Ultimate strength, softening temperature, and water absorption of the polymer composites based on epoxy resin (type ED-20) with unmodified and/or modified by tetraethoxysilane (TEOS) minerals diatomite and andesite are described. Comparison of experimental results obtained for investigated composites shows that the ones containing modified filler have better technical parameters mentioned above than composites with unmodified filler at corresponding loading. It was experimentally shown that the composites containing binary fillers diatomite and andesite at a definite ratio possess optimal characteristics – so called synergistic effect. Experimental results are explained in terms of structural peculiarities of polymer composites.
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