Water-induced degradations in MWCNT embedded glass fiber/epoxy composites: An emphasis on aging temperature Rajesh Kumar Prusty , 1 Dinesh Kumar Rathore, 1,2 Bankim Chandra Ray 1 1 Composite Materials Group, Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela 769008, India 2 School of Mechanical Engineering, KIIT University, Bhubaneswar 751024, India Correspondence to: R. K. Prusty (E - mail: prustyr@nitrkl.ac.in) ABSTRACT: This article is focused to elucidate the critical influence of diffusion temperature on the water uptake and subsequent deg- radation behavior of multi-walled carbon nanotube embedded glass fiber/epoxy (MWCNT-GE) composite. Presence of MWCNT in the glass fiber/epoxy (GE) composite significantly suppressed its water absorption propensity at lower aging temperature (25 8C). However, MWCNT reinforcement in GE composite adversely affected its high temperature water resistance due to generation of unfa- vorable thermal and hygroscopic stresses at the MWCNT/polymer interfaces. Effect of MWCNT and water diffusion temperature on the glass transition temperature and chemical bonding characteristics of GE composite have been verified by differential scanning cal- orimetry and Fourier transformed infrared spectroscopy. Flexural testing of the water saturated samples revealed that diffused water exerts more detrimental effect on mechanical performance of MWCNT-GE composite than that of control GE composite. The extent of recovery in mechanical performance of the composites has also been evaluated after complete desorption of the water saturated samples. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 45987. KEYWORDS: ageing; composites; degradation; mechanical properties; nanotubes; graphene and fullerenes Received 14 July 2017; accepted 27 October 2017 DOI: 10.1002/app.45987 INTRODUCTION Corrosion problems associated with metallic structures and environmental degradation of wood have driven the process of replacing these materials fully or partially by structural poly- meric composites in naval applications. However, other advan- tages of fiber reinforced polymer (FRP) composites over metallic counterparts include reduction of weight, particularly the topside weight of ships. Superior acoustic transparency of these composites has also directed their use in radomes on ships and sonar domes on submarines. The noteworthy demand of FRP patrol boat is mostly due to its excellent resistance against corrosion, which reduces maintenance cost significantly and light weight. Hence, better speed is achieved along with fuel economy. Offshore oil platforms are also a potential thrust application area of glass fiber reinforced polymer (GFRP) com- posite. 1 In addition, GFRP is also being used in oil and water pipelines, water storage tanks, desalinization plants, tidal, and wind turbines in sea. 2 Epoxy has been commonly used as a matrix material in struc- tural load-bearing FRP components due to its superior strength, stiffness, and thermal and chemical resistance. 3,4 Ingression of environmental moisture/water in epoxy-based materials is unde- sirable and very often limits its utilization in naval applica- tions. 5,6 Induced water plasticizes the polymer, which leads to degradation in its mechanical properties. The extent of this deg- radation depends on (1) structural features of the material, such as degree of crosslinking and polarity of matrix and (2) aging conditions that include temperature, structural load, relative humidity, and aging duration. 7–10 Moisture diffusion in poly- meric materials leads to alteration in its chemical, thermo- physical and mechanical characteristics due to swelling, plastici- zation, and hydrolysis. 11 In case of reinforced plastics, differen- tial volumetric expansion between the polymer and reinforcement leads to development of localized strain and stress fields in the interphase region. 12 Further, weaker interface may accelerate the process of water absorption due to interfacial capillary action. However, the demand for such light weight, high strength, and stiff material always motivates material scien- tists for its possible modification to make it further water resis- tant. Hydrophobic nanoscale reinforcements are expected to improve the barrier properties of polymeric materials. 13 Unique structure and extraordinary strength and stiffness of carbon nanotubes (CNTs) enable them as potential reinforcement in V C 2017 Wiley Periodicals, Inc. J. APPL. POLYM. SCI. 2017, DOI: 10.1002/APP.45987 45987 (1 of 9)