Effect of gamma-ray on the physical, morphological and biological durability properties of Abies wood composite

Abstract

This study's aim is to investigate the effect of ionizing rays such as gamma rays on the natural Durability and morphology of wood plastic composites against fungus (Trametes versicolor) and (Gloeophyllum trabeum), white rot, and brown rot respectively. Abies wood flour with weight ratios of 20% and 40% is mixed with three different polypropylene melt flow indices (H, M, and L) and maleic anhydride polypropylene as a compatibilizer material. The mixing process is performed by a Brabender mixer. Test specimens are made using a press machine. The test specimens are exposed to rainbow and brown fungus for one month at a temperature of 25 ± 1 °C and humidity of 65 ± 5% under EN113. Then, the percentage of mass reduction, water absorption, and thickness swelling on the samples were investigated. A scanning electron microscope (SEM) is used for the morphology of the composites. The results show that the mass reduction percentage, water absorption, and thickness shrinkage are reduced by irradiating gamma rays at a dose of 25 kGy and increasing the melt flow index on wood plastic composite pieces. Decreasing the percentage of wood flour reduces the severity of rot, water absorption, and thickness swelling of the samples. The effect of MFI on the natural durability of wood plastic composites is greater than the effect of gamma rays. The results showed that the gamma radiation effect in reducing the weight of white and brown fungus decay in LMFI, MMFI, and HMFI parameters in the composite sample with 40%, the difference between the irradiated and non-irradiated samples is statistically significant at 95% confidence level but for composite with 20% wood flour, the difference in the irradiated and non-irradiated samples in weight loss is not statistically significant at the 95% confidence level. Also, the results showed that the effect of gamma radiation on the amount of water absorption and thickness shrinkage in the mentioned parameters in the 20% and 40% wood flour composite is statistically significant at the 95% confidence level, and there is a significant difference between the irradiated and non-irradiated samples. Also, the uniformity of the micrographs obtained from SEM showed that by gamma irradiation to the wood plastic composite, the reflection between the wood fibers and the polymer improved.