Effect of vermiculite on the fire retarding properties of silicone pressure-sensitive adhesives

It is important for new materials, especially for everyday materials, to bear in mind the high quality of the product and its compliance with fire safety requirements. In this paper, new pressure-sensitive adhesives (based on silicone pressure-sensitive adhesives with powdered vermiculite addition) have been described. The adhesive properties (adhesion, cohesion, tack, pot-life, shrinkage) and functional properties (thermal degradation and generation of the smoke) were determined according to the international standards. The obtained pressure-sensitive adhesives exhibited good adhesive performance as well as fire-safety parameters. The addition of vermiculite as a filler significantly increased their thermal resistance and fire retardancy, with the decrease of the smoke generation, which is important for novel polymeric materials. Optimal vermiculite content of 0.5 pph reduced the amount of smoke generated by more than three times compared to samples without filler and reduced significantly the heat of combustion of the sample. It also provided sufficient adhesion and tack values (over 11 N/25 mm and over 9 N respectively) and the required shear strength value over 72 h and SAFT temperature over 225 °C.