Impact of Glass Fiber Content and Length on the Thermo‐Mechanical Properties of Expanded Perlite‐Based Sandwich Composites With Formica as Skin

This study investigates novel lightweight sandwich composites comprising an expanded perlite core reinforced with glass fibers and Formica skins. The effects of varying glass fiber content (5–20 wt% at a 10 mm length) and fiber length (5–20 mm at a 20 wt% loading) on thermo‐mechanical performance were evaluated. Results showed that increasing fiber content from 5% to 20% enhanced flexural and compressive strengths by 31% and 13%, respectively, while significantly improving flexural toughness by 63%. Fiber length optimization revealed that 10 mm fibers yielded the best mechanical performance, increasing flexural and compressive strengths by 51% and 47% over 5 mm fibers. However, lengths exceeding 10 mm degraded properties due to agglomeration. The composites maintained a very low density (0.51–0.55 g/cm 3 ), though thermal conductivity increased slightly (9%–10%) with higher fiber additions. Failure analysis indicated that increased fiber content enhances load‐bearing capacity but increases brittleness. Ultimately, optimizing fiber parameters produces a highly effective, low‐density composite suitable for structural and insulating applications.