Effect of •-RAY irradiation on mechanical and thermal properties of jute fabrics reinforced polypropylene composites

Abstract

Jute fabric or jute-mat (JM) reinforced isotactic polypropylene (iPP) biocomposites with various contents of triple super phosphate (TSP)-treated JM and non-TSP-treated JM were fabricated by compression moulding method at 180 ºC. The TSP-treated JM reinforced iPP composites were then irradiated by γ–ray at various doses. Thus, the samples produced in this study are neat iPP (N-iP), neat JM (N-JM), untreated-JM (UT-JM) and iPP composites (UT-JMiPC), TSP-treated JM and iPP composites (TSP-JMiPC) and γ-ray cum TSP-treated JM and iPP composites (γTSP-JMiPC). Chemical structure, mechanical properties, fractured surface morphology and thermal properties of these composites were characterized by a Fourier transform infra-red (FTIR) spectrometer, a universal testing machine, a scanning electron microscope and a differential thermal analyzer (DTA)/thermo-gravimetric analyzer (TGA) along with water intake (WI) property through a physical test. Mechanical properties, such as tensile strength (TS), flexural strength, (FS) and Young’s modulus (E) are observed to be 61, 63 and 710 MPa for γTSP-JMiPC, whereas these values are 55, 57, 452 MPa for TSP-JMiPC and 52, 55, 445 MPa for UT-JMiPC, respectively. The increase of TS, FS & E values for γTSP-JMiPC and TSP-JMiPC from UT-JMiPC are respectively 18, 15 & 60% and 6, 4 & 2% revealing a substantial increase of their mechanical performances by •-ray irradiation. The TS, FS and E of the TSP-JMiPC are also found to increase with radiation dose up to 500 krad and then decrease. This increase is attributed to both the improved adhesion between JM and iPP by TSP treatment and the development of cross-linking density in the composites by γ-ray irradiation, while the decrease at doses>500 krad can be assigned to the fact that higher radiation dose causes breaking of both iPP and JM molecules. The WI for UT-JMiPC, TSP-JMiPC and γTSP-JMiPC are respectively 14, 10 and 7%, indicating a gradual development of hydrophobic character of the composites first by TSP-treatment and then by γ-ray-treatment. FTIR spectra show distinct absorption peaks of TSP-JMiPC and γTSP-JMiPC from that of UT-JMiPC, confirming a good adhesion between JM and iPP matrix by TSP treatment as well as a formation of new C-C and C-O bonds between them and a breaking of O-H bonds by γ-ray treatment. Micrographs of the fractured surface reveal a better adhesion of JM and iPP in γTSP-JMiPC than in TSP-JMiPC and UT-JMiPC. A slight increase of melting temperature and onset temperature of weight loss for the treated composites from untreated ones is also observed by DTA and TGA. All these results indicate better performances of the biocomposites fabricated in this study.