Crystallization studies on heterogeneous melts of polybutene-1

Lu, Yaguang; Wang, Binghua; Jia, Nan; Shen, Changyu; Zhang, Bin

doi:10.1016/j.polymer.2022.125408

Cited by 5 publications

(4 citation statements)

References 60 publications

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“…[42] However recently, during the early stage of spherulite growth or the crystallization process of polymer blends, nonlinear spherulite growth is observed which results in a wide lamellar thickness distribution. [54,55] To clarify the effect of the chain entanglements in the amorphous phase on the growth of UHMWPE spherulites, the isothermal crystallization of commercial UHMWPE is carried out at different crystallization temperatures (T c ) of 127, 127.5, and 128 °C. The maximum heat flow point, namely the point of maximum crystallization rate, divided the crystallization process into two components: the faster primary crystallization and the slower secondary crystallization.…”

Section: Resultsmentioning

confidence: 99%

The Isothermal Melting Kinetics of Ultra‐High Molecular Weight Polyethylene Crystals

Xue,

Lu,

Wang

et al. 2024

Macromol. Rapid Commun.

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The isothermal melting behaviors of ultrahigh molecular weight polyethylene (UHMWPE) with different entangled states (i.e., nascent and melt‐crystallized samples) have been studied. For two kinds of UHMWPE samples, our result shows that the relative content of survived crystals (Xs) exponentially decreases with time and reaches a constant value. We suggest that such a melting behavior is related to the observed nonlinear growth of crystals induced by the kinetically rejected entanglements accumulated at the growth front. Additionally, the exponential decay of Xs with time provides a characteristic melting time (τ) for the melting process. Compared to the melt‐crystallized UHMWPE, the τ value of nascent UHMWPE is generally longer even in a higher temperature range, which is mainly because the former has a larger entanglement density difference. Furthermore, our observations demonstrated that UHMWPEs with different entangled states have an analogous melting mechanism since they exhibit a similar melting activation energy (∼1300 kJ/mol).This article is protected by copyright. All rights reserved

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Section: Resultsmentioning

confidence: 99%

The Isothermal Melting Kinetics of Ultra‐High Molecular Weight Polyethylene Crystals

Xue,

Lu,

Wang

et al. 2024

Macromol. Rapid Commun.

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“…the long-term storage or exposure to harsh processing conditions. Papers dealing with the kinetics of solid-state processes are thus frequently published not only in thermo-analytical journals [1][2][3][4][5][6][7][8][9][10], but also in journals focused on materials science [11][12][13][14][15], pharmacy [16][17][18][19][20], plastics [21][22][23][24][25], explosives [26][27][28][29][30] etc. In correspondence, the methodology for the kinetic calculations is constantly developed-reviews on the recent advancements in this field can be found e.g.…”

Section: Introductionmentioning

confidence: 99%

Simulation and non-linear optimization of kinetic models for solid-state processes

Luciano,

Svoboda

2024

Modelling Simul. Mater. Sci. Eng.

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Numerical simulations and optimizations methods are increasingly used in the field of kinetic analysis of solid-state processes, such as the crystallization of glassy materials. The influence of the simulations accuracy (with the two main factors being the initial value of conversion rate and the density of points) on the kinetic distortions was tested for the major solid-state kinetic models: nucleation-growth Johnson-Mehl-Avrami model, nth order reaction model, autocatalyzed nth order reaction model, diffusion models, contracting cylinder and contracting sphere models. The simulations were performed using a self-developed software based on the LSODA initial-value-problem-solver; the evaluation of the changes in the shape of the kinetic peaks was done using a commercial software that utilizes a standardized multivariate kinetic analysis approach. The accuracy was found to be influenced mainly by initial value of conversion rate. For majority of the tested kinetic models, the simulation accuracy had negligible effect on the consequently determined values activation energy, pre-exponential factor, integrated area of the kinetic peaks, or the asymmetry-determining values of the models kinetic exponents. Significant influence of the simulation accuracy was observed for the models with active autocatalytic features, which were identified to be the main source of the deviations introduced and propagated through the simulation algorithm. Contrary to the previous research, the deviations of the simulated peaks shape cannot be associated solely with the positive asymmetry of the kinetic peaks.

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“…Zhang et al explored the residual ordering objects originating from incomplete melting/relaxation. 19,20 By carefully characterizing the residual structured melt, these authors reported that partially ordered chain segments could remain aggregated with a cylinder-like geometry and greatly affect subsequent recrystallization. Sangroniz et al innovatively combined thermal and rheological approaches to study a selfseeded melt.…”

Section: Introductionmentioning

confidence: 99%

“…Different from the case described above, in which heterogeneity is initiated from the completely relaxed melt and appears during flow, a recent study disclosed that a heterogeneous melt can be generated even prior to the application of flow. Zhang et al explored the residual ordering objects originating from incomplete melting/relaxation. , By carefully characterizing the residual structured melt, these authors reported that partially ordered chain segments could remain aggregated with a cylinder-like geometry and greatly affect subsequent recrystallization. Sangroniz et al innovatively combined thermal and rheological approaches to study a self-seeded melt .…”

Section: Introductionmentioning

confidence: 99%

Flow-Induced Crystallization Coupled with Strong Memory Effect: Revealing Melt Heterogeneity

Zhao,

Liu,

Liu

et al. 2024

Macromolecules

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Herein, the flow-induced crystallization coupled with an intrinsic strong memory effect was investigated via in situ wide-angle X-ray diffraction. A poly(butene-1) random copolymer with 4.3 mol % ethylene co-units was utilized as the model polymorphic material to examine memory effect induced by crystallization kinetics and polymorphism. The quiescent crystallization results clearly demonstrated that the melt-memory effect was able to induce a heterogeneous melt even above the equilibrium melting temperature, in which locally segregated segments comprised the residual domains and effectively facilitated the formation of the most stable phase (trigonal form I′) rather than the kinetically favored phase (tetragonal form II). Form I′ exhibited more pronounced accelerated crystallization kinetics than form II as the melt temperature (T melt ) was decreased, enhancing melt heterogeneity, and became the kinetically favored phase at T melt = 120 °C. Subsequently, the complex mutual effect of flow was explored in the heterogeneous melt, in which crystallization exhibited a dependence on flow strength. For mild flow at 0.3 s −1 , flow mainly accelerated the crystallization of oriented form II while that of form I′ was hardly affected, in contrast to the melt-memory effect observed during the aforementioned quiescent crystallization. The distinct responses to macroscopic flow revealed not only the dependence of tetragonal and trigonal phase formation but also the heterogeneous melt response.

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Crystallization studies on heterogeneous melts of polybutene-1

Cited by 5 publications

References 60 publications

The Isothermal Melting Kinetics of Ultra‐High Molecular Weight Polyethylene Crystals

The Isothermal Melting Kinetics of Ultra‐High Molecular Weight Polyethylene Crystals

Simulation and non-linear optimization of kinetic models for solid-state processes

Flow-Induced Crystallization Coupled with Strong Memory Effect: Revealing Melt Heterogeneity

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