Utilisation of oil palm ash (OPA) in plastic packaging is concerned to environment-friendly, improving performance, and saving the costs of plastics. This study further discussed and compared the properties of un-plasticised polyvinyl alcohol (PVOH)/OPA (80/20) films with PVOH/OPA (80/20) film plasticised with glycerol and urea at different concentrations. Glycerol-plasticised PVOH/OPA (80/20) film showed a decrease of tensile strength but an increase of elongation at break, whereas ureaplasticised film showed gradual increase of both tensile strength and elongation at break when concentration of plasticising agents was increased. This is due to the extensive hydrogen bonding and formation of stable dimeric structure with the addition of urea to PVOH/OPA (80/20) films, which was confirmed by the Fourier transform infrared (FTIR) spectroscopy analysis. In water absorption measurement, the increased concentration of plasticising agent exhibited a decreased water uptake percentage. Both plasticised PVOH/ OPA (80/20) films showed substantial weight loss in natural soil burial study but ureaplasticised films had lower weight loss as compared to glycerol-plasticised films at similar plasticiser concentration. Thermal analysis proved the increase of segmental mobility of polymeric chain in glycerol-plasticised film by showing lower glass transition temperature (T g), while urea-plasticised films exhibited higher T g due to urea solidification and better interfacial interaction with the hydroxyl group of PVOH and OPA. Also, urea-plasticised films showed higher decomposition temperature than glycerol-plasticised films.

"In this study, cellulose was extracted and isolated from orange peel (OP) via alkaline treatment, followed by a bleaching process. The orange peel derived cellulose (OPDC) was characterized and compared with microcrystalline cellulose (MCC). FTIR characterization confirmed the absorption peaks of cellulose for both OPDC and MCC. From the DSC analysis, it was found that MCC possessed higher thermal stability than OPDC. In addition, the results of FESEM and particle size analysis revealed the micro-size dimension of OPDC after the pretreatments. The crystallinity index (CrI) of OPDC (80.14%) was found to be significantly higher than that of untreated OP (23.54%). After that, biodegradable blended films with different weight ratio were prepared using OPDC and MCC with polyvinyl alcohol (PVA) by the solution casting method. According to the FTIR spectra, the shift of the characteristic absorption band and the change of the band intensity observed in the spectra of the PVA/OPDC blended films were similar to those of the PVA/MCC blended films. This confirmed the development of new inter- and intramolecular hydrogen bonds and changes in the conformation between PVA and cellulose. The tensile strength and elongation at break of both PVA/OPDC and PVA/MCC blended films decreased when the cellulose content increased in the PVA matrix. However, the elastic modulus of both films was enhanced when the amount of cellulose increased. By comparison, the PVA/OPDC blended film presented higher tensile strength and elastic modulus than the PVA/MCC blended film. Based on the natural weathering tests, the degradability of blended films increased with a rising amount of cellulose after exposure to degradation tests. The biodegradability of blended films was confirmed by the tiny black spots observed on their surface, which reflected the growth of microorganisms. It was further proven by the morphology studies performed on the surface of the films using FESEM."

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