Effect of cyclic stress on enthalpy relaxation in polycarbonate

Liu, Liang B.; Yee, Albert F.; Gidley, David W.

doi:10.1002/polb.1992.090300301

Cited by 24 publications

(16 citation statements)

References 30 publications

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“…Some researchers have measured changes induced in polymers resulting from cyclic fatigue. On the macroscopic level, a number of researchers measured changes in the dynamic mechanical response of a variety of polymers and composites (12)(13)(14)(15)(16)(17)(18)(19)(20). These studies have shown that, in certain cases, changes in the dynamic mechanical response can be correlated with corresponding changes in the microstructure or morphology of the materials during fatigue.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, this relation was shown by Ehrenstein et al for composites (19) and more recently by the author for semicrystalline polymers (20, 2 1). In an interesting and related study, Yee et al (18) noticed that measurable changes in the enthalpy and mechanical proper-ties could be measured in polycarbonate as a result of fatigue loading. Yee noted that these changes resembled those produced by thermophysical aging and referred to the effects as fatigue agfng.…”

Section: Introductionmentioning

confidence: 99%

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Effective volume changes during fatigue and fracture of polyacetal

Lesser

1996

Polymer Engineering & Sci

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Conventional tensile dilatometry techniques are extended to cyclic fatigue applications to study volume changes that occur during controlled-load cyclic fatigue of polyacetal. During fatigue, In-situ measures of the irreversible and elastic volume change are monitored together with dynamic viscoelastic parameters (E', E", and Tan 81, and changes in the energy densities (strain energy, potential energy, and irreversible work). The results show that the effective irreversible volume of the polyacetal gradually increases over a wide range of applied cyclic stress. However, at high stress levels and/or frequencies be., low-cycle, thermally dominated regime), the effective Poisson's ratio of the polyacetal increases as it softens (evidenced by the dynamic viscoelastic data). Conversely, at lower stress levels, the Poisson's ratio continually decreases coincident with decreases in the loss modulus (E") and the irreversible work density. These results are indicative of entirely different mechanisms governing the low-cycle (high stress level) and high-cycle (low stress) regimes. Also, comparisons between tensile and fatigue dilatometry studies show that the dilational-strain response of samples fatigued at high stress levels are similar to data obtained from monotonic tensile dilatometry. However, the dilationstrain response of samples fatigued at lower stress levels are distinctly different from low-cycle fatigue and tensile dilatometry. Effective Volume Changes During Fatigue and Fracture of Po~Yacetal

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effective volume changes during fatigue and fracture of polyacetal

Lesser

1996

Polymer Engineering & Sci

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“…Numerous studies have been done to examine the effect of physical aging on the macroscopic mechanical behavior of glassy polymers and similarly for the enthalpy changes upon aging . Most of the studies are trying to explain their results based on the free‐volume theory, in which the changes of the properties of the material are interpreted solely by the changes in free volume .…”

Section: Introductionmentioning

confidence: 99%

Effect of low‐temperature physical aging on the dynamic transitions of atactic polystyrene in the glassy state

Grigoriadi

Putzeys

Wübbenhorst

et al. 2019

J Polym Sci B Polym Phys

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The local and cooperative dynamics of atactic PS (a‐PS) were studied by broadband dielectric relaxation spectroscopy (BDRS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR). The a‐PS has been subjected to thermal rejuvenation and subsequent quenching, short‐term aging (6 weeks), and long‐term aging (1 year) at ambient conditions. Where for the rejuvenated sample only an α‐ and a γ‐relaxation is observed, short‐term aging results in an additional β*‐relaxation that merges with the α‐relaxation at longer aging times. The γ‐relaxation is increasing in intensity and activation energy during aging. The α‐process shows no spectral changes and shift in the relaxation time upon aging. This may be attributed to a possible erasure of history of the material during the temperature‐sweep mode measurement. Fourier transform infrared spectroscopy (FTIR) results suggest that the energetically favorable trans‐trans (tt) conformers are increased in population with aging. © 2019 The Authors. Journal of Polymer Science Part B: Polymer Physics published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1394–1401

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“…Knauss et al investigated the aging effect on poly (vinyl acetate) with different pressure and aging time. Liu et al discussed the effect of cyclic stress on physical aging in polycarbonate using differential scanning calorimetry (DSC) measurements.…”

Section: Introductionmentioning

confidence: 99%

Application of time-temperature-stress superposition principle on the accelerated physical aging test of polycarbonate

Jiang

Zhu

et al. 2015

Polym Eng Sci

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The effect of physical aging on the polymer mechanical properties is very important for long-term safety assessment of engineering application. In this paper, the physical aging tests of polycarbonate (PC) were conducted systemically under different temperature and uniaxial tensile stress level. It was shown that both temperature and stress have obvious accelerated effect on the physical aging of PC. The higher the temperature and stress level are, the faster the aging process is. To predict the longterm behavior after physical aging using the short-term test results of PC, the elongation-at-break was chosen as the index of the severity of physical aging. An Arrheniustype time-temperature-stress superposition principle (TTSSP) was proposed to evaluate long-term performance using short-term test data. Using the proposed method, time and cost can be dramatically reduced for the assessment of long-term physical aging performance of polymeric material.

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Effect of cyclic stress on enthalpy relaxation in polycarbonate

Cited by 24 publications

References 30 publications

Effective volume changes during fatigue and fracture of polyacetal

Effective volume changes during fatigue and fracture of polyacetal

Effect of low‐temperature physical aging on the dynamic transitions of atactic polystyrene in the glassy state

Application of time-temperature-stress superposition principle on the accelerated physical aging test of polycarbonate

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