Mechanically robust and thermally insulating natural cotton fiber-reinforced biocomposite panels for structural applications

Natural cotton fiber-reinforced heat-insulating biocomposites with high mechanical strength were designed and developed in the present research for various structural applications. Novel cotton-reinforced polypropylene (PP) composites with improved interfacial adhesion were fabricated through uniform blending of cotton and PP fibers of different volume fractions for high mechanical strength. The developed cotton-PP specimens were characterized by examining their tensile, flexural and impact strength, heat barrier properties, and thermal stability at high temperatures. Among the composites, the material with a cotton and PP ratio of 40/60 demonstrated a maximum tensile and flexural strength of 62.09 MPa and 138.90 MPa, respectively, whereas the 50/50 cotton composite showed a maximum impact strength of 130.75 kJ m^-2. A decrease in tensile and flexural strength was noticed with increasing the reinforced cotton fiber in composites. In the case of thermal performance, however, specimen 60/40 showed the lowest thermal conductivity (0.063 W m^-1 K^-1) and the highest conductive heat resistance (0.063 m²·K W^-1). The composite 60/40, after exposure to radiant heat, also exhibited a maximum radiant heat resistance with the lowest surface temperature of 32.0 °C. Thermogravimetric analysis and differential scanning calorimetry showed adequate thermal stability and heat energy-absorbing capability of materials at elevated temperatures. The outcomes of the present study revealed that cotton-PP composites developed through uniform blending of fibers possess superior mechanical strength and adequate thermal insulation properties and suggested the practicability of using them in various structures where mechanical and thermal performance are the key requirements.