Investigation of morphology, mechanical, thermal and flame retardant properties of an EVA/EPDM blend by combination of organoclay with Na+-tripolyphosphate

Polymer blends of ethylene-vinyl acetate (EVA) and ethylene propylene diene monomer (EPDM) (50/50) containing 2.5 wt% organoclay (OMMT) and different loadings of Na+-tripolyphosphate (STPP) were prepared by a melt compounding method. The morphology, mechanical and flame retardant properties, as well as antimicrobial activity of the prepared polymers, were evaluated through applying scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and tensile and antimicrobial activity tests. XRD and TEM results showed that OMMT was exfoliated in the polymer blend, while SEM illustrated a good dispersion and compatibility of OMMT and STPP fillers in the investigated polymer blend. Moreover, the tensile strength and thermal stability of composites were increased up to 2.5 wt% concentration of STPP after which no additional increase occurred. The cone calorimeter results showed that the heat release rate (HRR) and peak heat release rate (PHRR) were significantly decreased with increasing STPP loading. This is because the use of 2.5 wt% of OMMT with 15 wt% STPP caused a reduction in PHRR by 81% as compared to that of the unfilled blend. FT-IR results were drawn the fire mechanism through the carbonaceous char formation after burning. The antimicrobial activity test revealed an inhibition in the growth of microorganisms, including Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Pseudomonas aeruginosa) and fungi (Candida albicans) at 10 and 15 wt% of STPP filler content. This novel EVA/EPDM blend nanocomposite can be used in different industrial applications such as roofing, lining in solar ponds and packaging applications.