Preparation and properties of new plywood composites made from surface modified veneers and polyvinyl chloride films

Abstract

To reduce the formaldehyde emissions of plywood used in furniture and interior decorations, new plywood composites made from surface modified veneers and polyvinyl chloride films were developed. These films were used as formaldehyde-free adhesives, and the veneer surfaces were modified with 3-aminopropyl(triethoxy)silane to enhance the compatibility with the films. Hot-pressing of composites was optimized using a response surface methodology. The effects of 3-aminopropyl(triethoxy)silane modification on various properties of veneers and composites were studied by Fourier transform infrared spectroscopy, contact angle, physico-mechanical, scanning electron microscope, dynamic mechanical, and thermogravimetric analyses. The optimum hot-pressing process for the composites was 183°C (temperature), 74 s/mm (duration), and 312.5 g/m2(adhesive). The modification with 3-aminopropyl(triethoxy)silane enhanced the hydrophobicity of veneer surfaces and improved the interfacial adhesion and physico-mechanical properties of composites. Adding 3% 3-aminopropyl(triethoxy)silane resulted in approximately 40% of decrease in water adsorption of composites and 30% increase in wet shear strength. The 3-aminopropyl(triethoxy)silane modification also improved the thermal stability of composites. The physico-mechanical properties of both the unmodified and modified composites met the requirements in Chinese national standard GB/T 9846 (2015) for the water-resistant plywood, indicating the potential of proposed composites as new building materials.