The Effect of wheat straw particle size on the mechanical and water absorption properties of wheat straw/low density polyethylene biocomposites for packaging applications

Natural composites with biodegradability properties can be used as a renewable alternative to replacing conventional plastics. Thus, to reduce the plastics applications in the packaging industry, biocomposites content of wheat straw (with 40, 100, 140 mesh) as a natural biodegradable composite and low density polyethylene (LDPE) as a common synthetic polymer in the packaging industry were prepared and characterized by the mechanical and water absorption properties. Polyethylene-graft-maleic anhydride was used as a compatibilizer material. Morphology of wheat straw flour was studied by optical microscope to obtain the aspect ratio (L/D). The tensile and flexural tests were applied for determining mechanical properties and scanning electron microscope (SEM) was used for particles distribution and sample structures. The water absorption of the samples was calculated by weight difference. The results indicated that the particle size of wheat straw four and the L/D amount are Significantly affected on the tensile strength and water absorption of the samples. However, the effect of wheat sraw particle size on the flexural strength was not significant. Overall conclusions show that by increasing the particle size of the filler (wheat straw), can prepare the biocomposite with better tensile strength and less water absorption compared with smaller particle size.