Solubility and diffusion behavior of compressed CO2 in polyurethane oligomer

In CO2-assisted polyurethane (PU) foaming, the solubility and diffusion coefficient of CO2 is vitally important to the cell nucleation and growth. This work is aimed at the effect of molecular weights (M-n) and crosslinking densities (V-e) on the solubility and diffusion coefficient of CO2 in PU oligomers. A series of PU oligomers with different M-n and V-e were synthesized. The solubility and diffusivity of CO2 in PU oligomers were measured experimentally in the temperature from 80 to 140 degrees C and with pressures up to 15MPa. It was shown that the solubility and diffusion coefficients of CO2 was decreased 20.5 and 21.0%, respectively, with the M-n increasing from 5864 to 153,754gmol(-1) at 80 degrees C, 15MPa. The solubility and the diffusion coefficient also decreased 11.1 and 38.0% as the V-e was increased from 64 to 1493molm(-3). Furthermore, the diffusion mechanism of CO2 in PU oligomers was explored via molecular dynamics simulations. The results indicated that the calculated diffusivity of CO2 showed the same changing trend as the experimental values, and the smaller M-n or crosslinking degree contributed to an increase in fractional free volume and stronger polymer-CO2 interactions. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47100.