Sub-T/sub g/ relaxation in cold-drawn polymers: thermally-stimulated-current methods

Yianakopoulos, G.; Vanderschueren, J.; Niézette, J.

doi:10.1109/14.30885

Cited by 12 publications

(11 citation statements)

References 18 publications

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“…The previously published data on elastic yielding of PPE involves a younger sample that has been stored for only 1 day at room temperature after cold drawing instead of 2 months. In contrast, we note that the duration of storage does not strongly affect the induction period for elastic yielding of cold-drawn PC, as shown in a previous study, 59 although the attainable retractive stress can decrease with the storage time.…”

Section: Reduction Of Retractive Stress During Elasticsupporting

confidence: 70%

Effects of Molecular Weight Reduction on Brittle–Ductile Transition and Elastic Yielding Due to Noninvasive γ Irradiation on Polymer Glasses

Lin

Cheng

et al. 2017

Macromolecules

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By exposing specimens to the γ irradiation, we show that polymer glasses including bisphenol A polycarbonate (PC) and poly(methyl methacrylate) (PMMA) turn from ductile to brittle due to chain scission by the irradiation that has noninvasively reduced their molecular weight. More importantly, by causing chain scission with the γ irradiation, we examine the origin of mechanical stress produced from cold drawing of four ductile polymer glasses (PC, PMMA, polystyrene, and poly(2,6-dimethyl-1,4-phenylene oxide)). Specifically, we elucidate the origin of the residual stress embedded in the glassy state from the cold-drawing of these polymer glasses into the strain hardening regime by investigating the elastic yielding behavior of these cold-drawn specimens. In contrast to the emergent retractive stress observed during annealing of the cold-drawn specimens above their storage temperature but still well below their glass transition temperatures, we find significantly lower retractive stress level and longer induction time for the retractive stress to show up when these specimens undergo sufficient dosage of the γ irradiation whose effect on the molecular weight and its distribution has been measured with gel permeation chromatography.

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Section: Reduction Of Retractive Stress During Elasticsupporting

confidence: 70%

Effects of Molecular Weight Reduction on Brittle–Ductile Transition and Elastic Yielding Due to Noninvasive γ Irradiation on Polymer Glasses

Lin

Cheng

et al. 2017

Macromolecules

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“…For high drawing ratio, the peak can be split into two components. This peak can be due to the relaxation of residual stresses, or an increase of free volume induced by the drawing process [3]. The samples are not oriented in the glassy state, actually the orientation is frozen in the solid as for a plastic deformation induced by drawing the sample.…”

Section: Internal Stressesmentioning

confidence: 99%

“…During the first run, one observes the relaxation of the internal stresses as the temperature increases. The sign of the [3] in cold drawn polycarbonate. For high drawing ratio, the peak can be split into two components.…”

Section: Internal Stressesmentioning

confidence: 99%

Characterization of polymers using the thermally stimulated current technique

Galop¹

1997

Journal of Thermal Analysis

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Thermally Stimulated Current (I'SC) technique is a relaxation technique, such as DMA, but works at very low equivalent frequency (10-3-10 -4 Hz) and thus clearly resolves the peaks related to the molecular mobility. The effect of orientation on Polypropylene fibers, the relaxation of internal stresses on Polycarbonate disks, and the effect of aging on acrylic airplane windows have been investigated using the TSC method.

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“…PTO sem pola.riza.~aoprevia., f 2,77xlO-4 Hz, T m =580C e E=lOKV/em. PTO sem pola.riz~ao previa., f 2, 77xlO-4 Hz, T m=650C e E= 1OKV/ em.…”

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“…Sio elas:Como a maior resistencia de medida utilizada foi de 10 11 0. a Capacitancia cia amostra em tomo de 0.63 nF. a maior frequencia utilizada 7xlO-4 Hz e, na situa~io mais crftica de (160 OC)temos Ro=4x1012 • temos entio. usando as Eq(59):Sendo assim, podemos observar que a primeira condi~io leva a uma garantia de que toda a tensio esta realmente aplicada na &mostra e, a segunda condi~io leva a uma diferen~a de fase de -150.…”

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Medidas elétricas no policarbonato durolon e o metododa temperatura oscilante.

Alfredo¹

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Policarbonato 2.2.1-Rel~io entre estrutura e propriedades 2.3-Prepar~io das amostras CAP1TULO III CARACTERIZAOAO MORFOL6GICA 3.1-Introdu~io 3.2-Calorimetria Diferencial de Varredura (DSC) 3.3-Difr~io de Rai08-X 3.4-Espectrometria de Infra-vermelho 3.5-DiscussOesPreliminares 3.5.1-Das medidas de DSC 3.5.2-Das medidas de Raios-X 3.5.3-Das medidas de Infra-vermelho CAP1TULO IV SISTEMA DE MEDIDAS 4.1-Introdu~io 4.2-0 Sistema de Medidas 4.2.1-Fontes de Tensio 4.2.2-Medidores 4.2.3-Camara e Suporte de Am08tra 4.2.4-Sistema de controle de temperatura e aquisi~io de dados

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Sub-T/sub g/ relaxation in cold-drawn polymers: thermally-stimulated-current methods

Cited by 12 publications

References 18 publications

Effects of Molecular Weight Reduction on Brittle–Ductile Transition and Elastic Yielding Due to Noninvasive γ Irradiation on Polymer Glasses

Effects of Molecular Weight Reduction on Brittle–Ductile Transition and Elastic Yielding Due to Noninvasive γ Irradiation on Polymer Glasses

Characterization of polymers using the thermally stimulated current technique

Medidas elétricas no policarbonato durolon e o metododa temperatura oscilante.

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