Effects of Curing Temperature and Adhesion Promoters on Adhesion of Addition-cure Liquid Silicone Rubber

It is of great interest and challenge to improve the bond strength of addition-cure liquid silicone rubber (ALSR) as packaging material. The aim of this work is to evaluate the influence of the curing temperature and adhesion promoters on adhesion of ALSR. We investigate the effects of various adhesion promoters, namely, epoxy-containing silane (EP-PHMS), ester-containing silane (EH-PHMS), and urethane-containing silane (N-PHMS), on bond strength of ALSR. The obtained results demonstrate that at heat curing temperature, bond strength is mainly affected by the chemical reactions of functional groups. At this condition, EH-PHMS best enhances the strengths of bonds between ALSR and aluminum and between ALSR and polycarbonate (by 316 and 300%, respectively); however, the bonding between ALSR and glass is most improved by EP-PHMS (increased by 1107% ). At room curing temperature, N-PHMS yields the best bond properties for all three substrates. In addition, the mechanisms of adhesion promoters were studied by time-viscosity testing, surface tension testing and scanning electron microscopy (SEM). The results certified the mechanism was attributed to chemical reactions, intermolecular forces, and wetting properties. The data reported herein are of great significance for the fabrication of ALSR materials that can strongly bind to various types of substrates.Graphical Abstract