Double-phase morphology of high molecular weight poly(methyl methacrylate)-epoxy blend
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The double-phase morphology of 5 wt% high molecular weight poly(methyl methacrylate) (PMMA) modified epoxy system was investigated by optical and scanning electron microscopic (SEM) techniques. PMMA-epoxy blend cured at 100 °C revealed that a bicontinuous secondary phase separation was observed in both epoxy and PMMA phases in the early stages of curing. Epoxy-rich particles were dispersed in the PMMA-rich phase, while PMMA-rich particles were segregated in the epoxy-rich phase, leading to double-phase bicontinuous morphology. The spinodal decomposition mechanism could probably be responsible for this secondary phase separation. From the SEM analysis, a morphology consisting of a rough striated continuous phase along with large smooth regions was observed. Rough striated domains are ascribed to the PMMA-rich phase and the smooth domains are assigned to the epoxy-rich phase, thus confirming the secondary phase separation. The PMMA-epoxy blend showed a slight increase in flexural properties and about 20% improvement in the fracture toughness.
KeywordsFracture Toughness PMMA Flexural Property Neat Epoxy Modify Epoxy
This work was supported by the Second Stage Brain Korea 21 Program of the Ministry of Education and Human Resources Development of Korea Government. Part of this research was supported by a grant 07KURC-A03 and 07RND B03 funded by Ministry of Construction & Transportation, also the grant R01-2007-000-20765-0 funded by Ministry of Science & Technology is appreciated.