Interfacial adhesion and molecular diffusion in melt lamination of wood sawdust/ebonite NR and EPDM

Adhesion mechanisms and peel strengths of wood/ebonite NR‐EPDM laminates were investigated. Three different chemical coupling agents: namely; N‐(β aminoethyl)‐γ‐aminopropyl‐triethoxysilane (AAS), 3‐methacryloxypropyl trimethoxysilane (ACS), and Bis‐(3‐triethoxylpropyl) tetrasulfan (Si69) were introduced into the wood/NR composites to enhance an interaction between wood sawdust (SD) particles and NR molecules, and to improve the adhesion strength between the SD/NR and EPDM layers. The quantitative evidences were given to explain the changes in the adhesion or peel strengths of the SD/NR‐EPDM laminates through scanning electron microscopy with energy dispersive X‐ray analysis (SEM‐EDS). The experimental results indicated that the suitable cure time and cure temperature for SD/NR‐EPDM melt‐laminates were the tc 90 of SD/NR composites and 140°C, respectively. The Si69 coupling agent was found to be the most effective coupling agent as compared with AAS and ACS coupling agents. The Si69 of 0.5 wt% was recommended for the optimizations of the tensile modulus of the SD/NR composites and the peel strength of the SD/NR‐EPDM laminates. The diffusion level between the SD/NR and EPDM layers could be quantitatively substantiated by determining the sulfur content transfer from the SD/NR layer to the EPDM layer. The diffusion and entanglement of molecular chains from the SD/NR to the EPDM layer initiated the co‐crosslinking reaction which played an important role on the changes in the interfacial strength in the SD/NR‐EPDM melt‐laminates. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers