Synthesis of polyacrylamide/layered double hydroxides hybrid composite gel via in situ polymerization and study of its rheological and thermal behavior

Abstract

A hybrid nanocomposite gel of layered double hydroxides (LDHs)/acrylamide was prepared by polymerization of acrylamide in the presence of LDH via sonochemical shaking method. Acrylamide monomer is initially intercalated in the interlayer of LDH and polymerized within the layers to get the hybrid gel. The morphology and structure properties of the prepared sample were characterized by FT‐IR, XRD, FESEM, particle size, as well as its flow behavior and rheology studies. Thermal analysis was investigated by thermogravimetric analysis method. The thermal analysis was performed at four different heating rates. The successful preparation of the nanocomposite and the intercalation of polyacylamide into the interlayer space of the LDH was confirmed by FT‐IR and XRD analysis. The synthesized gel exhibited a non‐Newtonian flow motion with a pseudo‐plastic behavior. Herschel‐Bulkley model gave a good description on the rheological behavior of the hybrid gel. Four mass loss steps were observed and could be attributed to the removal of weakly absorbed water from the external surface of the hydrotalcite, the removal of interlayer water, the decomposition of interlayer anions and dehydroxylation and the destruction of the layers of LDH, respectively. The apparent activation energy of the decomposition has been calculated by using Kissinger, Flynn‐Wall‐Ozawa (FWO) and modified Coats Redfern methods. The most probable mechanism function describing the nanocomposite degradation was found to be that of Jander equation: . The results are of great interest in the understanding the thermodynamic properties of polyacrylamide/Mg‐Al layered double hydroxide hybrid nanocomposite gel and for its further applications. POLYM. COMPOS., 39:E1606–E1617, 2018. © 2017 Society of Plastics Engineers