Effects of annealing and prior history on enthalpy relaxation in glassy polymers. 1. Experimental study on poly(vinyl chloride)

Berens, A. R.; Hodge, Ian M.

doi:10.1021/ma00231a015

Cited by 247 publications

(151 citation statements)

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“…Therefore, one might hypothesize that the degradative reactions inside the glassy matrix might be faster than the relaxation processes occurring, while the intracellular glass is slowly approaching equilibrium. The thermal behavior of the glass transition is also dependent on the thermal history of the vitrification process (Tant and Wilkes, 1981;Berens and Hodge, 1982;Eisenberg, 1984). This is also apparently the case in intracellular glasses in bean axes.…”

Section: Discussionmentioning

confidence: 99%

“…Such thermal behavior has also been ob,served at the glass -1iquid transition of a wide range of amorphous glassy materials, including synthetic polymers (Berens and Hodge, 1982;Eisenberg, 1984), saccharide mixtures (Green and Angell, 1989;Noel et al, 1990), and biopolymers, such as hemicellulose and lignin (Kelley et al, 1987). In the polymer and materials science, :similar endothermic peaks have been ascertained as a glass 3 liquid transition and are called "overshoot" (Moynihan et al, 1976;Tant and Wilkes, 1981;Berens and Hodge, 1982;Eisenberg, 1984;Jewell and Shelby, 1990;Angell et al, 1994;Perez, 1994). These studies support our interpretation of the endothermic peak in bean axes as a glass -+ liquid transition.…”

Section: Water Transitionsmentioning

confidence: 99%

“…The nonequilibrium nature of glasses can be studied by investigating the thermal history of glasses prior to and during their formation (Tant and Wilkes, 1981;Berens and Hodge, 1982;Eisenberg, 1984). This was examined in bean axes by measuring the effect of a brief exposure to 100°C on the thermal behavior of the different water transitions described above.…”

Section: Thermal Historymentioning

confidence: 99%

“…The kinetic stability of glasses is of fundamental importance when studying the effects of time and externa1 conditions (temperature, pressure, and humidity) on glassy behaviors (Moynihan et al, 1976;Tant and Wilkes, 1981;Berens and Hodge, 1982;Eisenberg, 1984;Jewell and Shelby, 1990;Levine, 1991,1994;Angell et al, 1994;Franks, 1994). The concept of kinetic stability originates from the way a glass is formed and can be explained using cryopreservation principles.…”

mentioning

confidence: 99%

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A Calorimetric Study of the Glass Transition Behaviors in Axes of Bean Seeds with Relevance to Storage Stability

Leprince

Walters

1995

Plant Physiol.

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Although the presence of intracellular aqueous glasses has been established in seeds, their physiological role in storage stability is s t i l l conjectural. Therefore, we examined, using differential scanning calorimetry, the thermal behavior of glass transitions in axes of bean (Phaseolus vulgaris 1.) with water contents (WC) between O and 1 g H,O/g dry weight (g/g) and temperatures between -120 and +120°C. Three types of thermal behaviors associated with the glass transition were observed. The appearance, the glass + liquid transition temperature, and the amount of energy released during these transitions were dependent on the tissue WC. No glass transitions were observed at WC lower than 0.03 and higher than 0.45 g/g. A brief exposure to 100°C altered the glass properties of tissues with WC between 0.03 and 0.08 g/g but did not affect the thermal behavior of glasses with higher WC, demonstrating that thermal history is important t o the intracellular glass behavior at lower WC. Correspondence of data from bean to models predicting the effects of glass components on the glass --z liquid transition temperature suggests that the intracellular glasses are composed of a highly complex sugar matrix, in which sugar and water molecules interact together and influence the glass properties. Our data provide evidente that additional glass properties must be characterized to understand the implications of a glassy state in storage stability of seeds.Water and temperature play a significant and fundamental role in determining the storage longevity of orthodox seeds. Early models developed from storage experiments suggested that water and temperature were independent variables (Justice and Bass, 1978; Roberts and Ellis, 1989). However, theoretical considerations (Vertucci, 1992;Vertucci and Roos, 1993) and experimental data (Vertucci and Roos, 1993;Vertucci et al., 1994aVertucci et al., , 1994b have demonstrated that the effects of water and temperature on seed aging are interdependent. Conceptual models have been introduced to describe the interdependencies of WC and temperature on seed longevity. They rely on the findings that the nature and kinetics of degradative reactions in seeds change according to the physical properties of water

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Section: Discussionmentioning

confidence: 99%

Section: Water Transitionsmentioning

confidence: 99%

Section: Thermal Historymentioning

confidence: 99%

mentioning

confidence: 99%

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A Calorimetric Study of the Glass Transition Behaviors in Axes of Bean Seeds with Relevance to Storage Stability

Leprince

Walters

1995

Plant Physiol.

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“…In other words the glass transition temperature interval shifts towards higher temperatures in the heating scan with respect to the cooling scan. This shift is highly dependent on the previous thermal history of the sample [52,53]. In the TSR experiments the transition from the Ahrrenius behaviour characteristic of the glass to the VFTH line characteristic of the equilibrium liquid is shifted towards higher temperatures with respect to the data obtained in isothermal experiments.…”

Section: Ts Linesmentioning

confidence: 91%

Departure from the Vogel behaviour in the glass transition—thermally stimulated recovery, creep and dynamic mechanical analysis studies

Alves

Mano

Ribelles

et al. 2004

Polymer

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Elsevier Alves, N.; Mano, J.; Gómez Ribelles, JL.; Gómez-Tejedor, JA. (2004). Departure from the Vogel behaviour in the glass transition -thermally stimulated recovery, creep and dynamic mechanical analysis studies. Polymer. 45(3): 1007-1017. doi:10.1016/j.polymer.2003.04.002. N.M. Alves et al. / Polymer 45 (2004 AbstractIn this work the study of the dynamics of the segmental motions close to T g of a poly(methyl methacrylate), PMMA, network was analysed by distinct mechanical spectroscopy techniques. Three techniques were employed: dynamic mechanical analysis (DMA), creep and thermally stimulated recovery (TSR). The timetemperature superposition principle was applied to the DMA and creep results, and master curves were successfully constructed. A change from a Vogel to an Arrhenius behaviour was observed in these results.Above T g it was found a distinct temperature dependence for the retardation times calculated from creep and the relaxation times calculated from DMA. This unexpected behaviour was attributed to the merging of the and the relaxations that occurs in PMMA systems. The activation energies (E a ) were also calculated from DMA, creep and TSR experiments. Above T g the E a values obtained agreed very well for all the techniques. In addition, the fragility exhibited by this material was investigated by the mechanical spectroscopy techniques referred above and by differential scanning calorimetry (DSC). The obtained values of the fragility index m indicated that the PMMA network is a kinetically fragile system. The thermodynamic manifestation of the fragility was also analysed.

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Physical Aging of Polymers

Cangialosi

2018

Encyclopedia of Polymer Science and Technology

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This article provides an overview of the most important aspects of physical aging of polymers. First, we briefly introduce basic concepts of the glass transition, that is, the way a nonequilibrium glass is formed. Subsequently, after presenting the way physical aging can be monitored, we describe the main well‐established signatures of physical aging, that is, its nonexponential and nonlinear nature. The next part of the article is dedicated to recent advancements in the physical aging of bulk polymers. In this context, recent experimental activity is discussed, where the existence of multiple mechanisms for equilibrium recovery is presented. In addition, important aspects of physical aging in polymers altered by geometrical confinement are scrutinized in light of the past 20 years efforts aiming to understand glass dynamics in such conditions. It is shown how confined polymers weakly interacting with the confining medium exhibit accelerated physical aging. Importantly, such acceleration was found to be decoupled from the molecular mobility of the glass. Finally, we briefly discuss how recent advancements in physical aging of polymers in bulk and under geometrical confinement should foster experimental efforts to unveil important basic aspects of the glass transition, such as the existence of the so‐called “ideal glass.”

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Effects of annealing and prior history on enthalpy relaxation in glassy polymers. 1. Experimental study on poly(vinyl chloride)

Cited by 247 publications

References 1 publication

A Calorimetric Study of the Glass Transition Behaviors in Axes of Bean Seeds with Relevance to Storage Stability

A Calorimetric Study of the Glass Transition Behaviors in Axes of Bean Seeds with Relevance to Storage Stability

Departure from the Vogel behaviour in the glass transition—thermally stimulated recovery, creep and dynamic mechanical analysis studies

Physical Aging of Polymers

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