Charphy Impact of Medium Molecular Weight Phenol Formaldehyde (MMwPF) Plywood

Abstract

Plywood is a wood product frequently utilized in building as part of concrete formwork systems. In the concreting process, plywood formwork needs to be strongly made to withstand the pressure subjected by the wet concrete as well as the impact. To reduce the dependency on solid timber as plywood, oil palm stem offers alternative materials. There are four main weaknesses of oil palm stem (OPS) as a material for plywood manufacturing; high variations in density and moisture content (MC), high water absorption and high surface roughness. Therefore, this study modified the drying and treatment process of OPS veneer. The veneer was predried by using roller presser for removing a large amount of water and later treated with medium molecular weight phenolformaldehyde (MMwPF) to bond together parenchyma tissue, cell wall, and a lumen for much uniform density and better surface bonding. The Charpy impact of OPS plywood developed in this study denoted as PTA was investigated. These properties were compared with the properties of another two types of commercial OPS plywood denoted as PTB and PTC which were manufactured using OPS veneer with tropical hardwood veneer for face and back veneer and control plywood denoted as PTD which was manufactured using 100% tropical hardwood veneer. The results showed that PTA has the highest mean value of energy and strength for both notched and unnotched Charpy impact.