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This study is focused on the development of sound absorbing materials based on natural fiber polymer composites. The natural fibers were modified through the alkaline treatment and the natural fiber polymer composites were fabricated using hot and cold compression hydraulic press machine. The sound absorption coefficients of the composites were measured using two-microphone transfer function impedance tube method. Characterizations of the natural fiber polymer composites were analyzed using scanning electron microscope and Fourier transform infrared spectroscopy. It was found that in all measured composites, the sound absorption coefficients increased as the frequency increased. Also, as the fiber loading increased, the sound absorption coefficients of the natural fiber polymer composites were increased. It was found that the alkaline treated fiber reinforced composites increased the sound absorption coefficients due to removal of impurities and change in the structure of composites. The alkaline treatment of fibers showed better adhesion interface between fiber and polymer as compared to untreated fibers. This can be seen clearly under morphological and spectral studies of the natural fiber polymer composites.

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In this research, the mechanical, acoustical, thermal, morphological, and infrared spectral properties of untreated, heat and alkaline-treated sisal fiber-reinforced poly-lactic-acid bio-composites were analyzed. The bio-composite samples were fabricated using a hot press molding machine. The properties mentioned above were evaluated and compared with heat-treated and alkalinetreated sisal fibers. Composites with heat-treated sisal fibers were found to exhibit the best mechanical properties. Thermogravimetric analysis (TGA) was conducted to study the thermal degradation of the bio-composite samples. It was discovered that the PLA-sisal composites with optimal heat-treated at 1608C and alkaline-treated fibers possess good thermal stability as compared with untreated fiber. The results indicated that the composites prepared with 30wt % of sisal had the highest sound absorption as compared with other composites. Evidence of the successful reaction of sodium hydroxide and heat treatment of the sisal fibers was provided by the infrared spectrum and implied by decreased bands at certain wavenumbers. Observations based on scanning electron microscopy of the fracture surface of the composites showed the effect of alkaline and heat treatment on the fiber surface and improved fiber-matrix adhesion.

This study focuses on the effects of fiber treatment on the mechanical, morphological, physical and thermal properties of kenaf/jute/polyethylene composites, by using alkaline-treated and raw fibers. The core of jute and kenaf fibers was chopped into shorter lengths and used for composite fabrication. The composites were then subjected to tensile, water absorption, SEM, FTIR, DSC and TGA tests. According to the FTIR spectroscopy results, the alkaline treatment removed a significant amount of lignin and other impurities, especially at lower infrared band. This reduced fibers' hydrophilicity, making it more compatible with the polymer. This is evident from the SEM results, as it shows improved interfacial bonding. Therefore, the treated fiber composites, especially for 15 wt% composites, have higher tensile strengths, more thermal stability and higher activation energy.

This research focuses on the simulation of sound absorption coefficient of banana fiber and experimentation of sound absorption coefficient of banana fiber epoxy composites. For simulation, ‘Mechel’ empirical model was used to manipulate the flow resistivity and ‘Delany and Bazley’ empirical model was used to develop the prediction of sound absorption coefficient at frequency ranges from 500 Hz to 6000 Hz. For experimentation, two-microphone transfer function impedance tube model was used to analyze the sound absorption coefficient at frequency ranges from 500 Hz to 6000 Hz. Based on simulation, it is predicted and analyzed that the sound absorption coefficient of banana fiber found to be as high as 0.97 for the effects on the material thickness of banana fiber and 0.64 for the effects on the fiber diameter size and flow resistivity of banana fiber in the frequency ranges from 500 Hz to 6000 Hz. According to experimental results, it is observed and analyzed that the sound absorption coefficient of banana epoxy composites found to be as high as 0.11 for untreated banana epoxy composites and 0.12 for treated banana epoxy composites in the frequency ranges from 500 Hz to 6000 Hz.

This study explores the mechanical, thermal and morphological properties of untreated and cyanoethyl-treated kempas wood sawdust cellulose fiber-reinforced unsaturated polyester composites. The fiber loadings of the composites were varied from 0 to 20 wt%, with the increment of 5 wt%. The composites were tested for water absorption, and their FTIR spectroscopy, SEM and TGA results were analyzed. The FTIR results show that the fiber treatment reduces the hydroxyl groups in the cellulose, replacing them with the cyanoethyl groups. The TGA results show that the composites are stable up to 324 °C. SEM images of the treated fiber composites showed that there were no visible gaps between fibers and matrix which indicates a strong interfacial bond. From the mechanical tests, 15 wt% fiber loading composite was strongest. Among all the composites, cyanoethyl cellulose fiber unsaturated polyester composites had the most desirable mechanical and thermal properties, whereas the fiber treatment showed the improvement of interfacial bonding. Abbreviations CECFUPC Cyanoethyl cellulose fiber unsaturated polyester composites WF Wood fiber WS Wood sawdust

This review paper explores the potential of commercial production and application of Acacia wood-polylactic acid (PLA), and Acacia wood-polyhydroxyalkanoates (PHA) bio-composites. The factors affecting the mechanical and physical properties of these materials were identified and deliberated. It was found that Acacia wood has the prospective to be efficiently produced and used in Borneo. It can be used in a variety of applications, including but not limited to: fire breaker, timber resource, furniture production, soil re-conditioning, and as reinforced materials. Since, today, there is heightened awareness regarding sustainability, manufacturers are driven towards producing completely biodegradable products that are created using PLA and PHA bio-composites. This review provides an overview on the performance of the existing composites and bio-composites, and their implementation and utilization, while focusing on the Borneo region.