Microfilled Epoxy-Composites, Capable of Thermo-Hardening and Thermo-Plasticization After Hard Heating (200-300 ОC) - For “in-Field\Offroad” Use in Bio-, Agro-, Medservice

Abstract

The work is devoted to the study of a new type of composites for the manufacture of special details, parts, tools or adhesive repair in the field. We have developed epoxy compounds that preserve or increase strength and ductility after heating at 200-250oC. That let, if necessary, an effective thermo-disinfection of composite toolsproducts at elevated temperatures. It is believed that conventional epoxy resins are unable to retain their physical and mechanical properties after heating above 200°C. Their feature is in simplicity of making (ordinary filling with available\cheap microfillers) without special qualification of personnel and in any conditions (outside clinics, laboratories and service centers). In this work some of such compositions (with SiC, TiN, SiO 2 -marshalite, cement) are considered. It offers to name such composites of "thermo-harden" or "thermo-plasticized". Bioneutrality, durability and heat-resistance, at 200-300 о С does him a good material for rapid repair and making of the special or failing instruments in the field, travelling, military and other difficult terms.

Scientific foundations of solving engineering tasks and problems

“…Another example of thermal hardening and thermal plasticization (elimination of unwanted brittleness) is observed for compositions of epoxy with water-bindersgypsum G5 and cements M400-M500 (table 4). These effects were recorded and published by us in works [118,124,126,130]. After 250 ° C, the compressive strength of composites with the neat (non-hydrated) cement almost does not change, and with pre-cured it increases, while the unfilled polymer noticeably (by one third) loses its strength.…”

“…In 2017, Starokadomsky first published a work with a cursory description of a new interesting effect -hardening of an epoxy composite with micro-iron [119] after destructive heating of the composite. This effect looked strange and even artifact, but later it was observed on epoxy composites with silicates [118], gypsum [118,124] and carbide [126,130] fillers. Thus, we are talking about a phenomenon that allows the creation on the basis of conventional (non-heatresistant) polymer components of epoxy composites with high durability (and even hardening & strengthening) of their characteristics in the "hot" range of 250  350 °C, which is uncharacteristic for plastics (even standard epoxy plastic).…”

Strength and chemical resistance of composites based on epoxy resins, filled with gypsum in the original and water­hardened forms

“…A series of promising gypsum epoxy polymers have been developed, described in several earlier published papers [3][4][5][6]. Thus, according to [3], the introduction of G-5 gypsum in the amount of 10-75 % by weight makes it possible to obtain composites with acceptable strength and durability; at the same time, certain characteristics considerably improve (adhesion to steel, resistance to organic solvents).…”

“…This is quite possible in the case of the use of epoxy resin as such a matrix. It is known [3][4][5][6] that epoxy resin is not water-soluble, so water impurities have an undesirable effect in the process of polymerization, leading, in particular, to the clouding and loss of mechanical properties of the polymer. The presence of gypsum-alabaster (binding such water) in resin can become an additional stimulant to enhance the epoxy polymer composite.…”