Juncus Acutus fiber-recycled expanded polystyrene composites for lower-impact insulation: experimental...

In response to the growing demand for lower-impact building insulation materials, this study investigates composites combining Juncus Acutus (JA) fibers with recycled expanded polystyrene (EPS) as a strategy for valorizing biomass and polymeric waste. Three JA/EPS formulations (70/30, 60/40, and 50/50) were experimentally characterized in terms of density, thermal properties, and compressive strength, followed by life-cycle assessment and transient numerical analysis. Increasing the JA content from 50 to 70% reduced the bulk density from 371.6 to 289.9 kg·m⁻³ and thermal conductivity from 0.117 to 0.096 W·m⁻¹·K⁻¹, while thermal diffusivity decreased by approximately 15% and specific heat capacity increased by about 10%. Despite the reduction in compressive strength with increasing fiber content, the JA70 formulation reached 0.16 MPa, indicating adequate mechanical integrity for handling and use in non-structural insulation applications. Among the investigated formulations, JA70 provided the most favorable balance between thermal and mechanical properties. Its cradle-to-gate global warming potential was estimated at 1.1 kg CO₂-eq·kg⁻¹, while transient numerical simulations demonstrated improved thermal inertia and indoor temperature regulation under representative climatic conditions. Overall, the results demonstrate the potential of JA fiber-recycled EPS composites as promising lower-impact insulation materials, while also highlighting the need to further address solvent-related impacts, moisture resistance, fire performance, and long-term durability before practical building application.