Studies on the adhesive properties of neoprene–phenolic blends

Polychloroprene (neoprene) rubber in combination with phenolic resins is a versatile adhesive formulation. The phenolic resin used in this case was derived from a mixture of cardanol, a meta-substituted naturally-occurring substance, and phenol. Cardanol is the main ingredient of cashew nut shell liquid (CNSL), a renewable resource. This study aims to investigate the adhesive properties of cardanol-based resin when used in combination with two grades of polychloroprene rubber. The effects of varying the solid content and resin content, choice of resin, fillers, crosslinking agents, adhesion promoters, solvents, etc. in the adhesive formulations were also studied. Moreover, relative proportions of rubber and resin that give optimum adhesion performance were identified. The results show that cardanol-phenol-formaldehyde resin is an effective ingredient in adhesives for bonding aluminium to aluminium and SBR to SBR. The addition of 3-aminopropyltriethoxysilane to the formulation improves the bond strength of metal-to-metal specimens.