Effect of Extreme Conditions On the Mechanical Properties of Wood Fiber-Polystyrene Composites. Ii. Sawdust as a Reinforcing Filler

The mechanical properties and dimensional stability of composites of polystyrene filled with sawdust of hardwood aspen and softwood spruce have been investigated under various extreme conditions, for example, exposure to water at room temperature for 14 days and at boiling temperature for 24 h, as well as heat exposure at ± 105°C for 5 days and at -20°C for 2 h. Mechanical properties improve due to the treatment of the composites with a coupling agent e.g., 3% poly methylene(polyphenyl isocyanate)] (PMPPIC)], or by using coated (10% polymer ± 8% PMPPIC) or grafted (styrene) fibers. the treated composites or treated fiber-filled composites also showed more dimensional stability compared to nontreated composites. In addition, mechanical properties improve due to the treatment of the composites under different extreme conditions compared to normal ones. From the experimental results, it is suggested that different compounding methods of preparation of composites play an important role in improving the mechanical properties of the wood fiber-filled thermoplastic composites, even under extreme conditions.