Crystallinity of foamed polycaprolactone

13 XRD diffractogram of foamed PCL and the Gaussian fit used to approximate the amount of the amorphous region in the sample. 

14 XRD results of A, original PCL B, original PCL melted and quenched rapidly C, foamed PCL (pressure = 10 MPa) D, foamed PCL (pressure = 15 MPa) E, foamed PCL (pressure = 15 MPa), re-melted and quenched. 

The crystallinity of these materials, as measured by XRD, is in good correspondence to the data obtained via DSC. A Perkin-Elmer Pyris-1 DSC with internal coolant (Intracooler IP) and nitrogen purge gas was used. Melting point and enthalpies of indium and zinc were used for temperature and heat capacity calibration. Samples were heated from 20 C to 100 C at 10 C/min to measure the heat capacity used for evaluation of crystallinity. The foamed samples were cooled down from 100 °C then heated again under the same conditions to confirm the effect of foaming on crystallinity. The variation of relative crystallinity was calculated by  

15 DSC curves ofvirgin and foamed PCL. (Temperature = 40°C, pressure = 10 MPa, saturation time =2 h.) 

PCL foam can be produced in supercritical CO2. Various factors affecting the foaming stmcture have been studied in detail. The experimental results indicate that there exists an optimum temperature to achieve a maximum expansion ratio of each polymer melt. Since high pressure and longer saturation time both decrease the Tg, and in effect are similar to controlling the temperature, quantification of 

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