Investigating the Effect of Cotton Stalks Bark on Physical and Mechanical Properties of Cotton Stalk Flour- Polypropylene Composite

This study seeks to investigate the possibility of producing polypropylene composite- cotton stalk flour with various percentages of cotton stalk flour. Determining the best treatment in terms of physical and mechanical properties and exploring the effect of using cotton stalks in the production of the composites were among the major objectives of this study. Six treatments consisting of Polypropylene, 40, 55 and 70 percent level of cotton stalks and two fillers (cotton stalks with and without barks) were developed. Maleic anhydride modified polypropylene (3% wt) was applied to each treatment. The mixing and granulation of the plastic and cotton silk flour was carried out using twin screw extruder model 4815. After preparing and shearing of samples, the mechanical properties of composites including tensile strength, rupture modulus and elasticity modulus were calculated in accordance with D-6109 and ASTM D-7031 standards. In addition, water absorption and thickness swelling tests were performed according to D-570-98 standard. The results showed that an increase in the flour of cotton stalk reduced the tensile strength and rupture modulus on the one hand, and increased the bending elasticity modulus on the other hand. In terms of the performance of the filler, there was a significant difference between values of rupture modulus and elasticity modulus at 95% level whereas this difference was not significant for tensile strength. Moreover, this difference was significant for values of water absorption and thickness swelling. The maximum tensile strength belonged to T4 with 40 percent of cotton stalk bark fibers.