Further Promoting Form <scp>II</scp>‐To‐Form I Phase Transition in Low‐Molecular‐Weight Polybutene‐1 by Addition of Heating/Cooling Cycles Into Nucleation Stage of Form I

ABSTRACT Despite employing a two‐step annealing method, Form II to Form I phase transitions in some low‐molecular‐weight polybutene‐1 (LMWPB‐1) samples are still slow. In this study, we checked if the phase transition in a LMWPB‐1 can be further accelerated or not by incorporating a number of heating/cooling cycles into the low‐temperature nucleation stage. Results indicated that the addition of heating/cooling cycles not only promoted the nucleation of Form I but also the growth of Form I. More importantly, it was found that when the cycle time was greater than 10, the phase transition can be further accelerated significantly. We conjecture that the abrupt increase in the peak at 128°C during a heating/cooling cycle was related to the intermediate layer between Form I and Form II. The heating/cooling cycle can promote the diffusion of the intermediate layer, especially the intermediate layer along the crystal edge. Constant heating/cooling can help the Form I domain obtain a stable and larger growth interface, promoting Form II to transform into Form I at the greatest rate. Based on the above results, we suggest incorporating a heating/cooling cycle into the two‐step annealing process to further accelerate the phase transition in LMWPB‐1.