Use of Sunflower Seed Shells as Filler in Polyester Resin and Characterization of Obtained Composite

Abstract

In this research, the shells of waste sunflower seeds (WSS) are ground and used in polyester resin as filler. The shells of the ground sunflower seeds are mixed into orthophthalic unsaturated polyester (UP) at the ratios of 0 wt.%, 1 wt.%, 3 wt.%, and 5 wt.%, and a homogeneous mixture is prepared for composite production. Then, certain amounts of methyl ethyl ketone peroxide (MEKP) and cobalt octoate (Co Oc) are added to the mixture. After the mixture becomes gel-like with physical interaction and chemical reactions, it is cast into standard molds. The shells of sunflower seeds provide a physical interaction in the polyester composite as filler. UP, MEKP, and Co Oc produce the polyester composite with an exothermic chemical reaction. After waiting for the obtained composite to cure for 24 hours, the necessary physical tests and chemical analyses are performed. According to the results, WSS reinforcement reduces the density, hardness, and activation energy of the polyester composite. The thermal conductivity coefficient of the composite increases with the addition of WSS, albeit slightly. In the experimental results, 3 wt.% WSS reinforcement is determined as the optimum ratio in polyester composite production. The use of higher ratios of filler adversely affects both the surface morphology and the pore structure of the composite.