Preparation of intercalated Mg-Al layered double hydroxides and its application in PVC thermal stability

摘要

The Mg-Al oxide precursor prepared by the calcination of Mg-Al-carbonated layered double hydroxide (LDH) at 500 K for 4 h is used as the host material, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (BP) is used as the guest material, BP-intercalated LDH (LDH-BP) is prepared by ion-exchange method. The structure of LDH-BP is characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and thermogravimetry and differential thermal analysis (TG-DTA). The thermal stability of PVC/BP, PVC/LDH, PVC/LDH-BP composites, as well as pure PVC is investigated by conventional Congo Red test and dynamic thermal stability analysis in both the open and closed processing environments. According to XRD and FTIR, BP anions have been intercalated into interlayer galleries of LDH. TG-DTA results show that the layer-anionic interaction results in the improvement of the thermal stability of BP. Congo Red tests indicate that the addition of BP catalyzes the thermal degradation of PVC. A little amount of LDH (such as 1 phr) makes PVC more stable, but excessive addition accelerates the thermal degradation of PVC. The addition of LDH-BP markedly improves the static thermal stability of PVC. The results of dynamic thermal stability tests in both the open and closed processing environments are consistent with that of Congo Red tests.