Bonding of air-formed wood fibre/polypropylene fibre composites

The effectiveness of a maleated polypropylene (MAPP) as a coupling agent in wood fibre/polypropylene fibre composites made by non-woven web technology has been evaluated. The composite panels were made with 70 or 85% wood fibre, wiht the MAPP being incorporated in the panels at a level of 1 or 3% by spraying an emulsified form on the wood fibres. Both levels of MAPP significantly increased bending and tensile strength and moduli, and dynamic modulus. At the 70% wood fibre level, impact energy was increased significantly in panels with 3% MAPP. At the 85% wood fibre level, both 1% and 3% MAPP significantly increased impact energy. The MAPP also led to small improvements in water resistance for composites containing 85% wood fibre. The effectiveness of MAPP is believed to be the result of efficient incorporation at the wood/polypropylene interface, thus providing effective coupling of the polar wood component to the non-polar polymer matrix.