Effects of isomorphic poly(butylene succinate-co-butylene fumarate) on the nucleation of poly(butylene succinate) and the formation of poly(butylene succinate) ring-banded spherulites

The nsucleation effects of isomorphic poly(butylene succinate-co-butylene fumarate)s (PBSFs) on poly(butylene succinate) (PBS) were investigated using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). When the content of PBSF is fixed at 2.0 wt% in the PBSF/PBS blends, the nucleation efficiency of PBSF is related to the BF molar ratio in PBSF. Nucleation efficiency is not observed when the molar ratio of BF is ≤5%; the nucleation efficiency is weak when the molar ratio of BF is between 10% and 30% and the nucleation efficiency is strong when the molar ratio of BF is ≥40%. In fixing the nucleating agent as PBSF-5 (the BF molar ratio of PBSF is 5%), the nucleation efficiency of PBSF-5 is related to its content in the PBSF-5/PBS blends. Nucleation efficiency is not observed when the content of PBSF-5 is ≤2.0 wt% and the nucleation efficiency strengthens dramatically when the content of PBSF-5 is ≥5.0 wt%. POM images reveal the changes of PBS ring-banded spherulites in the PBSF/PBS blends. The band spacing of PBS in the PBSF/PBS blends decreases with the increase of the BF molar ratio of PBSF or the content of PBSF-5. The cell parameters of the PBSF nucleating agent are important in the formation of PBS ring-banded spherulites. No PBS ring-banded spherulite forms when the BF molar ratio of PBSF is ≥40%. In the PBSF-5/PBS blends, the crystallization temperature range of the ring-banded spherulite formation gradually narrows when the content of PBSF-5 is ≥5.0 wt%. In this work, clarifying the slight structure difference of isomorphic PBSFs on the epitaxial nucleation and the formation of PBS ring-banded spherulites is advantageous.