Effect of Immersion Temperature on Mechanical, Water Absorption and Morphological Properties of Sodium Hydroxide Modified Fluted Stem Pumpkin Fiber Reinforced Polyester Bio-composites

The effect of immersion temperature on mechanical, water absorption and morphological properties of sodium hydroxide treated and untreated fluted pumpkin stem fiber (FPF) polyester bio-composites was investigated. Random matted FPF reinforced polyester composites were fabricated using a hand layup molding process, with 30wt% of FPF treated under the temperatures of 30oC, 40oC and 60oC were investigated. Fourier transform infra-red spectroscopy (FTIR) and Scanning electron microscope (SEM) analysis were employed in characterizing the microstructure and morphology of the materials. Mechanical tests showed that the treated FPF at 30oC improved the tensile modulus by 21.17% (1100-1300 Nmm-2) compared to the untreated FPF. The treated FPF at 45oC improved the tensile strength by 36.4% (14.42-19.71MPa), improved flexural strength by 14.77% (63.23-72.57MPa), improved impact strength by 48.28% (3.48-5.15kJm-2), improved compressive strength by 35.01% (17.99-24.29MPa) compared to the untreated FPF. Discrepancies in properties emanating from immersion temperatures were found to show enhanced properties at 45oC than 30oC and 60oC immersion temperatures. It was found that the highest improvement in tensile, flexural, compressive and impact strength was attained at a temperature of 45oC while the optimum tensile modulus was obtained at a temperature of 30oC for the FPF treated polyester composites compared to the untreated composites. The percentage water absorption for the treated FPF polyester composites decreased above 45oC. The initial increase from 30-45oC was ascribed to poor wetting of the fiber by the resin. The results obtained from FTIR and SEM confirmed that the chemical modification of the composites was successfully performed.