Thermal Expansion of Composite System Epoxy Resin/Recycled Carbon Fibers

Abstract

This experimental study deals with the problematics of thermal expansion α [10-6/K] of the composite systems based on recycled carbon fibres reinforced epoxy resin. The epoxy resin CHS – EPOXY 520 (EPOXY 15), cured with the hardener P11 (Districhem, s.r.o.), was chosen as a sample matrix. Recycled carbon fibres with a diameter of 7 μm and a length of 100 μm (Easy Composites Ltd.) were the filler. In the experiment, samples with the fulfilment of 10, 20, 40, 60, 80, 90 and 100 phr were prepared. The samples were being poured into silicone molds, cured at an overpressure of 0.7 MPa and a temperature of 23 ± 2 °C for 24 hours. A thermomechanical analyzer was used to determine the thermal expansion of composite systems. The addition of recycled carbon fibers to epoxy resin can reduce the coefficient of linear thermal expansion at 20°C in half, from the original α = 45 to 55 × 10-6/K for non-filled epoxy resin to α = 25 to 27 × 10-6/K for filled epoxy resin. Optimal filling is at the level of 40 phr, with higher filling there is no further reduction of the linear thermal expansion coefficient.

Use of Thermomechanical Analysis in the Design of a Composite System with a Low Coefficient of Longitudinal Thermal Expansion for End Gauges

“…The increase in the epoxy resin's fiber content has virtually no further significance for this physical property. [7] Graph of the dependence of the coefficient of longitudinal thermal expansion for the system epoxy resin -recycled carbon fibers -Fig. 5 practically copies the graph for pure epoxy resin.…”

“…The samples' composition and structure were designed to make the most of the presence of carbon fibers. In recycled carbon fibers, the fiber filling was 40 phr, which is the highest possible level of fiber content that is economical and technologically feasible [7]. In the roving and fabric case, the weight ratio of fibers to the matrix was designed to be 1:1 so that all fibers in the proposed system were perfectly wetted and samples could be prepared under laboratory conditions.…”

Destruction of Carbon and Glass Fibers during Chip Machining of Composite Systems

“…The obtained results are the basis for further research in machining composite materials and the simultaneous improvement of work safety in these operations. This experimental study followed up on previous work, which was primarily concerned with evaluating the delamination of composite systems and the wear of the tools used during chip machining [35][36][37][38]. The achieved results are essential for industrial practice, health, and safety protection in the machining of composites.…”