The epoxy-based resins are broadly utilized in polymer laminates, automobiles, aerospace, adhesives, paints fabrication, surface coating methodology, and other engineering materials (May and Tanaka, 1973; Rs, 1979). The performance of epoxy composites in sectors is because of their higher corrosion and chemical resistance, greater mechanical and thermal characteristics, lower shrinkage(Adams and Gannon, 1986). Epoxy composites can study in specific environmental situations. The cured epoxy polymer exhibited a 3D (three-dimensional) extremely cross-linked chain scheme. The characteristics of epoxy polymers are strained in different applications because of a higher range of cross-linking density which is influenced by intrinsic brittle behavior of components and lower toughness. Various investigations have been performed to enhance the toughness and other characteristics like thermal stability, dynamic mechanical and crack resistance of epoxy polymer by adding different kinds and quantities of nanoparticles in a polymer (Duraibabu et al., 2014). The breaking and uniform dispersion of nanoclusters inside the polymer are two primary issues for nanolaminates fabrication (Sun et al., 2015). Dispersion and cluster size of nanoparticles in polymer resin shows the confident development in pure polymer's fundamental characteristics with stronger interfacial bonding within the molecular networks and fillers (Radoman et al., 2014; Bal, 2010). The particle accumulation trend because of non-uniform dispersion and van der Waals forces in epoxy polymer has strengthened investigators for deciding the excellent processing methods to lower or decrease the accumulated filler size and provide its homogeneous distribution. Many ways are already in the tendency for polymer nanolaminates fabrication from shear comprising using manual stirring, melt mixing, solution mixing (Becker et al., 1996; Rong et al., 2001), direct addition with chemical route techniques (Kumar et al., 2017; Kang et al., 2001), acoustic cavitation (Eskin, 2001), ultrasound vibrations (Wang et al., 2001), ultrasonic waves (Kumar et al., 2016; Xu et al., 2004), and ultrasonic irradiation (Xia and Wang, 2003). The acoustic cavitation method is an efficient process for distributing nanoparticles in polymer resins (Zunjarrao and Singh, 2016; Halder et al., 2012; Tsekmes et al., 2015).
Tsekmes et al. (2015) have declared that epoxy-based laminates benefit from greater breakdown strength with enhanced thermal stability. Generally, utilization of 60–70 wt.% of silica microparticles in the epoxy laminate insulators can be observed in the industrial sector. Imai et al. (2006) have signified that the silica particle leads to show the lower coefficient of thermal expansion. Ramanujam et al. (2019) have investigated the corona treatment inaugurated because of water contents on IXEPLAS reinforced epoxy nanolaminates. IXEPLAS is a hydrotalcite component customized with zirconium phosphate. Inorganic ion exchangers such as zirconium phosphate lead to better resistance from oxidation and more significant ion entrapping capability. Thus, it can be suitable in the electrical schemes for enhancing their performance.
One of the considerable interests in epoxy laminate samples is water absorption in humid environmental situations. Nogueira et al. (2001) have signified that moisture in epoxy laminates is present in two dissimilar systems, such as bound water in interaction with hydrogen bonding of the laminate and moisture present in the accessible quantity micro-gaps in the resin. In composites' condition, this principle is profound compared to neat epoxy due to the interface between filler and matrix will act as a possible region for the moisture molecule to cooperate (Zou et al., 2008). This principle may potentially tend to considerable irreversible material modifications like final degradation, plasticization, and swelling of insulating material (Wang et al., 2006). Exposing polymeric samples to hot water is one of the usual techniques to affect the long-term process or accelerated aging of moisture uptake principle (Pitarresi et al., 2018). Ramanujam et al. (2019) have performed moisture absorption investigations with pure epoxy and their respective nanolaminates. They have signified that the percentage of the weight of the pristine epoxy polymer is around 0.5%. The epoxy polymer laminate sample applied in the current investigation has a gain in weight % of about 0.2. The pure epoxy polymer has a freer amount applicable in the bulk of the sample for the moisture to penetrate. The fillers reinforcement played as protection for water diffusion in the bulk amount of laminate sample, decreasing the moisture absorption compared to neat epoxy. When the moisture absorption of pure epoxy is higher than two times of moisture absorption in a laminate sample, the current investigation is concentrated more on an epoxy hybrid laminate sample to interpret the influence of water absorption and mechanical characteristics.
Nonetheless, it also has many limitations like thermal stability, softness, and flexural modulus (Wu et al., 2019). Incorporating inorganic particles like carbon-based fillers, calcium carbonate, silica, and calcium sulphate is an efficient technique for enhancing the overall characteristics of polymers (Abdel-Gawad et al., 2018; Yuan et al., 2016; Cui et al., 2017; Khaleghi et al., 2017). Among these fillers, fly ash is a reinforcing agent that can adequately enhance the thermal resistance, impact, and modulus of polymers, owing to their other advantageous properties like chemical corrosion resistance, lower cost, higher mechanical properties, availability, higher mechanical strength, and more necessarily usage of industrialization (Dahalan et al., 2018; Liu and Zhong, 2014). Fly ash is the primary solid waste released from pulverized coal's combusting process in thermal power plants. It is now the most excellent individual resource of solid waste management (Ding et al., 2017; Temuujin et al., 2019; Wang et al., 2014). The constituent, surface chemical reaction, and mineralogy of fly ash have essential influences on its utilization (Yao et al., 2015; Hower et al., 2017) like wastewater treatment in the industry, catalyst carriers for the modification of poisonous gases, raw materials for plastics, adsorbent, silica aerogels, soil conditioners in agriculture, and construction materials as admixture (Asl et al., 2018; Asl et al., 2019; Cai et al., 2020). When fly ash is made of adaptable active oxides, it can also be applied as a filler for polymer laminates. It can enhance polymer laminates' thermal and mechanical characteristics, whereas fabrication cost is furthermore decreased.
Furthermore, only a restricted quantity of hydroxyl functional group on the surface of fly ash may affect the poor compatibility between polymer and fly ash. Hence, avoid the movement of mechanical stress used to the laminate and subsequently control the laminates' damage (Civancik-Uslu et al., 2018). To enhance the bonding between organic matrix and fly ash, surface treatment of fly ash is essential. Patil et al. (2016) fabricated an optimized planetary ball milling technique from the Taguchi experimental design to manufacturing nano-sized fly ash. Van der Merweet et al. (2014) observed that the treatment of fly ash with sodium lauryl sulphate tends to no considerable modifications in the chemical constituents, and modified fly ash could be applied as reinforcement in polymers under lower content. Furthermore, previous investigations on the activation of fly ash by mechanical alloying have focussed mainly on the fabrication of nano-sized fly ash (Thongsang et al., 2012; Yuan et al., 2019), which generally lacks a long mechanical alloying period higher consumption of energy (Sundum et al., 2018; Li et al., 2017). An easy and efficient treatment technique would share fly ash utilization in the production of advanced industrial components.
Among the different ceramic nanofillers, the titanium carbide (TiC) nanoparticles are known for their higher thermal stability, larger surface area, superior electrical insulation characteristics, and excellent mechanical characteristics that produce it more prominent an inferior aspirant filler (Mallakpour and Khadem, 2015; Omrani et al., 2009). In the present study, the fly ash and TiC are selected as potential reinforcement. The fly ash and TiC are well-known for their higher mechanical characteristics and thermal stability. From the literature study, it has been observed that limited investigations have been conducted to manufacture hybrid composite with coir and Innegra fiber incorporated in the epoxy resin with fly ash and TiC. In this study, an experiment has been appointed to fabricate composites combined with Innegra fiber, fly ash, TiC filler comprised with coir fiber in the epoxy polymer. The effect of fly ash and TiC particles incorporation in Coir fiber-Innegra fiber-epoxy composite on morphological, mechanical, and thermal characteristics were measured from tensile, impact, inter-laminar shear strength, flexural, hardness, scanning electron microscope (SEM), differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA) is considered.