Effect of thermal ageing on electrical, mechanical properties of glass fiber reinforced polymer and its impact on service life

Abstract

The mechanical and electrical properties of polymer composites often degrade due to environmental factors and shorten their service life. This article presents the effect of high temperatures on the mechanical and electrical characteristics of glass fiber reinforced composites and from the measurements, an attempt is made to predict the service life. Electrical conductivity, impedance and resistance are studied with a short-term temperature effect at 30, 60, 120, and 180 °C. The effect of temperature exposure at 120 and 160 °C for 1000, 2000, and 3000 h has been investigated to assess the changes in flexural, compressive, and tensile properties and for prediction of service life. Morphological studies are carried out to support some of the experimental results. The mechanical properties of composites are observed to deteriorate with the duration of aging. Flexural, tensile, and compressive strengths reveal a reduction of 8, 10, and 9%, after aging at 3000 h at 160 °C. The tensile strength and tensile modulus at 120 °C aged for 3000 h exhibit minimal changes as compared to unaged composites. However, with an increase in temperature to 160 °C, there is a reduction in tensile strength and modulus of composites by less than 10%, and 6% compared to composites with nanofillers. The variations in compression strength at 120 and 160 °C is not significant. Based on the reduction of tensile strength with temperature, the service life of composites has been estimated. For a predicted service life of 20 years, composites with nanofillers would be able to retain tensile strength of 90% of tensile strength.