Use of Cotton–Polyester Hard Waste for Fabricating Thermal Insulation Composites

Recycled waste composites are critical for promoting sustainability, decreasing waste, and developing new, usable materials from wasted components. They contribute significantly to the development of a circular economy by offering cost‐effective and environmentally beneficial alternatives to conventional materials. This study investigates the creation of a sustainable thermal insulating composite by recovering cotton–polyester hard waste from spinning mills. The composite was made with arrowroot powder as the natural matrix and cotton–polyester waste as the reinforcing ingredient. A thorough characterization was performed to determine its mechanical, thermal, and physical characteristics. The composite has a tensile strength of 33.18 MPa and a flexural strength of 17 MPa, showing intermediate mechanical properties. The insulating foam had a water absorbency of 61%, shore hardness of 69, and density of 670 kg/m 3 , all of which were higher than average values. The developed composite’s thermal conductivity of 0.0368 W/m·K matches that of insulation materials, indicating its potential as an effective thermal insulator. Optical microscopy revealed a rough and diverse surface, typical of natural fiber‐reinforced composites. Despite having lower mechanical strengths than commercial insulation foams, the composite shows promise in terms of thermal performance, density, hardness, and environmental sustainability, making it a potential option for eco‐friendly thermal insulation applications.