Pine Cone and Boron Compounds Effect as Reinforcement on Mechanical and Flammability Properties of Polyester Composites

Abstract

Natural fibers are known to be environmentally friendly, and they can be used as an alternative to glass and carbon fibers because of their low cost. Pine cone fibers are a good choice for use in composite manufacturing because they mainly consist of cellulose, hemicelluloses, and lignin macromolecules which provide a hydrophilic character.The potential pine cone forest reserve of Turkey is 54,000 ha. Boron compounds such as borax, boric acid. and zinc borate are generally used for their flame-retardant effect. In this study, three kinds of boron compounds, boron oxide, borax pentahydrate and borax decahydrate, were used to provide better mechanical properties and better incombustibility. The synergistic effects of both waste pine cone and boron compounds were sampled for the manufacture of polyester composites by using a casting process. The composites produced with different fiber contents were characterized by some mechanical properties (bending strength, flexural modulus, izod impact); physical analyses (water absorption, swelling thickness, open porosity, bulk density); flame retardancy (LOI); and TGA, SEM-EDS, and FT-IR analyses. According to mechanical test results, boron oxide showed better bending strength and flexural modulus compared to the other boron compounds. The LOI of composites with a boron compound was higher than the composites with only pine cone reinforcement.