Blends of thermoplastic starch and recycled polyvinylbutyral from automotive windscreens were investigated. Mechanically compatible blends are formed at low to intermediate starch content. However, scanning electron microscopy and dynamic-mechanical analysis revealed a phase-separated nature for all blend compositions investigated. Tensile properties are negatively affected by aging in a high humidity environment and they deteriorate rapidly when the samples are soaked in water. Synergistic property enhancement was observed for a compound containing 22% thermoplastic starch. It features a higher tensile strength, shows better water resistance, and is significantly less affected by aging.

The limiting oxygen index (LOI) values of EVA‐PVB and low density polyethylene (LDPE)‐poly(ethylene‐co‐vinyl alcohol) (EVOH) polymer blends containing hydrated filler‐type flame retardants and red phosphorus were measured. When used as the sole flame retardant, magnesium hydroxide [Mg(OH)2] and alumina trihydrate (ATH) performed best in EVA and PVB, respectively. Magnesium hydroxide addition had a limited effect on the LOI of plasticized PVB, and addition of red phosphorus made little difference. This result is attributed to a mismatch between the decomposition temperature of Mg(OH)2 and the temperature at which the PVB plasticizer vaporizes. Otherwise, low‐level addition of red phosphorus significantly improved LOI values. The presence of hydroxyl groups on the polymer backbone had a beneficial effect with respect to LOI values in ATH‐filled blends. An LOI value of 30 was achieved in EVOH with as little as 32% of ATH and 3% of red phosphorus. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers