Durability of Pultruded Glass Fibre Reinforced Polymer Composite Subjected to Hygrothermal Ageing in Sea Water

Abstract

Durability of glass fibre reinforced polymer (GFRP) composite is an important research topic because the changes occur in GFRP composite with ageing can affect its properties and lifetime. For long term use, GFRP composites should be examined in real time and with reasonable in-service environments. However, this is not practical because the time involved would significantly delay product development and therefore, accelerated ageing technique is required. Conditioning in wet and elevated temperatures known as hygrothermal ageing is a very useful technique to evaluate the durability of GFRP composites in a reasonable timeframe. In this work, pultruded GFRP composites were aged in sea water and in dry conditions at 23, 55 and 75°C for 0, 8 and 20 months to assess the changes in shear properties (e.g. short beam shear strength, SBSS and transverse shear strength, TSS) and in glass transition temperature, Tg. After ageing in sea water for 20 months, SBSS was found to retain by about 101, 102 and 95% at 23, 55 and 75°C, respectively. On the other hand, SBSS was retained by around 106% after ageing in dry condition for 20 months at 55 and 75°C. TSS was found to retain by approximately 99, 95 and 91% after ageing in sea water for 20 months at 23, 55 and 75°C, respectively, whereas TSS of dry conditioned samples was retained by about 105 and 107% at 55 and 75°C, respectively. Tg, measured by dynamic mechanical thermal analyser, showed little change both in wet and dry conditions at different temperatures and time.