“…Besides, as the free volume continues to increase along with increasing temperature, the glass transition occurs where large chain segments start moving, whereby the transition is dependent on the degree of polymerization or the critical molecular weight [28,29]. Additionally, Hao et al [30] found that the higher the molecular mass, the stronger the crystallization ability, which is in the agreement with the observations made herein. Moreover, the values of heat capacities, corresponding to T g , are in the agreement with the estimations of the crystallinity degree, since T g occurs in either amorphous materials or amorphous region in the materials, so the corresponding heat capacities exhibited lower values for materials with higher M w , and thus T g and X c (PHF_2).…”