High-Strength Hollow Glass Microsphere/Epoxy Resin Composite Insulation Materials for Deep In-Situ Condition Preserved Coring

Abstract

To establish in-situ fluidized coal mining technology and a theory of mining mechanics for deep coal resources, it is crucial to obtain a “fidelity rock core” that maintains deep in-situ conditions to understand the physical mechanics of deep rock. Doing so requires the development of in-situ condition-preserved coring (ICP-coring) technology. In this work, hollow glass microsphere/epoxy resin (HGM/EP) composite insulation materials with high strengths were prepared. An epoxy resin matrix with high strength and high-temperature resistance was selected from among epoxy resins cured by different curing agents. Then, a series of composite insulation materials with different HGM volume fractions were prepared. The mechanical strengths of the composites decreased with increasing HGM volume fraction. Then, thermal insulation materials suitable for different ICP-coring depths were selected. Changes in the thermal conductivities and mechanical strengths of the composites were characterized after they were subjected to high water pressure (45 MPa). Verification of the applicability of the thermal insulation material under high water pressure (45 MPa) conditions demonstrated that it met the working requirements for the ICP-coring device.

Rational design of high‐performance epoxy/expandable microsphere foam with outstanding mechanical, thermal, and dielectric properties

“…The significant one over 400 C was attributed to the decomposition of epoxy matrix. Compared with the thermal stabilities of epoxybased foams prepared by chemical foaming (addition of a blowing chemical) or physical foaming (addition of HGMs or polymer particles) method, 22,23,28,29 it can be figured out from Table S2 that thermal stabilities of E-51/ EMP foams were competitive. The thermal stability of polymer foams are primarily related to the thermal resistance of matrix itself.…”

“…Figure 8 also gives a comparison on the performance of various epoxy foams. 22,23,26,28,29 Compared with other epoxy-based foams, E-51/EMP foam showed the most comprehensive mechanical, thermal, and dielectric properties. The introduction of EMP transforms the epoxy resin from a solid single-phase to a solid-gas two-phase structure.…”

“…25 A classical example is the epoxy/hollow glass microsphere (HGM) foam. [26][27][28][29] Zhu et al 26 mixed different HGM with epoxy and the lowest density of the foam was 0.691 g/cm 3 . In comparison with pure epoxy, the thermal expansion coefficient and dielectric constant of epoxy/HGM foam (0.6 g/cm 3 ) were decreased by 54.3% and 28.6%, respectively.…”

“…An epoxy/HGM insulation foam that could withstand a high liquid pressure of 45 MPa was also realized. 29 In these epoxy/HGM foams, the pore size could be well controlled by the reasonable choice of the HGM size. However, the maximum addition of HGM into epoxy resin was limited to around 60 wt% due to the filler effect.…”

“…Alternatively, introducing porous fillers into epoxy is a simple and mild operation manner 25 . A classical example is the epoxy/hollow glass microsphere (HGM) foam 26–29 . Zhu et al 26 mixed different HGM with epoxy and the lowest density of the foam was 0.691 g/cm 3 .…”