Effect of CNT/CNT-COOH Addition on Creep Performance and Water Absorption Behaviour of Embedded Glass Fiber/Epoxy Composites

Abstract

Present work is aimed to study the effects of CNT/CNT-COOH reinforcement and ageing temperature on the water uptake behavior and subsequent mechanical properties and long-term creep performance of CNT/CNT-COOH embedded glass fiber/epoxy composites. Control glass fiber/epoxy (GE) composites, CNT embedded GE (CNT-GE) composites and CNT-COOH embedded GE (CNT-COOH-GE) composites laminates were fabricated by hand lay method. For fabrication of CNT-GE and CNT-COOH-GE Composites laminate, different wt. % (0.1%, 0.3% and 0.5%) of CNT/CNT-COOH was added to epoxy. When flexural testing was done at Room temperature, 0.1 wt. % CNT-GE showed ~13% and 0.1 wt. % CNT-
COOH-GE showed ~20% increment in flexural strength as compared to control GE composites. Flexural testing done at 120 ̊C showed, 0.3 wt. % CNT-GE and 0.3 wt. % CNT-COOH-GE composites exhibited 10% and 32% respectively higher flexural strength than control GE composites. Flexural modulus increased by 26% for 0.3 wt. % CNT-COOH because of strong chemical bonding. Water absorption behaviour is affected by water ingression temperature (15 ̊C to 50 ̊C), 14% and 7% reduction in weight gain due to water absorption observed for 0.1 wt. % CNT-COOH-GE at 15 ̊C to 50 ̊C respectively as compared to neat GE composites. no considerable improvement in resistance observed for 0.1 wt. % CNT-GE composite. Effect of CNT/CNT-COOH addition on glass transition temperature (Tg) of GE composites evaluated by Dynamic Mechanical Analysis. Lifelong creep performances at different reference temperatures (30 ̊C, 60 ̊C, 90 ̊C, and 110 ̊C) for GE, 0.1 wt. % CNT-GE and 0.1 wt. % CNT-COOH-GE composites (without ageing) was carried out using accelerated deformation at higher temperatures and time-temperature superposition principle. It is revealed that CNT/CNT-COOH addition improved resistance against creep deformation even up to 105 years at 30 ̊C, after which it starts decreasing and shows resistance inferior to GE composite. At higher temperature, the time period for this reduction in resistance also decreases due to slippage of CNTs and interfacial debonding and generation
of thermal stresses at the CNT/polymer interface.