Thermal insulator from bamboo waste and bioplastic PLA for building materials: Effects of particle size and pretreatment temperature using compression molding

This study presents an eco-efficient route for producing thermal insulation composites from polylactic acid (PLA) and bamboo waste via low-carbon compression molding. To reduce energy demand, bamboo particles were pretreated under mild thermal conditions (121 and 134 °C) and sieved into coarse (10 mesh) and fine (250 mesh) fractions, yielding six composite samples. Structural analyses (XRD, SEM) showed that finer particles retained higher cellulose crystallinity and enhanced filler–matrix interaction, while coarse particles exhibited more lignocellulosic cracking. Mechanical, thermal, and water absorption tests confirmed that the 250 mesh composite pretreated at 134 °C (CMI_250_P134) achieved the best balance of strength, insulation, and sustainability, with a thermal conductivity of 0.0635 W/m·K and thermal resistance of 0.0774 m 2 ·K/W. The results highlight that optimizing particle size and applying low-temperature pretreatment under compression molding can deliver renewable insulation with competitive performance and a reduced carbon footprint. This work provides a novel pathway for developing biodegradable, low-CO 2 composites as alternatives to petroleum-based foams. • Development of Eco-Friendly Thermal Insulation: The article presents a method to create insulation from bamboo waste and bioplastic polylactic acid (PLA) using compression molding, resulting in an effective thermal insulator that reduces greenhouse gas emissions in production. • Impact of Particle Size and Pretreatment Temperature: The study found that smaller particle sizes and higher pretreatment temperatures enhanced the insulation’s strength and elasticity while reducing thermal conductivity, leading to improved thermal resistance compared to conventional insulation materials. • Sustainable Use of Bamboo Waste: Utilizing bamboo, a fast-growing and renewable material, as a raw input reduces agricultural waste and dependency on petroleum-based plastics, providing an environmentally friendly alternative for the construction industry.