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论文类型：期刊论文

发表时间：2017-08-01

发表刊物：JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY

收录刊物：SCIE

卷号：129

期号：2

页面范围：777-787

ISSN号：1388-6150

关键字：Poly(hexamethylene succinate); Melting behavior; Morphological changes; Annealing

摘要：The present study on the case of poly(hexamethylene succinate) is to provide a basis for a better understanding of the subtle relationship between melting behavior and morphological changes of semicrystalline polymers. The melting behavior and morphological changes of poly(hexamethylene succinate) during both isothermal secondary crystallization and annealing processes were investigated by DSC and SAXS. DSC results showed that, with increasing crystallization time or annealing time, the melting endotherm continuously shifted to higher temperature, which suggested that some minor structural or morphological changes must occur. However, almost no changes at all on the crystal thickness were observed from SAXS measurements. The observed evidence confirmed that the increase in the melting temperature is not attributed to crystal thickening but crystal perfection. More exactly, the rearrangement and smoothing of tie molecules at the folding surface result in the reduction of the fold surface free energy, which dominantly contributes to the increase in the melting peak temperature. The origin of the new endothermic peak observed after annealing at elevated temperature was also discussed. TMDSC results indicated that the annealing peak resulted from the enthalpy relaxation and devitrification transition of rigid amorphous fraction formed by the driving force of thermodynamic nonequilibrium, rather than usually regarded as the melting of thin lamellae or imperfect crystals formed by annealing secondary crystallization.