Sub-phase design for electrospun nanofibrous interlayer toughening in hierarchical composites
Bilge, Kaan (2017) Sub-phase design for electrospun nanofibrous interlayer toughening in hierarchical composites. [Thesis]
Interlayer toughening of composite materials forms the basis of this thesis work. Two out of the box application oriented case studies present incorporation of polystyreneco- glycidyl methacrylate (P(St-co-GMA)) based nanofibers to carbon/epoxy prepreg surfaces as interlayers. The effect of nanofibrous interlayer toughening approach on the in-plane strength of composites with/without stress raisers (such as holes) is initially evaluated. Performance of interlayer toughened thick laminated composites under high strain load conditions is then exemplified. While elaborating potential material limits for thermoplastic nanofibrous interlayers, novel heat stimuli in-situ crosslinking methodology and its integration into composite curing are discussed. Continously electrospinnable P(St-co-GMA)/Phtalic Anhydride(PA)- Tributyl Amine(TBA) nanofibers are able to crosslink inside the epoxy matrix upon reaching certain initiation temperature. The novel concept of self-same nanocomposites formed only through electrospinning and its stand-alone thermal processing is also presented. Enhanced curing associated with the epoxy-P(St-co-GMA)/PA-TBA nanofiber interaction is demonstrated through cure kinetics study. Superior mechanical properties in each case study are extensively elaborated through fracture surface analyses.
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