Thermal properties of epoxy–anhydride formulations cured using phosphonium accelerators

© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Influence of structure of epoxy resin and anhydride hardener, as well as type and content of accelerator on thermal properties of epoxy–anhydride networks were investigated by dynamic mechanical analysis (DMA). The experimental values of molecular weight between crosslinks (Mc) in the epoxy polymers were determined. Influence of the catalyst on defect structure of the polymer network was observed. The use of two phosphonium salts as curing accelerators to a greater extent than 2-methylimidazole allows fabricating polymers with a higher crosslink density. The concentration dependence of polymer’s thermal properties was studied and the optimum content of the accelerator giving the network with improved properties was determined

Estimation of kinetic parameters for curing of epoxy-anhydride compositions by DSC

© 2017, Springer Science+Business Media, LLC. The kinetics of the curing process of epoxy resin (ED-22) in the presence of the anhydride hardeners (iso-methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, and dodecylsuccinic anhydride) and accelerators (2-methyl imidazole and n-butyltriphenylphosphonium bromide) has been investigated by DSC method in the dynamic mode. Processing of experimental DSC thermograms recorded at different heating rates was carried out within the frameworks of isoconvertional analysis in two versions, namely "model-free" method of Friedman and the Ozawa—Flynn—Wall method. The possibility to describe the kinetics of epoxy compositions curing in the frameworks of one-step autocatalytic reaction model has been demonstrated. Obtained kinetic parameters were used to predict the curing kinetics under isothermal conditions and for comparative analysis of the compositions

Estimation of kinetic parameters for curing of epoxy-anhydride compositions by DSC

© 2017, Springer Science+Business Media, LLC. The kinetics of the curing process of epoxy resin (ED-22) in the presence of the anhydride hardeners (iso-methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, and dodecylsuccinic anhydride) and accelerators (2-methyl imidazole and n-butyltriphenylphosphonium bromide) has been investigated by DSC method in the dynamic mode. Processing of experimental DSC thermograms recorded at different heating rates was carried out within the frameworks of isoconvertional analysis in two versions, namely "model-free" method of Friedman and the Ozawa—Flynn—Wall method. The possibility to describe the kinetics of epoxy compositions curing in the frameworks of one-step autocatalytic reaction model has been demonstrated. Obtained kinetic parameters were used to predict the curing kinetics under isothermal conditions and for comparative analysis of the compositions

Thermal properties of epoxy–anhydride formulations cured using phosphonium accelerators

© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Influence of structure of epoxy resin and anhydride hardener, as well as type and content of accelerator on thermal properties of epoxy–anhydride networks were investigated by dynamic mechanical analysis (DMA). The experimental values of molecular weight between crosslinks (Mc) in the epoxy polymers were determined. Influence of the catalyst on defect structure of the polymer network was observed. The use of two phosphonium salts as curing accelerators to a greater extent than 2-methylimidazole allows fabricating polymers with a higher crosslink density. The concentration dependence of polymer’s thermal properties was studied and the optimum content of the accelerator giving the network with improved properties was determined

Estimation of kinetic parameters for curing of epoxy-anhydride compositions by DSC

© 2017, Springer Science+Business Media, LLC. The kinetics of the curing process of epoxy resin (ED-22) in the presence of the anhydride hardeners (iso-methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, and dodecylsuccinic anhydride) and accelerators (2-methyl imidazole and n-butyltriphenylphosphonium bromide) has been investigated by DSC method in the dynamic mode. Processing of experimental DSC thermograms recorded at different heating rates was carried out within the frameworks of isoconvertional analysis in two versions, namely "model-free" method of Friedman and the Ozawa—Flynn—Wall method. The possibility to describe the kinetics of epoxy compositions curing in the frameworks of one-step autocatalytic reaction model has been demonstrated. Obtained kinetic parameters were used to predict the curing kinetics under isothermal conditions and for comparative analysis of the compositions

Estimation of kinetic parameters for curing of epoxy-anhydride compositions by DSC

© 2017, Springer Science+Business Media, LLC. The kinetics of the curing process of epoxy resin (ED-22) in the presence of the anhydride hardeners (iso-methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, and dodecylsuccinic anhydride) and accelerators (2-methyl imidazole and n-butyltriphenylphosphonium bromide) has been investigated by DSC method in the dynamic mode. Processing of experimental DSC thermograms recorded at different heating rates was carried out within the frameworks of isoconvertional analysis in two versions, namely "model-free" method of Friedman and the Ozawa—Flynn—Wall method. The possibility to describe the kinetics of epoxy compositions curing in the frameworks of one-step autocatalytic reaction model has been demonstrated. Obtained kinetic parameters were used to predict the curing kinetics under isothermal conditions and for comparative analysis of the compositions

Structure and Mechanical Properties of a Dispersedly Filled Transparent Polycarbonate

© 2019, Springer Science+Business Media, LLC, part of Springer Nature. The structure and mechanical properties of a composition on the basic of polycarbonate filled with three types of dispersed particles (submicron corundum, micron boron nitride, and glass fiber ones) were investigated. It is shown that the method of sample preparation proposed ensures a uniform distribution of filler particles in them. Slight changes in the supramolecular structure of polycarbonate were seen only in the case of introduction of submicron corundum particles. No such changes occurred in the case of micron boron nitride or glass fiber particles in amounts providing an optical transparency no less than 70%, which can be explained by insufficient interaction forces between filler particles and polycarbonate molecules. It is shown that filling polycarbonate with various fillers allowing the retention of its optical transparency does not make it possible to increase its wear resistance and softening temperature. The weight parts of dispersed filler at which the transparency does not decrease below 70 % are ~0.06, ~0.03, and ~1.0% for corundum, boron nitride, and glass fiber particles, respectively

Structure and Mechanical Properties of a Dispersedly Filled Transparent Polycarbonate

© 2019, Springer Science+Business Media, LLC, part of Springer Nature. The structure and mechanical properties of a composition on the basic of polycarbonate filled with three types of dispersed particles (submicron corundum, micron boron nitride, and glass fiber ones) were investigated. It is shown that the method of sample preparation proposed ensures a uniform distribution of filler particles in them. Slight changes in the supramolecular structure of polycarbonate were seen only in the case of introduction of submicron corundum particles. No such changes occurred in the case of micron boron nitride or glass fiber particles in amounts providing an optical transparency no less than 70%, which can be explained by insufficient interaction forces between filler particles and polycarbonate molecules. It is shown that filling polycarbonate with various fillers allowing the retention of its optical transparency does not make it possible to increase its wear resistance and softening temperature. The weight parts of dispersed filler at which the transparency does not decrease below 70 % are ~0.06, ~0.03, and ~1.0% for corundum, boron nitride, and glass fiber particles, respectively