Effect of processing conditions on the foaming cell

In addition to advantages of the supercritical fluid (SCF), such as liquid-like densities which allow its solubiUty to be orders of magnitude higher than gases. 

6 Bulk foam density as a function of saturation temperature. (Pressure = 10 MPa, saturation time =2 h.) 

8 SEM photographs of cross-sections of PCL foams formed under different saturated pressure. (Temperature = 40-C, saturation time =3 h, magnification = 150/50.) Top 14 MPa center 15 MPa bottom 16 MPa. 

9 Average cell size as a function of saturation pressure. (Temperature 40 C, saturation time =3 h.) 

It should be noted that there is a peak of cell size for both saturation pressure (see Fig. 18.9) and saturation time (see Fig. 18.10) at a particular temperature. When the pressure is lower or saturation time is shorter, increasing pressure or time will increase the amount of CO2 diffused into PCL, which results in larger 

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