engleski

Simultaneous interpenetrating polymer network formation of epoxy resin and unsaturated polyester: kinetic study

In recent years, an intense research has been devoted to the development of interpenetrating polymer networks (IPNs). Interpenetrating polymer networks are a new class of polymer blends that can be defined as a mixture of two or more cross-linked polymers held together predominantly by permanent entanglement of networks rather than by covalent bond grafting. Blending of two thermosets such as an epoxy resin and an unsaturated polyester via interpenetrating polymer networks is reported in the literature. In this work, a kinetic study on simultaneous interpenetrating polymer network formation of epoxy resin based on diglycidyl ether of Bisphenol A (DGEBA) and unsaturated polyester (UP) was carried out by means of differential scanning calorimetry (DSC). Isothermal DSC characterizations of neat resins and their mixture (in weight ratio of 50/50) were performed at different temperatures. Dynamic DSC characterization of the systems were performed at three different heating rates. A lower total heat of reaction developed during simultaneous polymerization in dynamic DSC tests was found, compared to the total heats developed during pure resins network formation. This phenomenon can be interpreted as an effect of network interlock that could not be compensated completely by an increase of curing temperature. The kinetics of reactions were described by empirical models. The DGEBA in a 50/50 UP/DGEBA blend indicated higher rate constant than the pure DGEBA. The obtained results suggest that the hydroxyl end group of UP in the blend provided favorably catalytic environment for DGEBA cure. The results are in good agreement with the literature data.

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