This article is focused on prediction of the long‐term creep performance of glass fiber/epoxy (GE) composites reinforced with pristine carbon nanotube (CNT) and functionalized carbon nanotube (FCNT). 0.1 wt% of CNT and FCNT are added to GE composites to fabricate CNT‐GE and FCNT‐GE composite laminates, respectively. Flexural tests were carried out at room temperature (RT) and 120°C to assess the effect of environment temperature on the flexural properties of the aforesaid materials. FCNT‐GE showed highest improvement in flexural properties at RT followed by CNT‐GE composite and control GE composite, due to better stress transfer with strong chemical interfacial bonding. By using accelerated deformation at elevated temperature and time‐temperature superposition principle, long‐term creep behavior of GE, CNT‐GE, and FCNT‐GE composites at various reference temperatures (30°C, 60°C, 90°C, and 110°C) has been anticipated. Positive reinforcement efficiency is noted up to ~1010.5 and ~1012.5 years for CNT‐GE and FCNT‐GE, respectively at reference temperature of 30°C, following which it neutralized and moderately became negative. However, at higher temperature this time period is reduced abruptly due to unfavorable thermal stress generation at the CNT/polymer interface. Evaluation of thermomechanical properties were also carried out using dynamic mechanical analysis. Differential scanning calorimetry was used to investigate the variation in glass transition temperature due to CNT/FCNT addition to GE composite. Fractographic study was also carried out to know the mode of failure for CNT‐GE and FCNT‐GE composite flexural tested at room temperature.
In this article, modification of carbon fiber surface by carbon based nanofillers (multi‐walled carbon nanotubes [CNT], carbon nanofibers, and multi‐layered graphene) has been achieved by electrophoretic deposition technique to improve its interfacial bonding with epoxy matrix, with a target to improve the mechanical performance of carbon fiber reinforced polymer composites. Flexural and short beam shear properties of the composites were studied at extreme temperature conditions; in‐situ cryo, room and elevated temperature (−196, 30, and 120°C respectively). Laminate reinforced with CNT grafted carbon fibers exhibited highest delamination resistance with maximum improvement in flexural strength as well as in inter‐laminar shear strength (ILSS) among all the carbon fiber reinforced epoxy (CE) composites at all in‐situ temperatures. CNT modified CE composite showed increment of 9% in flexural strength and 17.43% in ILSS when compared to that of unmodified CE composite at room temperature (30°C). Thermomechanical properties were investigated using dynamic mechanical analysis. Fractography was also carried out to study different modes of failure of the composites.
Enhancing the performance of polymeric composites by incorporating carbon nanotube (CNT) is a current research trend. In this article, the performance of glass fiber reinforced epoxy (GE) composite with and without CNT has been observed under repeated hydrothermal cycling (HC) between 15 and 50°C water baths. Before carrying out the HC, the optimum concentration of CNT in the GE composite was obtained by flexural test. This study first confirms that the addition of 0.1 wt% of CNTs resulted in a 6.68% and 6.47% increment in flexural strength and modulus compared to neat GE composite. Alteration in the performance of the neat GE and 0.1 wt% CNT‐GE was then analyzed after performing HC for 20, 40, and 60 cycles by conducting mechanical (flexural), thermomechanical (dynamic mechanical thermal analysis [DMA]), chemical (Fourier transform infrared spectroscopy [FTIR]) and fractographic (scanning electron microscopy [SEM]) analysis. Degradation in the mechanical performance of the CNT embedded GE composite was found to be faster than the neat one with the increasing number of HC. The possible reason has been explained based on the evidence obtained from DMA, FTIR, and SEM analysis.
Owing to the superior corrosion resistance, fiber-reinforced polymer (FRP) composites are the prime choice of structural materials for various marine and chemical industries, where there is a long-term direct contact of the components takes place with corrosive fluids. In this present work, glass fiber/epoxy (GE) composites have been fabricated with and without carbon nanofibers (CNFs), and aging has been carried out in acidic (pH = 1), seawater (pH = 8.2), and alkaline (pH = 13) solutions for 150 days. The resistance of CNF-filled GE composites toward the corrosive fluids has been evaluated in terms of alteration in the mechanical (flexural), microstructural (fractography analysis by field emission scanning electron microscope), and thermomechanical (dynamic mechanical analysis) behavior of the materials. It is revealed that as the immersion time increases, there is a continuous decrement in flexural strength and modulus, and glass-transition temperature (T g ) of all the materials in all these solutions. Compared to the 1% CNF-filled GE composite, control GE composite showed more degradation in the case of alkaline aging and seawater aging. Maximum reduction (56%) in the strength of GE composite was observed due to 150 days of alkaline aging. However, the control GE composite showed better resistance to the acidic solution than that of CNF-filled GE composite. Possible failure modes, changes in the chemistry of the material due to aging have been studied by fractography analysis.
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