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Cellulose hydrogel was produced from pretreated oil palm empty fruit bunch fiber (EFB) that went through acid hydrolysis and thermal hydrolysis. The pretreated EFB was dissolved in LiOH/urea aqueous solution using the rapid dissolution method and was subjected to a crosslinking process with the aid of epichlorohydrin to form hydrogel. The effects of both hydrolyses' time on average molecular weight (Mŋ), solubility, and properties of EFB hydrogels were evaluated. Both hydrolyses led to lower Mŋ, lower crystallinity index (CrI) and hence, resulted in higher cellulose solubility. X-ray diffraction (XRD) characterization revealed the CrI and transition of crystalline structure of EFB from cellulose I to II. The effects of hydrolysis time on the transparency, degree of swelling (DS), and morphology of the regenerated cellulose hydrogel were also investigated using an ultraviolet-visible (UV-Vis) spectrophotometer and a Field emission scanning electron microscope (FESEM), respectively. These findings provide an efficient method to improve the solubility and properties of regenerated cellulose products. [ABSTRACT FROM AUTHOR]

Biocomposites of recycled high-density polyethylene (rHDPE)/recycled polyethylene terephthalate (rPET) matrices with a high loading of rice husk flour (RHF) were fabricated through a two-step extrusion. The use of ethylene-glycidyl methacrylate (E-GMA) copolymer improved the compatibility of the immiscible rHDPE/rPET blend. Maleic anhydride polyethylene (MAPE) was used as a coupling agent to increase the adhesion of the fibre–matrix interface. In this study, the effect of natural fibre loadings on rHDPE/rPET blends was examined. The water absorption process in the RHF-filled composites followed the kinetics and mechanisms of Fickian diffusion. Compared with samples without RHF, the rHDPE/rPET/RHF system had 58–172% higher tensile modulus and 80–305% flexural modulus. The thermal stability of the composites slightly increased with the addition of the RHF filler. The storage modulus of biocomposites was greatly enhanced by RHF. From these results, we can conclude that RHF can work well with rHDPE/rPET for manufacturing high loading biocomposite products. [ABSTRACT FROM AUTHOR]

ABSTRACT Rice husk flour (RHF) biocomposites based on uncompatibilized and compatibilized recycled high density polyethylene/recycled polyethylene terephthalate (rHDPE/rPET) with ethylene-glycidyl methacrylate (E-GMA) copolymer were prepared through a two-step extrusion and hot pressing with fiber loadings of 40, 60, and 80 wt %. Results showed that tensile and flexural properties increased. However, the elongation to break and impact strength decreased as the RHF loading increased. Compatibilizing polymer blend matrices can further enhance the mechanical properties. Water absorption (WA) test were examined in distilled and seawater. It is interesting to note that for composites made from uncompatibilized matrix, the calculated D and KSR were lower in seawater, but for the compatibilized matrix composites, the D and KSR obtained were generally lower in distilled water. However, compatibilization of rHDPE/rPET has been markedly reduced the WA and thickness swelling. Scanning electron microscope analysis of the compatibilized matrix composites confirmed the improved interfacial bonding of matrix-matrix and filler-matrix phases. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41494. [ABSTRACT FROM AUTHOR]