Blends of poly(ϵ‐Caprolactone) with poly(vinyl chloride). I. Morphology

Abstract

AbstractThe morphology of blends of poly(ϵ‐caprolactone) (PCL) with poly(vinyl chloride) (PVC) was investigated. The observations made with the optical microscope and electron microscopes indicate that for the blends rich in PCL, the samples are almost completely filled with spherulites composed of lamellas radiating from the spherulite center and twisting regularly. As the concentration of PVC increases, the texture of the spherulites becomes increasingly coarse and open. The results of the elementary analysis, made with an x‐ray spectrometer, indicate a uniform distribution of chlorine atoms in the blends regardless of the composition. X‐Ray diffraction studies reveal that the unit cell dimensions of PCL are not changed by the presence of PVC. It is believed that the PVC molecules were trapped within the spherulites and rejected preferentially into interlamellar regions. The results of differential scanning calorimetry measurement show that the crystallinity of PCL decreases with increasing PVC content. PCL in the blend containing more than 70% PVC exhibits no tendency to crystallize. The blends show a depression of the melting point of PCL. Over a wide range of composition, the blends display a single glass transition intermediate between the transition of the respective components. The glass transition shows a systematic increase with PVC concentration.