Effects of Rice Husk Derived Amorphous Silica on the Thermal-Mechanical Properties of Unsaturated Polyester Composites

• Published in: Journal of macromolecular science. Physics Vol. 57; no. 6; pp. 479 - 496
• Main Authors: Halim, Zulhelmi Alif Abd, Yajid, Muhamad Azizi M., Idris, M. Hasbullah, Hamdan, Halimaton
• Format: Journal Article
• Language: English
• Published: New York Taylor & Francis 03.06.2018; Marcel Dekker, Inc
• Subjects: Aerogel; Aerogels; Composite materials; composites; Drying; Fillers; Mechanical properties; Modulus of elasticity; Polyesters; Polymer matrix composites; Polymers; Silica; Silicon dioxide; Skeletal composites; Sodium; Sodium silicates; Sol-gel processes; Stiffness; Stress-strain curves; Stress-strain relationships; Tensile stress; tensile test; Thermal insulation; Thermogravimetric analysis; unsaturated polyester
• ISSN: 0022-2348; 1525-609X
• DOI: 10.1080/00222348.2018.1476440

Rice husk is rich in amorphous silica which has found various applications as a filler in rubbers and plastics. In the research described here silica was extracted from rice husk ash in the form of sodium silicate which was used to produced amorphous precipitated silica (PS) and silica aerogel (SA) using a sol - gel process and supercritical drying. These materials were then physically mixed with unsaturated polyester (UP) resin and cured at room temperature to form polymer composites. The experimental results showed that the UP composites with 30% (volume percent) of SA filler had lower density and better thermal insulation than the composites with the same amount of PS. Thermogravimetric analysis (TGA) results showed that the T onset of the PS and SA composites were slightly delayed by 15 and 10°C, respectively. The tensile stress-strain curves showed that addition of the fillers reduced the tensile strength, but increased the elastic moduli of the UP matrix. PS filled UP composites exhibit higher moduli (higher stiffness) than that of SA filled UP composites. This was due to agglomeration and poor adhesion of the SA particles to the UP matrix while better dispersion was observed for the PS filled composite.