The results of DC-electrical conductivity monitoring of radiation and thermally initiated crossli... more The results of DC-electrical conductivity monitoring of radiation and thermally initiated crosslinking of unsaturated polyester resins are interpreted using conductivity data itself instead of commonly used logarithmic data form. The main setbacks of logarithmic conductivity data were the shift toward longer reaction time compared to non-logarithmic conductivity data and extraction analysis results and pronounced scattering at the end of the reaction so it was impossible to detect vitrification point. By revision of approach to analysis of results, full sensitivity of the electrical conductivity method to structural changes in the reacting system was shown. The apparent rate constants calculated from conductivity itself showed the influence of upper liquid–liquid transition on the rate of radiation induced reaction that could not be seen if the logarithm of conductivity was used. Influence of dose rate effects and electrical field effects on reaction rate were detected too and confirmed by DSC measurements. All details of reaction can be detected using first derivative of conductivity and in the case of thermally initiated reaction two maxims of reaction rate were found that are probably caused by local increase of temperature due to highly exothermic reaction.
The post-irradiation crosslinking of unsaturated polyester (UP) resin samples irradiated to diffe... more The post-irradiation crosslinking of unsaturated polyester (UP) resin samples irradiated to different doses was monitored during the 15-days period. The post-reaction sensitivity of three experimental techniques was evaluated. Significant changes were detected by extraction analysis that also included determination of the free styrene content. The most substantial changes were detected by differential scanning calorimetry, even up to 5 days after the irradiation. The sensitivity and reproducibility of FTIR was the lowest. The first two techniques detected the influence of particular reaction periods, at which the radiation crosslinking was terminated, on the post-reaction.
Phase separation during radiation-initiated crosslinking of unsaturated polyester resin was studi... more Phase separation during radiation-initiated crosslinking of unsaturated polyester resin was studied. Residual reactivity of liquid phases and gels of partially cured samples was determined by DSC. Uncured resin and liquid phases showed double reaction exotherm, gels had a single maximum that corresponded to higher-temperature maximum of liquid parts. The lower-temperature process was attributed to styrene–polyester copolymerization. At higher temperatures, polyester unsaturations that remained unreacted due to microgel formation homopolymerized. FTIR revealed different composition of phases. In thicker samples, reaction heat influenced microgel formation causing delayed appearance of gel and faster increase in conversion.
The course of radiation crosslinking of unsaturated polyester resins was followed by measuring el... more The course of radiation crosslinking of unsaturated polyester resins was followed by measuring electrical conductivity change. Both the electrical field strength and dose rate influenced the crosslinking. The electrical field somewhat increased the reaction rate possibly due to the orientation of a polar polyester chains. To investigate the effect of electrical field, the samples were irradiated to different doses at
Radiation curing of unsaturated polyester resin with styrene was chosen to test the d.c.-electric... more Radiation curing of unsaturated polyester resin with styrene was chosen to test the d.c.-electrical conductivity method for in-source monitoring of the curing reaction. The dependence of electrical conductivity on electrical field strength and temperature were tested to determine the optimal experimental conditions. The relationship between changes of electrical conductivity and the extent of crosslinking in the resin was determined by
A series of catanionic surfactants were prepared by making an equimolar mixture of cationic (alky... more A series of catanionic surfactants were prepared by making an equimolar mixture of cationic (alkylammonium chloride) and anionic (sodium alkyl sulfate) surfactants, both containing an isomer of the same chain length, namely, C10, C12, or C14. The prepared compounds exhibited complex thermal behavior, characterized by several successive phase transitions in the solid state as proved by differential scanning calorimetry, X-ray diffraction, and optical birefringence observation using a polarizing microscope. On heating, three main phase transitions were observed for all compounds; solid crystalline–solid crystalline, solid crystalline–liquid crystalline, and liquid crystalline–isotropic liquid. On cooling, all three compounds underwent reversibly the isotropic liquid–liquid crystalline phase transition, while the liquid crystalline–solid crystalline phase transition displayed peculiar properties. Phase transition temperatures increased with an increase in hydrocarbon chain length.
The results of DC-electrical conductivity monitoring of radiation and thermally initiated crossli... more The results of DC-electrical conductivity monitoring of radiation and thermally initiated crosslinking of unsaturated polyester resins are interpreted using conductivity data itself instead of commonly used logarithmic data form. The main setbacks of logarithmic conductivity data were the shift toward longer reaction time compared to non-logarithmic conductivity data and extraction analysis results and pronounced scattering at the end of the
... 1052–1057. Lu, 2001 (1998) MG Lu, MJ Shim and SW Kim, Curing behavior of an unsaturated polye... more ... 1052–1057. Lu, 2001 (1998) MG Lu, MJ Shim and SW Kim, Curing behavior of an unsaturated polyester system analysed by avrami equation. ... Radiation Physics and Chemistry Volume 67, Issues 3-4, June 2003, Pages 415-419 10th Tihany Symposium on Radiation Chemistry. ...
The results of DC-electrical conductivity monitoring of radiation and thermally initiated crossli... more The results of DC-electrical conductivity monitoring of radiation and thermally initiated crosslinking of unsaturated polyester resins are interpreted using conductivity data itself instead of commonly used logarithmic data form. The main setbacks of logarithmic conductivity data were the shift toward longer reaction time compared to non-logarithmic conductivity data and extraction analysis results and pronounced scattering at the end of the reaction so it was impossible to detect vitrification point. By revision of approach to analysis of results, full sensitivity of the electrical conductivity method to structural changes in the reacting system was shown. The apparent rate constants calculated from conductivity itself showed the influence of upper liquid–liquid transition on the rate of radiation induced reaction that could not be seen if the logarithm of conductivity was used. Influence of dose rate effects and electrical field effects on reaction rate were detected too and confirmed by DSC measurements. All details of reaction can be detected using first derivative of conductivity and in the case of thermally initiated reaction two maxims of reaction rate were found that are probably caused by local increase of temperature due to highly exothermic reaction.
The post-irradiation crosslinking of unsaturated polyester (UP) resin samples irradiated to diffe... more The post-irradiation crosslinking of unsaturated polyester (UP) resin samples irradiated to different doses was monitored during the 15-days period. The post-reaction sensitivity of three experimental techniques was evaluated. Significant changes were detected by extraction analysis that also included determination of the free styrene content. The most substantial changes were detected by differential scanning calorimetry, even up to 5 days after the irradiation. The sensitivity and reproducibility of FTIR was the lowest. The first two techniques detected the influence of particular reaction periods, at which the radiation crosslinking was terminated, on the post-reaction.
Phase separation during radiation-initiated crosslinking of unsaturated polyester resin was studi... more Phase separation during radiation-initiated crosslinking of unsaturated polyester resin was studied. Residual reactivity of liquid phases and gels of partially cured samples was determined by DSC. Uncured resin and liquid phases showed double reaction exotherm, gels had a single maximum that corresponded to higher-temperature maximum of liquid parts. The lower-temperature process was attributed to styrene–polyester copolymerization. At higher temperatures, polyester unsaturations that remained unreacted due to microgel formation homopolymerized. FTIR revealed different composition of phases. In thicker samples, reaction heat influenced microgel formation causing delayed appearance of gel and faster increase in conversion.
The course of radiation crosslinking of unsaturated polyester resins was followed by measuring el... more The course of radiation crosslinking of unsaturated polyester resins was followed by measuring electrical conductivity change. Both the electrical field strength and dose rate influenced the crosslinking. The electrical field somewhat increased the reaction rate possibly due to the orientation of a polar polyester chains. To investigate the effect of electrical field, the samples were irradiated to different doses at
Radiation curing of unsaturated polyester resin with styrene was chosen to test the d.c.-electric... more Radiation curing of unsaturated polyester resin with styrene was chosen to test the d.c.-electrical conductivity method for in-source monitoring of the curing reaction. The dependence of electrical conductivity on electrical field strength and temperature were tested to determine the optimal experimental conditions. The relationship between changes of electrical conductivity and the extent of crosslinking in the resin was determined by
A series of catanionic surfactants were prepared by making an equimolar mixture of cationic (alky... more A series of catanionic surfactants were prepared by making an equimolar mixture of cationic (alkylammonium chloride) and anionic (sodium alkyl sulfate) surfactants, both containing an isomer of the same chain length, namely, C10, C12, or C14. The prepared compounds exhibited complex thermal behavior, characterized by several successive phase transitions in the solid state as proved by differential scanning calorimetry, X-ray diffraction, and optical birefringence observation using a polarizing microscope. On heating, three main phase transitions were observed for all compounds; solid crystalline–solid crystalline, solid crystalline–liquid crystalline, and liquid crystalline–isotropic liquid. On cooling, all three compounds underwent reversibly the isotropic liquid–liquid crystalline phase transition, while the liquid crystalline–solid crystalline phase transition displayed peculiar properties. Phase transition temperatures increased with an increase in hydrocarbon chain length.
The results of DC-electrical conductivity monitoring of radiation and thermally initiated crossli... more The results of DC-electrical conductivity monitoring of radiation and thermally initiated crosslinking of unsaturated polyester resins are interpreted using conductivity data itself instead of commonly used logarithmic data form. The main setbacks of logarithmic conductivity data were the shift toward longer reaction time compared to non-logarithmic conductivity data and extraction analysis results and pronounced scattering at the end of the
... 1052–1057. Lu, 2001 (1998) MG Lu, MJ Shim and SW Kim, Curing behavior of an unsaturated polye... more ... 1052–1057. Lu, 2001 (1998) MG Lu, MJ Shim and SW Kim, Curing behavior of an unsaturated polyester system analysed by avrami equation. ... Radiation Physics and Chemistry Volume 67, Issues 3-4, June 2003, Pages 415-419 10th Tihany Symposium on Radiation Chemistry. ...
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