Ethyl vinyl acetate (EVA) composites with nanoclays and boric acid: Thermal and mechanical properties

The polymers are widely used materials in various applications. Their flammability is a concern when the material will be facing high temperatures and/or conditions resulting in the incidence of ignition. The flame resistance of the polymers tends to be enhanced by the utilization of inorganic materials as additives. Versatile inorganic materials can be used for this purpose, e.g., ceramics (oxides, hydroxides, clays, etc.). The addition of inorganic additives could alter the mechanical properties of the polymer-inorganic composite structure, which should be considered during composite preparation as well. In this study, two different nanoclays (up to 20/100 by weight) and boric acid (BA) were added to ethyl vinyl acetate (EVA) to investigate possible enhancement in flame retardancy of the polymer. The mechanical properties were also determined for the neat polymer and polymer-inorganic composites to determine the effect of nanoclay and BA addition. The prepared nanocomposites were evaluated in terms of their chemical structures (Fourier transform infrared spectroscopy and X-Ray diffraction analysis), thermal characteristics (thermogravimetric analysis), mechanical properties (tensile test), and flammability behaviours. The NC 1.4 sample containing the highest amount of nanoclay had the longest burning time and Young’s modulus. The NC 2.3 and NC 1.3-BA samples had relatively higher stress-bearing capabilities. The addition of BA enhanced the stress-bearing capability of NC 1 containing samples and it slightly increased the burning time for NC 2 containing composites. The organic surface modifiers of nanoclays and BA addition were effective on the thermal and mechanical characteristics of the nanoclay/EVA composites.were effective on the thermal and mechanical characteristics of the nano-clay/EVA composites.