The current study is a bibliographic observation on prevailing tendencies in the development of acoustic absorption by natural fiber composites. Despite having less detrimental environmental effects and thorough availability, natural fibers are still unsuitable for wide implementation in industrial purposes. Some shortcomings such as the presence of moisture contents, thicker diameter, and lower antifungus quality hold up the progress of natural fiber composites in staying competitive with synthetic composites. The review indicates the importance of the pretreatment of fresh natural fiber to overcome these shortcomings. However, the pretreatment of natural fiber causes the removal of moisture contents which results in the decrease of its acoustic absorption performance. Incorporation of granular materials in treated fiber composite is expected to play a significant role as a replacement for moisture contents. This review aims to investigate the acoustic absorption behavior of natural fiber composites due to the incorporation of granular materials. It is intended that this review will provide an overview of the analytical approaches for the modeling of acoustic wave propagation through the natural fiber composites. The possible influential factors of fibers and grains were described in this study for the enhancement of low frequency acoustic absorption of the composites.

Natural fibers and their composites are being widely used in almost all the applications in this modern era. However, the properties of natural fibers have to be enhanced in order to compete with synthetic fibers. This review paper opens up additive manufacturing, as a novel method for developing an acoustic panel using natural fiber composites with enhanced mechanical and acoustical properties. This approach will help to replace synthetic-based acoustic absorbers with biodegradable composite panels in acoustic applications. This review also covers, poly(lactic acid) as a polymer matrix and its advantages, the available variety of natural fibers as reinforcement in terms of mechanical and acoustical properties. The natural fiber-based filaments used in additive manufacturing and acoustic panels made from the available natural fibers are also elaborated here. This review shows the importance of additive manufacturing and its application to develop novel acoustic panels made of agricultural waste.

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In recent years, Natural Fibre-Reinforced Composites (NFRC) making its impact in all applications, and they have reached their way into the field of Additive Manufacturing (AM) as well. This increases the demand for natural fibre based filaments in the field of AM. Hence, this research aims to develop filaments made of Polylactic acid (PLA) reinforced with Oil Palm Empty Fruit Bunch Fibre (OPEFBF) and to investigate its physical, thermal and mechanical properties. PLA with 10, 20, 30, and 40 wt.% of OPEFBF were melt blended, hot-pressed, and successfully extruded as filaments. Later, its physical, thermal, water absorption, biodegradation, and mechanical properties are investigated. OPEFBF reinforced filaments show lesser values of densities, increased Tensile Modulus (TM), better bio and thermal degradation compared to the pure PLA. However, its rate of water absorption is high with reduced Tensile Strength (TS) than the pure PLA. Later these filaments reinforced with different OPEFBF contents are 3D printed using Fused Deposition Modeling (FDM) technology. Filaments with lesser fibre content were easy to print. Filaments with 10 wt.% OPEFBF was continuously printed whereas, filaments with higher fibre content clogged in the nozzle. Overall, PLA reinforced with OPEFBF has been developed and successfully applied to the field of additive manufacturing by FDM.

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