Transkristallisation in hochmolekularen Stoffen

Jenckel, Ernst; Teege, Ernst; Hinrichs, Walter

doi:10.1007/bf01802755

Cited by 149 publications

(41 citation statements)

References 1 publication

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“…The isothermal crystallization represents the heat treatment process and nonisothermal crystallization represents the nonheat treatment process. It was very interesting that the transcrystallization, which was first mentioned in Jenckel et al work 25 was clearly observed in Figure 4(a,b) during the isothermal crystallization. The first and fast growing crystals were around single BF and the transcrystallization was formed around BFs in the PLA/20 wt % BF/20 wt % talc.…”

Section: Pom-hsmentioning

confidence: 81%

Influence of heat treatment on the heat distortion temperature of poly(lactic acid)/bamboo fiber/talc hybrid biocomposites

Shi

Mou

et al. 2011

J of Applied Polymer Sci

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Influence of heat treatment and fillers on the heat distortion temperature (HDT) of poly(lactic acid) hybrid biocomposites was intensively studied through HDT testing, polarizing microscope (POM), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). With loading 20 wt % BF or 20 wt % talc, improvement of HDT in PLA composite was about 10 C comparing with neat PLA after heat treatment. Moreover, there was a great improvement (above 45 C) of HDT in PLA composites with loading 20 wt % BF and 20 wt % talc simultaneously after heat treatment. Transcrystallization was observed during heat treatment and isothermal crystallization of PLA composites with loading BF and talc simultaneously. There was no similar phenomenon in other PLA composite with loading only one filler. The possible mechanism of forming transcrystallization was proposed. DSC and DMA were also used to clarify the variation in HDT before and after heat treatment, and the results suggest that the crystallinity, modulus and glass transition changed, especially formation of transcrystallization played a key role in improvement of HDT in PLA composites.

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Section: Pom-hsmentioning

confidence: 81%

Influence of heat treatment on the heat distortion temperature of poly(lactic acid)/bamboo fiber/talc hybrid biocomposites

Shi

Mou

et al. 2011

J of Applied Polymer Sci

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“…Ein Großteil der Untersuchungen wurde bisher mit Glasfasern durchgeführt, wobei diese nur infolge Schmelzescherung Transkristallisation induzieren. Das Grenzphasenphänomen "Transkristallisation" wurde erstmals 1952 für Hochpolymere von Jenckel et al 7) beschrieben und wurde von Lovinger et al 8) über Zonen(um)schmelzen in einem Temperaturgradienten erzeugt. 11,12) .…”

Section: Einflußfaktorenunclassified

Transkristallisation in naturfaserverstärktem Polypropylen

Mildner

Błędzki

1999

Angew. Makromol. Chem.

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Mittels thermomikroskopischer Analyse wurden sowohl der Einfluß der thermischen Bedingungen (Kristallisationstemperatur, Abkühlgeschwindigkeit) als auch der Einfluß unterschiedlicher Faserbehandlungen auf die Transkristallisation von Polypropylen untersucht. Die Untersuchungen zeigten, daß die Nukleierungsdichte von unbehandelten und mit MAH‐PP behandelten Jutefasern aufgrund der veränderten chemischen Zusammensetzung und physikalischen Eigenschaften der Faseroberfläche höher als bei alkalisierten Jutefasern ist. Mit zunehmender Kristallisationstemperatur verschiebt sich das Dickenmaximum der transkristallinen Schicht bei Anwesenheit von Jutefasern zu höheren Kristallisationszeiten. Die Abhängigkeit der Wachstumsrate der transkristallinen Schicht von der Kristallisationstemperatur kann mit den experimentell ermittelten Daten als eine Beziehung vom Arrhenius‐Typ dargestellt werden. Bei nicht‐isothermer Kristallisation verschiebt sich erwartungsgemäß der Beginn der Transkristallisation mit zunehmender Abkühlgeschwindigkeit zu niedrigeren Temperaturen.

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“…Observa-se, com frequência, o fenômeno da transcristalinidade que se refere ao crescimento preferencial de lamelas da matriz em direção perpendicular à fibra, em vez do tradicional crescimento radial que normalmente é responsável pela formação de esferulitos. Embora conhecido há muito tempo 12 , o crescimento transcristalino voltou recentemente a chamar a atenção dos pesquisadores, preocupados em descobrir meios para melhorar a adesão interfacial nos compósitos poliméricos. No entanto, a transcristalinidade nem sempre melhora as propriedades mecânicas 13,14 , e diferentes teorias estão sendo discutidas a respeito de suas causas [15][16][17][18] .…”

Section: Transcristalinidade Em Compósitos Poliméricosunclassified

Resolução lamelar num novo microscópio eletrônico de varredura

Kestenbach

Nocite

Loos³

et al. 1997

Polímeros

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Resumo: Trabalhando com elétrons de baixa energia (na faixa de 1keV), o novo microscópio eletrônico de varredura dispensa a etapa de metalização e permite a observação direta da estrutura lamelar de polímeros semicristalinos, sem a necessidade de preparação de amostras. São apresentados exemplos da morfologia lamelar do PVDF em função das condições de processamento e da temperatura de cristalização, em filmes contendo as fases α, β e γ. Um outro exemplo revela o crescimento inicial da camada transcristalina que se formou ao longo de uma fibra de polietileno de ultra-alto peso molecular embutida em matriz de polietileno de alta densidade. Palavras-chave:Resolução lamelar, microscopia eletrônica de varredura, estrutura supramolecular, transcristalinidade.

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Transkristallisation in hochmolekularen Stoffen

Cited by 149 publications

References 1 publication

Influence of heat treatment on the heat distortion temperature of poly(lactic acid)/bamboo fiber/talc hybrid biocomposites

Influence of heat treatment on the heat distortion temperature of poly(lactic acid)/bamboo fiber/talc hybrid biocomposites

Transkristallisation in naturfaserverstärktem Polypropylen

Resolução lamelar num novo microscópio eletrônico de varredura

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