吸收剂量对二甲基硅橡胶与甲基乙烯基硅橡胶分子量和凝胶含量的影响

EFFECT OF ABSORBING DOSE ON MOLECULAR WEIGHT AND GEL CONTENT OF DIMETHYL SILCONE RUBBER AND METHUL VINYL SILICONE RUBBER

将ＧＰＣ和特性粘数［η］测定相结合，在室温和－７８℃下，用Ｃｏ^（６０）辐射源辐照，研究了二甲基硅橡胶（ＭＱ，吸收剂量２．０５×１０~３～３．９７×１０~４Ｇｙ）和甲基乙烯基硅橡胶（ＭＶＱ，吸收剂量１０~２～１０~４）分子量和凝胶含量的变化。结果表明，辐照ＭＶＱ较辐照ＭＱ易生成凝胶，在凝胶点前的较低吸收剂量时，溶胶的分子量出现极大值，分子量分布曲线呈单峰；随吸收剂量的增加，分子量分布变窄，分子量降低；出现凝胶的吸收剂量，ＭＱ大约是ＭＶＱ的１０倍。辐照ＭＱ时，凝胶点前的溶胶的分子量分布曲线为双峰，并随吸收剂量的增加，双峰消失，分子量下降；在凝胶点时，分子量出现极大值。

The change of gel content and molecular weight of dimethyl silicone rubber(MQ,absorbing dose 2.05×103～3.97×104Gy) and methyl vinyl silicone rubber (MVQ,absorbing dose 102～104GY)with Co(60)irradiation at room and -78℃were investigated by GPC and [η]measurements.The MVQ was found to be easier to form gel than MQ.For MVQ,the maximum molecular weight of sol fraction appeared at a lower absorbing dose before the gel point,and the molecular weight distribution was monomodal.With the further increase of absorbing dose,its molecular weight distribution became narrower [η] decreased.In the case of MQ,the sol fraction exhibited a bimodal molecular weight distribution curve before the gel point and then changed to monomodal dixtribution with the further increase of absorbing dose,and the maximum intrinsic viscosity of the sol fraction appeared at the gel point.