Ringed spherulite in binary blends of poly(ε-caprolactone) and ε-caprolactone-butadiene diblock copolymer

• Published in: Polymer journal Vol. 23; no. 12; pp. 1473 - 1482
• Main Authors: NOJIMA, S, DAJING WANG, ASHIDA, T
• Format: Journal Article
• Language: English
• Published: Tokyo Society of Polymer Science 01.01.1991
• Subjects: Applied sciences; Crystallization; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Butadiene copolymer; Ester polymer; Temperature effect; Experimental study; Mixture; Structure composition relationship; Melt crystallization; Lamellar structure; Caprolactone copolymer; Spherulites; Morphology; Diblock copolymer; Polycaprolactone
• ISSN: 0032-3896; 1349-0540
• DOI: 10.1295/polymj.23.1473

Ringed spherulites were found in binary blends of poly( epsilon -caprolactone) (PCL) and epsilon -caprolactone--butadiene diblock copolymer (PCL-b-PB), while the regularly banded structure could not be observed in an oligomeric blend of PCL and polybutadiene (PB). The repeating distance of the ring and its distribution (irregularity) were evaluated as a function of PCL homopolymer (host polymer) fraction, total PCL fraction in the blend, and crystallization temperature. The morphology and melting behavior of the PCL/PCL-b-PB blends were also investigated by small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC). These results suggest that the PCL block of the copolymer takes part in the crystallization of th host polymer and is incorporated into the PCL lamellar crystal. The PB block is, as a result, forced to remain in the amorphous layer between PCL lamellae to lengthen the long spacing (alternating period of the lamella and amorphous layer). This existence of the PB block in the amorphous layer may play an important role in the lamellar twist during the course of crystallization.