乙烯基含量对热硫化硅橡胶抗撕裂性能的影响

研究不同乙烯基含量对热硫化硅橡胶的力学性能尤其是抗撕裂性能的影响,采用平衡溶胀法测定硅橡胶的交联密度,研究不同乙烯基含量的硅橡胶并用胶的撕裂强度和交联密度的关系。结果表明,随着硅橡胶乙烯基含量的增大,硅橡胶硫化胶的断裂伸长率减小,300%定伸应力和硬度升高,当乙烯基摩尔分数为0.15%时,撕裂强度和拉伸强度较高。乙烯基摩尔分数为0.15%的硅橡胶和乙烯基摩尔分数为0.06%的硅橡胶并用,当并用比为50/50时,撕裂强度高达45.8 kN/m,乙烯基摩尔分数为0.30%的硅橡胶和乙烯基摩尔分数为0.06%的硅橡胶并用,当并用比为4/96时,撕裂强度可达42.9kN/m。乙烯基摩尔分数为0.30%的硅橡胶和乙烯基摩尔分数为0.15%的硅橡胶并用,并用比对硫化胶的撕裂强度影响不大。高乙烯基含量和低乙烯基含量的硅橡胶并用,有利于使硅橡胶的交联结构由"分散交联"转变为"集中交联",当并用胶的乙烯基摩尔分数在0.15%以内,硅橡胶并用胶的撕裂强度随乙烯基摩尔分数的增加而先增大后降低,而此时并用胶的交联密度与撕裂强度成反比。

Effect of ethylene content on tear strength of silicone rubber

The effect of ethylene content on mechanical properties especially for tear strength of silicone rubber was researched.The crosslinking density was determined by equilibrium swelling.And the relationship between tear strength and crosslinking density was also studied.The results showed that elongation at break decreases,while 300% modulus and Shore A hardness increase with the increasing of the ethylene content from 0.03% to 0.30%.When the ethylene content is 0.15%,the tear strength and tensile strength are higher.The 50/50 silicone rubber blends with the ethylene content of 0.15% and 0.06% respectively shows highest tear strength of 45.8 kN/m.In the silicone rubber blends with the ethylene contents of 0.30% and 0.06%,the tear strength is 42.9 kN/m when the blend ratio is 4/96.The blend ratio has no effect on the mechanical properties of the blends with ethylene contents of 0.30% and 0.15%.The crosslinking structure tends to be changed from dispersive crosslinking to concentrative crosslinking by blending silicone rubber with the higher and lower ethylene content,which causes an increasing of tear strength at first and then an decreasing with the increasing of ethylene content of the blends and the crosslinking density has inverse relation with tear strength when the ethylene content is within 0.15%.