On the Glass Transition Temperature of Polyethylene as Revealed by Microhardness Measurements

Fakirov, S.; Krasteva, B.

doi:10.1081/mb-100100386

Cited by 37 publications

(22 citation statements)

References 22 publications

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“…In the limit that all atoms are completely mobile (i.e., ζ = 1), this correlation in Fig. 4a predicts a T g of −120°C, which is comparable with the T g of polyethylene [43][44][45][46] and the alkyl side chain T g s of P3HT (−100°C), P3OT (−65°C), and P3DDT (−50°C) 16 . In the other limit, that of conjugated polymers without any side chains, the T g of unsubstituted polythiophene (ζ = 0.72) lies reasonably close to the correlation, even though this value is determined from a weak signature in DSC ( Supplementary Fig.…”

Section: Resultsmentioning

confidence: 60%

Glass transition temperature from the chemical structure of conjugated polymers

et al. 2020

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The glass transition temperature (T g) is a key property that dictates the applicability of conjugated polymers. The T g demarks the transition into a brittle glassy state, making its accurate prediction for conjugated polymers crucial for the design of soft, stretchable, or flexible electronics. Here we show that a single adjustable parameter can be used to build a relationship between the T g and the molecular structure of 32 semiflexible (mostly conjugated) polymers that differ drastically in aromatic backbone and alkyl side chain chemistry. An effective mobility value, ζ, is calculated using an assigned atomic mobility value within each repeat unit. The only adjustable parameter in the calculation of ζ is the ratio of mobility between conjugated and non-conjugated atoms. We show that ζ correlates strongly to the T g , and that this simple method predicts the T g with a root-mean-square error of 13°C for conjugated polymers with alkyl side chains.

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Section: Resultsmentioning

confidence: 60%

Glass transition temperature from the chemical structure of conjugated polymers

et al. 2020

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“…Independent of the correct T g , these values fall well within the range of temperatures investigated. [53] −42±9°C Chang [55] −33°C Ng et al [56] −69°C Alberola et al [57] −40 to 25°C a G'Sell and Dahoun [29] −20°C Fakirov and Krasteva [58] −23°C Kwon et al [59] −36 to −23°C Pyda and Wunderlich [60] −13°C Khonakdar et al [38] −30 to 10°C b a Depending on frequency b Denoted it as the " transition In each case part (a) shows the compressive response as a function of temperature and part (b) provides the response as a function of strain-rate. For ease of comparison the same scale is used for all of the plots.…”

Section: Thermomechanical Analysis and Differential Scanning Calorimetrymentioning

confidence: 98%

Influence of Molecular Conformation on the Constitutive Response of Polyethylene: A Comparison of HDPE, UHMWPE, and PEX

et al. 2007

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The current work presents the characterization and comparison of the mechanical response of three different industrial forms of polyethylene. Specifically, high-density polyethylene (HDPE), ultra high molecular weight polyethylene (UHMWPE), and cross-linked polyethylene (PEX) were tested in compression as a function of temperature (−75 to 100°C) and strain-rate (10 −4 to 2,600 s −1 ). The responses of UHMWPE and PEX are very similar, whereas HDPE exhibits some differences. The HDPE samples display a significantly higher yield stress followed by a flat flow behavior. Conversely UHMWPE and PEX both exhibit significant strain hardening after yield. The temperature and strain-rate dependence are captured by simple linear and logarithmic fits over the full range of conditions investigated. The yield behavior is presented in terms of an empirical mapping function that is extended to analytically solve for the mapping constant. The power-law dependence on strain-rate observed in some polymers is explained using this mapping function.

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“…For example, natural rubber transits from glass into viscoelastic state at 200 K. However, polymers with complicated structure can have multiple isophase transitions. One such polymer, polyethylene, has three glass transitions: 153 K for completely amorphous domains, 240 K for mesomorphous domains on, and at 200 K for intermediate amorphous domains (Bartenev et at., 1981;Fakirov et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Isophase Transitions of Cellulose – A Short Review

Ioelovich¹

2016

AJS

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Cellulose has a complicated supramolecular structure consisting of nanofibrils, which are built of ordered crystallites and low ordered noncrystalline domains. In this critical review, isophase temperature transitions in noncrystalline domains of cellulose were described and discussed. It has been shown that due to structural heterogeneity the noncrystalline domains have three isophase temperature transitions, where the α1 and α2 transitions are caused by the occurrence of segmental mobility in dense mesomorphous and medium packed amorphous clusters, respectively; whereas the β transition is related to the mobility of small segments in loose packed amorphous clusters, which probably are located on the outer surface of nanofibrils. Under the action of water and other plasticizers all three isophase transitions are shifted to lower temperatures.

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On the Glass Transition Temperature of Polyethylene as Revealed by Microhardness Measurements

Cited by 37 publications

References 22 publications

Glass transition temperature from the chemical structure of conjugated polymers

Glass transition temperature from the chemical structure of conjugated polymers

Influence of Molecular Conformation on the Constitutive Response of Polyethylene: A Comparison of HDPE, UHMWPE, and PEX

Isophase Transitions of Cellulose – A Short Review

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