Coir is a lignocellulosic natural fiber derived from the coconut's husk, an abundantly found fruit or nut worldwide. This fiber has some unique characteristics, such as its resistance to seawater, microbial attack, high impact, etc. But its low thermal conductivity or high thermal insulating property makes it suitable for being used as insulators in civil engineering sites. On the other hand, the sustainability of a material depends heavily on its environmental impact of the material. For making sustainable materials like biocomposite, there are no options other than using polymers derived from natural renewable sources. Polylactic acid(PLA) is an example of those types of material. And these materials are often being reinforced by fibers like coir for various reasons including improving mechanical properties, reducing the cost of the material, and improving the material's sustainability. Many coir-reinforced sustainable biopolymer composites have already been produced in many pieces of research, which will be discussed in this paper, along with the chemical and physical structure of coir fiber. In addition, this paper will try to focus on the insulating properties of coir and coir-reinforced composites while will also compare some properties of the composites with some commonly used materials based on different parameters to show the suitability of using the coir fiber in heat-insulating applications and to produce sustainable biocomposite materials.

The textile industry has historically shifted from natural to synthetic dyes and mordants due to factors such as broader color range, improved colorfastness, and large-scale production efficiency. However, synthetic alternatives raise serious environmental and health concerns owing to their toxicity, nonbiodegradability, and resource-intensive manufacturing. With increasing global emphasis on sustainable and eco-conscious practices, there is renewed interest in natural dyes and biomordants. This review critically examines the resurgence of these bio-based colorants, comparing traditional natural dyes and mordants to modern innovations in terms of performance, environmental impact, and feasibility for industrial use. While natural dyes offer biodegradability and reduced toxicity, they face limitations in color consistency, fastness, and scalability. Advances in biotechnology have led to the development of bioengineered dyes from microorganisms, waste-derived pigments, and biomordants such as chitosan, tannins, and enzymes that address some of these challenges. Additionally, hybrid approaches incorporating nanotechnology are enhancing dye uptake and durability. By integrating insights from materials science and green chemistry, this review outlines the current state and future prospects of natural dyes and biomordants in transforming textile manufacturing into a more sustainable industry.