调节剂 ,采用本体淤浆聚合法 ,制备了重均相对分子质量及其分布分别为 42 70 0和 5 0 ,特性黏数为 0 697dL/g的低相对分子质量反 -1 ,4-聚异戊二烯蜡 (LMTPIW) ,并对其级分进行了表征。结果表明 ,随着数均相对分子质量的降低 ,LMTPIW的熔体流动性增加 ,结晶度下降 ,熔点降低 ,反 -1 ,4-结构摩尔分数下降 ,但基本在90 %以上 ,3 ,4-结构摩尔分数为 1 0 %～ 1 5 %。当数均相对分子质量超过 860时 ,LMTPIW由黏性转变为脆性 ;大于 1 80 0时 ,又转变为韧性物质。所得LMTPIW为相对分子质量分布宽、结构性能差异较大的分子混合物。

Low relative molecular mass trans-1,4-polyisoprene wax(LMTPIW) of intrinsic viscosity 0.697 dL/g, w 42 700, n/ w 50, was synthesized by bulk precipitation polymerization of isoprene with TiCl 4/MgCl 2-Al(i-Bu) 3 as supported titanium catalyst,high pressure hydrogen of 1.48 MPa as relative molecular mass regulator.The results showed that with the decrease of relative molecular mass, melt fluidity of LMTPIW increased, crystallinity and melt point decreased,mole fraction of trans-1,4-unit decreased but typically maintained above 90%. Mole fraction of 3,4-unit was about 1.0%～1.5%. When number average relative molecular mass exceeded 860,LMTPIW transformed from viscous to brittle polymer,when it exceeded 1 800 , it transformed again to tough material. The LMTPIW was a kind of mixture at molecule level, relative molecular mass distribution was wide, and structure and properties were different.