Curing Effects on Interfacial Adhesion between Recycled Carbon Fiber and Epoxy Resin Heated by Microwave Irradiation

Abstract

The interfacial adhesion of recycled carbon fiber (CF) reinforced epoxy composite heated by microwave (MW) irradiation were investigated by changing the curing state of the epoxy resin. The recycled CF was recovered from the composite, which was prepared by vacuum-assisted resin transfer molding, by thermal degradation at 500 or 600 °C. Thermogravimetric analysis showed that the heating at 600 °C caused rough damage to the CF surface, whereas recycled CF recovered at 500 °C have few defects. The interfacial shear strength (IFSS) between recycled CF and epoxy resin was measured by a single-fiber fragmentation test. The test specimen was heated by MW after mixing the epoxy resin with a curing agent or pre-curing, in order to investigate the curing effects on the matrix resin. The IFSSs of the MW-irradiated samples were significantly varied by the curing state of the epoxy resin and the surface condition of recycled CF, resulting that they were 99.5 to 131.7% of oven heated samples Furthermore, rheological measurements showed that the viscosity and shrinking behaviors of epoxy resin were affected based on the curing state of epoxy resin before MW irradiation.

Combined Molecular Dynamics and DFT Simulation Study of the Molecular and Polymer Properties of a Catechol-Based Cyclic Oligomer of Polyether Ether Ketone

“…These polymers exhibit attractive material properties. For example, thermosetting polymer resins feature lower processing viscosity [4] and excellent fiber adhesion [5], and have found applications in injection and prepreg manufacture [6], paints [7], and nanocomposite materials [8]. Likewise, their thermoplastic features include high molecular weight [9], excellent thermal insulation ability [10] and high heat resistance [11].…”

Microwave Modification of an Epoxy Basalt-Filled Oligomer to Improve the Functional Properties of a Composite Based on It

“…Thus, under the action of an external load on the epoxy matrix, it transfers this load to the filler more effectively due to stronger bonds at the phase boundary, thereby reducing the number of defects on the chipped surface. The improvement in interfacial interaction can be noted in a decrease in the number of basalt microfibers pulled out of the matrix and in the uniformity of the matrix at the chipped boundary (Figure 14b) [39,40]. The study of the brittle chip of the EB PCM is important for the development of the theory of the influence of a microwave EMF on the mechanism of the structural interaction between the epoxy matrix and the basalt filler (Figure 14) under the influence of a microwave EMF.…”

“…Thus, under the action of an external load on the epoxy matrix, it transfers this load to the filler more effectively due to stronger bonds at the phase boundary, thereby reducing the number of defects on the chipped surface. The improvement in interfacial interaction can be noted in a decrease in the number of basalt microfibers pulled out of the matrix and in the uniformity of the matrix at the chipped boundary (Figure 14b) [39,40]. Analysis of the results of IR spectroscopy (Figure 15) showed the presence of OH groups (3446 cm −1 ), CH2 (2967 cm −1 ) and CH3 (2928-2873 cm −1 ) in the unmodified epoxybasalt plastic, confirmed by the peaks of their deformation vibrations.…”

Modeling of the Modification Process of an Epoxy Basalt-Filled Oligomer in Traveling Wave Microwave Chambers

“…When an external electric field is applied, the molecules are polarized; that is, the symmetry of the arrangement of their charges breaks and they acquire a certain electric moment [15,19]. Epoxy oligomers are the most promising among other organic macromolecular substances and are of great interest as objects of the study of the effects of microwave electromagnetic fields due to their polarity [33,34]. However, there is no information in the literature on obtaining optimal parameters of electrical and thermal processes in the "epoxy oligomer-dispersed filler" system under microwave exposure, which confirms the relevance of solving the problem of choosing a microwave chamber design.…”