China Petroleum Processing & Petrochemical Technology ›› 2022, Vol. 24 ›› Issue (4): 76-85.

• Process Research • Previous Articles     Next Articles

Diffusion Characteristics and Removal of Cyclohexane in Polyolefin Elastomer Melt

Qi Jibing1; Yang Tong2; Liu Yandong1; Yuan Zhiguo1Zhang Qiaoling1; Liu Youzhi1; Yi Jianjun2   

  1. 1. Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering, North University of China,
    Taiyuan 030051, China; 2. Petrochemical Research Institute, PetroChina Co., Ltd., Beijing 102206, China
  • Received:2022-06-12 Revised:2022-07-01 Online:2022-12-30 Published:2022-12-30

Abstract: Diffusion coefficient of volatiles in polymer solutions is a crucial parameter to describe the mass transfer efficiency and ability of volatiles. In this research, polyolefin elastomer (POE) was used as polymer, and cyclohexane was used as volatiles, the gravimetric analysis was applied to measure the diffusion coefficient of cyclohexane in POE. The devolatilization rate of POE-cyclohexane system under different conditions was measured. The effects of temperature, film sample thickness and initial concentration of volatiles on the devolatilization rate were discussed. Based on the devolatilization rate data, the average diffusion coefficient of cyclohexane in POE was obtained by fitting with the mathematical model. Experimental results indicate that the devolatilization rate increased with increasing temperature and initial concentration of volatiles, but decreased with increasing thickness of sample. With the thickness increases, the overall diffusion resistance increases. With the temperature increases, the molecular movement increases, resulting in the increase of average diffusion coefficient. The diffusion coefficient of POE-cyclohexane system with temperature follows the Arrhenius law. The diffusion activation energy E=6201.73 J·mol-1, and the pre-exponential factor of the diffusion coefficient D0=2.64×10-10 m2/s. This work can provide basic data for exploring the devolatilization of POE polymer, and provide a useful reference for enhancing the effect of devolatilization.

Key words: diffusion coefficient, gravimetric analysis, polyolefin elastomer (POE), cyclohexane, devolatilization rate