Preparation, mechanical and thermal properties of polydimethylsiloxane coating for synthetic leathers

The curing process of polydimethylsiloxane (PDMS) coating was systematically investigated by nonisothermal differential scanning calorimeter (DSC), and accordingly, the thermodynamic as well as kinetic parameters were obtained. Meanwhile, effect of structural factors, including different divinyl-terminated polydimethylsiloxane (^ViPDMS^Vi), divinyl-terminated polymethylvinylsiloxane (^ViPMVS^Vi), polymethylhydrosiloxane (PMHS), and reinforcing filler content, on mechanical and thermal properties of coating was studied. The results demonstrated that platinum compounds could significantly accelerate the hydrosilylation and reduce the curing temperature and activation energy. The viscosity, vinyl/hydrogen sites, and quantities of ^ViPDMS^Vi, ^ViPMVS^Vi, and PMHS were important factors to influence mechanical and thermal properties. Low viscosity ^ViPDMS^Vi and PMHS with side hydrogen atoms could increase crosslinking density, and then enhance the tensile strength and heat resistance. ^ViPMVS^Vi with higher viscosity and vinyl content could dramatically improve tensile strength while maintaining breaking elongation. Reinforcing filler was another vital factor to enhance strength and thermostability. 550% improvement in tensile strength occurred when reinforcing filler content was 40 wt%. All aforementioned results provided a comprehensive guidance for the preparation and property regulation of PDMS coating. This kind of PDMS coating can be applied in synthetic leather manufacturing.