Abstract
This paper reports the results of studying epoxy compositions with gypsum taken in the form of dispersed powders in the original and water-hardened form. The exact pattern has been shown in the way the introduction of a gypsum additive in the amount of 50 % by weight affects the strength, chemical stability, and morphology of the composites. Under conventional heat treatment (60‒110 °C) of the hardened composites, the maximum stress at compression σ m and the elasticity module at compression Е с , as well as wear resistance, decrease after the introduction of gypsums (of both types). At the same time, after a hard (destructive) heating at 250‒260 °C, the elasticity module Е с of the hardened composites increases. The maximum stress at compression σ m is also increased. The same applies to the wear resistance, which grows especially noticeably after 250 °C. The micro-hardness after filling is prone to increase but the fragility of epoxy-gypsum composites does not make it possible to measure it when a punch (a steel hemisphere) penetrates it deeper than 20 µm. However, after the heat treatment at 250‒260 °C, the unfilled polymer, on the contrary, is embrittled while the filled ones are plasticized, thus showing a high micro-hardness at significant (30‒50 µm) immersion. The composites with gypsum, in contrast to the unfilled ones, do not disintegrate in acetone and retain integrity at any aging duration (up to 75 days and beyond). In this case, the original gypsum produces a composite with less swelling in acetone than the hardened gypsum. Based on the data from atomic-strength microscopy (ASM) microscopy, the morphologies of the non-filled composite, the composites with the hardened gypsum and original gypsum are different. The original gypsum forms a composite with a more pronounced (possibly crystalline) filler structure; the morphology for the hardened composite reflects the distribution of inert particles; for the unfilled composite (H-composite), only pores are visible against the background of a relatively smooth relief
Highlights
G5 gypsum is a thin-ground white powder derived from the thermal treatment of gypsum raw materials ‒ calcium sulfate dihydrate (CaSO4*2H2O) in various modifications [1]
The introduction of gypsum to the epoxy resin alters the consistency of the composition and the morphology of the composites, which depends on the type of gypsum
The introduction of 50 % by weight of gypsum after a soft (55 °C) heat treatment of polymers leads to a drop in the strength at compression, the module, and wear resistance
Summary
G5 gypsum is a thin-ground white powder derived from the thermal treatment of gypsum raw materials ‒ calcium sulfate dihydrate (CaSO4*2H2O) in various modifications [1] In nature, it occurs in the form of rose-like druses, plates, and layers. Gypsum is capable of capturing impurity and atmospheric water, which may well contribute to its self-organization in the polymer matrix This is quite possible in the case of the use of epoxy resin as such a matrix. The results to be obtained could be useful for industrial, service, and construction practices as the technologies to form such formulations are currently mainly at the level of experimental application Those large organizations that can afford specialized laboratories and appropriate research often do not report results for open access because of their commercial use
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
