Influence of cellulose fiber reinforcement in mechanical and morphological properties of polyurethane‐silica aerogel composites for thermal insulation applications

Abstract Polyurethane‐silica aerogel (PUSA) composite has shown promising performance in thermal insulation application, owing to its microstructure that offers thermal resistance within its cellular matrix. The inclusion of silica aerogel into polyurethane enhances both the mechanical and thermal properties of the composite. Previous research reported 1 wt.–% silica aerogel loading as optimal in material compressive strength and higher concentrations was found to negatively impact the cell structure and ultimately hinder thermal performance. In the quest for enhanced properties cellulose fibre (CF) was introduced into polyurethane‐silica aerogel. Composites with variable loading of cellulose fibre (0.5 wt.–%, 0.75 wt.–% and 1.0 wt.–%) as PUCF1S, PUCF2S and PUCF3S were fabricated. It was found that composite PUCF2S has the highest compressive strength of 0.92 MPa, demonstrating 64 % increase compared to pristine composite (polyurethane‐silica aerogel). The matrix microstructure as revealed by field emission scanning electron microscopy was discovered to have uniform cell size facilitated by uniform particle dispersion within the matrix. The cellulose fibre participated in the cell nucleation leaving behind an enhanced cell with reduced cell size that supports compressive loads and thermal insulation performance.