Effect of veneer drying process on some technological properties of polystyrene composite plywood panels

Hasan Ozturk,Aydin Demir,Cenk Demirkir,Gursel Colakoglu

doi:10.5552/drvind.2019.1844

Abstract

The aim of study was to determine the effect of veneer drying process on some technological properties of polystyrene composite plywood panels. For this reason, 2 mm-thick rotary cut veneers were obtained from beech (Fagus orientalis, Lipsky), Alder (Alnus glutinosa subsp. Barbata) and Scots pine (Pinus sylvestris L.) logs. The veneers obtained from three different wood species were divided into two groups to produce polystyrene composite plywood (PCP) and traditional plywood. While PCP was produced both air dried (at 20 °C) and oven dried (at 110 °C), the veneer sheets for production of traditional plywood were dried at 110 °C until reaching 7 % equilibrium moisture content. Two different types of polystyrene with high density (30 kg/m3) and low density (16 kg/m3) were used as bonding material for PCP panel production. The urea-formaldehyde adhesive was used as a bonding material for traditional plywood panels. Bonding shear strength, bending strength, modulus of elasticity and density of plywood and polystyrene composite plywood panels were investigated. It was found that the technological properties observed in the study of composite plywood panels manufactured with natural dried veneers gave similar results compared to those of composites produced with technical dried veneers.

Highlights

The veneers obtained from three different wood species were divided into two groups to produce polystyrene composite plywood (PCP) and traditional plywood
It was found that the bonding strength values of Polystyrene composite plywood panels with high density Styrofoam were lower than those of composite panels manufactured with low density polystyrene
Demirkir et al (2013) stated that, since PCP panels produced with low density polystyrene could be pressed and homogenously, stronger fastening could be achieved between veneer and polystyrene (Demirkir et al, 2013)

Summary

Introduction

In 1995 the International Agency for Research on Cancer (IARC) classified formaldehyde, in terms of human health, as “Possible Carcinogenic Substances” class and the ratio of formaldehyde that can be released from wood-based materials was limited in most of countries (IARC, 2004; Colakoglu, 1993). After this area was investigated comprehensively, in June 2004 IARC removed formaldehyde from “Possible Carcinogenic Substances” class and identified it as directly carcinogenic to humans (Jianying et al, 2010). Polystyrene composite plywood (PCP) can be manufactured without synthetic resins such as urea-formaldehyde or phenol-formaldehyde (Demirkir et al, 2013; Hu et al, 2005). Some revisions should be made in PCP manufacturing process to increase productivity, since no adhesive is used in the process

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