Formation of phase structure and crystallization behavior in blends containing polystyrene–polyethylene block copolymers
Formation of phase structure and crystallization behavior in blends containing polystyrene–polyethylene block copolymers
复制标题
DOI：
10.1016/j.polymer.2007.11.002
复制
发表时间：
2007-12
期刊：
影响因子：
4.6
通讯作者：
Hiroki Takeshita;Yuan Gao;T. Natsui;E. Rodríguez;M. Miya;K. Takenaka;T. Shiomi
中科院分区：
文献类型：
--
作者：
Hiroki Takeshita;Yuan Gao;T. Natsui;E. Rodríguez;M. Miya;K. Takenaka;T. Shiomi
用同步辐射小角X射线散射技术(SAXS)研究了聚苯乙烯-聚乙烯嵌段共聚物(SE)与聚苯乙烯均聚物(PS)和聚乙烯均聚物(PE)共混物以及由两种不同组成的嵌段共聚物组成的共混物熔融状态下的微相分离结构和有序熔体中结晶结构的形成。SE嵌段共聚物的组成分别为0.34、0.58和0.73重量份，熔体形态分别为圆柱形、片状和片状。到目前为止，熔体中的大相分离或形态变化取决于分子量和共混物的组成。在这种宏观相分离和微相分离熔体的结晶过程中，所有共混物的熔体形态都完全保持不变。并对共混物的结晶行为进行了研究。在SE/PS共混物中，未观察到玻璃态PS包围的球形和圆柱形微区内的结晶。在大相分离熔体的结晶过程中，在DSC测量中观察到两个放热峰，而对于其他共混物则观察到一个单峰。与纯SE相比，PS共混物的结晶度降低，结晶表观活化能增大。对于SE/PE和SE/SE共混物，这些变化取决于共混物的组成。
The microphase separation structure in the molten state and the structure formation in crystallization from such ordered melt were investigated for the blends of polystyrene–polyethylene block copolymers (SE) with polystyrene homopolymer (PS) and polyethylene homopolymer (PE) and for the blends consisting of two kinds of SE with different copolymer compositions from each other, using synchrotron small-angle X-ray scattering techniques (SAXS). The copolymer compositions of SE block copolymers employed were 0.34, 0.58 and 0.73 wt. fraction of PE, and their melt morphologies were cylindrical, lamellar and lamellar, respectively. Macrophase separation or the morphology change in the melt occurred depending on the molecular weight and the blend composition, as reported so far. In crystallization from such macrophase-separated and microphase-separated melts, the melt morphology was completely kept for all the blends. Crystallization behavior was also investigated for the blends. The crystallization within the spherical and cylindrical domains surrounded by glassy PS was not observed for SE/PS blends. In the crystallization from the macrophase-separated melt, two exothermal peaks were observed in the DSC measurements, while a single peak was observed for other blends. For the blends with PS, the degree of crystallinity was depressed and the apparent activation energy of crystallization was high, compared to those for the corresponding neat SE. For SE/PE and SE/SE blends, those were changed depending on the blend composition.