Mechanical and rheological properties of polyethylene compositions with vegetable fibers
Polimery 2002, No 5, 332
Two varieties of low-density polyethylene (PE-LD) with differing molecular weights were filled with short cotton and flax fibers (10—30%). The systems without or with (2%) compatibilizer (mixture of glycerol monoethers with C12—C14 alkohols) were homogenized using a laboratory tworoll-mill. The effects of PE-LD variety, fiber length (ca. 1—2 mm) and content, and manner of adding the compatibilizer on mechanical and heological properties were investigated. It was found that the compatibilizer addition improves the blend homogeneity, but at the same time deteriorates mechanical properties and lowers the viscosity. Increase in fiber length improves mechanical properties as observed for compositions of PE-LD variety with higher molecular weight. Higher fiber content increases viscosity of the composition and intensifies its non-Newtonian behavior resulting in lowering of the n exponent value in power law equation (1). The blend composition does not have any sinificant effect on flow activation energy (150 °C—180 °C, cutting speed 100 s-1).
Keywords: low-density polyethylene, cotton and flax fibers, blending, mechanical and rheological properties