Relaxation time of polypropylene glycol and polypropylene glycol dimethylether-like polymers in terms of fluid-phase temperature and pressure dependent hole fraction

Yahşi, Uğur; Coşkun, Bilgehan; Yumak, A.; Boubaker, K.; Tav, Cumali

doi:10.1016/j.eurpolymj.2015.04.038

Cited by 13 publications

(8 citation statements)

References 32 publications

(44 reference statements)

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“…Its viscosity at room temperature and macroscopic scale is  = 100 mPa.s. The low frequency range probed in this study rules out any coupling with molecular relaxation times [19]. The liquid is submitted to an oscillatory shear strain using the standard dynamic mechanical analysis.…”

Section: Methodsmentioning

confidence: 98%

Thermal Shear Waves Induced in Mesoscopic Liquids at Low Frequency Mechanical Deformation

Kume

Noirez

2022

Journal of Non-Equilibrium Thermodynamics

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We show that a confined viscous liquid emits a dynamic thermal response upon applying a low frequency (∼1 Hz) shear excitation. Hot and cold thermal waves are observed in situ at atmospheric pressure and room temperature, in a viscous liquid (polypropylene glycol) at various thicknesses ranging from 100 µm up to 340 µm, upon applying a mechanical oscillatory shear strain. The observed thermal effects, synchronous with the mechanical excitation, are inconsistent with a viscous behaviour. It indicates that mesoscopic liquids are able to (partly) convert mechanical shear energy in non-equilibrium thermodynamic states. This effect called thermo-elasticity is well known in solid materials. The observation of a thermal coupling to the mechanical shear deformation reinforces the assumption of elastically correlated liquid molecules. The amplitude of the thermo-elastic waves increases linearly by increasing the shear strain amplitude up to a transition to a non-linear thermal behavior, similar to a transition from an elastic to plastic regime. The thermo-elastic effects do not give rise to any change in stress measurements and thus the dynamic thermal analysis provides unique information about dynamic liquid properties.

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Section: Methodsmentioning

confidence: 98%

Thermal Shear Waves Induced in Mesoscopic Liquids at Low Frequency Mechanical Deformation

Kume

Noirez

2022

Journal of Non-Equilibrium Thermodynamics

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“…The molecular weight is given as 3500–4500 g/mol, which corresponds to about 55 repetition units. It is a viscous liquid at room temperature ( η = 100 mPa s) and its relaxation time is out of the dynamic range of conventional mechanical tools [ 29 ]. Glycerol is a very well-studied liquid due its extremely wide range of uses and its biocompatibility.…”

Section: Methodsmentioning

confidence: 99%

Highlighting Thermo-Elastic Effects in Confined Fluids

2021

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The recent identification of a finite shear elasticity in mesoscopic fluids has motivated the search of other solid-like properties of liquids. We present an innovative thermal approach of liquids. We identify a dynamic thermo-elastic mesoscopic behavior by building the thermal image produced by different liquids upon applying a low frequency mechanical shear field. We selected three fluids: a low molecular weight polybutylacrylate (PBuA), polypropyleneglycol (PPG), and glycerol. We demonstrate that a part of the energy of the shear strain is converted in cold and hot shear bands varying synchronously with the applied shear field. This thermodynamic change suggests a coupling to shear elastic modes in agreement with the low frequency shear elasticity theoretically foreseen and experimentally demonstrated.

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“…Free volume phenomenon in the polymers, which is defined as the gap or spaces occupied between the chains of polymers, may give the key explanations about some significant physical quantities of the polymers such as mechanical, 27 thermodynamic properties, 28 permeability. 29 Viscosity, 30,31 the ionic conductivity, 32 the dielectric relaxation 33 etc. It is known that there exists an inverse relationship between free volume and mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the relation between free volume and physico-mechanical performance in rigid polyurethane foam containing turkey feather fibers: Part 2

Soykan

Khaleel

Çetin

et al. 2022

Journal of Cellular Plastics

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Rigid polyurethane foams (RPUFs) were modified with 0–15 wt.% turkey feather fibers (TFFs) produced from waste turkey feathers. One-shut free rising method was used for the production of TFFs-filled-RPUFs in a closed mold. The dependence of mechanical performance and water vapor permeability (WVP) feature of the final foams on TFFs loading was evaluated with free volume change. The free volume analysis was performed via Positron Annihilation Lifetime Spectroscopy (PALS), while the mechanical and WVP characteristics were determined with the use of the universal tester machines. PALS findings showed that the incorporation of TFFs with RPUF matrix caused the considerable diminishment in the free volume due to TFFs serving as a filling material and formation of strong secondary bonds between components. Moreover, tensile strength and extension of the foams decreased with the increasing of TFFs, which caused by the occurrence of noteworthy restriction on the spatial alignment and orientation capability of polyurethane chains due to the lack of sufficient free volume allowing the chains to move freely. As for the compression tests, all the TFFs-loaded RPUFs depicted substantially lower performance due to TFFs interfering with the ordered organization of isocyanate domains. Moreover, impact test results showed that the addition of TFFs into RPUF matrix brought about the insufficient impact energy delocalization throughout the matrix due to the restriction on the mobility of polymer chains. Additionally, the remarkable diminishment in WVP was recorded due to the reduction in the number of vacancies and constitution of keratin composed of roundly 60% of hydrophilic protein (especially cystine). All in all, this study established a strong links between free volume and characteristics of TFFs-loaded RPUFs.

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Relaxation time of polypropylene glycol and polypropylene glycol dimethylether-like polymers in terms of fluid-phase temperature and pressure dependent hole fraction

Cited by 13 publications

References 32 publications

Thermal Shear Waves Induced in Mesoscopic Liquids at Low Frequency Mechanical Deformation

Thermal Shear Waves Induced in Mesoscopic Liquids at Low Frequency Mechanical Deformation

Highlighting Thermo-Elastic Effects in Confined Fluids

Investigation of the relation between free volume and physico-mechanical performance in rigid polyurethane foam containing turkey feather fibers: Part 2

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