Mechanisms of the Complex Thermo-Mechanical Behavior of Polymer Glass Across a Wide Range of Temperature Variations

Liu, Weidong; Zhang, Liangchi

doi:10.3390/polym10101153

Cited by 9 publications

(8 citation statements)

References 36 publications

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“…The advantages of this technique are in its solid theoretical background of vibration, simple set-up, and non-destructive nature. The technique has been applied successfully in characterizing the internal structure and property changes of many different type of materials such as glassy carbons 26 , 27 , borosilicate glass 28 , and polymer glass 29 .…”

Section: Introductionmentioning

confidence: 99%

Elastic modulus evolution of rocks under heating–cooling cycles

Liu

Zhang

Luo

2020

Sci Rep

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Rocks decay significantly during or after heating-cooling cycles, which can in turn lead to hazards such as landslide and stone building collapse. nevertheless, the deterioration mechanisms are unclear. this paper presents a simple and reliable method to explore the mechanical property evolutions of representative sandstones during heating-cooling cycles. It was found that rock decay takes place in both heating and cooling processes, and dramatic modulus changes occurred near the α − β phase transition temperature of quartz. Our analysis also revealed that the rock decay is mainly attributed to the internal cracking. the underlying mechanism is the heterogeneous thermal deformation of mineral grains and the α-β phase transition of quartz. The mechanical properties of rocks are significantly affected by heating-cooling cycles 1-7 , which in turn can dramatically increase the risk of landslide 8 , rockfall 2 and stone building collapse 9 during or after fire-related accidents. This has been evidenced by many landslide events after the extreme 2003 wildfire in the southern interior of British Columbia (Canada) 10 , and by the fire-induced loss of about one historic stone building in the European Union each day 11. Revealing rock deterioration mechanisms has become critical for developing fire rescue scheme and for establishing criteria of post-fire hazard assessment. Furthermore, deep understanding of the rock deterioration mechanisms is the key to conducting thermally assisted excavation/drilling in mining engineering 12 , to the extraction of geothermal energy 13 , and to evaluating the geological conditions in geosciences 2,14. Some studies on the property changes of heat-treated rocks have been reported, mainly focusing on the density, porosity, permeability, compressional wave velocity, strength and modulus 4-6,15-18. The types of rocks studied include sandstones 4-6,19 , granite 15-17 , Marble 6 and limestone 6,18. It was found that when the heat treatment temperature T ht is below 250 °C, the physical and mechanical property changes are very small 4-6,15-18. However, if T ht is greater than 250 °C, significant rock deterioration can occur and new cracks and pores can be observed in post-heat treatment rocks 4-6,15-18. It was suggested that the α − β phase transformation of quartz would have contributed to the deterioration of quartz-rich rocks 20,21. In these studies, however, most of the property and structure characterizations were conducted either before or after a heat treatment. Quantitative characterization of the deterioration process and the effects of thermal expansion/shrinkage and the α-β transition of quartz are not available. It is unclear how an individual factor influences the mechanical properties of a rock-the key knowledge-base for developing fire rescue schemes and for establishing reliable criteria of post-fire hazard assessment. Young's modulus is an important mechanical property measure of rocks, and has been widely used in rock engineering design 3. The Young's modulus of a rock can dec...

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Section: Introductionmentioning

confidence: 99%

Elastic modulus evolution of rocks under heating–cooling cycles

Liu

Zhang

Luo

2020

Sci Rep

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“…The cause of this effect has not been identified except in amorphous solids, as in polymers and silicate glasses. Theoretical approaches discussed above seem to provide rational explanation [53,[61][62][63][64][65][66][67][68]. For metallic materials, the most plausible mechanism was provided in [13] relying on cyclic dislocation bow-out under imposed ultrasonic vibration.…”

Section: Discussionmentioning

confidence: 99%

“…Atomic and molecular origins of low frequency damping in PMMA were listed in [61] and come from the molecular rotation of different parts of monomers (known as α, β, γ, and δ relaxations), backbone chain bending, and sid × chain tangling. Intermolecular vibration and density variation are other sources of energy loss [53,54].…”

Section: Materials Groupmentioning

confidence: 99%

Dynamic Viscosity and Transverse Ultrasonic Attenuation of Engineering Materials

Ono

2020

Applied Sciences

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In this paper, ultrasonic attenuation of the transverse waves of engineering materials is evaluated, covering metals, ceramics, polymers, fiber-reinforced plastics, and rocks. After verifying experimental methods, 273 measurements are conducted and their results are tabulated. Fifty of the tests are for the longitudinal mode. Attenuation behavior is determined over broadband spectra. The attenuation spectra are characterized in four patterns, with 2/3 of the tests showing linear frequency dependence and another ¼ linear spectrum plus Rayleigh scattering (Mason-McSkimin relation). The longitudinal and transverse damping factors varied from 0.004 to 0.065, which are 1/3 to 5 times those of polymethyl methacrylate, suggesting that almost all the engineering materials tested may be viscoelastic. The present test results make the term dynamic viscosity more appropriate for exploring the underlying processes. The observed results were compared between the longitudinal and transverse modes and among similar material types. In more than a half of the tests, the transverse attenuation coefficients were higher than the corresponding longitudinal attenuation coefficients by 1.5× or more. Some material groups had similar attenuation coefficients for the two modes. Since the physical basis for viscous damping is hardly understood, especially in hard solids, further studies from new angles are keenly desired. This collection of new attenuation data will be of value for such works. Practically, this will assist in materials selection and in designing structural health monitoring and non-destructive inspection protocols.

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“…With temperature increases, inter-domain bonds of polymer structure lose elasticity, and polymer deformations become viscoelastic [ 21 , 22 , 23 , 24 ]. A curve illustrating the viscoelastic behavior of thermosetting polymers is presented, for example, in [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Prolonged Thermal Relaxation of the Thermosetting Polymers

et al. 2021

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The rigidity of structures made of polymer composite materials, operated at elevated temperatures, is mainly determined by the residual rigidity of the polymer binder (which is very sensitive to elevated temperatures); therefore, the study of ways to increase the rigidity of polymer materials under heating (including prolonged heating) is relevant. In the previous research, cured thermosetting polymer structure’s non-stability, especially under heating, is determined by its supra-molecular structure domain’s conglomerate character and the high entropy of such structures. The polymer elasticity modeling proved the significance of the entropy factor and layer (EPL) model application. The prolonged heating makes it possible to release adsorptive inter-layer bonds and volatile groups. As a result, the polymer structure is changing, and inner stress relaxation occurs due to this thermo-process, called thermo-relaxation. The present study suggests researching thermo-relaxation’s influence on polymers’ deformability under load and heating. The research results prove the significant polymer structure modification due to thermo-relaxation, with the polymer entropy parameter decreasing, the glassing onset temperature point (Tg) increasing by 1.3–1.7 times, and the modulus of elasticity under heating increasing by 1.5–2 times.

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Mechanisms of the Complex Thermo-Mechanical Behavior of Polymer Glass Across a Wide Range of Temperature Variations

Cited by 9 publications

References 36 publications

Elastic modulus evolution of rocks under heating–cooling cycles

Elastic modulus evolution of rocks under heating–cooling cycles

Dynamic Viscosity and Transverse Ultrasonic Attenuation of Engineering Materials

Prolonged Thermal Relaxation of the Thermosetting Polymers

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