Effects of Branch Content and Branch Length on Polyethylene Crystallization: Molecular Dynamics Simulation

2016 ◽  
Vol 25 (3) ◽  
pp. 303-311 ◽  
Author(s):  
Rui Gao ◽  
Xuelian He ◽  
Yunqi Shao ◽  
Yanling Hu ◽  
Haiyang Zhang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Branch Length ◽  
Dynamics Simulation

scholarly journals Dominant Effects of Short-Chain Branching on the Initial Stage of Nucleation and Formation of Tie Chains for Bimodal Polyethylene as Revealed by Molecular Dynamics Simulation

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1840 ◽  
Author(s):  
Yanling Hu ◽  
Yunqi Shao ◽  
Zhen Liu ◽  
Xuelian He ◽  
Boping Liu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Branch Length ◽  
Dynamics Simulation ◽  
Short Chain ◽  
Sequence Length ◽  
Chain Branching ◽  
Initial Stage ◽  
Long Chain ◽  
Bimodal Polyethylene

The molecular mechanism of short-chain branching (SCB), especially the effects of methylene sequence length (MSL) and short-chain branching distribution (SCBD) on the initial stage of nucleation, the crystallization process, and particularly the tie chain formation process of bimodal polyethylene (BPE), were explored using molecular dynamics simulation. This work constructed two kinds of BPE models in accordance with commercial BPE pipe resins: SCB incorporated in the long chain or in the short chains. The initial stage of nucleation was determined by the MSL of the system, as the critical MSL for a branched chain to nucleate is about 60 CH2. SCB incorporated in the long chain led to a delay of the initial stage of nucleation relative to the case of SCB incorporated in the short chains. The increase of branch length could accelerate the delay to nucleation. The location of short chain relative to the long chain depended on the MSL of the short chain. As the MSL of the system decreased, the crystallinity decreased, while the tie chains concentration increased. The tie chains concentration of the BPE model with branches incorporated in the long chain was higher than that with branches incorporated in the short chain.

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