MECHANICAL, WEATHERING, THERMAL, AND FIRE PERFORMANCE OF TREE BARK REINFORCED WOOD PLASTIC COMPOSITES

This study investigated some technological properties of wood plastic composites (WPCs) containing tree bark. Tree bark led to a decrease in the mechanical properties of WPCs. The flexural strength (FS) and modulus of elasticity (MOE) decreased with an increasing tree bark content by 23% and 39%, respectively, while the decrease of tensile strength was of 35%. On the other hand, outdoor weathering testing revealed that increasing tree bark content slowed UV degradation and reduced surface color fading. This effect is attributed to the inhibition of photodegradation reactions due to the higher antioxidant activity of the bark. TGA and DSC analyses have revealed the potential of tree bark to significantly influence material properties. The TG analysis indicated that tree bark enhances the degradation onset temperature, while the high lignin content in tree bark, compared to wood, increases the maximum degradation temperature. Moreover, the DSC analysis showed that the melting enthalpy (triangle Hm) increases with adding tree bark. The high extractive content in tree bark not only enhances thermal movement, but also promotes crystallization. However, an increase in tree bark content led to a limited improvement in fire performance by LOI values, possibly because of the higher extractive content.