SYNCHROTRON X-RAY DIFFRACTION STUDY OF PINEAPPLE LEAF FIBER REINFORCED NATURAL RUBBER COMPOSITES DURING STRETCHING
Keywords:
Natural rubber, pineapple leaf fiber, composite, WAXS, strain-induced crystallizationAbstract
Structural development in preferentially aligned short pineapple leaf fiber (PALF) reinforced natural rubber (NR) composites was investigated with synchrotron wide angle X-ray scattering (WAXS) during stretching. NR and NR reinforced with 2 types of PALF, i.e. untreated and sodium hydroxide-treated PALF, were found to have different stress-strain behaviors. Normally, NR displays very low stress in the low strain region. This pattern changed considerably with the addition of the PALF. Stress for the composites increased sharply in the initial strain region and then remained roughly constant in the strain range of 60 to 200% before displaying an upturn. The composite containing sodium hydroxide-treated PALF displays a stress upturn at a lower strain than that with untreated PALF. A comparison of the WAXS patterns for stretched NR and the NR-PALF composites revealed that the onset of crystallization of the NR in the NR-PALF composites occurred at a lower macroscopic strain than that in the NR. Both types of NR-PALF composites display similar crystallinity at the same strain. Analysis of azimuthal scans of the 2 composites revealed a better orientation of the amorphous phase in the composite containing the sodium hydroxide-treated PALF. This suggests that the early stress upturn in the system containing treated PALF should be attributed to better stress transfer to the fiber.
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