Crystallization and Higher-Order Structure Formation in Multiphase Polymers - Effects of Microphase Separation -

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(1)Formation of higher-order structure on crystallization from microphase-separated melts was studied for both block copolymers having rubbery and glassy amorphous components, respectively. For the former block copolymers the structure was reorganized on crystallization from lamellar melt, while for the block copolymers having a crystalline component in the cylindrical microdomain they crystallized within the microdomain. On the other hand, the latter block copolymers crystallized within the microdomain regardless of their microphase separation structure, lamella or cylinder. In the crystallization of the latter block copolymers a small Avrami exponent and high apparent activation energy of crystallization were observed. (2) In crystalline-crystalline block copolymers where the melting temperatures of both components are close to each other, one component took priority in crystallization, followed by crystallization of the other component, as a result double spherulites like a concentric circle were formed in the ABA triblock copolymer. (3) Both nucleation densities and growth rates depended on the graft density in crystallization of graft copolymers.