a b s t r a c tIn this study, the cure kinetics, rheological and electrical behaviors of the MWCNTs/epoxy nanocomposites produced using a three-roll mill are studied. After defining the domain of linear response, the influence of temperature and MWCNTs on the shear viscosity has been investigated. The shear-thinning effect caused by adding CNTs to the epoxy matrix is more pronounced at increased temperature and MWCNT weight content. Furthermore, a mechanical manifestation of the percolation phenomenon may have been observed. At last the electrical conductivity was investigated to characterize the percolation behavior and determine the best CNT content/electrical properties ratio.
Ring filament winding enables processing of continuous fibers for manufacturing unidirectional non-crimp unidirectional preform plies on straight-, curved-, or closed-mandrel geometries. However, unidirectional processing of tows can lead to increased lateral tow slippage. The objective of the present study is thus to validate unidirectional winding methods for ring filament winding, performing geodesic and non-geodesic trajectories analytically and experimentally. Implementation of geodesic paths investigates the influence of the tensile force and take-up velocity on the winding angle reproducibility. Non-geodesic winding paths are conducted here dependent on winding methods, slippage coefficients, and the mandrel's surface materials, evidencing the occurrence of lateral tow slippage by measurements of nip-point forces. Findings indicate an excellent reproducibility of geodesic paths independent of the process velocity. Non-geodesic paths were partially validated because of the occurrence of lateral tape-slippage and a tape side-inclination effect, correlating an increased stick behavior to higher local normal pressure.
The aim is to study methods to improve the fire properties of carbon fibre reinforced epoxy composites with interlayers without compromising structural performance, i.e. using a carbon fibre veil with expandable graphite, an intrinsically flame retardant thermoplastic film or a carbon fibre reinforced thermoplastic (CFTP) layer. The CFTP layer seems the most promising, with a significant improvement in fire properties as determined with cone calorimetry, while the mechanical performance of the modified composite appears unaffected.
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