Magnetic cork particles as reinforcement in an epoxy resin: effect of size and amount on thermal properties

Abstract

Natural brightness of epoxy adhesives can be reduced by adding cork. Besides, when cork was magnetized, it was possible to move them depending on the properties required in each section of the adhesive bond (PAT354/2019). The main objective of this work was to study possible changes in the thermal properties of the adhesive due to the addition of magnetic cork particles. If changes were significant, the use of magnetic cork particles would be compromised. To this end, natural cork particles and magnetic cork particles, with two different particle size (53–38 and 250–125 μm) and percentage (1 and 5 v/v%), were compared as reinforcement material. Magnetic cork was obtained by co-precipitated coating, according to patent number WO2019025651. The thermal properties studied by Differential Scanning Calorimetry were activation energy of curing reaction, glass transition temperature (Tg) and thermal conductivity. Two different hardeners were studied and a factorial design (2k with k = 4) was carried out. It allowed to determine which variable or combination of variables had most impact on thermal properties. Results showed that the main parameter affecting thermal properties was the hardener, regardless of the kind of particle used. However, the presence of magnetic cork highlights further the differences found between hardeners. The conclusion of this study was that magnetic cork particles can be used as fillers in epoxy resin to make graded joints, since they do not affect the thermal properties of the resin. Graphical abstract

Influence of the Magnetization of Thermally Expandable Particles on the Thermal and Debonding Properties of Bonding Joints

“…The resulting Tg was 107 °C i initial scan, accompanied by a minor relaxation enthalpy peak. In a subsequent scan Tg rose to 117 °C [19]. This temperature closely aligns with the expansion temperatu TEPs.…”

“…Numerous empirical models have been developed to explore these effects in epoxy resins, given their applications as structural adhesives and in the production of composite materials, such as those incorporating carbon and glass fibers. Several models have been investigated in previous studies for both pure resins and composites [19,61,62]. In this work, Kamal's method has been chosen because it gives an idea of the two mechanisms, Equations ( 2) and (3) [63].…”

“…Adhesives like epoxy, polyurethane, and acrylics offer high structural strength and load-bearing capacities. However, handling them can be tricky, as they require special surface treatments [15][16][17] and extended curing times [18,19]. Nevertheless, adhesives offer benefits such as weight reduction, improved stress distribution, and increased corrosion resistance [15,20].…”

Novel Sustainable Composites Incorporating a Biobased Thermoplastic Matrix and Recycled Aerospace Prepreg Waste: Development and Characterization

“…Bahrami et al [ 17 ] obtained the T g of the polyamide using DSC at a heating rate of 20 °C/min. The considered T g value corresponds to the second heating cycle after erasing PA11 thermal history [ 42 ]. Butenegro et al [ 26 ] obtained the T g of the polyamide and that of composites manufactured with reused CFRP and polyamide using DMA at a heating rate of 3 °C/min.…”

Kinetic Study of Anaerobic Adhesive Curing on Copper and Iron Base Substrates

“…This model is typically applied in epoxy adhesives, but can be applied in any process in which an exothermic or endothermic reaction occurs, such as polymerization or curing [ 34 ] and decomposition [ 35 ].…”