Print Email Facebook Twitter Synergistic Toughening of Epoxy through Layered Poly(ether imide) with Dual-Scale Morphologies Title Synergistic Toughening of Epoxy through Layered Poly(ether imide) with Dual-Scale Morphologies Author Teuwen, Julie J.E. (TU Delft Aerospace Structures & Materials) Farooq, U. (TU Delft Aerospace Structures & Materials) Alderliesten, R.C. (TU Delft Aerospace Structures & Materials) Dransfeld, C.A. (TU Delft Aerospace Manufacturing Technologies; TU Delft Aerospace Structures & Materials) Department Aerospace Structures & Materials Date 2023 Abstract Toughness of epoxies is commonly improved by adding thermoplastic phases, which is achieved through dissolution and phase separation at the microscale. However, little is known about the synergistic effects of toughening phases on multiple scales. Therefore, here, we study the toughening of epoxies with layered poly(ether imide) (PEI) structures at the meso- to macroscale combined with gradient morphologies at the microscale originating from reaction-induced phase separation. Characteristic features of the gradient morphology were controlled by the curing temperature (120–200 °C), while the layered macro structure originates from facile scaffold manufacturing techniques with varying poly(ether imide) layer thicknesses (50–120 μm). The fracture toughness of the modified epoxy system is investigated as a function of varying cure temperature (120–200 °C) and PEI film thickness (50–120 μm). Interestingly, the result shows that the fracture toughness of modified epoxy was mainly controlled by the macroscopic feature, being the final PEI layer thickness, i.e., film thickness remaining after partial dissolution and curing. Remarkably, as the PEI layer thickness exceeds the plastic zone around the crack tip, around 62 μm, the fracture toughness of the dual scale morphology exceeds the property of bulk PEI in addition to a 3 times increase in the property of pure epoxy. On the other hand, when the final PEI thickness was smaller than 62 μm, the fracture toughness of the modified epoxy was lower than pure PEI but still higher than pure epoxy (1.5–2 times) and “bulk toughened” system with the same volume percentage, which indicates the governing mechanism relating to microscale interphase morphology. Interestingly, decreasing the gradient microscale interphase morphology can be used to trigger an alternative failure mode with a higher crack tortuosity. By combining facile scaffold assemblies with reaction-induced phase separation, dual-scale morphologies can be tailored over a wide range, leading to intricate control of fracture mechanisms with a hybrid material exceeding the toughness of the tougher phase. Subject reaction-induced phase separationfracture toughnessepoxypoly(ether imide) (PEI)interphase formationmorphology To reference this document use: http://resolver.tudelft.nl/uuid:df125f34-2ed7-47b8-8b9b-7955eb677054 DOI https://doi.org/10.1021/acsami.3c10096 ISSN 1944-8244 Source ACS applied materials & interfaces, 15 (45), 53074–53085 Part of collection Institutional Repository Document type journal article Rights © 2023 Julie J.E. Teuwen, U. Farooq, R.C. Alderliesten, C.A. Dransfeld Files PDF farooq_et_al_2023_synergi ... logies.pdf 9 MB Close viewer /islandora/object/uuid:df125f34-2ed7-47b8-8b9b-7955eb677054/datastream/OBJ/view