Two-matrix composites: Carbon fiber micropultrusions embedded in flexible epoxy matrices

Abstract

Two-matrix composites combine fibers with two distinct matrices. This is achieved by impregnating fiber bundles with a high-stiffness matrix and embedding the cured bundles in a flexible matrix. Two-matrix composites have been shown to offer unprecedented combinations of transverse flexibility and longitudinal tensile strength, and could offer improved fiber alignment and manufacturability. Here, we explore this concept further by embedding carbon fiber micropultrusions in flexibilized epoxy matrices and examining the longitudinal compression behavior. Our results on thin-walled rings reveal that the failure mode depends on micropultrusion diameter, with small diameters resulting in micropultrusion kinking and larger diameters in splitting and crushing. Additionally, we find that two-matrix composites can offer higher compression strength than conventional composites with the same flexible matrix, despite a lower fiber volume fraction. The inherent manufacturing advantages and high anisotropy could make two-matrix composites interesting candidates for specific applications, such as morphing wings or additively manufactured composites.

Thermoplastic Pultrusion: A Review

“…In addition, the appliance compatible with magnetic resonance (MR) was pultruded and tested in various MR-guided cases aimed to study the behavior of arteries [ 385 ]. Recently, an experimental study [ 386 ] demonstrated the feasibility of thermoset micropultrusion of 280 µm-diameter carbon fiber elements, and proposed the use of thermoplastic matrices as a recommendation for further research.…”

Pultruded materials and structures: A review

“…171 With the current level of technology, the profiles as small as 280 micrometers in diameter can be pultruded. 172 It is possible to pultrude both thermoset and thermoplastic components. 172,173 An extensive outlook regarding the possible future of thermoplastic micro-pultrusion can be found in the recent paper of Callens and Bergsma.…”

“…172 Generally speaking, knowledge of micro-pultrusion is very limited, and the only applications discussed in the literature so far are the following: medical 174–176 and aircraft industry. 172…”

“…172 It is possible to pultrude both thermoset and thermoplastic components. 172,173 An extensive outlook regarding the possible future of thermoplastic micro-pultrusion can be found in the recent paper of Callens and Bergsma. 172 Generally speaking, knowledge of micro-pultrusion is very limited, and the only applications discussed in the literature so far are the following: medical [174][175][176] and aircraft industry.…”

“…172,173 An extensive outlook regarding the possible future of thermoplastic micro-pultrusion can be found in the recent paper of Callens and Bergsma. 172 Generally speaking, knowledge of micro-pultrusion is very limited, and the only applications discussed in the literature so far are the following: medical [174][175][176] and aircraft industry. 172 Development of fast curing alternatives for composites manufacturing processes still goes on.…”