{"id":{"repo_id":"freiburg-diss","oai_identifier":"oai:freidok.uni-freiburg.de:2068"},"canonical_url":"https://search.dev.ndltd.org/etd/freiburg-diss/oai:freidok.uni-freiburg.de:2068","repository":{"repo_id":"freiburg-diss","name":"University of Freiburg","base_url":"https://freidok.uni-freiburg.de/oai/oai2.php"},"display":{"title":"Order phenomena in polymer crystallization","abstract":"Within the frame work of these thesis the influence of order phenomena in polymer melts on crystallization kinetics has been investigated by means of nuclear magnetic resonance (NMR) spectroscopy. In particular the so-called memory effect in syndiotactic polypropylene (s-PP) and the influence of entangled polymer chains (entanglements) on the crystal growth rate have been the key points of investigation. Qualitative differences in the degree of order of chain segments were measured using relaxation as well as static double quantum (DQ) experiments. Crystallisation kinetics in polymer melts has been followed with an improved NMR pulse sequence which is sensitive to differences in the mobility of polymer chains or chain segments. In comparison to X-ray measurements, in which structural changes can be monitored, with these experiments we were hoping to gain new insights in to the mechanism of polymer crystallisation. Besides the NMR experiments DSC measurements have been conducted. <br>Crystallization Kinetics Experiments: An improved NMR pulse sequence (MSE-CPMG) which consists of a combination of a magic sandwich echo (MSE) and a modified Carr-Purcell sequence (CPMG), has been used. The MSE allows the measurement of the free induction decay (fid) without signal loss from fast decaying signal of immobile chain segments during the so called dead time. The decay of the slowly decaying amorphous regions was measured via the CPMG sequence. Three different fractions of the sample can be identified via a simple analysis of the acquired signal: A crystalline fraction, a mobile-amorphous fraction and amorphous fraction with a highly reduced mobility. A continuous repetition of the experiment during the course of isothermal crystallization allows the analysis of crystallization kinetics. <br>Memory Effect in s-PP: The memory effect was reproduced in NMR crystallization kinetics experiments. Differences between NMR and other methods were explained by the influence of sample preparation. However, the analysis of the NMR kinetics data did not yield further information about the mechanism of polymer crystallization. In literature, the memory effect is often explained by the existence of a pre-ordered melt. Neither relaxation nor DQ experiment could show that this picture is justified. Instead of that it was shown that the memory effect might be related to thermo-oxidative modification of the outer shell of the granular PP pellets. <br>Entropic Effects in the Crystallization of PDMS: The presence of entanglements accelerate the crystallization of PDMS as demonstrated in DSC and NMR experiments. All samples that crystallized from the entangled melt crystallized faster than the unentangled, low-molecular weight sample. Bimodal mixtures of high (Mn = 115000 g/mol) and low (Mn = 5000 g/mol) molecular weight PDMS did not show a continuous increase in their crystallization rates but a maximum at a mixture with 40 % short and 60 % long chains. The existence of a maximum indicates that the crystallization rate of PDMS is governed by both entropic effects and the viscosity. The idea of an antagonistic interplay between these two factors was affirmed by the implementation of piezo-rheological experiments.","abstract_html":"Within the frame work of these thesis the influence of order phenomena in polymer melts on crystallization kinetics has been investigated by means of nuclear magnetic resonance (NMR) spectroscopy. In particular the so-called memory effect in syndiotactic polypropylene (s-PP) and the influence of entangled polymer chains (entanglements) on the crystal growth rate have been the key points of investigation. Qualitative differences in the degree of order of chain segments were measured using relaxation as well as static double quantum (DQ) experiments. Crystallisation kinetics in polymer melts has been followed with an improved NMR pulse sequence which is sensitive to differences in the mobility of polymer chains or chain segments. In comparison to X-ray measurements, in which structural changes can be monitored, with these experiments we were hoping to gain new insights in to the mechanism of polymer crystallisation. Besides the NMR experiments DSC measurements have been conducted. &lt;br&gt;Crystallization Kinetics Experiments: An improved NMR pulse sequence (MSE-CPMG) which consists of a combination of a magic sandwich echo (MSE) and a modified Carr-Purcell sequence (CPMG), has been used. The MSE allows the measurement of the free induction decay (fid) without signal loss from fast decaying signal of immobile chain segments during the so called dead time. The decay of the slowly decaying amorphous regions was measured via the CPMG sequence. Three different fractions of the sample can be identified via a simple analysis of the acquired signal: A crystalline fraction, a mobile-amorphous fraction and amorphous fraction with a highly reduced mobility. A continuous repetition of the experiment during the course of isothermal crystallization allows the analysis of crystallization kinetics. &lt;br&gt;Memory Effect in s-PP: The memory effect was reproduced in NMR crystallization kinetics experiments. Differences between NMR and other methods were explained by the influence of sample preparation. However, the analysis of the NMR kinetics data did not yield further information about the mechanism of polymer crystallization. In literature, the memory effect is often explained by the existence of a pre-ordered melt. Neither relaxation nor DQ experiment could show that this picture is justified. Instead of that it was shown that the memory effect might be related to thermo-oxidative modification of the outer shell of the granular PP pellets. &lt;br&gt;Entropic Effects in the Crystallization of PDMS: The presence of entanglements accelerate the crystallization of PDMS as demonstrated in DSC and NMR experiments. All samples that crystallized from the entangled melt crystallized faster than the unentangled, low-molecular weight sample. Bimodal mixtures of high (Mn = 115000 g/mol) and low (Mn = 5000 g/mol) molecular weight PDMS did not show a continuous increase in their crystallization rates but a maximum at a mixture with 40 % short and 60 % long chains. The existence of a maximum indicates that the crystallization rate of PDMS is governed by both entropic effects and the viscosity. The idea of an antagonistic interplay between these two factors was affirmed by the implementation of piezo-rheological experiments.","abstract_has_math":false,"creators":["Maus, Andreas"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Saalwächter, Kay"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-24T02:22:33Z","subjects":["Polymerkristallisation","Ordnungsphänomene","Doppelquanten-NMR","Kristallisationskinetik","Relaxationsexperimente","polymer crystallization","order phenomena","double quantum NMR","crystallization kinetics","relaxation experiments"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://freidok.uni-freiburg.de/data/2068","outbound_label":"Repository record","outbound_source":"source_url"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Saalwächter, Kay"]},{"key":"dc:creator","label":"Author","values":["Maus, Andreas"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:type","label":"Dc Type","values":["DoctoralThesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Polymerkristallisation","Ordnungsphänomene","Doppelquanten-NMR","Kristallisationskinetik","Relaxationsexperimente","polymer crystallization","order phenomena","double quantum NMR","crystallization kinetics","relaxation experiments"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Within the frame work of these thesis the influence of order phenomena in polymer melts on crystallization kinetics has been investigated by means of nuclear magnetic resonance (NMR) spectroscopy. In particular the so-called memory effect in syndiotactic polypropylene (s-PP) and the influence of entangled polymer chains (entanglements) on the crystal growth rate have been the key points of investigation. Qualitative differences in the degree of order of chain segments were measured using relaxation as well as static double quantum (DQ) experiments. Crystallisation kinetics in polymer melts has been followed with an improved NMR pulse sequence which is sensitive to differences in the mobility of polymer chains or chain segments. In comparison to X-ray measurements, in which structural changes can be monitored, with these experiments we were hoping to gain new insights in to the mechanism of polymer crystallisation. Besides the NMR experiments DSC measurements have been conducted. <br>Crystallization Kinetics Experiments: An improved NMR pulse sequence (MSE-CPMG) which consists of a combination of a magic sandwich echo (MSE) and a modified Carr-Purcell sequence (CPMG), has been used. The MSE allows the measurement of the free induction decay (fid) without signal loss from fast decaying signal of immobile chain segments during the so called dead time. The decay of the slowly decaying amorphous regions was measured via the CPMG sequence. Three different fractions of the sample can be identified via a simple analysis of the acquired signal: A crystalline fraction, a mobile-amorphous fraction and amorphous fraction with a highly reduced mobility. A continuous repetition of the experiment during the course of isothermal crystallization allows the analysis of crystallization kinetics. <br>Memory Effect in s-PP: The memory effect was reproduced in NMR crystallization kinetics experiments. Differences between NMR and other methods were explained by the influence of sample preparation. However, the analysis of the NMR kinetics data did not yield further information about the mechanism of polymer crystallization. In literature, the memory effect is often explained by the existence of a pre-ordered melt. Neither relaxation nor DQ experiment could show that this picture is justified. Instead of that it was shown that the memory effect might be related to thermo-oxidative modification of the outer shell of the granular PP pellets. <br>Entropic Effects in the Crystallization of PDMS: The presence of entanglements accelerate the crystallization of PDMS as demonstrated in DSC and NMR experiments. All samples that crystallized from the entangled melt crystallized faster than the unentangled, low-molecular weight sample. Bimodal mixtures of high (Mn = 115000 g/mol) and low (Mn = 5000 g/mol) molecular weight PDMS did not show a continuous increase in their crystallization rates but a maximum at a mixture with 40 % short and 60 % long chains. The existence of a maximum indicates that the crystallization rate of PDMS is governed by both entropic effects and the viscosity. The idea of an antagonistic interplay between these two factors was affirmed by the implementation of piezo-rheological experiments.","Im Rahmen dieser Arbeit wurde der Einfluss von Ordnungsphänomenen in Polymerschmelzen auf die Kristallisationskinetik mittels Kernresonanzspektroskopie (NMR) untersucht. Im Detail wurde der sogenannte Gedächtniseffekt (Memory Effect) in syndiotaktischem Polypropylen (s-PP) und der Einfluss von Kettenverschlaufungen (Entanglements) auf die Kristallwachstumsrate von Polydimethylsiloxanen (PDMS) untersucht. Qualitative Unterschiede bezüglich der Ordnung der Polymerkettensegmente wurden anhand von Relaxationsexperimenten sowie statischen Doppelquanten (DQ)-Experimenten untersucht. Die Kinetik der Kristallisation aus der Polymerschmelze wurde mit einer von uns verbesserten NMR-Pulssequenz verfolgt, wobei man sich die Sensitivität des NMR-Signals auf Änderungen in der Beweglichkeit der Polymerkette zunutze machte. Von der Messung dieser Änderungen der Mobilität anstelle von strukturellen Änderungen (wie z.B. aus Röntgen-Experimenten) erhoffte man sich neue Erkenntnisse über den der Polymerkristallisation zugrunde liegenden Mechanismus. Die durchgeführten NMR-Experimente wurden dabei durch DSC-Experimente ergänzt. <br>Untersuchung der Kristallisationskinetik: Die verbesserte NMR-Pulssequenz (MSE-CPMG) besteht aus einer Kombination eines magischen Echos (MSE) mit einer CPMG Pulsfolge. Die Verwendung des MSE erlaubte die Messung des freien Induktionszerfalls (fid) ohne Intensitätsverlust des Signals der unbeweglichen Bereiche der Gesamtprobe während der sogenannten `Totzeit´. Das Abklingen des Signals der mobilen, amorphen Bereiche wurde mittels der CPMG Sequenz verfolgt. Eine einfache Analyse des fid erlaubte eine Absolutbestimmung von drei verschiedenen Bestandteilen: Kristalline Bereiche, mobil-amorphe Bereiche und amorphe Bereiche mit einer stark reduzierten Beweglichkeit. Eine kontinuierliche Wiederholung dieser Messung im Verlauf der isothermen Kristallisation ermöglichte eine Analyse der Kristallisationskinetik. <br>Memory Effect in s-PP: Der Memory Effect konnte in den NMR Kristallisationskinetik-Experimenten gut reproduziert werden. Unterschiede zu bereits bekannten Untersuchungen aus der Literatur konnten u.a. durch den Einfluss der Probenpräparation auf die NMR Ergebnisse erklärt werden. Die Analyse der Kinetikdaten führte allerdings zu keinen neuen Erkenntnissen bzgl. des Mechanismus der Polymerkristallisation. Der Memory Effect wird in der Literatur teilweise durch die Existenz einer \"geordneten\" Schmelze erklärt. Die durchgeführten Relaxations- und DQ-Experimente zeigten allerdings keinerlei Hinweise darauf, dass dieses Bild gerechtfertigt ist. Stattdessen stellte sich heraus, dass der Memory Effect in Polymeren möglicherweise durch eine herstellungsbedingte, oxidative Veränderung der chemischen Struktur an der äußeren Schale des Polymergranulats verursacht wird. <br>Entropische Effekte in der Kristallisation von PDMS: In DSC- und NMR-Untersuchungen konnte gezeigt werden, dass die Kristallisation von PDMS durch das Vorhandensein von Verschlaufungen der Polymerketten begünstigt wird. Alle verschlauften Proben kristallisierten schneller als die Probe mit einem Molekulargewicht ( ) unterhalb des `Entanglement-Molekulargewichts´ ( ). Bimodale Mischungen aus hoch- ( = 115000 g/mol) und nieder-molekularem ( = 5300 g/mol) PDMS zeigten jedoch keinen kontinuierlichen Anstieg der Kristallisationsraten mit steigenden Massenanteil an hochmolekularem PDMS, sondern ein Maximum bei einer Mischung bestehend aus 40 % nieder- und 60 % hochmolekularem PDMS. Das Vorhandensein eines Maximums deutet darauf hin, dass die Kristallisationsrate von PDMS sowohl durch entropische Effekte (Kettenordnung durch Verschlaufungen) als auch durch die Viskosität (Diffusion der Kettensegmente zur wachsenden, kristallinen Lamelle) bestimmt wird. Die Idee eines antagonistischen Zusammenspiels dieser beiden Einflussfaktoren konnte durch die Im-plementierung von piezo-rheologischen Experimenten bekräftigt werden."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Order phenomena in polymer crystallization","Ordnungsphänomene in der Polymerkristallisation"]}]}],"canonical_facts":{"dc:contributor":["Saalwächter, Kay"],"dc:creator":["Maus, Andreas"],"dc:description.abstract":["Within the frame work of these thesis the influence of order phenomena in polymer melts on crystallization kinetics has been investigated by means of nuclear magnetic resonance (NMR) spectroscopy. In particular the so-called memory effect in syndiotactic polypropylene (s-PP) and the influence of entangled polymer chains (entanglements) on the crystal growth rate have been the key points of investigation. Qualitative differences in the degree of order of chain segments were measured using relaxation as well as static double quantum (DQ) experiments. Crystallisation kinetics in polymer melts has been followed with an improved NMR pulse sequence which is sensitive to differences in the mobility of polymer chains or chain segments. In comparison to X-ray measurements, in which structural changes can be monitored, with these experiments we were hoping to gain new insights in to the mechanism of polymer crystallisation. Besides the NMR experiments DSC measurements have been conducted. <br>Crystallization Kinetics Experiments: An improved NMR pulse sequence (MSE-CPMG) which consists of a combination of a magic sandwich echo (MSE) and a modified Carr-Purcell sequence (CPMG), has been used. The MSE allows the measurement of the free induction decay (fid) without signal loss from fast decaying signal of immobile chain segments during the so called dead time. The decay of the slowly decaying amorphous regions was measured via the CPMG sequence. Three different fractions of the sample can be identified via a simple analysis of the acquired signal: A crystalline fraction, a mobile-amorphous fraction and amorphous fraction with a highly reduced mobility. A continuous repetition of the experiment during the course of isothermal crystallization allows the analysis of crystallization kinetics. <br>Memory Effect in s-PP: The memory effect was reproduced in NMR crystallization kinetics experiments. Differences between NMR and other methods were explained by the influence of sample preparation. However, the analysis of the NMR kinetics data did not yield further information about the mechanism of polymer crystallization. In literature, the memory effect is often explained by the existence of a pre-ordered melt. Neither relaxation nor DQ experiment could show that this picture is justified. Instead of that it was shown that the memory effect might be related to thermo-oxidative modification of the outer shell of the granular PP pellets. <br>Entropic Effects in the Crystallization of PDMS: The presence of entanglements accelerate the crystallization of PDMS as demonstrated in DSC and NMR experiments. All samples that crystallized from the entangled melt crystallized faster than the unentangled, low-molecular weight sample. Bimodal mixtures of high (Mn = 115000 g/mol) and low (Mn = 5000 g/mol) molecular weight PDMS did not show a continuous increase in their crystallization rates but a maximum at a mixture with 40 % short and 60 % long chains. The existence of a maximum indicates that the crystallization rate of PDMS is governed by both entropic effects and the viscosity. The idea of an antagonistic interplay between these two factors was affirmed by the implementation of piezo-rheological experiments.","Im Rahmen dieser Arbeit wurde der Einfluss von Ordnungsphänomenen in Polymerschmelzen auf die Kristallisationskinetik mittels Kernresonanzspektroskopie (NMR) untersucht. Im Detail wurde der sogenannte Gedächtniseffekt (Memory Effect) in syndiotaktischem Polypropylen (s-PP) und der Einfluss von Kettenverschlaufungen (Entanglements) auf die Kristallwachstumsrate von Polydimethylsiloxanen (PDMS) untersucht. Qualitative Unterschiede bezüglich der Ordnung der Polymerkettensegmente wurden anhand von Relaxationsexperimenten sowie statischen Doppelquanten (DQ)-Experimenten untersucht. Die Kinetik der Kristallisation aus der Polymerschmelze wurde mit einer von uns verbesserten NMR-Pulssequenz verfolgt, wobei man sich die Sensitivität des NMR-Signals auf Änderungen in der Beweglichkeit der Polymerkette zunutze machte. Von der Messung dieser Änderungen der Mobilität anstelle von strukturellen Änderungen (wie z.B. aus Röntgen-Experimenten) erhoffte man sich neue Erkenntnisse über den der Polymerkristallisation zugrunde liegenden Mechanismus. Die durchgeführten NMR-Experimente wurden dabei durch DSC-Experimente ergänzt. <br>Untersuchung der Kristallisationskinetik: Die verbesserte NMR-Pulssequenz (MSE-CPMG) besteht aus einer Kombination eines magischen Echos (MSE) mit einer CPMG Pulsfolge. Die Verwendung des MSE erlaubte die Messung des freien Induktionszerfalls (fid) ohne Intensitätsverlust des Signals der unbeweglichen Bereiche der Gesamtprobe während der sogenannten `Totzeit´. Das Abklingen des Signals der mobilen, amorphen Bereiche wurde mittels der CPMG Sequenz verfolgt. Eine einfache Analyse des fid erlaubte eine Absolutbestimmung von drei verschiedenen Bestandteilen: Kristalline Bereiche, mobil-amorphe Bereiche und amorphe Bereiche mit einer stark reduzierten Beweglichkeit. Eine kontinuierliche Wiederholung dieser Messung im Verlauf der isothermen Kristallisation ermöglichte eine Analyse der Kristallisationskinetik. <br>Memory Effect in s-PP: Der Memory Effect konnte in den NMR Kristallisationskinetik-Experimenten gut reproduziert werden. Unterschiede zu bereits bekannten Untersuchungen aus der Literatur konnten u.a. durch den Einfluss der Probenpräparation auf die NMR Ergebnisse erklärt werden. Die Analyse der Kinetikdaten führte allerdings zu keinen neuen Erkenntnissen bzgl. des Mechanismus der Polymerkristallisation. Der Memory Effect wird in der Literatur teilweise durch die Existenz einer \"geordneten\" Schmelze erklärt. Die durchgeführten Relaxations- und DQ-Experimente zeigten allerdings keinerlei Hinweise darauf, dass dieses Bild gerechtfertigt ist. Stattdessen stellte sich heraus, dass der Memory Effect in Polymeren möglicherweise durch eine herstellungsbedingte, oxidative Veränderung der chemischen Struktur an der äußeren Schale des Polymergranulats verursacht wird. <br>Entropische Effekte in der Kristallisation von PDMS: In DSC- und NMR-Untersuchungen konnte gezeigt werden, dass die Kristallisation von PDMS durch das Vorhandensein von Verschlaufungen der Polymerketten begünstigt wird. Alle verschlauften Proben kristallisierten schneller als die Probe mit einem Molekulargewicht ( ) unterhalb des `Entanglement-Molekulargewichts´ ( ). Bimodale Mischungen aus hoch- ( = 115000 g/mol) und nieder-molekularem ( = 5300 g/mol) PDMS zeigten jedoch keinen kontinuierlichen Anstieg der Kristallisationsraten mit steigenden Massenanteil an hochmolekularem PDMS, sondern ein Maximum bei einer Mischung bestehend aus 40 % nieder- und 60 % hochmolekularem PDMS. Das Vorhandensein eines Maximums deutet darauf hin, dass die Kristallisationsrate von PDMS sowohl durch entropische Effekte (Kettenordnung durch Verschlaufungen) als auch durch die Viskosität (Diffusion der Kettensegmente zur wachsenden, kristallinen Lamelle) bestimmt wird. Die Idee eines antagonistischen Zusammenspiels dieser beiden Einflussfaktoren konnte durch die Im-plementierung von piezo-rheologischen Experimenten bekräftigt werden."],"dc:format.medium":["application/pdf"],"dc:subject":["Polymerkristallisation","Ordnungsphänomene","Doppelquanten-NMR","Kristallisationskinetik","Relaxationsexperimente","polymer crystallization","order phenomena","double quantum NMR","crystallization kinetics","relaxation experiments"],"dc:title":["Order phenomena in polymer crystallization","Ordnungsphänomene in der Polymerkristallisation"],"dc:type":["DoctoralThesis"]},"updated_at":"2026-07-24T02:22:33Z"}