Characterisation and adhesion properties of UV-cured natural rubber-based adhesives

The adhesion properties of rubber adhesives based on SMR-L, ENR-25 and ENR-50 elastomers cured by ultraviolet (UV) light radiation were examined. Various parameters were studied, namely the effects of UV radiation dosages and coating thickness on adhesion properties such as tackiness, peel strength, and shear resistance. Prior to curing, the viscosity of uncured adhesives was analysed in order to understand the effect of adding benzoyl peroxide cross-linker. The reduction of double bonds due to UV-curing was confirmed by FTIR analysis. These adhesives were properly cured after 15 passes (repetitive irradiation on moving conveyor belt) inside UV-curing machine, as proven by both pendulum hardness and gel content tests. Results indicated that for all rubber-based adhesives, 120 μm coated samples showed higher peel strengths than their 60 μm counterparts. ENR-25 based adhesives showed better peel strength as compared to the others, while SMR-L based adhesives possessed higher tackiness and shear resistance than those of ENR-25 and ENR-50 based adhesives.