Enhancement in bonding strength and ageing resistance of polychloroprene solvent-base adhesives through graft copolymerization

Abstract

In this research, graft copolymerization of Methyl methacrylate (MMA; hereafter) on to Polychloroprene rubber (CR; hereafter) has been processed in the presence of hydrogen peroxide as an initiator. Grafting reaction has been carried out in a mechanical mixer, and factors such as time, temperature, monomer, and initiator’s concentration were investigated and optimized. FTIR confirmed the grafting reaction occurred in the CR polymer as evident from a peak of a carbonyl group. The adhesive strength of grafted adhesive was analyzed by standard peel testing on canvas–canvas and leather–leather substrates. The effect of variation in environmental conditions such as storage time, exposure to elevated temperature, and immersion of adhesively joined substrates in the water on the peel strength of adhesive bonding was also studied. The results were compared with the strength of commercially available adhesives in local market. The solid content of grafted adhesive (55%) showed their greater applicability and high strength characteristics. The maximum peel strength achieved was 79 N/mm for canvas–canvas while 73 N/mm for leather–leather substrates. The percentage fall in peel strength after exposure to different environmental conditions was shallow as compared to commercially available adhesives. ‘GA-13’ the grafted adhesive has a high potential for the Leather-base industry and other applications.