Optimizing physical aging in poly(ethylene terephthalate)-glycol (PETG)

Guo, Junyuan; Tian, Chuanshuai; Jiang, Minqiang

doi:10.1016/j.jnoncrysol.2018.10.021

Cited by 26 publications

(9 citation statements)

References 32 publications

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“…Decreasing the aging temperature entails an increase of the thermodynamic driving force, which implies an increase of

to a maximum. For aging times of 10 and 1000 s (see Figure 4 ), this maximum is located at

−25

C. The presence of a temperature maximum in the amount of recovered enthalpy implies that there exists an optimum aging temperature to maximize equilibrium recovery at fixed aging time [ 53 ]. At lower aging temperatures, the slowing down of molecular mobility becomes dominant; therefore, the reduction in

over limited aging time scales progressively decreases.…”

Section: Resultsmentioning

confidence: 99%

Physical Aging Behavior of a Glassy Polyether

et al. 2021

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The present work aims to provide insights on recent findings indicating the presence of multiple equilibration mechanisms in physical aging of glasses. To this aim, we have investigated a glass forming polyether, poly(1-4 cyclohexane di-methanol) (PCDM), by following the evolution of the enthalpic state during physical aging by fast scanning calorimetry (FSC). The main results of our study indicate that physical aging persists at temperatures way below the glass transition temperature and, in a narrow temperature range, is characterized by a two steps evolution of the enthalpic state. Altogether, our results indicate that the simple old-standing view of physical aging as triggered by the α relaxation does not hold true when aging is carried out deep in the glassy state.

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“…Decreasing the aging temperature entails an increase of the thermodynamic driving force, which implies an increase of

to a maximum. For aging times of 10 and 1000 s (see Figure 4 ), this maximum is located at

−25

over limited aging time scales progressively decreases.…”

Section: Resultsmentioning

confidence: 99%

Physical Aging Behavior of a Glassy Polyether

et al. 2021

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“…After thermo-mechanical processing, physical aging at around room temperature over a prolonged period, which is common in engineering practice, may induce significant changes in some mechanical properties of polymers [ 10 , 11 , 12 , 13 ]. Numerous experimental and theoretical works have been documented in the literature about the influence of physical aging of amorphous polymers [ 14 , 15 , 16 , 17 ]. Nevertheless, most of these studies are limited to small processing deformation.…”

Section: Introductionmentioning

confidence: 99%

On-Demand Tailoring between Brittle and Ductile of Poly(methyl methacrylate) (PMMA) via High Temperature Stretching

et al. 2022

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Dog-bone shaped poly(methyl methacrylate) (PMMA) samples were pre-stretched at different temperatures (within the glass transition range and slightly above) to different strains. Subsequently, these pre-stretched samples were aged at 40 °C for up to three months, and finally, all samples were uniaxially stretched to fracture. The Young’s modulus, ultimate stress and toughness of the samples were obtained and plotted as a function of the temperature, and strain in pre-stretching in the contour format. The influence of aging was revealed when the contours of different aging times were compared. One of the most interesting findings was that the toughness of this PMMA can be tailored via controlling the temperature and strain in pre-stretching. The toughness of the pre-stretched samples ranged from 1.317 MJ/m3 to 23.281 MJ/m3 (without aging) and from 1.476 MJ/m3 to 27.532 MJ/m3 (after three months of aging). Based on the results of a series of additional experiments, a mechanism was proposed to reveal the fundaments behind the influence of the temperature and strain in pre-stretching and aging.

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“…In this paper, we investigate the relationship between physical aging and the shape memory effect for polystyrene (PS) based SMP using dynamic mechanical analysis (DMA) 35,37 and modulated differential scanning calorimetry (MDSC). 31,36 Amorphous PS SMP is selected for its low cost, availability, recyclability, and ease of processing.…”

Section: Introductionmentioning

confidence: 99%

Relationship between recovered enthalpy and the shape‐memory effect in shape memory polymers

Siwakoti,

Mailen

2023

J of Applied Polymer Sci

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Shape memory polymers (SMPs) maintain a temporary shape after pre‐straining, wherein the polymer chains are constrained in a non‐equilibrium thermodynamic state. Physical aging lowers the chain conformational energy, which affects the mechanical properties. Herein, we investigate the relationship between physical aging and the shape recovery of SMP sheets, whereas both processes involve motion of polymer chains. We induce conformational changes to polymer chains either by physical aging or via a thermomechanical pre‐straining process. We then quantify structural relaxation via recovered enthalpy measurements using modulated differential scanning calorimetry (MDSC), and the shape recovery performance using dynamic mechanical analysis (DMA). We vary pre‐straining holding time, amount, and rate and observe the relationship between physical aging, recovered enthalpy, and the shape recovery performance. The results indicate that an increase in recovered enthalpy correlates with an increase in characteristic shape recovery time. Further, a maximum decrease in recovery time of 65% is observed at the highest strain rate, and only small amounts of recovered enthalpy occur for aging times longer than 16 h. The results provide insight into the relationship between physical aging and its effects on shape memory, which is important for applications requiring storage for long durations.

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Optimizing physical aging in poly(ethylene terephthalate)-glycol (PETG)

Cited by 26 publications

References 32 publications

Physical Aging Behavior of a Glassy Polyether

Physical Aging Behavior of a Glassy Polyether

On-Demand Tailoring between Brittle and Ductile of Poly(methyl methacrylate) (PMMA) via High Temperature Stretching

Relationship between recovered enthalpy and the shape‐memory effect in shape memory polymers

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