Epoxy resins are used to find many industrial applications, It can be widely used as adhesives, construction materials, composites, laminates, coatings and aircraft and spacecraft and so on. owing to their high strength, low viscosity, low volatility and low shrinkage during cure, low creep and good adhesion to may substrates. Nanocomposites, made up of epoxies and inorganic materials, have been a energetic subject of investigation not only because of epoxies and also it is one of the most important type of thermosetting resins, widely used as surface coatings, adhesives, castings and laminate and also because of epoxy-clay nanocomposites may offer inimitable properties compared with conventional epoxy based composites due to their distinctive size, surface chemistry and topology.
The crosslinking curing process of epoxy resins are generally divided into three types: free radical polymerization, condensation reaction and addition reaction types. It has been form a three-dimensional network of thermosetting material when it reacts with the curing agent such as polyamines, polyamides, anhydrides and mercaptants. The common feature is that it releases the chemical reaction heat during the curing reaction. An environmental problem of epoxy resins is that all these curing agents are toxic before the cure. Therefore, it is of considering the importance to use green, biocompatible alternative to toxic curing agents in industrial applications and attempts to move towards on sustainability. Li et al. synthesized a lead free amino acid as the curing agent of epoxy resin in an electronic application. Continuing this research path, the authors interesting to introducing amino acid such as tryptophan as a hardener of epoxy resin. The curing kinetics of the reaction between diglycidyl ether of bisphenol-A and tryptophan as an environ-mentally friendly curing agent in the presence of triphenylimidazole was reported by Ahmad Motahari et al.
It has been established that montmorillonite clay is the most commonly used layered silicate system for the preparation of polymer nanocomposites because of its larger active surface area (700–800 m2/g) and moderately negative surface charge (cation-exchange capacity). Isil Isik et al examine the impacts of diglycidyl ether of bisphenol A type epoxy resin (DGEBA) with montmorillonite nanoclay. Pinnavaia et al. synthesized epoxy–clay nanocomposites and obtained exfoliation of organoclays. Synthesis of intercalated nanocomposites prepared by modified montmorillonite and glassy epoxy which was cured with an aliphatic diamine curing agent studied by Zerda and Lesser.
Taking into consideration the synthesize of novel tetra glycidyl ether of spirobiindane epoxy [SBIE] nanocomposites using montmorillonite nanoclay and tryphtophane as a curing agent. In manufacturing an epoxy nanocomposite, the curing reaction first occurs to form optimal adhesion between the matrix and nanoparticles. It is very important to study the mechanism of curing process, to reveal the mechanism of curing reaction, and control the curing reaction process. It is also important to optimize the curing process parameters. Therefore, cure kinetics of the matrix material is a key parameter for manufacturing high-performance nanocomposites. There are many ways to study the curing process, among which the thermal analysis method is the major one. However, the publications to examine the effect of nanoparticles on the mechanism of epoxy nanocomposites are very rare. And also, there is no report on the kinetic study and thermo-mechanical properties of spirobiindane based epoxy resin cured with a green hardener such as tryptophan.
Model fitting kinetic methods are used to determine the kinetic triplets using multiple heating rate programs and the kinetic triplet obtained from these methods for non-isothermal condition is highly uncertain and cannot be compared with the kinetic triplets obtained from isothermal condition. According to the different mathematical methods, it can be divided into two categories of differential and integral methods. At present, in the method of research dynamics, the differential method is mainly represented by Friedman method, and the integral methods are represented by Flynn-Wall-Ozawa25 (FWO) and Vyazkovin (VYZ) method. Vyazovkin model-free approach through use of isoconversion method leads to a trust worthy way of obtaining reliable and consistent kinetic information from nonisothermal data from curing and degradation studies. Hence in the present investigations the apparent activation energy (Ea) for the polymerization of the SBIE-montmorillonite nanocomposites are obtained using three model-free kinetic FWO and VYZ methods. The results obtained are compared. This study has been carried out to understand the curing behaviour, to establish the curing schedule.
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