Molecular Simulation of Permeation Behavior and Mechanism of CH4 in PVDF

doi:10.19491/j.issn.1001-9278.2021.03.014

Abstract

Abstract:

The adsorption and diffusion behavior of CH₄ in poly（vinylidene fluoride）（PVDF） was studied by a combination of molecular dynamics （MD） and Grand Canonical Monte Carlo （GCMC） simulations. The effects of temperature and pressure on the adsorption and diffusion capabilities of CH₄ were discussed， and the adsorption sites and diffusion paths of CH₄ in PVDF were analyzed. It was found that the solubility coefficient and permeability coefficient of CH₄ in PVDF increased at first and then tended to decrease with an increase in temperature. However， these two parameters always increased with an increase in pressure. As the temperature and pressure increased， the diffusion coefficient and fractional free volume increased. The simulated results indicated that the CH₄ molecules exhibited a selectively aggregated adsorption in PVDF， and they were mostly absorbed in the low potential region of the simulated cell. The CH₄molecules in PVDF diffused within the free volumes in the form of cavities. The higher temperature and greater pressure can result in a better diffusion capability.

Key words: poly（vinylidene fluoride）, permeation, adsorption, diffusion, molecular simulation

CLC Number:

TQ325.4

ZHANG Xuemin, WANG Pin, LI Houbu, ZHOU Teng, XIAO Chunhong, FENG Jinmao, ZHONG Mingqiang. Molecular Simulation of Permeation Behavior and Mechanism of CH₄ in PVDF[J]. China Plastics, 2021, 35(3): 97-104.

Figures/Tables 14

Fig.1. Gas molecule and cell structural model

Fig.2. Adsorption isotherm and mean square displacement curve of CH4 molecules in PVDF at 30 ℃ and 0.1 MPa

Fig.3. Adsorption isotherm of CH4 in PVDF under different temperatures at 2.5 MPa

温度/℃	吸附热/kJ·mol^-1	溶解系数/×10^-5 cm³ (STP)·cm^-3·Pa^-1
30	16.163	0.699
40	18.276	0.719
50	17.845	0.434
60	16.723	0.349

Tab.1. Isosteric heat and solubility coefficient of CH4 in PVDF under different temperature at 2.5 MPa

压力/MPa	吸附热/kJ·mol^-1	溶解系数/×10^-5 cm³ (STP)·cm^-3·Pa^-1
2.5	16.163	0.699
6.4	23.522	1.056
8.5	24.108	1.241
10	25.179	1.392

Tab.2. Isosteric heat and solubility coefficient of CH4 in PVDF under different pressures at 30 ℃

Fig.4. Mean square displacement curve of CH4 in PVDF under different temperatures at 2.5 MPa

温度/℃	自由体积分数	扩散系数/×10^?6cm²·s^-1
30	0.270	0.737
40	0.292	1.178
50	0.327	1.760
60	0.342	2.318

Tab.3. Fractional free volume and diffusion coefficient of CH4 in PVDF under different temperature at 2.5 MPa

压力/MPa	自由体积分数	扩散系数/×10^-6cm²·s^-1
2.5	0.270	0.737
6.4	0.281	0.812
8.5	0.293	1.149
10	0.316	1.572

Tab.4. Fractional free volume and diffusion coefficient of CH4 in PVDF under different pressure at 30 ℃

Fig.5. Free volume distribution of PVDF/CH4 mixed cells

温度/℃	渗透系数/×10^-11 cm³(STP)·cm·cm^-2·s^-1·Pa^-1
30	0.515
40	0.847
50	0.818
60	0.809

Tab.5. Permeability coefficient of CH4 in PVDF under different temperature at 2.5 MPa

压力/MPa	渗透系数×10^-11/ cm³(STP)·cm·cm^-2·s^-1·Pa^-1
2.5	0.515
6.4	0.875
8.5	1.550
10	2.606

Tab.6. Permeability coefficient of CH4 in PVDF under different pressure at 30 ℃

Fig.6. Density field distribution and isopycnic of CH4 molecules in PVDF

Fig.7. Diffusion trajectory and displacement of a CH4 molecule in PVDF under different temperatures at 2.5 MPa

Fig.8. Diffusion trajectory and displacement of a CH4 molecule in PVDF under different pressure at 30 ℃

References 24

1	张建强. 热塑性塑料管材在油气田腐蚀介质中性能退化规律研究［D］. 西安：西安石油大学， 2015.
2	张学敏，李厚补，戚东涛，等. 油气田模拟环境下聚偏氟乙烯的适用性研究［J］. 天然气与石油， 2016， 34（2）： 68⁃71.
	ZHANG X M， LI H B， QI D T， et al. Research on Compatibility of Polyvinylidene Fluoride in Simulated Oilfield Environments ［J］. Natural Gas and Oil， 2016， 34（2）： 68⁃71.
3	SHAMSUDDOHA M， ISLAMA M， ARAVINTHAN T， et al. Effectiveness of Using Fiber⁃Reinforced Polymer Composites for Underwater Steel Pipeline Repairs ［J］. Composite Structures， 2013， 100（5）： 40⁃50.
4	SCHEICHL R， KLOPFFER M H， BENJELLOUN D Z， et al. Permeation of Gases in Polymers： Parameter Identi⁃Cation and Nonlinear Regression Analysis ［J］. Journal of Membrane Science， 2005， 254（1）： 275⁃293.
5	NOVAKA A， BOBAK M， KOSEK J， et al. Ethylene and 1⁃hexene Sorption in LLDPE under Typical Gas⁃Phase Reactor Conditions： Experiments ［J］. Journal of Applied Polymer Science， 2006， 100（2）： 1 124⁃1 136.
6	WANG Z L， CHEN W， YANG Y R， et al. Adsorption Equilibrium of Volatile in Condensed Mode Polyethylene Process ［J］. Chinese Journal of Chemical Engineering， 2000， 8（1）： 41⁃45.
7	WANG J D， YANG Y R. Adsorption Equilibria of Hexane and Isopentane on Polyethylene at Different Temperatures， Pressures， and Particle Sizes ［J］. Journal of Chemical and Engineering Data， 2001， 46（5）： 1 222⁃1 224.
8	SATO Y， YURUGI M， FUJIWARA K， et al. Solubilities of Carbon Dioxide and Nitrogen in Polypropylene under High Temperature and Pressure ［J］. Fluid Phase Equilibria， 1996， 125（1/2）： 129⁃138.
9	SATO Y， FUJIWARA K， TAKIKAWA T， et al. Solubilities and Diffusion Coefficients of Carbon Dioxide and Nitrogen in Polypropylene， High⁃Density Polyethylene， and Polystyrene under High Pressures and Temperatures ［J］. Fluid Phase Equilibria， 1999， 162（1/2）： 261⁃276.
10	SATO Y， YURUGI M， YAMABIKI T， et al. Solubility of Prolylene in Semicrystalline Polypropylene ［J］.Journal of Applied Polymer Science， 2001（79）：1 134⁃1 143.
11	MCKENNA T F. Solubility and Crystallinity Data for Ethylene/Polyethylene Systems ［J］.European Polymer Journal， 1998， 34（9）： 1 255⁃1 260.
12	陶长贵，冯海军，周健，等. 氧气在聚丙烯内的吸附与扩散的分子模拟［J］. 物理化学学报， 2009， 25（7）： 1 373⁃1 378.
	TAO C G， FENG H J， ZHOU J， et al. Molecular Simulation of Oxygen Adsorption and Diffusion in Polypropylene ［J］. Chinese Journal of Chemical Physics，2009， 25 （7）： 1 373⁃1 378.
13	钟颖. 分子模拟研究气体在高渗透性膜中扩散溶解行为［D］. 重庆：西南大学， 2012.
14	岳雅娟. 有机分子在聚乙烯膜中的过程溶解扩散过程的分子模拟［D］.青岛：中国海洋大学， 2011.
15	何也，傅雪海，路露. 煤对H₂S、CH₄和N₂的吸附性差异分析［J］. 中国科技论文， 2016， 11（15）： 1 775⁃1 796.
	HE Y， FU X H， LU L. Differences of H₂S、CH₄ and N₂Adsorption Ability on Coal ［J］. China Science Paper， 2016， 11（15）： 1 775⁃1 796.
16	MOZAFFARI F， ESLAMI H， MOGHADASI J. Molecular Dynamics Simulation of Diffusion and Permeation of Gases in Polystyrene ［J］. Polymer， 2010（51）：300⁃307.
17	BARRER R M. Diffusivities in Glassy Polymers for the Dual Mode Sorption Model ［J］. Journal of Membrane Science， 1984， 18 ： 25⁃35.
18	FENG H. Modeling of Vapor Sorption in Glassy Polymers Using A New Dual Mode Sorption Model Based on Multilayer Sorption Theory ［J］. Polymer， 2007， 48（10）：2 988⁃3 002.
19	METROPOLIS N， ROSENBLUTH A W， ROSENBLUTH M N， et al. Equation of State Calculation by Fast Computing Machines ［J］. Journal of Chemical Physics， 1953（21）： 1 087⁃1 097.
20	MULLER P F. Permeation of Polymers—A Computational Approach ［J］. Acta Polymerica， 1994， 45： 259⁃293.
21	TROHALAKI S， KLOCZKOWSKI A， MARK J E， et al. Estimation of Diffusion Coefficient for Small Molecularpenetrants in Amorphous Polyethylene ［J］. Computational Simulation Polymer， 1992， 2 （4）： 147⁃152.
22	EINSTEIN A. On The Movement of Small Particles in a Stationary Liquid Demanded by Themolecular⁃Kinetic Theory of Heat ［J］. Annals of Physics， 1905（17）： 549⁃560.
23	YEGANEGI S， GHOLAMPOUR F. Simulation of Methane Adsorption and Diffusion in a Carbon Nanotube Channel ［J］. Chemical Engineering Science， 2016， 140： 62⁃70.
24	朱绘丽. 水和盐分子在反渗透膜中溶解扩散过程的分子模拟［D］. 青岛：中国海洋大学， 2011.

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Molecular Simulation of Permeation Behavior and Mechanism of CH₄ in PVDF

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