Synergetic light stabilizing effects of reducing agent and UV absorber co-intercalated layered double hydroxides for polypropylene

Light stabilizers are widely used in the plastic industry to extend the service life of plastics for outdoor use. Herein, a novel organic-inorganic hybrid light stabilizer was prepared by co-intercalating a reducing agent sorbic acid (SA) and an UV absorber 2-hydroxy-4-methoxy-benzophenone-5-sulphonic acid (UVA) into the interlayer galleries of MgAl layered double hydroxides (LDH) by a separate nucleation and aging steps method. The prepared SA-UVA-LDH was characterized by XRD, FT-IR, SEM, TG-DTA and UV-vis, and was added into the matrix of PP as light stabilizer to evaluate its stabilization efficiency. The results showed that SA-UVA-LDH was evenly distributed in PP, and can offer excellent UV-blocking effect for PP. The addition of SA-LDH, UVA-LDH and SA-UVA-LDH can enhance both the thermal and light stability of PP. It was found that the stabilizing mechanism of SA-LDH arising from the reducing ability of SA is different from the UV-blocking mechanism of UVA-LDH. SA-UVA-LDH/PP has better light stability than SA-LDH/PP and UVA-LDH/PP due to the existence of synergistic stabilizing effect between SA and UVA. Therefore, the prepared SA-UVA-LDH can be potentially used as novel hybrid light stabilizer for PP.