M. I. Syakir

A review on chitosan-cellulose blends and nanocellulose reinforced chitosan biocomposites: Properties and their applications

Chitin is one of the most abundant natural polymers in world and it is used for the production of chitosan by deacetylation. Chitosan is antibacterial in nature, non-toxic, and biodegradable thus it can be used for the production of biodegradable film which is a green alternative to commercially available synthetic counterparts. However, their poor mechanical and thermal properties restricted its wide spread applications. Chitosan is highly compatible with other biopolymers thus its blending with cellulose and/or incorporation of nanofiber isolated from cellulose namely cellulose nanofiber and cellulose nanowhiskers are generally useful. Cellulosic fibers in nano scale are attractive reinforcement in chitosan to produce environmental friendly composite films with improved physical properties. Thus chitosan based composites have wide applicability and potential in the field of biomedical, packaging and water treatment. This review summarises properties and preparation procedure of chitosan-cellulose blends and nano size cellulose reinforcement in chitosan bionanocomposites for different applications.

Isolation and Characterization of Cellulose Nanofibers from Gigantochloa scortechinii as a Reinforcement Material

Cellulose nanofibers CNF were isolated from Gigantochloa scortechinii bamboo fibers using sulphuric acid hydrolysis. This method was compared with pulping and bleaching process for bamboo fiber. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis were used to determine the properties of CNF. Structural analysis by FT-IR showed that lignin and hemicelluloses were effectively removed from pulp, bleached fibers, and CNF. It was found that CNF exhibited uniform and smooth morphological structures, with fiber diameter ranges from 5 to 10 nm. The percentage of crystallinity was significantly increased from raw fibers to cellulose nanofibers, microfibrillated, along with significant improvement in thermal stability. Further, obtained CNF were used as reinforcement material in epoxy based nanocomposites where tensile strength, flexural strength, and modulus of nanocomposites improved with the addition of CNF loading concentration ranges from 0 to 0.7%.

Microcrystalline cellulose from oil palm empty fruit bunches as filler in polylactic acid

Acid hydrolysis method was used to isolate microcrystalline cellulose (MCC) from oil palm empty fruit bunches (OPEFB) total chlorine free bleached pulp. The derived MCC was incorporated into polylactic acid (PLA) using solution casting technique in order to produce PLA/MCC composites. The chemical structure of the cellulose fragments remains unaltered as demonstrated by Fourier transform infrared spectroscopy despite acid hydrolysis. X-ray diffraction showed that the MCC has a cellulose I polymorph with 87% crystallinity index. The addition of MCC into PLA enhanced not only the thermal stability but also the Youngs modulus of the PLA/MCC composites by approximately 30% at 5 phr MCC contents compared to pure PLA. However a decrease in tensile strength and elongation at break of the PLA/MCC composites were observed due to the poor dispersion of MCC in the PLA matrix

Polychaetes as Ecosystem Engineers: Agents of Sustainable Technologies

Polychaetes are the so-called ecosystem engineers as they are constantly feeding, digging, burrowing, irrigating, reworking and ingesting particles in the sediment and near to the sediment–water interface. Their behaviour through bioturbation has significant impact on sediment biogeochemistry, in processing highly enriched sediments, and provides tolerance towards hypoxia and highly polluted areas. In this paper, the review introduced briefly about the distribution of polychaetes in the world, explained its role in tackling environmental issues such as detoxifying inorganic contaminants into less toxic compounds, processing organically enriched sediments via their digestive system and overcoming hypoxia and anoxia cases plus sulphidic conditions. All these criteria enable polychaetes to be agents of sustainable technology. Then, the focus is emphasized on the lack of studies about polychaetes in Malaysia. Increasing number of studies is currently in place to document their distribution in Malaysia. Research that addresses how polychaete processes their waste and how their body adapts to various environmental degradation would be vital as key towards sustainability in environmental applications.

Flame retardancy, Thermal and mechanical properties of Kenaf fiber reinforced Unsaturated polyester/Phenolic composite

Unsaturated polyester (UP) resin has been blended with phenolic resin (PF) resole type at various ratios to obtain a homogeneous blend with improved flame resistance compared to its parent polymers. The polymer blend was reinforced with 20 wt% kenaf using hand lay out technique. Fourier transform infrared spectroscopy (FT-IR) was used to characterize changes in the chemical structure of the synthesized composites. The thermal properties of the composites were investigated using thermogravimetric analysis (TGA). The thermal stability of UP/PF kenaf composites co-varies with the PF content, as shown by the degradation temperature at 50 % weight loss. The char yield of the composites increases linearly with PF content as shown by the TGA results. The flammability properties of the composites were determined using the limiting oxygen index (LOI) and UL-94 fire tests. The LOI increased with the PF content while the composites exhibit improved flame retardancy as demonstrated by UL-94 test. The mechanical and morphological properties of the composites were determined by tensile test and scanning electron microscopy (SEM), respectively. The tensile strength and the Young’s modulus of the blend/composites slightly decreased with increasing PF content albeit higher than PF/kenaf fiber composites.

Application of Nitrate Stable Isotopes, δ15N-NO3- and δ18O-NO3-, in Bukit Merah Reservoir, Malaysia

Identifying nitrate sources in Bukit Merah Reservoir (BMR), Perak, Malaysia is important in order to understand the productivity of the ecosystem. For the first time, the dual stable isotopes of nitrate, δN-NO3 and δO-NO3, were applied to assess its potential use to trace the sources of nitrate in surface water of BMR. Water samples were collected in the months of August 2016, December 2016, March 2017 and October 2017 from 10 sites within Kurau River Basin covering the upper stream, tributaries and reservoir. Water samples were analysed using the bacterial denitrification method. The variation of nitrate isotopes ranged from +0.4‰ to +14.91‰ for δN-NO3 and –0.01‰ to +39.4‰ for δO-NO3, respectively. Overall, based on the crossplots between δN-NO3 and δO-NO3, majority of the δO-NO3 in the samples reflects atmospheric deposition Application of Nitrate Stable Isotopes 2 whereas δN-NO3 indicates sources from both ammonium fertiliser and soil nitrogen, and a minor contribution of sewage and manure in BMR water catchment.

Design of green laminated composites from agricultural biomass

The logging of trees from natural resources for manufacturing laminated products is causing environmental concerns. This has led researchers to find alternatives to develop sustainable and eco-friendly source of raw materials for this purpose. Agricultural biomass is a potential candidate regarding this due to their sheer abundance, low cost, biodegradability, inherently water resistance, fibrous structure, and mechanical properties. Furthermore, billions of tons of agricultural waste are released around the world through farming practices annually. Raw materials derived from agricultural biomass have great potential to be used in various applications including lamination that are beneficial to our environment. Therefore, the aim of this chapter is to discuss the type of laminated composites and their desired applications followed by physical and mechanical properties. Multilayered structures, hybrid fibers and materials, lamination manufacturing process, and application based on automotive, construction, furniture, and building are also widely discussed.

Nanofibrillated cellulose reinforcement in thermoset polymer composites

The development of nanofibrillated cellulose (NFC) composite using renewable and biodegradable materials is extensively reviewed in this article. Excellent mechanical properties, remarkable reinforcing capabilities, low density, thermal stability, and environmental benefits of cellulose have gained the interest of researchers in utilizing fibers as reinforced materials. Nanobased polymer composites utilize the advantages of each component and thus hold functional superiority over conventional polymer-based materials. NFC composites are widely researched materials because of their high strength, functional properties, and wide applicability. This article discusses characterization and various chemical and mechanical treatments for isolation of NFC. Incorporation of obtained NFC in thermoset composites and its subsequent processing and properties, along with diverse applications, are also discussed. Chronological events on the development of NFC composites are also provided. The aim of this chapter is to shed some light on the current state of development in the field of NFC-based composites.

Nanoclay Reinforced on Biodegradable Polymer Composites: Potential as a Soil Stabilizer

Polymeric composites (biodegradable and non-biodegradable materials) have been extensively used in diverse types of applications ranging from automotive industries to packaging industries using natural fibres, man-made fibre and other biomass as reinforced materials. Soil erosion, triggered by two main events, anthropogenic activities and natural causes conceivably gives bad impacts to living things by altering the stability of the ecosystem and causing human to lose lives and damage their properties. Nanoclay reinforced on biodegradable polymeric is the preferred candidate for developing soil stabilizer materials as this material possesses hydrophilic properties that adsorb liquid molecules to handle erosion of soil. The capacity of the materials to retain a significant amount of water that releases gradually into the ground as it decays will not only mitigate soil erosion, but also improves soil fertility and productivity by enhancing the aeration of water and air in soil. Recent studies concerning nanoclay/biodegradable composite materials are cited in this paper. Overall, this chapter summarizes the definition, the properties, as well as the applications of nanoclay and biodegradable materials, to further generate the idea of combining both of these materials for soil erosion mitigation. Potentially, this fundamental study pertaining to special characteristics of nanoclay/biodegradable composite offers limelight on the green solution potentials for cost-effective and sustainable plantations management.