The Effect of Nano-Hydrotalcite-Zinc Oxide on Flame Retardant and Smoke Suppression of Flexible PVC

摘要

To reduce the smoke release of flexible poly (vinyl chloride) (PVC) as its burning, nano-hydrotalcite and nano-Zinc oxide (ZnO) were used to modify the polymer. The results indicated that the addition of hydrotalcite-ZnO had a significant effect for flame retardant. The limiting oxygen index (LOI) is up to a maximum value and the smoke density rank (SDR) exhibited a lower value when the weight percentages of hydrotalcite and ZnO in PVC are 3% and 2%, respectively. Thermal stabilities of the modified PVC and decomposed products were investigated by means of thermogravimetry and prolysis - gas chromatography - mass spectrum (Py-GC-MS). As a result, hydrotalcite- ZnO obviously accelerated decomposition of PVC to release hydrogen chloride, and the decomposed PVC consequently produced the trans-conjugated polyene sequences, which easily formed cross-linked structures. However, a cyclization reaction in PVC chain without the additives produced aromatic compounds such as benzene and naphthalene at 400℃. Even though the amount of aromatic compounds was released from the PVC modified with hydrotalcite-ZnO at the temperature of 600℃, the content of the decomposed products is relatively lower, comparing with unmodified PVC.