Melt and glass crystallization of PDMS and PDMS silica nanocomposites.

Silica nanoclusters were homogeneously dispersed into an end-linked PolyDiMethylSiloxane (PDMS) matrix. Dynamic relaxation, glass and melt crystallization of end-linked PDMS-silica nanocomposites (PDMSnanoSi) were compared to those of PDMS. A particular emphasis is made on the kinetic aspects of these transitions by corroborating investigations conducted by means of Dynamic Mechanical Analysis (DMA) and Differential Scanning Calorimetry (DSC). Addition of silica nanoclusters does not modify the relaxation behavior of the amorphous phase and the glass transition kinetics. However, melt and glass crystallizations are significantly promoted in the presence of silica nanoclusters. The secondary crystallization process is more pronounced for PDMSnanoSi and higher crystal perfection due to structuring effects of silica nanoclusters is also highlighted. For the two systems, one set of Hoffman-Lauritzen parameters have been evaluated by combining melt and glass crystallization kinetic data.