Effect of Phase Separation Morphology on the Adhesion of PS/PMMA Interface Reinforced with Mixed Composition of Random Copolymers

Autor: Hao-Ching chien, 簡豪慶
Rok vydání: 2004
Druh dokumentu: 學位論文 ; thesis
Popis: 92
We have measured the fracture toughness of interface between polystyrene (PS)/poly methyl methacrylate (PMMA) using mixed composition of different random copolymers of PSf-r-PMMA1-f, where f is the volume fraction of PS in the random copolymer. Nine different composition of PS-PMMA were used with f ranging from 0.1 to 0.9. We have found the fracture toughness of interface can be significantly increased with mixed random copolymer compared with that from the copolymer of single composition. It is found that with increasing concentration of the mixed random copolymer at the interface, the Gc of the interface increase quickly and finally reaches a plateau around 140 j/m2. SIMS experiments confirmed that the mixed composition of differ- ent random copolymers organize at the interface to form an artificial composition drift .It also shows the fracture toughness of a interface with multicomponents is strongly affected by annealing time. We interpret this time-effect on Gc is related with the formation of the two dimension phase separation of the blending thin film followed by TEM and AFM technic. We suggest that fracture toughness increases with time in the beginning of annealing under the interfacial welding mechanism and the rearrangement of random copolymers at PS/PMMA interface, and decreases later with the dilute mechanism which minimizes the domain size of PS-rich island. Because such phase separation structure is submicrometer-scale, minimizing of the domain size would result in the worse stability of the initiation and the widening of PS-crazing fibril. The failure mechanism is examined by ATR-FTIR technique. This method suggests a simple method for one to effectively use random copolymers for reinforcement.
Databáze: Networked Digital Library of Theses & Dissertations
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