Radiopaque iodinated poly(ester-urethane)s based on poly(butylene succinate): Retarded crystallization and dual recrystallization behaviour

Crystallization and melting of unentangled poly(ε-caprolactone) cycles containing pendants

The Rouse model provides a basic framework to understand the chain dynamics of polymers, which is confirmed to be more suitable for exploring the linear dynamics of unentangled polymers. The crystalline morphology governed by chain dynamics and crystallization kinetics is expected to differ in linear and cyclic polymers. Cyclic poly(ε-caprolactone)s (c-PCLs) containing two bi-anthracenyl group pendants with molecular weights close to the critical molecular weight (M_c) were synthesized to investigate the chain dynamics based crystallization and melting behavior by DSC, POM, and in situ simultaneous small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) investigations during heating of the isothermally crystallized samples. Double endothermic peaks were observed in the DSC curves with a low heating rate of c-PCLs without entanglement after isothermal crystallization, especially for c-PCLs with M_c. The structure evolution of the crystalline structures observed from the in situ investigations during the heating and double endothermic peaks in DSC heating curves of the c-PCLs indicate the role of pendants in the chain dynamics, which leads to the reorganization of the metastable structures. Banded spherulites of c-PCL without entanglement were observed for the first time, and the uneven growth of spherulites along the radial direction may be caused by the mismatch between chain dynamics and crystallization kinetics.

An environmentally sustainable isosorbide-based plasticizer for biodegradable poly(butylene succinate)

In this article, isosorbide divalerate (SDV), an alternative renewable resource plasticizer for degradable poly(butylene succinate) (PBS) was successfully synthesized with isosorbide and valeric acid, and was characterized by Fourier transform infrared (FTIR). The mechanical properties, glass transition temperature (T g ), crystallization properties, rheological behavior of PBS/SDV blends was studied in detail. The results showed that incorporation of SDV had successfully reduced T g of the PBS composites, particularly at 20 wt% SDV, where the value of T g exhibited a reduction of 12 °C or 39% compared to pure PBS, demonstrating SDV possessed plasticizing efficacy. The crystallinity of PBS was declined by presence of SDV in the blends, and the incorporation of 20 wt% SDV into PBS matrix promoted an impressive decrease of exceeding 22%. Significant enhancement of the toughness and flexibility of PBS was achieved by the addition of SDV. The rheological test revealed that the decrease of modulus and viscosity improved the processing properties of the materials, which broadened the PBS applications. Altogether the SEM showed the fracture surface of the composites undergoes a brittle-tough transition with increasing SDV content below 12% content, meanwhile, significant phase separation was observed in the composites with high content of SDV.

Biobased copolyesters from renewable resources: synthesis and crystallization kinetics of poly(propylene sebacate-co-isosorbide sebacate)

The thermal properties and crystallization kinetics of a novel bio-based poly(propylene sebacate-co-isosorbide sebacate) copolyesters are explored.