Foaming behavior regulation of silicone rubber via evolution of crosslinked structure

The cellular structure and foam density of silicone rubber foam are known to be influenced by its rheological behavior, which could be adjusted by crosslinked density and crosslinked structure. However, the effect of the crosslinked structure evolution in methyl vinyl silicone rubber (MVQ) on the supercritical foaming behavior has never been investigated. In this research, the crosslinked density and T2 relaxation time of MVQ were charactered by low-field nuclear magnetic resonance (LF-NMR), which revealed the evolution of crosslinked structures and change of the crosslinked density under different vinyl group contents and pre-cure time in MVQ. In addition, a processing strategy which utilized conjunctively crosslinked structure and crosslinked density of MVQ was used to design the cellular structure and prepare low density foam. The resulting MVQ foam had an adjustable density range from 1.12 g/cm3 to 0.08 g/cm3 and different cellular structures. In this study, the effective control of foaming behavior was realized by manipulating the crosslinked density and crosslinked structure, and this approach would pave a new possibility to obtain desired cellular structures.