The preparation of polyolefin elastomer functionalized with polysiloxane and its effect in ethylene-propylene-diene monomer/silicon rubber blends

Abstract

The functionalization of polyolefin elastomer with polysiloxane can prepare novel elastomer with great compatibility, antifouling property, thermal stability and dielectricity. Herein, norbornene-derived polysiloxane was synthesized by anionic ring-opening polymerization of hexamethylcyclotrisiloxane (D3) and further used in terpolymerization with ethylene and cyclodiolefin (ethylidene norbornene or dicyclopentadiene) to prepare polysiloxane-functionalized polyolefin elastomer. High polymerization activity was obtained using vanadium-based Ziegler-Natta catalyst, and the terpolymer exhibited high polysiloxane content and Mn, which respectively reach as high as 8.5 mol% and 176.6 kg/mol. The introduction of cyclodiolefin into terpolymer could increase molecular weight, regulate crystallinity and provide reactive sites, especially ethylidene norbornene. With the polysiloxane content in terpolymer increasing, terpolymers transformed from thermoplastic to elastomer and showed better elasticity. The polysiloxane-functionalized polyolefin elastomer (Silo-70) was subsequently added into ethylene-propylene-diene monomer (EPDM)/silicone rubber (SR) blend to prepare high-performance composite. After the addition of 2 phr Silo-70, the blend showed the tensile strength and elongation at break respectively at 11.5 MPa and 878%, comparable to EPDM rubber, and the initial decomposition temperature (T5) significantly increased from 410.0 to 456.3 °C. The better miscibility between EPDM and SR was verified from DMA and SEM results.