| Poly[(methylsilylene)ethynylene](MSE)which contains Si-H and C≡C bonds,produces a very high thermal stable resin by pretreatment at 150-180℃, and by pyrolysis givesβ-SiC-containing ceramics in high yield.The curing process affects the thermal stability of cured resin and ceramic yield in decomposition of the resin.Therefore,it is necessary to study the curing process and curing mechanism of MSE.The isothermal pretreatment process of MSE(at 160,170 and 180℃) was investigated by DSC and FTIR.The results showed that hydrosilylation of MSE proceeded on isothermal process with the reactive degree of approximately 33%,the pretreatmeat time t and the temperature T has a relationship of t(T)/t(T+10K)=2:1.The curing kinetics of MSE was investigated by means of dynamic and isothermal DSC experiments.The kinetic parameters(the apparent activation energy Ea,the frequency factor A and the reaction model f(α))were obtained from DSC experiments respectively.Results are as follows:(1)Ea =110.0kJ/mol,A=2.77×109 and reaction-order model f(α)=(1-α)n(the reaction order n=0.93,pseudo first-order reaction)and(2)Ea=112.4kJ/mol, A=5.46×109s-1and nucleation model f(α)=n(1-α)[-ln(1-α)]1-1/n(the parameter n=2.53,homogeneous nucleation and three-dimensional growth).The thermosetting mechanism of MSE was studied using FTIR,NMR, XRD,GC-MS and so on.The results showed that the curing process of MSE consist reactions of hydrosilylation between Si-H and C≡C,addition and cyclization of C≡C bonds,rearrangerment reaction,oxidation crosslinking reaction(aerobic condition)and so on to finish the curing of MSE.
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