Equilibrium melting temperature and crystallization kinetics of α- and β′-PBN crystal forms

Abstract

The melting behavior and crystallization kinetics of PBN-PDEN and PBN-PTDEN copolymers were investigated using differential scanning calorimetry. Multiple endotherms were observed in all of the copolymers under investigation, originating from melting and recrystallization processes. By applying the Hoffman-Weeks method, the T m° of the α and β′-PBN phases were derived. The T m° value of the β′-form, which has not been determined before, is significantly higher, as expected, because the β′-phase is thermodynamically favored and more tightly packed. The isothermal crystallization kinetics were analyzed according to the Avrami treatment. The presence of either oxygen or sulfur atoms in the PBN polymeric chain was found to reduce its crystallizability. In particular, the crystallization rate regularly decreased as the co-unit content was increased. Lastly, the α-PBN phase was found to crystallize faster than β′-one, which is expected, as it the more kinetically favored phase. © 2012 The Society of Polymer Science, Japan (SPSJ) All rights reserved.