No abstract

The solubility of CO, in PETG, a glycol-modifled PET, was measured at different tempentures and over a broad pressure range, and diffusion coefficients were derived at the corresponding conditions. The solubility of CO, is quite high. For example, almost 15 wt% CO, can be dissolved in PETG at 35°C and 6.0 MPa. Consequently, CO, is a god blowing agent for PETG. Cellular foams in the density range of about 0.04 to 1.2 g/cm3 and cell diameters in the range of about 10 to 150 pm were produced. The foam density and the cell size were found to depend on the foaming temperature and time, with larger cells obtained at higher temperatures or when the sample was foamed for a longer time. The foam density decreased with an increase in the foaming temperature to about 90°C beyond which the density tended to increase slightly due to the cell collapse or coalescence. The density reduction also depended on the pressure at which the polymer was saturated with CO,; the higher the saturating pressure at a given temperature, the greater the density reduction.

No abstract