The effect of temperature and pressure on polycaprolactone morphology

Publication date: Available online 7 February 2020Source: PolymerAuthor(s): Cameron Baptista, Aharon Azagury, Hyeseon Shin, Christopher M. Baker, Eileen Ly, Rachel Lee, Edith MathiowitzAbstractThe morphology and melting behavior of poly(ε-caprolactone) (PCL) processed at varying pressure-temperature-time conditions (2000–20,000 lbf, 22–70 °C, and 5–15 min) were studied using polarized light microscopy (PLM), differential scanning calorimetry (DSC), and X-Ray diffraction (XRD). Samples processed well below the melting region at 22 °C displayed minimal to no birefringent properties, with broadened crystalline XRD scattering patterns, indicative of plastic crystal mesophase morphology. Plastic crystal quantity was shown to gradually increase from 16% to 30% with processing pressure increasing from 2000 lbf to 20,000 lbf. The mechanism of this formation is thought to be the result of crystal disorganization upon plastic deformation, related to the low-energy barrier slip-planes in the crystalline structure. With sufficient chain mobility achieved at higher processing temperatures (50 °C and 60 °C), samples displayed broad birefringent strokes under PLM and were characterized by XRD scattering patterns of broad anisotropic arcs around the equator of the 2D azimuthal pattern, which are indicative of condis crystal mesophase orientation. As opposed to plastic crystal, the condis crystal quantities showed no correlation with increased pressure, ranging between 28...

Source: Polymer - February 7, 2020 Category: Chemistry Source Type: research