Assessment of efficiency of polyethylene reinforcement by filling with wood flour
Polimery 2005, No 6, 436
Polyethylene PE-LD or PE-HD and its recyclates were filled with high quality wood flour Lignocel® using 10, 20 or 30 wt. % of filler. Elasticity modulus of the composites investigated significantly increased with increasing content of wood flour and its relative increase was much bigger in case of PE-LD than for PE-HD (Fig. 2). However tensile strength nearly did not change with filling of polymer independently on the product treatment (the samples were investigated either dry or after soaking in water for 30 days) (Fig. 3). It was found melt flow rate systematically decrease with increase in wood flour content (Fig. 4) what adversely affects the processing of high-filled polyethylene. Investigations of creep showed that even addition of 10 wt. % of wood flour significantly reduces the deformation being a result of long term load (Fig. 5). Investigation of morphology showed Lignocel® played a role of "joint" of crystalline regions because of expanded surface of its fibers. Filling of the ducts in wood fibers with polyethylene prevents water absorption by the composite (Fig. 6 and 7). The results obtained show polyethylene filling with wood flour (maximum up to 30 wt. %) advantageously affects mechanical and functional properties.
Key words: low-density polyethylene, high-density polyethylene, filling, wood flour, mechanical properties, morphology