Current Status of Research on the Modification of Thermal Properties of Epoxy Resin-Based Syntactic Foam Insulation Materials

Abstract

As a lightweight and highly insulating composite material, epoxy resin syntactic foam is increasingly widely used for insulation filling in electrical equipment. To avoid core burning and cracking, which are prone to occur during the casting process, the epoxy resin-based syntactic foam insulation materials with high thermal conductivity and low coefficient of thermal expansion are required for composite insulation equipment. The review is divided into three sections concentrating on the two main aspects of modifying the thermal properties of syntactic foam. The mechanism and models, from the aspects of thermal conductivity and coefficient of thermal expansion, are presented in the first part. The second part aims to better understand the methods for modifying the thermal properties of syntactic foam by adding functional fillers, including the addition of thermally conductive particles, hollow glass microspheres, negative thermal expansion filler and fibers, etc. The third part concludes by describing the existing challenges in this research field and expanding the applicable areas of epoxy resin-based syntactic foam insulation materials, especially cross-arm composite insulation.

Study on the foaming behavior of density‐controllable epoxy resin composite foam under negative pressure environment

“…At present, the preparation methods of thermosetting ERCF are mainly focused on the chemical foaming method, physical foaming way, and hollow microsphere‐filled foaming strategy 7–11 . For example, Ma et al 12 prepared a new composite foaming agent by filling the cells of microporous silica with the chemical foaming agent 4,4′‐oxobenzenesulfonyl hydrazide (OBSH), which can be used as both filler and foaming agent, and the ERCF can be easily produced by the decomposition of the foaming agent.…”

“…[4][5][6] At present, the preparation methods of thermosetting ERCF are mainly focused on the chemical foaming method, physical foaming way, and hollow microspherefilled foaming strategy. [7][8][9][10][11] For example, Ma et al 12 prepared a new composite foaming agent by filling the cells of microporous silica with the chemical foaming agent 4,4 0oxobenzenesulfonyl hydrazide (OBSH), which can be used as both filler and foaming agent, and the ERCF can be easily produced by the decomposition of the foaming agent. The advantage of this method is that good-performance foam can be produced by simple process operations, 13,14 but the disadvantage is obvious, for example, lots of organic chemical foaming agents or their by-products are toxic, and the incomplete decomposition of foaming agent as well as its decomposition residues make negative effect on mechanical properties of the material, so the use of chemical foaming agent has become one of the main problems affecting the performance of ERCF.…”

High-Strength and Shape-Memory Epoxy Cellular Material with Wood-Like Architecture

“…Cellular plastics have been extensively applied in packaging, − transportation, − engineering, , and aircraft , due to their outstanding mechanical performance, shock absorption, thermal insulation, and low density. In particular, epoxy cellular plastics, , one of the most commonly used cellular plastics, have drawn considerable attention for their excellent mechanical properties. Especially, epoxy cellular plastics with excellent compression resistance, low weight, and thermal stability are broadly applied in marine equipment, aircraft, − and vehicles. − During the past decades, many foaming technologies, such as chemical, solid-state, and CO 2 foaming, , have been developed to manufacture epoxy cellular plastics in the industry.…”

Teardrop-Shaped Hollow Polystyrene Nanoparticles for Improving the Mechanical and Thermal Properties of Polyvinyl Alcohol-Based Syntactic Foam Films

“…Among them, hollow glass and fly ash microspheres as the reinforcing fillers have been widely investigated. − Nevertheless, the interface incompatibility between the inorganic hollow particle and the polymeric matrix usually sacrifices mechanical properties of syntactic foams. The surface treatment for inorganic hollow particles by grafting polymer compatibilizers and coupling agents is an effective and practical solution. , However, these pre-processing measures easily cause the inevitable defects on the hollow surface glass/carbon microspheres, which weakens the durability of syntactic foams.…”

“…The surface treatment for inorganic hollow particles by grafting polymer compatibilizers and coupling agents is an effective and practical solution. 5,6 However, these preprocessing measures easily cause the inevitable defects on the hollow surface glass/carbon microspheres, which weakens the durability of syntactic foams.…”