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

Abstract

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.