Interfacial toughening and consequent improvement in fracture toughness of carbon fiber reinforced epoxy resin composites: induced by diblock copolymers

Abstract

Abstract. Carbon fibers chemically grafted with hydroxyl-terminated diblock copolymer poly (n-butylacrylate)-b-poly (glycidyl methacrylate) (OH-PnBA-b-PGMA), were used as the reinforcement for epoxy composites. The multi-filament composite specimens were prepared and measured by dynamic mechanical analysis (DMA), to study the interfacial toughness of carbon fiber reinforced epoxy composites with the diblock copolymers. The loss modulus and loss factor peaks of !-relaxation indicated that composites with diblock copolymers could dissipate more energy at small strain and possess better interfacial toughness, whereas composites without the ductile block PnBA having the worse interfacial toughness. The glass transition temperature and the apparent activation energy calculated from the glass transition showed that the strong interfacial adhesion existed in the composites with diblock copolymers, corresponding with the value of interfacial shear strength. Therefore, a strengthening and toughening interfacial structure in carbon fiber/epoxy composites was achieved by introducing the diblock copolymer OH-PnBA-b-PGMA. The resulting impact toughness, characterized with an Izod impact tester, was better than that of composite without the ductile block PnBA.

Effect of Meltable Triazine-DOPO Additive on Rheological, Mechanical, and Flammability Properties of PA6

“…This result sustains the higher resistance of the newly-developed DTE-DOPO FR additive which exhibits a strengthening effect on PA6. The results are similar with the data obtained by rheological measurements where lower values of the loss modulus were registered as compared to neat PA6, suggesting a good interfacial compatibility which restricts the movement of the chain segments, resulting in a lower toughness [49]. The better compatibility of the PA6/DTE-DOPO formulation when compared to PA6/Exolit may be explained by the nature of the two FR additives: DTE-DOPO melts during the compounding process enabling a better homogeneity with PA6, while Exolit OP 1230 is a non-meltable salt which may lead to a less uniform distribution in the polymer matrix.…”

Recent advances in fiber/matrix interphase engineering for polymer composites

“…For that purpose, functional diblock copolymers were used which are covalently bonded to the fiber surface and sufficiently compatible on the other side with the matrix. Their stress transferring and toughening effects depend obviously on the molecular weight of the block segments (diffusion into and entangling with the bulk of the matrix molecules) [90].…”

Enhanced thermal and mechanical properties of epoxy composites by mixing thermotropic liquid crystalline epoxy grafted graphene oxide

“…However, their brittleness, poor resistance to crack propagation and poor wear resistance [3,4] limit their applications. Numerous studies have been conducted to explore the toughness of epoxy composites [5,6]. Addition of thermoplastic polymers can improve fracture toughness, but it is always at the expense of the glass transition temperature (T g ) and modulus or high cost [7].…”