Application of Peanut Hulls as Filler for Plastics

Abstract

Composite materials consisting of peanut hulls and polylactic acid (PLA) resin were developed by a compression molding method. The density, water absorption properties and flexural properties of the composite materials were evaluated. The density of the composite materials was lower than the theoretical density, which was calculated by the peanut hull density, PLA resin density and peanut hull weight content because these materials have many voids. The saturated water absorption rate and mass diffusivity increased with the increase in peanut hull weight content. Especially, the saturated water absorption rate and mass diffusivity of the composite material with a peanut hull weight content of 75% were approximately 15 times and 2.4 times higher, respectively, than those of PLA resin. As a result of 3-point flexural tests, the flexural modulus of the composite materials improved as the peanut hull weight content increased up to 50%. At the peanut hull weight content greater than 25%, the flexural strength degraded as the peanut hull weight content increased. Furthermore, the cost performance of the composite materials based on flexural rigidity, material cost and thickness was discussed.