The diffusion behavior of ethylene in polyethylene is of great importance for the polymerization and degassing of polyethylene (PE) industry. Based on the gravimetric sorption and desorption measurement approach, an intelligent gravimetric analyzer is applied to obtain the solubility and diffusion coefficients of ethylene in solid low‐density PE (LDPE) with different melt indices at 30°C to 70°C, 0 to 4 atm and in molten LDPE at 160°C to 230°C, 0 to 4 atm, respectively. Results indicate that both the solubility and diffusion coefficients of ethylene in solid LDPE are smaller than those in molten LDPE, while the dissolution enthalpy and diffusion activation energy of ethylene in solid LDPE are higher. In addition, one‐ and two‐dimensional diffusion models are built and the effects of particle size, polymer properties, and operation conditions are systematically investigated on the diffusion behaviors of ethylene in solid and molten LDPE.

中文翻译：

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乙烯在不同熔体指数的固体和熔融低密度聚乙烯中的溶解度和扩散系数的测量

乙烯在聚乙烯中的扩散行为对于聚乙烯（PE）工业的聚合和脱气至关重要。基于重量吸收和解吸测量方法，使用智能重量分析仪获得乙烯在30°C至70°C，0至4的不同熔体指数下在固体低密度PE（LDPE）中的溶解度和扩散系数atm和在LDPE在160°C至230°C（0至4 atm）下的温度。结果表明，乙烯在固态LDPE中的溶解度和扩散系数均小于熔融LDPE，而乙烯在固态LDPE中的溶解焓和扩散活化能较高。此外，还建立了一维和二维扩散模型，并研究了粒径，聚合物性质，