Accelerated creep testing of polymers using the stepped isothermal method

Achereiner, Frédéric; Engelsing, Kurt; Bastian, Martin; Heidemeyer, Peter

doi:10.1016/j.polymertesting.2013.01.014

Cited by 82 publications

(50 citation statements)

References 11 publications

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“…A similar approach was utilized by Lu et al [23] to study the linear visco-elastic properties of polymethyl methacrylate (PMMA) and polycarbonate (PC). Based on the timetemperature superposition principle, Achereiner et al [24] investigated the long-term creep behavior of polypropylene via accelerated testing by elevating the temperature in brief steps. By rescaling the results of short-term tests, master curves for longterm creep capable to predict polypropylene creep response at different times were summarized [24].…”

Section: Introductionmentioning

confidence: 99%

Creep properties of catalyst coated membranes for polymer electrolyte fuel cells

Alavijeh

Khorasany

Habisch

et al. 2015

Journal of Power Sources

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Section: Introductionmentioning

confidence: 99%

Creep properties of catalyst coated membranes for polymer electrolyte fuel cells

Alavijeh

Khorasany

Habisch

et al. 2015

Journal of Power Sources

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“…Increasing the T causes increase in the strain rate at the stationary creep and shortening its length and vice versa, at a constant T, increasing the σ leads to enhanced strain rate and shortening of the secondary creep region. 57 Transition between the secondary and tertiary creep is accompanied by substantial increase of segmental mobility. 2,3 Considering the experimental protocol used a nonisothermal creep with superimposed small oscillatory deformation, we can assign the positions of the individual relaxations observed in the DMA spectra to specific stages of the creep process with progressively increasing strain rate.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Temperature, Frequency, and Small Static Stress Dependence of the Molecular Mobility in Deformed Amorphous Polymers near Their Glass Transition

Ondreáš

Jančář

2015

Macromolecules

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For the first time, we report on using dynamic mechanical analysis (DMA) to directly follow molecular mobility in PMMA and PC deformed by small constant tensile stress (σ) over the temperature interval from T g − 60 K to T g + 60 K. At T α′ > T g , a pronounced secondary α′-relaxation was observed exhibiting larger frequency shift and stronger σ-dependence compared to the main α-relaxation. After reaching its maximum at approximately the T g , the strain rate was progressively reduced at the onset of the α′-relaxation, attaining its minimum value at approximately the T α′ . Above the T α′ , the strain rate increased gradually again, suggesting that mobility has again been enhanced. We ascribe the observed variation in mobility to the strain-induced transition of segments from less mobile into more mobile domains, resulting in the alteration of conformational and orientational distribution. The macroscopic deformation (ε) dependence of the transient modulus, defined to characterize the system stiffness between the α and α′ relaxation (Γ*(ε)) and above the α′-relaxation (Ω*(ε)), collapsed to a single linear master curve for Γ*(ε) and the nonlinear Ω*(ε) master curve. Our results seem to indicate that the observed α′-relaxation may be caused by the process of intrabasin jump diffusion of small portions of the backbone chain over the characteristic length scale smaller than or equal to the dynamic Kuhn segment length (l K ). The existence of the α′-relaxation may be a manifestation of the large strain-altered chain packing associated with the polyamorphic phase transition as the process accompanying yielding in polymer glasses. ■ INTRODUCTIONPolymer glasses are generally considered random packing of low and high density nanometer scale domains bound together by intra-and intermolecular forces. 1 Because of chain connectivity, local strain affects the degree of freedom of structural units, an effect not observed in molecular glasses. 1 Macroscopic deformation and temperature both alter the potential energy landscape and modify structural disorder, segmental mobility, and dynamic heterogeneity in polymer glasses. In a single step isothermal creep photobleaching experiment and MD simulation, it was shown 2−4 that deformation-induced segmental mobility correlates with strain rate, increasing at the onset of yielding and decreasing during postyield strain hardening. The reduced mobility during strain hardening was related to the segment scale thermally activated yielding processes, 5−9 supposedly coupled with the increase in rate of nonaffine segmental displacements represented by the increase of the effective stiffness length (Kuhn length, l K ) with deformation. 10 However, using a multistep creep photobleaching experiments, Lee et al. 11 found no correlation between strain rate and mobility, suggesting that most likely the connection between any simple mechanical variable and segmental mobility is much more complex than anticipated originally, 12,13 and despite significant progress, the understanding of this phenomeno...

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“…42 The creep behavior could be observed at a high temperature within a short time, also could be observed at a low temperature within a long time. Due to the limitations caused by performing creep experiment covering the entire service life time, the evaluation of long-term performance and durability for the application of PBX in weapon systems is difficult.…”

Section: Morphology Analysismentioning

confidence: 97%

Non-linear viscoelastic properties of TATB-based polymer bonded explosives modified by a neutral polymeric bonding agent

Lin

Liu

et al. 2015

RSC Adv.

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The neutral polymeric bonding agent (NPBA) was selected to enhance the interface adherence between 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) crystals and fluoropolymer. The interfacial performance of the composites was investigated by the measurement of contact angle and the interfacial bonding mechanism was studied by XPS analysis. The results indicate that a hydrogen bond between TATB and NPBA is formed. The mechanical analysis of the TATB-based polymer bonded explosives (PBXs) revealed that the storage modulus, the mechanical strength and the elongation at break of the formulation modified by NPBA were improved. The creep behaviors of the TATB-based PBXs with and without NPBA were also investigated at different temperatures and stresses. Reduced creep strain and steady-state creep strain rate and prolonged creep failure time were observed for the modified formulation, suggesting enhanced creep resistance performance. The creep experimental data were evaluated using a six-element mechanical model and the long-term creep performance of the materials was predicted using the time-temperature superposition principle. The creep behavior up to 6.0 years at 30 C/4 MPa could be predicted by the short-term experimental data (5400 s) acquired at 30-80 C under 4 MPa.The application of NPBA provides an efficient route to reinforce, toughen, and improve the creep resistance of explosive composites, such as TATB-based PBXs in this study.

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Accelerated creep testing of polymers using the stepped isothermal method

Cited by 82 publications

References 11 publications

Creep properties of catalyst coated membranes for polymer electrolyte fuel cells

Creep properties of catalyst coated membranes for polymer electrolyte fuel cells

Temperature, Frequency, and Small Static Stress Dependence of the Molecular Mobility in Deformed Amorphous Polymers near Their Glass Transition

Non-linear viscoelastic properties of TATB-based polymer bonded explosives modified by a neutral polymeric bonding agent

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