Effect of biological degradation by termites on the flexural properties of pinewood residue/recycled high-density polyethylene composites

摘要

Wood-plastic composites (WPCs) are considered to be highly durable materials and immune to any type of biological attack. However, when one of these composites is exposed to accelerated weathering, its surface is affected by the appearance of cracks, which constitute an ideal access route for biotic agents. Although the destruction of wood caused by termites is recognized worldwide, information on their effects on WPC-based products is scarce. Thus, in this study, we aimed to examine the effects of termite attacks on weathered and nonweathered pinewood residue/recycled high-density polyethylene composites. In this study, WPCs with 40 wt % wood were prepared. Test samples obtained by compression molding and profile extrusion were subjected to weathering cycles for 1000 and 2000 h with a UV-type accelerated tester equipped with UVA-340 fluorescent lamps. Afterward, specimens were exposed to the attack of higher termites (Nasutitermes nigriceps) native to the Yucatan Peninsula. Subsequently, flexural mechanical essays, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) analyses were performed. FTIR spectroscopy and DSC showed that the surfaces of the compression-molded specimens were degraded to a higher extent because of the accelerated weathering. The microscopy results revealed that severe damage was caused by the termites on the surface of the compression-molded samples. Statistical analysis of the mechanical test results showed that biotic attack produced significant changes in the samples previously exposed to accelerated weathering. The results show that the processing method directly affected the sample performance because of differences in the surface composition. The profile-extruded composites seemed to better resist termite attack.