Natural fibers, as replacement of engineered fibers, have been one of the most researched topics over the past years. This is due to their inherent properties, such as biodegradability, renewability and their abundant availability when compared to synthetic fibers. Synthetic fibers derived from finite resources (fossil fuels) and are thus, affected mainly by volatility oil prices and their accumulation in the environment and/or landfill sites as main drawbacks their mechanical properties and thermal properties surpass that of natural fibers. A combination of these fibers/fillers, as reinforcement of various polymeric materials, offers new opportunities to produce multifunctional materials and structures for advanced applications. This article intends to cover recent developments from 2013-up to date on hybrid composites, based on natural fibers with other fillers. Hybrid composites preparation and characterization towards their applicability in advanced applications and the current challenges are also presented.

Hard tissue regeneration and regrowth have continued to be a challenge in the field of conventional medicine in this 21 st century. Over the years, the regrowth of broken bones and diseased hard tissue has remained a major concern in medical research. Since the discovery of hydroxyapatite (HA), a bioceramic compound that possesses the ability to activate bone regrowth and bond directly with regenerated bone, it has subsequently become an indispensable biomaterial. Currently, it is being used across the medical fields due to its exceptional biocompatibility. This became plausible because the main mineral phase of mammalian bones is HA. It has found application in various medical fields like medical instruments, drug delivery, bone and tooth fillers, prosthetics, orthotics, and in-vitro implants. As the importance of HA geometrically increases, it is necessary to critically evaluate and propose the most economic process of synthesizing and manufacturing this important bioceramic material. This review, therefore, highlights the different sources of HA and the synthesis/production methods for each source with a strong emphasis on the environment. Thus, the appraisal was carried out based on the properties of the derived HA. Such properties include but are not limited to geometry, particle size, morphology, thermal stability, and stoichiometry to suggest the most economic and environmentally sustainable sources and processing routes.

High density polyethylene (HDPE) composites reinforced with short bamboo fibre (BF) were fabricated by compression moulding technique. BF were extracted from bamboo culm and treated with 0.5 M NaOH. The composites were developed by melt-compounding various weight fractions (2, 4, 6, 8 and 10 wt.%) of the treated BF with HDPE with the aid of single screw laboratory extruder at a temperature of 180–220 °C. The extrudates were thereafter moulded into various test specimens with the aid of carver laboratory press at a temperature of 230 °C and applied pressure of 0.2 kPa for 10 min. Effect of the treated BF on the mechanical properties and water uptake behaviour of the composites were studied. The results revealed that there was enhancement in the mechanical properties from 2 – 4 wt.% of BF while the water absorption rate increased with increase in the fibre weight fraction. The morphology of the composites showed that there was a homogenous dispersion of BF at lower weight fraction, although fibre agglomeration was noticed at higher weight fraction. The results of this study revealed that treated bamboo fibres are suitable for reinforcing HDPE.