Unraveling the influential mechanism of short-chain branching on the crystallization of trimodal polyethylene by molecular dynamics simulation

Cai, Min; He, Xuelian; Liu, Zhen; Liu, Boping

doi:10.1039/d3cp00664f

Cited by 5 publications

(3 citation statements)

References 50 publications

(68 reference statements)

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“…15−17 Additionally, molecular dynamics simulations of simple polymer model systems have revealed that crystallization is strongly influenced by molecular features such as chain entanglement 18 and branching. 19 In particular, the crystallization kinetics was observed to be influenced by branching content but not by branch length, which however affected the obtained crystal morphologies. 20 This underpins the complexity of understanding polymer crystallization.…”

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confidence: 92%

“…Furthermore, Raman spectroscopy has successfully revealed nonhomogeneous spatial distribution of the degree of crystallinity within the bulk of a polymer. Experimental observations show that crystalline structures are also spatially nonuniformly distributed, which can be attributed to spatial differences of dispersity in molecular weight and branching, kinetic effects, and local micromechanical interactions. − Additionally, molecular dynamics simulations of simple polymer model systems have revealed that crystallization is strongly influenced by molecular features such as chain entanglement and branching . In particular, the crystallization kinetics was observed to be influenced by branching content but not by branch length, which however affected the obtained crystal morphologies …”

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confidence: 99%

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Lattice-Cluster-Theory-Informed Cross-Fractionation Chromatography Revealing Degree of Crystallinity of Single Macromolecular Species

Fan,

Zimmermann,

Ciacchi

et al. 2024

ACS Macro Lett.

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The relationship between macromolecular architecture and crystallization properties is a relevant research topic in polymer science and technology. The average degree of crystallinity of disperse polymers is a wellstudied quantity and is accessible by various experimental methods. However, how the different macromolecular species contribute to the degree of crystallinity and, in particular, the relationship between a certain macromolecular architecture and the degree of crystallinity are not accessible today, neither experimentally nor theoretically. Therefore, in this work, a lattice cluster theory (LCT)-informed cross-fractionation chromatography (CFC) approach is developed to access the degree of crystallinity of single and nonlinear macromolecular species crystallizing from solution. The method entangles high-throughput experimental data from CFC with the LCT for semicrystalline polymers to predict the degree of crystallinity of polymer species with different molecular weights and branching. The approach is applied to a linear low-density polyethylene (ethylene/1-octene copolymer) and a high-density polyethylene, which have specific and different bivariate distributions. The degree of crystallinity of individual macromolecular species of these polymer samples is calculated, and the predicted average degree of crystallinity is compared with experimental measurements, thus successfully validating the approach. Furthermore, the average segment length between branches is introduced as a characteristic molecular feature of branched polyethylene, and its relationship with the degree of crystallinity of certain species is established.

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confidence: 92%

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confidence: 99%

Lattice-Cluster-Theory-Informed Cross-Fractionation Chromatography Revealing Degree of Crystallinity of Single Macromolecular Species

Fan,

Zimmermann,

Ciacchi

et al. 2024

ACS Macro Lett.

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“…However, as a cutting-edge material, trimodal PE has gradually entered people’s vision, and the study of the effect of MWD on the crystallization process can be helpful for the design of trimodal PE materials for industrial production. In our previous work [ 48 ], a series of trimodal PE models, including different short-chain branching characteristics, were established. The results revealed that the effect of SCBC and SCBL on the trimodal PE crystallization process was similar to that of unimodal and bimodal PE.…”

Section: Introductionmentioning

confidence: 99%

Revealing the Effect of the Molecular Weight Distribution on the Chain Diffusion and Crystallization Process under a Branched Trimodal Polyethylene System

Cai,

He,

Liu

2024

Polymers

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With the increasing demand for high-end materials, trimodal polyethylene (PE) has become a research hotspot in recent years due to its superior performance compared with bimodal PE. By means of molecular dynamics (MD) simulations, we aim to expound the effect of the molecular weight distribution (MWD) on the mechanism of nucleation and crystallization of trimodal PE. The crystallization rate is faster when short-chain branching is distributed on a single backbone compared to that on two backbones. In addition, as the content of high molecular weight backbone decreases, the time required for nucleation decreases, but the crystallization rate slows down. This is because low molecular weight backbones undergo intra-chain nucleation and crystallize earlier due to the high diffusion capacity, which leads to entanglement that prevents the movement of medium or high molecular weight backbones. Furthermore, crystallized short backbones hinder the movement and crystallization of other backbones. What is more, a small increase in the high molecular weight branched backbone of trimodal PE can make the crystallinity greater than that of bimodal PE, but when the content of high molecular weight backbone is too high, the crystallinity decreases instead, because the contribution of short and medium backbones to high crystallinity is greater than that of long backbones.

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Characterization of the molecular structure of masticated natural rubber using rheological techniques

Jiang,

Kong,

Luo

et al. 2023

J of Applied Polymer Sci

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Mastication can improve the plasticity and reduce the molar mass of natural rubber (NR). The end product properties greatly depend on the efficiency of mastication. For NR before and after mastication, the changes in molecular properties are mainly attributed to the effects of mechanical and thermo‐oxidative degradation. We investigated the variations in molecular weight, molecular weight distribution, degree of branching, and thermal stability of NR after mastication at 35, 75, and 110 rpm for 20 min. The results show that NR has a smaller molecular weight, broader molecular weight distribution, and a lower degree of structural branching at higher rotor speeds. Additionally, the rheological measurements were compared with gel permeation chromatography results, and the comparative outcomes reflect a strong correlation between these data. Rheological analysis reveals considerable complex relationships, and this measurement is more efficient, simple, and convenient than the other technique.

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Unraveling the influential mechanism of short-chain branching on the crystallization of trimodal polyethylene by molecular dynamics simulation

Abstract: Trimodal polyethylene (PE) has become the focus of research in recent years due to its excellent performance. By means of molecular dynamics simulations, we aim to expound the molecular mechanism...

Cited by 5 publications

References 50 publications

Lattice-Cluster-Theory-Informed Cross-Fractionation Chromatography Revealing Degree of Crystallinity of Single Macromolecular Species

Lattice-Cluster-Theory-Informed Cross-Fractionation Chromatography Revealing Degree of Crystallinity of Single Macromolecular Species

Revealing the Effect of the Molecular Weight Distribution on the Chain Diffusion and Crystallization Process under a Branched Trimodal Polyethylene System

Characterization of the molecular structure of masticated natural rubber using rheological techniques

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