Poly[(3-hydroxybutyrate)-co-(3-hydroxyvalerate)]/layered double hydroxide nanocomposites

BACKGROUND: The thermomechanical performance of poly[(3-hydroxybutyrate)-co-(3-hydroxyvalerate)] (PHBV) is associated with its crystallization. Enhanced nucleation using a stearate-functionalized synthetic layered double hydroxide (LDH) presents a potential solution. RESULTS: PHBV crystallization varied with concentration of LDH. At lower LDH concentration, thermal history-induced cold crystallization was present. The extent of this order-disorder transition decreased with increasing LDH concentration and was completely eliminated at 7 wt% LOH. PHBV did not have a melt recrystallization peak but the introduction of LDH resulted in an increasingly pronounced melt recrystallization with increasing LDH concentration. Polarized optical microscopy coupled with differential scanning calorimetry and wide angle X-ray diffraction (WAXD) analysis indicated increased lamella thickness in the nanocomposites compared to pure PHBV. WAXD and transmission electron microscopy showed that the nanocomposites had an intercalated but aggregated dispersion. CONCLUSION: The concentration of nanofiller provides unique effects in PHBV. Mechanical performance was found to scale with composition as determined using dynamic mechanical analysis and tensile testing. (C) 2008 Society of Chemical Industry