Relaxation transitions in polyethylene

Бартенев, Г. М.; Aliguliyev, R.M.; Khiteyeva, D.M.

doi:10.1016/0032-3950(81)90243-4

Cited by 26 publications

(8 citation statements)

References 10 publications

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“…Our data on temperatures of maxima clearly observed on spectra of internal friction and values of activation energy calculated from experimental results are in agreement with the results obtained earlier in a number of studies conducted by methods of DSC, DMA and RTL [43][44][45][46]. On the spectra of internal friction obtained on a horizontal torsion pendulum, these maxima are observed more clearly than, for example, on DSC.…”

Section: Resultssupporting

confidence: 91%

“…Two temperature regions of the most intense local dissipative processes (β and β k ) are observed on the spectra λ = f (T) in the temperature range from −150 • C to +150 • C for PE. The temperature regions of these processes partially coincide with the data published earlier [39][40][41][42][43][44][45][46]. In addition, two temperature regions with very weak intensity of local dissipative processes are identified on the spectra λ = f (T) and temperature dependencies of the frequency ν = f (T) of freely damped oscillatory process.…”

Section: Resultssupporting

confidence: 85%

“…In addition, the entire spectrum consists of a large number of peaks, each of which has its own values of temperatures, intensities, frequencies, and calculated values of the activation energy and relaxation time. The structural nature of the observed peaks and their temperature positions are still under debate [43][44][45][46], which testifies to the relevance of this topic at present.…”

Section: Resultsmentioning

confidence: 99%

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Spectra of Internal Friction in Polyethylene

2022

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The study of spectra of internal friction λ=fT and temperature dependencies of frequency of freely damped ν=fT oscillatory process excited in investigated samples of polyethylene with different degree of crystallinity in the temperature range from −150 ∘C to +150 ∘C. It is established that four local dissipative processes of different intensity shown in different temperature intervals are observed on the spectra λ=fT. These are μ, β, α, βk processes. The theoretical analysis of the relationship between the anomalous changes of the vibrational process frequency ν=fT and the shift modulus defect ΔG=fT and the internal friction mechanisms for each of the dissipative loss processes detected on the spectrum λ=fT is carried out. The influence of supramolecular structures on local dissipative βk process in polyethylene is estimated.

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

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Spectra of Internal Friction in Polyethylene

2022

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“…The knowledge about structure reorganization upon heating/ cooling is critical for processing and creating polymeric materials with pre-defined properties [1][2][3][4]. Despite numerous studies [1][2][3][4][5][6][7][8][9][10] on the temperature behavior of polymers to-date, certain key features about structural changes with temperature remain a subject of critical discussion even for the simplest and well-studied polyethylene (PE) [3]. For instance, the existence of an intermediate phase, which is structurally * Author to whom any correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Sensitive temperature-dependent phase resolution of polyethylene-clay nanocomposites

Sagitova¹,

Donfack²,

Prokhorov³

et al. 2022

Laser Phys.

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With the help of spectroscopic and differential scanning calorimetry (DSC) techniques, we have studied conformational and phase reorganizations as function of temperature in intercalated polymer-clay nanocomposites based on low-, middle-, and high-density polyethylene (PE) matrices. We show that Raman spectroscopy is sensitive to structural changes appearing during heating at much lower temperatures (about 47 °C) in comparison to DSC measurements. In fact, in the melting region where DSC traces show endotherms, Raman spectra reveal dramatic changes in the phase and conformational compositions of PE and PE-matrices within PE-clay nanocomposites. Noteworthy, the structural reorganization pathway, through which the semicrystalline nanocomposites transform into a melt state, depends primarily on the PE density and weakly on the filler (nanoclay). Moreover, the temperature-dependent crystallinity degree and the total amount of trans-conformers of the PE system are determined, and the evidence for the formation of intermediate crystal-like phase during heating is shown.

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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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Relaxation transitions in polyethylene

Cited by 26 publications

References 10 publications

Spectra of Internal Friction in Polyethylene

Spectra of Internal Friction in Polyethylene

Sensitive temperature-dependent phase resolution of polyethylene-clay nanocomposites

Isophase Transitions of Cellulose – A Short Review

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