China Plastics ›› 2021, Vol. 35 ›› Issue (10): 51-55.DOI: 10.19491/j.issn.1001-9278.2021.10.009

• Materials and Properties • Previous Articles     Next Articles

Molecular Dynamics Simulation of Diffusion Behavior of CO2 and O2 in PLA/PVDF Blend

LI Shaoyuan, SUN Ling(), CAI Hengfang   

  1. College of Mechanical and Electrical Engineering,Nanchang University,Nanchang 330031,China
  • Received:2021-03-26 Online:2021-10-26 Published:2021-10-27

Abstract:

The diffusion behavior of CO2 and O2 molecules in the poly(lactic acid) (PLA)/polyvinylidene fluoride(PVDF) blends was studied using a molecular dynamics simulation method. The free volume fraction of the blending system model and the diffusion coefficient of CO2 and O2 molecules in the system were calculated through the Fick’s first law using the Einstein relational formula. The relationships between free volume fraction and probe radius and the between the free volume fraction and diffusion coefficient were explored. The results indicated that the CO2 and O2 molecules exhibited the smallest diffusion coefficients at mass ratio of PLA to PVDF of 9 to 1. The blends exhibited optimal barrier performance. The smaller the dynamic radius of small molecules in the blending system, the larger was the diffusion coefficient. The free volume fraction decreased with an increase in probe radius according to the hard?ball probe model. In different blending systems, the free volume fraction showed a variation trend consistent with the diffusion coefficient. This result was in good agreement with the Fox's and Flory's theories in free volume.

Key words: molecular dynamics, diffusion coefficient, poly(lactic acid), polyvinylidene fluoride, free volume fraction, probe radius

CLC Number: