Julia Martins - Academia.edu (original) (raw)
Papers by Julia Martins
Polymer Bulletin, Nov 1, 1996
Block copolymers of poly(ethylene terephthalate) (PET) and a thermotropic liquid crystalline poly... more Block copolymers of poly(ethylene terephthalate) (PET) and a thermotropic liquid crystalline polyester have been synthesized by high temperature solution polycondensation. The influence of the reaction time on thermal behavior of the block copolymers has been determined by Differential Scanning Calorimetry (DSC). Block copolymers were also characterized by Carbon 13 Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric
Polimeros-ciencia E Tecnologia, 1996
European Polymer Journal, 1991
Abstract The emulsion polymerization of styrene initiated by the ceric ammonium nitrate-dodecyl p... more Abstract The emulsion polymerization of styrene initiated by the ceric ammonium nitrate-dodecyl poly(ethylene oxide) redox system in strongly acid medium at 20° was studied. The initiation occurred with the radicals generated in the disproportionation of the complex formed between the ceric salt and dodecyl poly(ethylene oxide). The effects of reagent concentrations on the polymerization rate and molecular weight of the polystyrene were examined. The activation energy of this polymerization was estimated to be 23 kJ/mol and the activation energy for the initiation process as 108 kJ/mol.
Polimeros-ciencia E Tecnologia, Jun 1, 1998
Polymer Bulletin, Oct 1, 1996
Polymer, Dec 1, 1998
The non-isothermal crystallization kinetics of two thermotropic polyesters with flexible spacers ... more The non-isothermal crystallization kinetics of two thermotropic polyesters with flexible spacers in the main chain were studied. The influence of the spacer type on the kinetics has been considered. The Ozawa theory for non-isothermal crystallization was used to analyse the differential scanning calorimetry data. The polyester with an oxyethylenic group as the flexible spacer followed the Ozawa equation and allowed
Polymer Bulletin, 1998
Abstract. A series of linear thermotropic polyesters derived from 4,4′-dihydroxy-α,ω-diphenoxy al... more Abstract. A series of linear thermotropic polyesters derived from 4,4′-dihydroxy-α,ω-diphenoxy alkanes and 4,4′-dichloroformyl-α,ω-diphenoxy alkanes, was prepared by polycondensation in diphenyl ether. This method yielded polyesters that were characterized by a wider persistence range of the nematic phase with respect to the corresponding polyesters prepared by a conventional technique. The linear polyester series was characterized by calorimetric, optical microscopy, and thermogravimetric measurements. The linear thermotropic polyester series formed a stable nematic liquid crystalline phase in the melt and presented high thermal stabilities in the range of 410 – 449 °C.
Macromolecular Symposia, Aug 1, 1997
A thermotropic liquid crystalline polyester (LCP) with a flexible spacer group in the main chain ... more A thermotropic liquid crystalline polyester (LCP) with a flexible spacer group in the main chain has been synthesized by polycondensation and mixed with poly(ethy1ene terephthalate) (PET). The influence of the LCP's contents on thermal properties of the blends has been determined by Differential Scanning Calorimetry (DSC). LCP and blends were also characterized by Carbon 13 Nuclear Magnetic Resonance (NMR), Fourier Transform Inbred Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA).
Polimeros Ciencia E Tecnologia, 1996
Polymer Bulletin, 1996
Block copolymers of poly(ethylene terephthalate) (PET) and a thermotropic liquid crystalline poly... more Block copolymers of poly(ethylene terephthalate) (PET) and a thermotropic liquid crystalline polyester have been synthesized by high temperature solution polycondensation. The influence of the reaction time on thermal behavior of the block copolymers has been determined by Differential Scanning Calorimetry (DSC). Block copolymers were also characterized by Carbon 13 Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric
Polymer, 1998
The non-isothermal crystallization kinetics of two thermotropic polyesters with flexible spacers ... more The non-isothermal crystallization kinetics of two thermotropic polyesters with flexible spacers in the main chain were studied. The influence of the spacer type on the kinetics has been considered. The Ozawa theory for non-isothermal crystallization was used to analyse the differential scanning calorimetry data. The polyester with an oxyethylenic group as the flexible spacer followed the Ozawa equation and allowed
Polymer Bulletin, 1998
Abstract. A series of linear thermotropic polyesters derived from 4,4′-dihydroxy-α,ω-diphenoxy al... more Abstract. A series of linear thermotropic polyesters derived from 4,4′-dihydroxy-α,ω-diphenoxy alkanes and 4,4′-dichloroformyl-α,ω-diphenoxy alkanes, was prepared by polycondensation in diphenyl ether. This method yielded polyesters that were characterized by a wider persistence range of the nematic phase with respect to the corresponding polyesters prepared by a conventional technique. The linear polyester series was characterized by calorimetric, optical microscopy, and thermogravimetric measurements. The linear thermotropic polyester series formed a stable nematic liquid crystalline phase in the melt and presented high thermal stabilities in the range of 410 – 449 °C.
Polímeros, 1998
Foi realizado o estudo cinético da cristalização dinâmica de um poliéster líquido-cristalino term... more Foi realizado o estudo cinético da cristalização dinâmica de um poliéster líquido-cristalino termotrópico com espaçadores flexíveis na cadeia principal. O objetivo deste estudo foi verificar o mecanismo da cinética de cristalização do poliéster termotrópico semi-flexível através de um método não-isotérmico. O método empregado (método de Ozawa) permitiu descrever a cinética de cristalização dinâmica do poliéster e os valores de n (expoente de Avrami) encontrados correspondem a um crescimento de cristais em forma de feixe sem crescimento esferulítico posterior.
Polymer Bulletin, Nov 1, 1996
Block copolymers of poly(ethylene terephthalate) (PET) and a thermotropic liquid crystalline poly... more Block copolymers of poly(ethylene terephthalate) (PET) and a thermotropic liquid crystalline polyester have been synthesized by high temperature solution polycondensation. The influence of the reaction time on thermal behavior of the block copolymers has been determined by Differential Scanning Calorimetry (DSC). Block copolymers were also characterized by Carbon 13 Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric
Polimeros-ciencia E Tecnologia, 1996
European Polymer Journal, 1991
Abstract The emulsion polymerization of styrene initiated by the ceric ammonium nitrate-dodecyl p... more Abstract The emulsion polymerization of styrene initiated by the ceric ammonium nitrate-dodecyl poly(ethylene oxide) redox system in strongly acid medium at 20° was studied. The initiation occurred with the radicals generated in the disproportionation of the complex formed between the ceric salt and dodecyl poly(ethylene oxide). The effects of reagent concentrations on the polymerization rate and molecular weight of the polystyrene were examined. The activation energy of this polymerization was estimated to be 23 kJ/mol and the activation energy for the initiation process as 108 kJ/mol.
Polimeros-ciencia E Tecnologia, Jun 1, 1998
Polymer Bulletin, Oct 1, 1996
Polymer, Dec 1, 1998
The non-isothermal crystallization kinetics of two thermotropic polyesters with flexible spacers ... more The non-isothermal crystallization kinetics of two thermotropic polyesters with flexible spacers in the main chain were studied. The influence of the spacer type on the kinetics has been considered. The Ozawa theory for non-isothermal crystallization was used to analyse the differential scanning calorimetry data. The polyester with an oxyethylenic group as the flexible spacer followed the Ozawa equation and allowed
Polymer Bulletin, 1998
Abstract. A series of linear thermotropic polyesters derived from 4,4′-dihydroxy-α,ω-diphenoxy al... more Abstract. A series of linear thermotropic polyesters derived from 4,4′-dihydroxy-α,ω-diphenoxy alkanes and 4,4′-dichloroformyl-α,ω-diphenoxy alkanes, was prepared by polycondensation in diphenyl ether. This method yielded polyesters that were characterized by a wider persistence range of the nematic phase with respect to the corresponding polyesters prepared by a conventional technique. The linear polyester series was characterized by calorimetric, optical microscopy, and thermogravimetric measurements. The linear thermotropic polyester series formed a stable nematic liquid crystalline phase in the melt and presented high thermal stabilities in the range of 410 – 449 °C.
Macromolecular Symposia, Aug 1, 1997
A thermotropic liquid crystalline polyester (LCP) with a flexible spacer group in the main chain ... more A thermotropic liquid crystalline polyester (LCP) with a flexible spacer group in the main chain has been synthesized by polycondensation and mixed with poly(ethy1ene terephthalate) (PET). The influence of the LCP's contents on thermal properties of the blends has been determined by Differential Scanning Calorimetry (DSC). LCP and blends were also characterized by Carbon 13 Nuclear Magnetic Resonance (NMR), Fourier Transform Inbred Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA).
Polimeros Ciencia E Tecnologia, 1996
Polymer Bulletin, 1996
Block copolymers of poly(ethylene terephthalate) (PET) and a thermotropic liquid crystalline poly... more Block copolymers of poly(ethylene terephthalate) (PET) and a thermotropic liquid crystalline polyester have been synthesized by high temperature solution polycondensation. The influence of the reaction time on thermal behavior of the block copolymers has been determined by Differential Scanning Calorimetry (DSC). Block copolymers were also characterized by Carbon 13 Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric
Polymer, 1998
The non-isothermal crystallization kinetics of two thermotropic polyesters with flexible spacers ... more The non-isothermal crystallization kinetics of two thermotropic polyesters with flexible spacers in the main chain were studied. The influence of the spacer type on the kinetics has been considered. The Ozawa theory for non-isothermal crystallization was used to analyse the differential scanning calorimetry data. The polyester with an oxyethylenic group as the flexible spacer followed the Ozawa equation and allowed
Polymer Bulletin, 1998
Abstract. A series of linear thermotropic polyesters derived from 4,4′-dihydroxy-α,ω-diphenoxy al... more Abstract. A series of linear thermotropic polyesters derived from 4,4′-dihydroxy-α,ω-diphenoxy alkanes and 4,4′-dichloroformyl-α,ω-diphenoxy alkanes, was prepared by polycondensation in diphenyl ether. This method yielded polyesters that were characterized by a wider persistence range of the nematic phase with respect to the corresponding polyesters prepared by a conventional technique. The linear polyester series was characterized by calorimetric, optical microscopy, and thermogravimetric measurements. The linear thermotropic polyester series formed a stable nematic liquid crystalline phase in the melt and presented high thermal stabilities in the range of 410 – 449 °C.
Polímeros, 1998
Foi realizado o estudo cinético da cristalização dinâmica de um poliéster líquido-cristalino term... more Foi realizado o estudo cinético da cristalização dinâmica de um poliéster líquido-cristalino termotrópico com espaçadores flexíveis na cadeia principal. O objetivo deste estudo foi verificar o mecanismo da cinética de cristalização do poliéster termotrópico semi-flexível através de um método não-isotérmico. O método empregado (método de Ozawa) permitiu descrever a cinética de cristalização dinâmica do poliéster e os valores de n (expoente de Avrami) encontrados correspondem a um crescimento de cristais em forma de feixe sem crescimento esferulítico posterior.