Enhanced fire retardancy with excellent electrical breakdown voltage, mechanical and hydrophobicity of silicone rubber/aluminium trihydroxide composites by milled glass fibres and graphene nanoplatelets

Abstract

The integrity of polydimethylsiloxane (PDMS) based silicone rubber (SR) is highly critical in the electrical insulation industry during a wildfire event. In this work, SR composites are prepared with milled glass fires (MGFs) and graphene nanoplatelets (GNPs) to study the limiting oxygen index (LOI), cone calorimeter parameters, electrical breakdown voltage, mechanical and hydrophobic properties of solely aluminium trihydroxide (ATH) filled PDMS. Results exhibit that ATH could help in improving the aforementioned characteristics of pristine SR whereas, the MGFs and GNPs impart a pronounced impact on further improving the properties of solely ATH-filled SR. It is noticed that LOI improves to 35% and 36% whilst the maximum average rate of heat emission (MARHE) reduces to 78.6 kW/m2, and 69.6 kW/m2 in SR4 and SR5. In addition, the electrical breakdown voltage is slightly reduced at 24.65 kV/mm and 25.78 kV/mm in SR4 and SR5 relative to 27.47 kV/mm in SR1. GNPs and MGFs mutually render a positive impact on improving the tensile strength of SR2. Furthermore, SR composites are found with excellent hydrophobicity. The static contact angle marginally decreases in SR2 relative to SR1 whilst it is measured comparatively high at ∼115° in MGFs and GNPs-filled SR composites. SR4 and SR5 seem propitious composites comparatively with improved LOI, excellent fire retardancy, better mechanical strength and hydrophobicity whilst retaining the electrical breakdown strength.