Poly(oxymethylene)/poly(butylene succinate) blends: Miscibility, crystallization behaviors and mechanical properties

In this work, we investigated the miscibility, crystallization behaviors and mechanical properties of the crystalline/crystalline poly(oxymethylene)/poly(butylene succinate) (POM/PBSU) blends. It was found that POM and PBSU are miscible in the melt state. The POM with a higher melting temperature (T-m) crystallizes first into banded spherulites and the crystals fill the whole melt space when cooling from the melt state. The low-T-m PBSU is simultaneously excluded into interfibrillar regions of the POM spherulitic frameworks. The crystallization of PBSU then takes place within the POM spherulites over a wide composition range. Moreover, we observed a significant increase in the crystallization rate of PBSU in the blends with PBSU content > 50%. It is ascribed to the nucleating effect of POM crystals on PBSU crystallization. However, the growth kinetics of PBSU is depressed when PBSU content is < 50%, which is attributed to the decrease of the interconnectedness of the PBSU molten phase within the interfibrillar regions of POM spherulites. Therefore, POM/PBSU blends form a crystal interfibrillar structure with the independent glass transition temperature in the solid state at room temperature. It was further found that the toughness of POM is enhanced by incorporation with PBSU, while the heat resistance of PBSU is improved due to the solid POM crystal frameworks in the blends.