Flame retardant biodegradable nanocomposites

Since starch is not only inexpensive but completely biodegradable, starch-based polymers are a new class of biodegradable nanocomposites with nanofillers. Despite the benefits of using the starch, it is difficult for the starch-based nanocomposites to form thermoplastic polymers because starch is very brittle. Furthermore, melt-blending starch with other biodegradable polymers is difficult since very few polymers are compatible with starches. In this paper, we have successfully synthesized the resorcinol diphenyl phosphates (RDP)-coated starch by the simple absorption method and then we show that the addition of the RDP-coated starch can improve the compatibility of Ecoflex and polylactic acid (PLA), blends. We found that over 60% RDP-coated starch could render the blend of 40% Ecoflex selfextinguishing without any nanoparticles. By examining the scanning transmission X-ray microscopy (STXM) images of the blend, the RDP-coated starch phases were well dispersed in the Ecoflex matrix. However, too much the RDP-coated starch added in the Ecoflex matrix significantly decreased the impact toughness. In order to keep the property and to obtain the UL-94-V0 at the same time, we have shown that the addition of the Halloysite nanotube (HNTs) clays can achieve the goals due to the increased interfacial area on the RDP-coated starch surfaces by being attached the HNTs clays, which could decrease the interfacial tension between the two biodegradable polymers. Hence the RDP-coated biodegradable polymer would become a new type of polymer, which has the good flame retardant and mechanical properties as well as biodecomposition properties.