热硫化硅橡胶撕裂强度的影响因素探讨

Discussion on Influencing Factors of Tear Resistance of HTV Silicone Rubber

以甲基乙烯基硅橡胶(生胶)为主要原料,添加气相法白炭黑、羟基硅油、含氢硅油、硬脂酸等制得热硫化硅橡胶。探讨了生胶、气相法白炭黑、多乙烯基硅油、四甲基二乙烯基二硅氮烷对热硫化硅橡胶性能的影响。结果表明,当采用单一乙烯基摩尔分数的生胶时,随着生胶中乙烯基摩尔分数从0.05%提高到0.23%,二次硫化后的硅橡胶邵尔A硬度从55.5度升至76.5度,拉伸强度先由10.7 MPa升至11.2 MPa后再降至8.9 MPa,拉断伸长率由540%逐渐降至260%;采用较高乙烯基含量的生胶与较低乙烯基含量的生胶并用时,能大幅提升硅橡胶的撕裂强度;随着气相法白炭黑N20用量从30份增加到55份,二次硫化后硅橡胶的邵尔A硬度由50度升至70度,拉伸强度由7.7 MPa升至11 MPa,拉断伸长率先降后升再下降,撕裂强度在气相法白炭黑N20用量为40份时达到最大值26.3 kN/m;在2种生胶并用的体系中,对于同一系列的气相法白炭黑来讲,随着气相法白炭黑比表面积的增加,硅橡胶的撕裂强度逐渐提高;随着多乙烯基硅油中乙烯基摩尔分数和用量的增加,硅橡胶的邵尔A硬度变化不明显,拉伸强度和撕裂强度均先升后降;随着四甲基二乙烯基二硅氮烷用量的增加,硅橡胶的邵尔A硬度变化不明显,拉伸强度和撕裂强度均先升后降。当四甲基二乙烯基二硅氮烷用量为0.4份时,二次硫化后硅橡胶的撕裂强度达到最大值44.3 kN/m。

The high temperature vulcanized(HTV)silicone rubber was prepared from methyl vinyl silicone rubber by adding fumed silica,hydroxyl silicone oil,hydrogen silicone oil and stearic acid.The effects of raw rubber,fumed silica,polyvinylsilicone oil and tetramethyldivinyl disilazane on the properties of HTV silicone rubber were investigated.The results showed that the Shore A hardness of silicone rubber increases from 55.5℃to 76.5℃with the increase of the vinyl mole fraction from 0.05%to 0.23%,the tensile strength increases from 10.7 MPa to 11.2 MPa,then decreases to 8.9 MPa,and the elong ation at break decreases from 540%to 260%,as fumed silica N20 increases from 30 phr to 55 phr,the Shore A hardness of silicone rubber increases from 50 to 70 degrees,and the tensile strength increases from 7.7 MPa to 11 MPa,the tear strength reaches the maximum of 26.3 kN/m when N20 was 40 phr in fumed silica.For the same silica in the other systems,the tear strength reached the maximum of 26.3 kN/m when N20 was 40 phr,the tear strength of silicone rubber increases with the increase of the specific surface area of fumed silica,and the hardness of silicone rubber changed little with the increase of the contents and mole fraction of vinyl in polyvinylsilicone oil,the tensile strength and tear strength increases firstly and then decreases,but the shore A hardness of silicone rubber is not change obviously with the increase of tetramethyldivinyldisilazane.When tetramethyldivinyldisilazane is 0.4 phr,the maximum tear strength of silicone rubber is 44.3 kN/m.