WOOD RESEARCH Volume 70, Number 4, 2025
EMRE BIRINCI

INVESTIGATION OF THE EFFECT OF EXTREME TEMPERATURE ON SCREW DIRECT WITHDRAWAL RESISTANCE OF WOOD PLASTIC COMPOSITE DECKING PROFILES

In this study, the effects of extreme temperatures on screw direct withdrawal resistance (SDWR) of wood plastic composite (WPC) decking profiles were systematically investigated. Commercially produced WPC decking profiles were tested at different temperature levels (-40°C, -20°C, 0°C, room temperature, +40°C and +60°C); their effects on SDWR were evaluated by controlling parameters such as screw diameter (3.0 mm and 3.5 mm) and pilot hole diameter (60%, 70% and 85%). Additionally, the relationships between Shore D hardness and SDWR measured at each temperature level were revealed through statistical analyses. The results show that as the temperature increases, Shore D hardness decreases and accordingly, significant decreases occur in SDWR. The highest SDWR was obtained at -40°C temperature, 60% pilot hole ratio and 3.5 mm screw diameter combination. This highlights the influence of material hardness and screw-material interaction on joint performance. According to Pearson correlation analysis, a strong and statistically significant (r=0.939, p=0.0055) positive relationship was determined between Shore D hardness and SDWR.

WOOD RESEARCH Volume 62, Number 5, 2017
Ling Chen, Jingquan Han, Runzhou Huang, Xinwu Xu, and Qiinglin Wu

Thermal decomposition properties of recycled tire rubber filled wood/high density polyethylene composites

Dynamic thermo-gravimetric analysis under nitrogen was applied to investigate the thermal decomposition process of wood/HDPE composites (WPC) modified with different amount of ground tire rubber (GTR). Degradation models, including the Friedman and Flynn-Wall-Ozawa (F-W-O) were used to determine the apparent activation energy (Ea) of various materials. Composites with various GTR contents exhibited a similar two-stage degradation process. Initial decomposition temperature (T0) of the composites gradually decreased from 250.1°C to 238.2°C with the increasing GTR concentration, while the peak temperature (Tp) values remained about the same. Kinetic analysis demonstrated an average activation energy decreasing with the incorporation of 5 % GTR within the composites through both methods, but no big difference was observed with further increasing the GTR content from 5 % to 15 %. The established thermal decomposition kinetic parameters allow developing the reutilization of waste tire rubber in composite materials with appropriate loading level.