首页> 外文期刊>Journal of Macromolecular Science. Physics >Crystallization in microdomains of a block copolymer comprising semicrystalline block observed by simultaneous measurement of SAXS and WAXS with H-v-SALS or DSC
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Crystallization in microdomains of a block copolymer comprising semicrystalline block observed by simultaneous measurement of SAXS and WAXS with H-v-SALS or DSC

机译:通过同时用H-v-SALS或DSC测量SAXS和WAXS观察到的包含半结晶嵌段的嵌段共聚物在微区中的结晶

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摘要

Semicrystalline block copolymers provide us with a fascinating model for studying the kinetics of crystallization. We performed the simultaneous measurement of small-(SAXS) and wide-angle (WAXS) x-ray scattering (SWAXS) with differential scanning calorimetry (DSC), or SWAXS with small-angle light scattering (H-v-SALS). The specimen used was polyethylene-b-poly(ethylene propylene) (PE-b-PEP) with the molecular weight of 44,200. The PE block has the melting point (T-m) at 108degreesC. We observed the time evolution of crystallization in the lamellar microdomains of PE-b-PEP after a temperature drop from 180degreesC (T-m) to a variety of temperatures slightly below T-m. The exothermic signal was observed by DSC right after the temperature drop, while the four-leaf-clover pattern of H-v-SALS and the SAXS peaks due to the lamellar microdomains were observed several minutes after the temperature equilibration. The WAXS peaks of (110) and (200) reflection were almost simultaneously detected with the H-v-SALS and the SAXS peaks at crystallization temperature of 100degreesC. With the crystallization temperature closer to T-m, the WAXS crystalline signals showed up with longer time lag after the H-v-SALS and the SAXS peaks began to appear. Interestingly, these phenomena are interpreted as that long-range order of density fluctuation up to the order of micrometers was generated prior to the formation of crystals with partially ordered phase rather than the instantaneous crystalline nucleation. [References: 31]
机译:半结晶嵌段共聚物为我们提供了一个有趣的模型,用于研究结晶动力学。我们使用差示扫描量热法(DSC)或小角度光散射(H-v-SALS)同时测量了小(SAXS)和广角(WAXS)X射线散射(SWAXS)。所用的样品是分子量为44,200的聚乙烯-b-聚(乙烯丙烯)(PE-b-PEP)。 PE嵌段的熔点(T-m)为108℃。我们观察到温度从180摄氏度( T-m)降至略低于T-m的各种温度下降后,PE-b-PEP的层状微区中结晶的时间演变。降温后立即通过DSC观察到放热信号,而在温度平衡后几分钟观察到H-v-SALS的四叶三叶草图案和由片状微区引起的SAXS峰。在100℃的结晶温度下,几乎同时检测到(110)和(200)反射的WAXS峰与H-v-SALS和SAXS峰。随着结晶温度接近T-m,在H-v-SALS和SAXS峰开始出现之后,WAXS结晶信号以更长的时间延迟出现。有趣的是,这些现象被解释为,在形成具有部分有序相的晶体而不是瞬时晶体成核之前,产生了直至微米级的密度波动的长范围序列。 [参考:31]

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