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This paper describes the preparation of poly(vinyl alcohol)/kenaf fiber (PVOH/KF) composites with entrapped urea. The major FTIR peaks of these composites could be identified. These composites are intended for agricultural applications as biodegradable mulches and could be potential carrier materials for fertilizer. The water solubility, release behavior, chemical properties, and thermal stability of the composites were evaluated. The composites lost 25% of their weight after 7 days in water. In a wet environment, urea was released from the composites through its dissolution in water, and around 57% of the urea was released from the composites in 24 h; Thermagravimetric analysis showed that these composites were stable up 150 C. These composites would be able to withstand rain and protect seedlings from the sun when applied in the field as mulches. For around three to four weeks, these biobased mulches could slowly disintegrate as the PVOH binder was gradually dissolved by moisture, releasing the kenaf fibers to serve as soil fertilizer without leaving any undegradable waste for disposal. Hence, they would not pose any risks to the land or biological systems. Keywords INTRODUCTIONThere have been increasing concerns in recent years regarding environmental pollution consisting of non-biodegradable polyethylene mulch films. Previous literature has reported the uses of polyethylene films as mulches in reducing soil erosion and maintaining soil moisture for better crop growth (Adegbidi et al. 2003). Petroleum-based films are widely used due to their properties such as low density, good mechanical properties, excellent water resistance, and low cost (Nurfatimah et al. 2015). However, this synthetic plastic has generated a number of disposal difficulties because it requires huge labor forces for manual disposal. Land application is not a suitable disposal method for non-degradable plastic mulch due to its interference in the root development of subsequent crops (Kasirajan and Ngouajio 2012). An alternative disposal method for agricultural plastic wastes is through biodegradation processes.Many studies have demonstrated the use of biodegradable materials as alternatives to conventional polyethylene mulch films (Moreno and Moreno 2008). Some of the biodegradable materials used were composites developed from a combination of cellulose and starch (Moreno and Moreno 2008). These biodegradable films have not gained widespread use, possibly due to their high production cost and the unpredictable nature of their biodegradation behavior (Kasirajan and Ngouajio 2012). PEER-REVIEWED ARTICLEbioresources.com Tan et al. (2015). "PVOH/kenaf/urea mulches," BioResources 10(3), 5532-5543. 5533Poly(vinyl alcohol) (PVOH) is a non-toxic material that presents no adverse effects to biological systems, and has become highly attractive for various applications (DeMerlis and Schoneker 2003;. In the agriculture sector, PVOH could be a promising material for biodegradable mulches due to its water solubility (Guohua et al. 2006). This material ...

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In this research work, nanowires were grown on brass (Cu - 37.2 wt% Zn) substrate by thermal oxidation. The substrate was oxidized at temperatures ranging from 350 °C to 600 °C in the presence of varying concentrations of O2 (1%–100%) in N2 flown at a rate of 200 sccm. The oxidized brass surface was characterized by field emission scanning electron microscope equipped with energy dispersive x-ray spectroscope and transmission electron microscope. Four different types of morphological variations such as thin, thick with branches, circular-flake and flat-cone shape nanostructures were observed during oxidation at different conditions. However, the prevalence of thin and thick morphology with branches was more prominent and found in all growth conditions. The length and diameter of the nanowires varied from 1 to 30 μm and 50 to 500 nm, respectively, whereas the length of the branches varied from 1 to 3 μm. The composition of the nanowires was ZnO possessing of hexagonal wurtzite structure. The selected area diffraction confirms that the nanowires grew along 〈1 1 0〉 directions. Based on the results, a stress induced mechanism is proposed for the growth of ZnO nanowires on Cu - 37.2 wt% Zn substrate.