Effect of diphenylsiloxane unit content on relaxation behavior of poly(dimethylsiloxane-co-diphenylsiloxane)
2008
Qu, Liangliang | Xie, Zhijian | Huang, Guangsu | Tang, Zhenhua
The relaxation behaviors of poly(dimethylsiloxane-co-diphenylsiloxane)s with different compositions were investigated using dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). It is indicated that the content of Ph₂SiO unit, which is closely associated with crystallinity of polysiloxane, has a remarkable influence on its relaxation behavior. Two-phase (crystalline and amorphous phase) structure in the semicrystalline polysiloxane of the present system can be determined for discussing relaxation behavior. An increase in relaxation strength can be reasoned to a cooperative effect of decrease in fraction of crystalline phase and increase in friction between molecular chains. And enhancements in glass transition temperature (Tg) and effective activation energy for glass transition (Ea(eff)) were ascribed more to the stiffness imposed by Ph₂SiO unit than decrease in fraction of crystalline phase.
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