Dependence of the elastomeric properties of bimodal networks on the lengths and amounts of the short chains
Dependence of the elastomeric properties of bimodal networks on the lengths and amounts of the short chains
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DOI：
10.1002/pol.1984.180221101
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发表时间：
1984-11
期刊：
影响因子：
--
通讯作者：
J. E. Mark;M. Tang
中科院分区：
文献类型：
--
作者：
J. E. Mark;M. Tang
双峰弹性体网络是通过四官能末端连接非常短和相对较长的聚（二甲基硅氧烷）羟基封端链合成的。短链分子量的降低（从 880 到 660 到 460 g mol−1）通常会导致极限强度和断裂能显着增加。然而，短链数量的减少会导致这两个数量达到最大值。太多的短链本质上会产生脆性的热固性材料，这会妨碍由于短链的有限延伸性而引起的模量的任何上升。短链太少使得它们有限的可扩展性变得无关紧要，因为整个宏观变形可以由网络中存在的长链承担。
Bimodal elastomeric networks were synthesized by tetrafunctionally end-linking very short and relatively long hydroxyl-terminated chains of poly(dimethylsiloxane). Decrease in the molecular weight of the short chains (from 880 to 660 to 460 g mol−1) generally results in significant increases in ultimate strength and energy for rupture. Decrease in the number of short chains, however, causes these two quantities to go through a maximum. Too many short chains gives essentially a brittle thermoset, and this precludes any upturn in the modulus from the limited extensibility of the short chains. Having too few short chains makes their limited extensibility irrelevant since the entire macroscopic deformation can then be taken up by the long chains present in the network.