Rheological, Thermal and Mechanical Properties of Wood Plastic Composites (WPCs) Based on Virgin and Recycled Polypropylenes and Birch Plywood Waste

Article summarizes investigation results of rheological, thermal and some mechanical properties of industrially prepared wood plastic composites (WPCs), based on virgin and recycled polypropylenes (vPP, rPP) and birch plywood production waste product-plywood sanding dust (PSD). Investigated WPCs contain 40 and 50 wt. % PSD different another modifier, such as functional lubricant Struktol TWP-113, antioxidant 1010, thermal stabilizer 168, UV stabilizer 770 and different color pigments. According to our studies, we can conclude that rheological properties studied by capillary rheometry method depends on WPCs composition and experimental parameters: shear stress, shear deformation rate and temperature. The curves of the fluidity indicate to the character of typical pseudo-plasticity of all polymer melts of which viscosity not only depends on temperature, but also decreases with an increase of shear stress and shear deformation rate Pseudo-plastic properties confirm also the signed values of fluidity index (n) which for pseudo-plastic liquids always are smaller than one. TGA measurements showed that all systems have the high thermal stability and the weight losses after dynamic heating up to processing temperature 215°C are not more than 5.53 %, but during isothermal heating (1 h) at 215°C only 4.51%. Differential scanning calorimetry (DSC) showed a small changes of melting temperatures, but the beginning of thermal destruction temperature fluctuates between 256.96 and 188.5°C. Density of all composites changes in limits 1.02-1.09 g/cm3, temperatures by Vika 154.4-158.7°C, microhardness 125.1-151.8 MPa and impact strength 7.81-15.39 kJ/m2