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Oil palm mesocarp fiber (OPMF) is rich in cellulose and suitable to be used as raw material for the production of cellulose nanofiber (CNF) and biocomposite. Recently, there have been reports on the use of CNF as filler in polypropylene (PP) for improving the mechanical properties of PP, however the process requires two steps: (i) nanofibrillation for CNF production and (ii) biocomposite compounding. In this study, a one-pot process was developed whereby nanofibrillation of cellulose and subsequently melt-blending of the CNF with PP were conducted at once, in a twin-screw extruder. Morphological analysis of the biocomposites by SEM showed that the cellulose was successfully fibrillated into CNF and compounded homogeneously with PP. The highest tensile strength, Young's modulus, flexural strength, and flexural modulus recorded were 34.9 ± 0.5 MPa, 12.1 ± 0.1 GPa, 59.3 ± 1.3 MPa, and 2.3 ± 0.05 GPa, respectively when 3 % CNF was used in the biocomposite. The reinforcement of CNF-OPMF in PP improved the mechanical properties of the biocomposite by 33.4 % compared to neat PP. It is interesting to note that the addition of CNF managed to improve the crystallinity of the biocomposite (54.6 %) compared to neat PP (50.1 %), despite of the lower crystallinity of CNF compared to PP. This observation can be attributed to the high density of covalent bonds per cross-sectional area and the large number of hydrogen bonding sites. Additionally, the observation can be explained by the role of CNF in composite which acted as nucleation agent, which eventually increased the crystallinity of the biocomposite.

Oil palm mesocarp fibre (OPMF) is one of the major biomass generated from palm oil industry and it is currently inefficiently burnt at palm oil mill for energy and as a mean of disposal. With the growing concern on environmental sustainability and finite supply of non-renewable resources, particular attention has been given to produce value-added materials from OPMF, such as biocomposite and biocompost. Since OPMF contains mainly cellulose, there is high potential for the production of cellulose nanofiber (CNF) from OPMF. In this study, cellulose was obtained from OPMF by chemical extraction. OPMF-cellulose obtained was then soaked in distilled water [0.2 - 1% (w/v)] prior to nanofibrillation using an ultrasonicator at 125 W and 36 kHz for 3 to 12 hours. Scanning electron microscopy (SEM) micrographs of fiber undergone ultrasonication confirmed the occurrence of CNF having diameter in the range of 40-200 nm. CNF produced had crystallinity value in the range of 31-43%, and was thermally stable up to 340 °C.