Role of in‐situ polymethyl‐methacrylate in addition type silicone rubber with specific reference to adhesion and damping properties

Abstract

AbstractHerein, a strategy of embedding in‐situ polymethyl‐methacrylate (PMMA) domains in polydimethylsiloxane (PDMS) networks is proposed to enhance adhesive and damping properties of addition type silicone rubber (SR). PMMA domains improve the modulus of SR (at room temperature), which is stronger correlated to its adhesive performance, according to the Griffith criterion. Besides, the damping performance at high temperature is provided by the glass transition of thermoplastic PMMA. The PMMA/SR blends are obtained by the crosslink of PMMA and vinyl‐terminated polydimethylsiloxane (vi‐PDMS) liquid blends with polymethylhydrosiloxane, and the PMMA/vi‐PDMS liquid blends are prepared by in‐situ radical polymerization of methyl‐methacrylate (MMA) in vi‐PDMS with toluene as compatibilizer. Effects of disperse speed, compatibilizer content, and PMMA proportion on the morphologies and properties of PMMA/SR blends are studied. Small PMMA domains (around 800 nm) in PMMA/vi‐PDMS blends with narrow size distribution and well dispersion are formed at appropriate disperse speed (100–300 rpm) and abundant compatibilizer content (~100 wt% refers to vi‐PDMS). The blends with 20 wt% PMMA possess tensile strength over 8 MPa and lap shear strength over 5 MPa to stainless steel. And the blends with 50 wt% PMMA show good damping properties with tan δ over 0.15 at temperature range from −50 to 150°C. Tg‐PMMA moves slightly to lower temperature with less PMMA embedded, but Tg‐PDMS remained stable relatively.