Investigation on the tensile properties and dimensional stability of polypropylene/wheat straw fiber/paper mill sludge composites

Abstract

In this investigation, tensile and physical properties of polypropylene (as matrix)/wheat straw fiber/paper mill sludge (as filler) composites was studied. The ratio of wheat straw fiber/ paper mill sludge was selected as 40/0, 30/10, 20/20, 10/30 and 0/40 (w/w) were used. Also, for better compatibility between the two phases 3% MAPP as coupling agent was used. Mixing process was done in twin screw internal mixer extruder, and then composite samples were manufactured by injection molding. Result indicated that the tensile modulus of elasticity improved with increasing fillers and also it was observed that the toughness of composite increased when compared to the pure PP, while due to the usage of more paper sludge, these properties was improved. Tensile strength of composite decreased with adding 40% wheat straw fiber, but with addition of sludge tensile strength increased significantly. Adding wheat straw in PP matrix and its hydrophilic properties resulted in the highest rates of water absorption and thickness swelling. However, adding paper sludge and lower amount of lignocellulosic material, and the compatibilizer noticeably decreased the physical properties due to better bonding between two phases.

Keywords

• wheat straw fiber
• paper mill sludge
• tensile properties
• Dimensional stability
• Composite