Crystallization of polycaprolactone with reduced entanglement

Tian, Nan; Dong, Lixin; Wei, Hanghang; Liu, Yanping; Kong, Jie

doi:10.1016/j.eurpolymj.2018.03.017

Cited by 21 publications

(20 citation statements)

References 44 publications

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“…Corresponding crystallinity X c , long period L, lamellar thickness L c and thickness of amorphous region L a are listed in Table . It can be observed from Figure (a) that intensity peak q * of SAXS curves shifts to lower value with increasing shear rate, indicating an increase in long period L. L slightly increases from 29.36 nm for PE0 to 30.80 nm for PE12, which is consisted with the result of crystallization with reduced entanglement from dilute solution . We can rationally conclude that less entanglement will result in a larger long period, regardless of the disentangling method (shear or freeze‐drying).…”

Section: Resultsmentioning

confidence: 76%

“…Thus, the entanglement‐induced “spinning effect” is supposed to influence both primary nucleation and later lamellar crystal growth. Reduced chain entanglement has been confirmed to accelerate melt‐crystallization kinetics and the ultimate crystalline structure including crystallinity and lamellar thickness is therefore changed . Here, we examined the crystalline structure of HDPE samples by means of DSC and SAXS.…”

Section: Resultsmentioning

confidence: 99%

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Insight into shear‐induced modification for improving processability of polymers: Effect of shear rate on the evolution of entanglement state

Wang

Shen

et al. 2019

J Polym Sci B Polym Phys

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Many experimental results have revealed that the re‐entanglement kinetics of disentangled polymers is much slower than that predicted by tube theory. This retarded recovery of fully entangled state is of practical significance that shear‐induced modification may offer a way to improve processability for a polymer by reducing viscosity. This work tried to figure out the shear‐rate dependence variation of viscosity in the view of evolution of entanglement state through disentanglement and re‐entanglement, aiming to provide fundamental insights into application prospect of shear‐induced modification in preparing “in‐pellet” disentangled polymers prior to final processing. High‐density polyethylene was sheared on a parallel‐plate rotational rheometer with a linearly increased shear rate. Results showed that higher shear rate could induce further disentanglement, resulting in a lower viscosity with a reduction rate up to 93.7%, larger molecular weight between entanglements Me, and longer re‐entanglement time. Additionally, less entanglement would give a larger lamellar thickness of sheared samples after nonisothermal crystallization. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 598–606

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Section: Resultsmentioning

confidence: 76%

Section: Resultsmentioning

confidence: 99%

Insight into shear‐induced modification for improving processability of polymers: Effect of shear rate on the evolution of entanglement state

Wang

Shen

et al. 2019

J Polym Sci B Polym Phys

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“…[ 11,12 ] The viscosity of polymer melts can be drastically decreased by disentangling the polymer without increasing the molding temperature, resulting in improved fluidity, fewer defects, and improved quality. Furthermore, less entanglement can aid in the crystallization and formation of desired morphologies, [ 13–16 ] contributing to the high mechanical properties of the final products. [ 17–19 ] Therefore, research into the theories, technologies, and equipment for controlling entanglement has significant theoretical and practical implications, with the potential to revolutionize polymer processing.…”

Section: Introductionmentioning

confidence: 99%

Control of Polymer Properties by Entanglement: A Review

Kong

Yang

Zhang

et al. 2021

Macro Materials & Eng

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Chain entanglement, either cohesional or topological, distinguishes polymers from other engineering materials. It impedes the movement of molecular segments and influences the polymer rheology, morphology, and mechanical properties. Although a high level of entanglement can increase the polymer toughness, excessive entanglement should be avoided because it causes a high melt viscosity making the processing difficult. This review tended to elucidate the influence of entanglement on the polymer structure, determining the material properties and processability. A wide range of methods used to fine control the degrees of chain entanglement are summarized. The methods are applicable to polymers in solutions, melts, and condensed states with advantages and limitations discussed in detail. The authors also examined the effect of the entanglement on polymer crystallization—the mechanism remains a controversial issue. This review will provide general guidance to designing and processing polymer materials with desired properties via a rational route of controlling the chain entanglement.

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“…Subsequently, the processability, 5,6 crystallization behavior, [7][8][9] and mechanical properties in the solid state 10,11 would be altered dramatically. The ways to disentanglement involving polymerization, 12,13 dilute solution method, [14][15][16] slow crystallization from solution 17 and shear modification [18][19][20][21] were widely applied to understand the role of entanglement on the comprehensive properties of polymer materials. We could have a reasonable and good vision that disentanglement of polymer with extremely high viscosity such as ultrahigh molecule weight polyethylene (UHMWPE) results in a large reduction in viscosity, and then is benefit for processability.…”

Section: Introductionmentioning

confidence: 99%