Preparation And Properties Of Polypropylene / Layered Double Hydroxide Nanocomposites

Layered double hydroxides(LDHs) were synthesized by coprecipitation method, and Polypropylene(PP)/CaAl-LDH was prepared successfully through melting intercalation. The structure and properties of LDH, organic LDH and PP/LDH nanocomposites were characterized by FT-IR, XRD, TG, TEM, SEM and DSC.The results showed that the size of CaAl-LDH is 42nm, the layered space is about 0.84nm and the stacking number is about 50. The layered space of organic CaAl-LDH widened to 2.8nm. When the content of organic CaAl-LDH was present 13.04, tensile strength, flexural strength, impact strength with gap and impact strength without gap of PP/CaAl-LDH reached respectively 23.53MPa, 43.69MPa, 0.142kJ/m, 1.481kJ/m2, which improved separately by 13.65%, 3.8%, 40% and 1005%, comparing with pure PP. The flow indexes of PP/CaAl-LDH nanocomposites were reduced with the increasing of shear rate, so PP/CaAl-LDH nanocomposites can be seen as the non-Newtonian fluilds. The CaAl-LDH was dispersed in PP with nanoscale and promoted charring process during the degradation, so that the thermal stability of PP/ CaAl-LDH nanocomposites had been enhanced and the decomposition rate was decelerated. When 50%wt weight lost was selected as a comparison point, the decomposition temperature of PP/ CaAl-LDH nanocomposites was 33℃higher than that of pure PP (398℃).DSC result shows that the PP crystallization process was mechanism of homogeneous nucleation, while the of crystallization process PP/CaAl-LDH nanocomposites was heterogeneous nucleation. The activation energies(△E) of PP/CaAL-LDH nanocomposites were increased than pure PP.