材料科学
退火(玻璃)
吸热
焓
聚合物
结晶
结晶度
小角X射线散射
玻璃化转变
去玻璃化
热力学
结晶学
差示扫描量热法
化学工程
复合材料
聚合物结晶
聚合物混合物
高分子化学
形态学(生物学)
熔点
球晶(高分子物理)
聚变焓
聚乙烯
无定形固体
熔点下降
微观结构
热分析
作者
Juncheng Jiang,Yang Yu,Cheng Zhou,Liuchun Zheng,Xuefei Leng,Yang Li
标识
DOI:10.1007/s10973-017-6255-y
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.
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