| Epoxy resins are widely used in the electronics industry because of their superior thermal, mechanical and electrical properties. As applications of epoxy resins spread into the advanced technical fields, such as printed wiring boards and plastic IC packages, high performance resins have been demanded. Improvements in heat resistance and toughness are highly desired features. In most cases, enhancement of these characteristics is not achieved by improving only the structure of the epoxy resins. Therefore, modifications by elastomers (rubbers) or thermoplastic polymers have been investigated.The modification of epoxy resins with reactive liquid elastomer, such as carboxyl-terminated butadiene acrylonitrile rubbers (CTBN) or crosslinked-elastomers, have been investigated as a successful means of enhancing the fracture toughness of brittle epoxy resins. In general, the effective improvement in toughness of elastomer-toughened epoxy resins can be achieved when the elastomer particles are dispersed on a micro-level. However, toughness improvements in most elastomer modified epoxy systems usually result in a significant decrease in the modulus and the glass transition temperature (Tg) of the cured epoxy resins.Recently, many attempts have been made to modify epoxy resins with high-performance engineering thermoplastic polymers that have high Tg and toughness, such as polysulfone (PSF) poly(ether sulfate) (PES), poly(ether imide) (PEI) and polyimide (PI). An effective improvement in toughness in only obtained at high fractions of the engineering thermoplastic polymers, where the thermoplastic polymer forms a continuous phase with the epoxy spherical domain or the thermoplastic polymer and the epoxy form a co-continuous phase. However, the viscosity of the epoxy resins modified with high fractions of the engineering thermoplastic polymer drastically increases, which causes a decrease in handling. In addition, the Tg of the resins modified with the thermoplastic polymer is equal to or only slightly higher than that of the unmodified resin, due to the formation of the phase separation morphologies.On the other hand, attempts have been made to homogeneously dissolve the linear thermoplastic polymers in the epoxy resins. This is a semi-interpenetrating polymer network (semi-IPN) technique that blends two polymers by entangling the molecular chain of thermoplastic polymer to an epoxy network without chemical bonding between them. The formation of the semi-IPN structure makes it possible to homogeneously blend the epoxy matrix and the thermoplastic polymer, or, to microscopically disperse the thermoplastic polymer in the epoxy matrix in a combination of immiscible polymers. We may expect that the semi-IPN structure blend combine the properties of two polymers because of the composite at a molecular level.The IPN or semi-IPN technique is one of the most effective modifications for epoxy resins with low &actions of the thermoplastic polymer.We also investigated the curing kinetics of the epoxy resin and modified epoxy resin by non-isothermal DSC test, and the apparent activation energy(ΔE) and the reaction order(n) of the curing reaction were calculated by using the Kissinger, Ozawa, and Crane equations.On the same time, we discussed the effects of the cure reaction behaviors on the performance of the cured resin by testing the static mechanical performance and the Dynamical Mechanical Thermal Analysis (DMTA), found that the degree of cure and the linked network were all influence the performance of the cured resin.By using isothermal DSC, we studied the phenomenological(empirical) curing kinetics of the epoxy resin, obtained the relationship of , and , and by using a non-linear fitting algorithm, we obtained the value of the parameters of the curing kinetics equation, then we drew the curve of them, and compared with that obtained by experiments.In summary, an attempt was made to simultaneously improve the heat resistance and toughness of a cured epoxy resin, reducing resin viscosity at mixing.
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