Summary: The effect of poly(ε‐caprolactone) (PCL) molecular weight on the orientation of crystalline PCL in miscible poly(ε‐caprolactone)/poly(vinyl chloride) (PCL/PVC) blends, melt crystallized under strain, has been studied by a combination of wide angle X‐ray diffraction (WAXD) and small angle X‐ray scattering (SAXS) studies. An unusual crystal orientation with the b‐axis parallel to the stretching direction was observed in miscible PCL/PVC blends with PCL of high molecular weight (>21 000). SAXS showed the presence of nanosize confined PCL in the PCL/PVC blends, which could be preserved at temperatures higher than the Tm of PCL but lower than the Tg of PVC. A mechanism based on the confinement of PCL crystal growth was proposed, which can explain the formation of b‐axis orientation in PCL/PVC blends crystallized under strain.
SAXS pattern of stretched PCL/PVC blend after annealing at 90 °C for 5 min.
