"Restorative Bio-Compatible Prosthetic Epoxy-Zeolite Composites: Strength and Resistance"

A study on the complex effect of the microdisperse fraction of zeolite 50 wt% on the strength...

Prosthetics has a long history. Even medieval Caribbean pirates also often had wooden legs and iron hooks instead of hands and fingers, and there have been attempts at dental prosthetics since primitive times. However, real shifts in science and practice began in the last century. Already in the 2 nd World War, there are vivid examples of the effectiveness of prosthetics for maintaining extreme loads. So, the Soviet pilot A. Maresyev (Figure 1), after being wounded and amputated of his legs, returned to the sky and flew with prostheses.
In total, during the war, he made 86 sorties, shot down 10 enemy (german) aircraft: three before being wounded and seven after.
A. Maresyev  lost his legs at the age of 37, but with prostheses he lived an active life for another 59 years, and died almost at 90 years old in the new XXI-th century. He became the prototype for the hero of the soviet bestseller "The Story of a Real Man" [28,29].  [28][29] and Wikipedia.org).

Required Reagents and Method of Obtaining Composites
The Czech cold-hardening epoxy resin "Epoxy520" (Figure 2) was used for the works, which was cured with PEPA polyamine in a ratio of 5:1. The filler was added immediately after mixing these components, after which the composition was homogenized and immediately formed into samples (Figure 3, Table1). As a filler were used nano-and micro-sized zeolite particles (manufactured by PE "Eco Instinct") for which sieving up to 100 μm was performed. Its supramolecular structure provides for the presence of micropores and internal nanopores ( Figure 4). Visually, it is a gray powder converting the epoxy composition to a viscous ocher mass ( Figure  5). Of the strength properties, we were interested in those that practically determine the applicability of these compositions. These

Adhesion Strength of the Epoxy-Composite to Steel
Shear adhesion to steel tends to be enhanced after the addition of 50% by weight of the zeolite. This can be seen from

Mechanical Abrasion of the Epoxy Composites
As can see (Table 3), the injection of fillers leads to a marked increase in abrasion resistance. This is also noticeable while Here need to notice also that the density of the sample naturally increases, especially after the addition of copper -even more (see the masses of the samples, Table 3).      Figure 6).
This can be seen from the results obtained. The unfilled sample is strongly swollen already in the first hours of endurance, and at the end of 1 day of endurance completely destroys (scatters in solvent).
After the introduction of zeolite, the charge does not destroy, and swells much more slowly than the H-polymer. The addition of copper powder enhances this effect (Table 8).

Water Absorption of Composites:
Polyepoxides are generally quite stable in water. A water absorption rate of up to 1-2% during the month of exposure is considered normal. However, often even this figure needs to be improved. In addition. Epoxy products (coatings, parts, structures or ships) are often in the water for many years, and they need high water resistance. From our research we can conclude that the addition of zeolite makes the composite somewhat more resistant to water in the first half of the exposure (Table 9). Filling even causes the effect of slight weight loss, which can be caused by the phenomena of leaching of substances from the structure of the zeolite filler.

Thermo-Oxidative Destruction of Polymer Powders without and with Filler
A significant increase in fire resistance (Table 6) gives reason to expect certain changes in resistance to destructive thermal oxidation (DTO). A typical thermogram of unfilled polyepoxide is presented in Figure 9H. It shows that the maximum weight loss due to destructive thermal oxidation (DTO) occurs at 300 оС. The temperature of the 5% weight loss of the H-polymer, respectively, is 275 oC, and 10% 300 oC ( Figure 9H. TG curve). After that, the DTO processes are significantly slowed down, forming a cycle of primary destruction processes. Starting from 450 оС, secondary processes (called burnout of coke residue) are activated. They also have their peak activity but occur with a more active and stable (without sharp differences) dynamics of heat release and weight loss ( Figure 9). Half  in record time -up to 630 оС. From Figure 9 and Table 10 it is seen that the filling generally impairs the resistance of polyepoxide to thermal oxidative destruction.  2) It is experimentally shown that the introduction of zeolite can dramatically increase the stability in an aggressive solvent (a mixture of acetone: ethyl acetate). Unlike unfilled (which completely destroys in 1 day of endurance), composites don`t destroy in it, and swell much more slowly. Also, the filling (after 2-3 days of exposure) increases the resistance to swelling in highly concentrated (60%) H 2 O 2 peroxide: after 5 days of exposure, the unfilled swells by almost 5%, while the composite with zeolite -less than 3%.
3) It is established that the zeolite filling gives a double