{"id":{"repo_id":"aachen","oai_identifier":"oai:publications.rwth-aachen.de:59167"},"canonical_url":"https://search.dev.ndltd.org/etd/aachen/oai:publications.rwth-aachen.de:59167","repository":{"repo_id":"aachen","name":"RWTH Aachen University","base_url":"https://publications.rwth-aachen.de/oai2d"},"display":{"title":"Analyse der viskoelastischen Eigenschaften von Poly(tetrafluorethylen) im Bereich des Beta-Übergangs","abstract":"The ß-relaxation of poly(tetrafluoroethylene) (PTFE) takes place at room temperature. Therefore, an in-depth understanding of the viscoelastic performance is of fundamental importance and of particular interest for technical applications. The ß-relaxation is admittedly complicated by two first order transitions in the crystalline phase at 19°C and 30°C. The basis of the investigations are isothermal creep tests on preconditioned PTFE sheets with a degree of crystallinity of 27%. The creep compliance is converted into relaxation data by an approximation method, because the analysis of relaxation curves by the Two-Component-Model (TC-Model) provides more reliable results. The TC-model takes into account the morphological structure of semicrystalline polymers and, consequently, provides information on the processes in the different morphological phases as well as a consistent description of the mechanical performance of the material. As a result of a first analysis, the exponent m of the TC-Model shows a dependency on temperature. In the ß-transition region the exponent shows a minimum of 0,11. This is inconsistent with the observation of Struik who found a material as well as a temperature invariance of the overall relaxation phenomenon. The dependency of m on temperature can be described by a Gaussian function. Outside the ß-transition region, the threshold value of 0,3 proves Struiks postulated value of m~1/3. In order to exclude that the dependency on temperature is just an artefact resulting from the curve fitting analysis to not less than four parameters or a result of an interaction of two different processes, modified fitting analyses by an modified TC-Model which is extended by another relaxation function are carried out. None of these analyses give a consistent description of the material performance. In this way the dependency of m on temperature needs to be accepted. To minimise the scattering of the fitting process the gauss description of m is used as a specification in a final restricted fitting. The change of the limiting elastic fraction of Young’s modulus shows the influence of the first order transition at 30°C. The relaxation strength confirms the existence of a viscoelastic transition. The change of relaxation times t exhibits an exceptional discontinuity at 30°C, associated with an increase of two decades. Previously a quick sigmoidal decrease in the region of the first order transition at 19°C is observed. This result is confirmed by Thermally Stimulated Creep Recovery experiments with Thermal Sampling. Within the distribution of activation energies, these experiments show two maxima of 278kJ.mol-1 and 214kJ.mol-1 at 15°C and 30°C. This result corresponds with the predicted distribution of activation energies of the TC-model and confirms the cooperative character of the ß-relaxation. In the domain of linear viscoelasticity, dynamic parameters can be calculated from static values. Despite the complex processes at the ß-transition, the dependency of the predicted dynamic values of the TC-Model on temperature and on frequency corresponds to independent dynamical measurements. Both, TC-Model and dynamical measurements show a discontinuous spectrum of tand around 19°C caused by the transition in the crystalline phase and confirm the link of the viscoelastic performance with the first order transitions in the crystalline phase. Consequently the ß-transition can be attributed to the region which behave viscoelastic because of imperfections in the crystalline phase.","abstract_html":"The ß-relaxation of poly(tetrafluoroethylene) (PTFE) takes place at room temperature. Therefore, an in-depth understanding of the viscoelastic performance is of fundamental importance and of particular interest for technical applications. The ß-relaxation is admittedly complicated by two first order transitions in the crystalline phase at 19°C and 30°C. The basis of the investigations are isothermal creep tests on preconditioned PTFE sheets with a degree of crystallinity of 27%. The creep compliance is converted into relaxation data by an approximation method, because the analysis of relaxation curves by the Two-Component-Model (TC-Model) provides more reliable results. The TC-model takes into account the morphological structure of semicrystalline polymers and, consequently, provides information on the processes in the different morphological phases as well as a consistent description of the mechanical performance of the material. As a result of a first analysis, the exponent m of the TC-Model shows a dependency on temperature. In the ß-transition region the exponent shows a minimum of 0,11. This is inconsistent with the observation of Struik who found a material as well as a temperature invariance of the overall relaxation phenomenon. The dependency of m on temperature can be described by a Gaussian function. Outside the ß-transition region, the threshold value of 0,3 proves Struiks postulated value of m~1/3. In order to exclude that the dependency on temperature is just an artefact resulting from the curve fitting analysis to not less than four parameters or a result of an interaction of two different processes, modified fitting analyses by an modified TC-Model which is extended by another relaxation function are carried out. None of these analyses give a consistent description of the material performance. In this way the dependency of m on temperature needs to be accepted. To minimise the scattering of the fitting process the gauss description of m is used as a specification in a final restricted fitting. The change of the limiting elastic fraction of Young’s modulus shows the influence of the first order transition at 30°C. The relaxation strength confirms the existence of a viscoelastic transition. The change of relaxation times t exhibits an exceptional discontinuity at 30°C, associated with an increase of two decades. Previously a quick sigmoidal decrease in the region of the first order transition at 19°C is observed. This result is confirmed by Thermally Stimulated Creep Recovery experiments with Thermal Sampling. Within the distribution of activation energies, these experiments show two maxima of 278kJ.mol-1 and 214kJ.mol-1 at 15°C and 30°C. This result corresponds with the predicted distribution of activation energies of the TC-model and confirms the cooperative character of the ß-relaxation. In the domain of linear viscoelasticity, dynamic parameters can be calculated from static values. Despite the complex processes at the ß-transition, the dependency of the predicted dynamic values of the TC-Model on temperature and on frequency corresponds to independent dynamical measurements. Both, TC-Model and dynamical measurements show a discontinuous spectrum of tand around 19°C caused by the transition in the crystalline phase and confirm the link of the viscoelastic performance with the first order transitions in the crystalline phase. Consequently the ß-transition can be attributed to the region which behave viscoelastic because of imperfections in the crystalline phase.","abstract_has_math":false,"creators":["Hying, Klaus"],"institution":"Publikationsserver der RWTH Aachen University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Höcker, Hartwig"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2003,"date_issued":"2003","date_published":"2003","updated_at":"2026-07-30T19:42:39Z","subjects":["info:eu-repo/classification/ddc/540","Polytetrafluorethylene","Teilkristalline Struktur","Viskoelastizität","Phasenumwandlung","Temperaturabhängigkeit","Chemie","PTFE"],"languages":["ger"],"rights":["info:eu-repo/semantics/openAccess"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-120977%22"],"render_values":[{"text":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-120977%22","href":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-120977%22","code":true}]}]},"links":{"outbound_url":"https://publications.rwth-aachen.de/record/59167","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Höcker, Hartwig"]},{"key":"dc:creator","label":"Author","values":["Hying, Klaus"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:coverage","label":"Dc Coverage","values":["DE"]},{"key":"dc:date","label":"Dc Date","values":["2003"]},{"key":"dc:publisher","label":"Institution","values":["Publikationsserver der RWTH Aachen University"]},{"key":"dc:relation","label":"Dc Relation","values":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-7054"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["info:eu-repo/classification/ddc/540","Polytetrafluorethylene","Teilkristalline Struktur","Viskoelastizität","Phasenumwandlung","Temperaturabhängigkeit","Chemie","PTFE"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["ger"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/record/59167","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-120977%22"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The ß-relaxation of poly(tetrafluoroethylene) (PTFE) takes place at room temperature. Therefore, an in-depth understanding of the viscoelastic performance is of fundamental importance and of particular interest for technical applications. The ß-relaxation is admittedly complicated by two first order transitions in the crystalline phase at 19°C and 30°C. The basis of the investigations are isothermal creep tests on preconditioned PTFE sheets with a degree of crystallinity of 27%. The creep compliance is converted into relaxation data by an approximation method, because the analysis of relaxation curves by the Two-Component-Model (TC-Model) provides more reliable results. The TC-model takes into account the morphological structure of semicrystalline polymers and, consequently, provides information on the processes in the different morphological phases as well as a consistent description of the mechanical performance of the material. As a result of a first analysis, the exponent m of the TC-Model shows a dependency on temperature. In the ß-transition region the exponent shows a minimum of 0,11. This is inconsistent with the observation of Struik who found a material as well as a temperature invariance of the overall relaxation phenomenon. The dependency of m on temperature can be described by a Gaussian function. Outside the ß-transition region, the threshold value of 0,3 proves Struiks postulated value of m~1/3. In order to exclude that the dependency on temperature is just an artefact resulting from the curve fitting analysis to not less than four parameters or a result of an interaction of two different processes, modified fitting analyses by an modified TC-Model which is extended by another relaxation function are carried out. None of these analyses give a consistent description of the material performance. In this way the dependency of m on temperature needs to be accepted. To minimise the scattering of the fitting process the gauss description of m is used as a specification in a final restricted fitting. The change of the limiting elastic fraction of Young’s modulus shows the influence of the first order transition at 30°C. The relaxation strength confirms the existence of a viscoelastic transition. The change of relaxation times t exhibits an exceptional discontinuity at 30°C, associated with an increase of two decades. Previously a quick sigmoidal decrease in the region of the first order transition at 19°C is observed. This result is confirmed by Thermally Stimulated Creep Recovery experiments with Thermal Sampling. Within the distribution of activation energies, these experiments show two maxima of 278kJ.mol-1 and 214kJ.mol-1 at 15°C and 30°C. This result corresponds with the predicted distribution of activation energies of the TC-model and confirms the cooperative character of the ß-relaxation. In the domain of linear viscoelasticity, dynamic parameters can be calculated from static values. Despite the complex processes at the ß-transition, the dependency of the predicted dynamic values of the TC-Model on temperature and on frequency corresponds to independent dynamical measurements. Both, TC-Model and dynamical measurements show a discontinuous spectrum of tand around 19°C caused by the transition in the crystalline phase and confirm the link of the viscoelastic performance with the first order transitions in the crystalline phase. Consequently the ß-transition can be attributed to the region which behave viscoelastic because of imperfections in the crystalline phase."]},{"key":"dc:source","label":"Dc Source","values":["Aachen : Publikationsserver der RWTH Aachen University XI, 145 S. : graph. Darst. (2003). = Aachen, Techn. Hochsch., Diss., 2003"]},{"key":"dc:title","label":"Title","values":["Analyse der viskoelastischen Eigenschaften von Poly(tetrafluorethylen) im Bereich des Beta-Übergangs"]}]}],"canonical_facts":{"dc:contributor":["Höcker, Hartwig"],"dc:coverage":["DE"],"dc:creator":["Hying, Klaus"],"dc:date":["2003"],"dc:description":["The ß-relaxation of poly(tetrafluoroethylene) (PTFE) takes place at room temperature. Therefore, an in-depth understanding of the viscoelastic performance is of fundamental importance and of particular interest for technical applications. The ß-relaxation is admittedly complicated by two first order transitions in the crystalline phase at 19°C and 30°C. The basis of the investigations are isothermal creep tests on preconditioned PTFE sheets with a degree of crystallinity of 27%. The creep compliance is converted into relaxation data by an approximation method, because the analysis of relaxation curves by the Two-Component-Model (TC-Model) provides more reliable results. The TC-model takes into account the morphological structure of semicrystalline polymers and, consequently, provides information on the processes in the different morphological phases as well as a consistent description of the mechanical performance of the material. As a result of a first analysis, the exponent m of the TC-Model shows a dependency on temperature. In the ß-transition region the exponent shows a minimum of 0,11. This is inconsistent with the observation of Struik who found a material as well as a temperature invariance of the overall relaxation phenomenon. The dependency of m on temperature can be described by a Gaussian function. Outside the ß-transition region, the threshold value of 0,3 proves Struiks postulated value of m~1/3. In order to exclude that the dependency on temperature is just an artefact resulting from the curve fitting analysis to not less than four parameters or a result of an interaction of two different processes, modified fitting analyses by an modified TC-Model which is extended by another relaxation function are carried out. None of these analyses give a consistent description of the material performance. In this way the dependency of m on temperature needs to be accepted. To minimise the scattering of the fitting process the gauss description of m is used as a specification in a final restricted fitting. The change of the limiting elastic fraction of Young’s modulus shows the influence of the first order transition at 30°C. The relaxation strength confirms the existence of a viscoelastic transition. The change of relaxation times t exhibits an exceptional discontinuity at 30°C, associated with an increase of two decades. Previously a quick sigmoidal decrease in the region of the first order transition at 19°C is observed. This result is confirmed by Thermally Stimulated Creep Recovery experiments with Thermal Sampling. Within the distribution of activation energies, these experiments show two maxima of 278kJ.mol-1 and 214kJ.mol-1 at 15°C and 30°C. This result corresponds with the predicted distribution of activation energies of the TC-model and confirms the cooperative character of the ß-relaxation. In the domain of linear viscoelasticity, dynamic parameters can be calculated from static values. Despite the complex processes at the ß-transition, the dependency of the predicted dynamic values of the TC-Model on temperature and on frequency corresponds to independent dynamical measurements. Both, TC-Model and dynamical measurements show a discontinuous spectrum of tand around 19°C caused by the transition in the crystalline phase and confirm the link of the viscoelastic performance with the first order transitions in the crystalline phase. Consequently the ß-transition can be attributed to the region which behave viscoelastic because of imperfections in the crystalline phase."],"dc:identifier":["https://publications.rwth-aachen.de/record/59167","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-120977%22"],"dc:language":["ger"],"dc:publisher":["Publikationsserver der RWTH Aachen University"],"dc:relation":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-7054"],"dc:rights":["info:eu-repo/semantics/openAccess"],"dc:source":["Aachen : Publikationsserver der RWTH Aachen University XI, 145 S. : graph. Darst. (2003). = Aachen, Techn. Hochsch., Diss., 2003"],"dc:subject":["info:eu-repo/classification/ddc/540","Polytetrafluorethylene","Teilkristalline Struktur","Viskoelastizität","Phasenumwandlung","Temperaturabhängigkeit","Chemie","PTFE"],"dc:title":["Analyse der viskoelastischen Eigenschaften von Poly(tetrafluorethylen) im Bereich des Beta-Übergangs"],"dc:type":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]},"updated_at":"2026-07-30T19:42:39Z"}