Enhanced thermal and mechanical properties of poly(methyl acrylate)/ZnAl layered double hydroxide nanocomposites formed by in situ polymerisation

Poly(methyl acrylate)/ZnAl layered double hydroxide intercalated nanocomposite (PMA/OZnAl-LDH NANO) was synthesized by in situ bulk polymerisation of methyl acrylate (MA) with an organo-modified ZnAl-LDH (OZnAl-LDH). After the in situ bulk polymerisation of MA, the basal spacing of OZnAl-LDH in PMA/OZnAl-LDH NANO increases to 2.85 nm from 2.63 nm of pristine OZnAl-LDH, which confirms the intercalation of PMA into OZnAl-LDH to form the intercalated nanocomposite. The transmission electron microscopy image shows that most of the OZnAl-LDH layers are stacked with about 3 nm spacing while some of them are exfoliated and dispersed randomly in the PMA matrix. The tensile strength of the obtained nanocomposite dramatically increases due to the physical interaction between the layers of OZnAl-LDH and PMA chains. If measured at 10% weight loss, the decomposition temperature of PMA/OZnAl-LDH NANO with 5 wt% OZnAl-LDH is about 17 °C higher than that of pure PMA or PMA/OZnAl-LDH microcomposite with 5 wt% OZnAl-LDH due to the strong interactions between the nanolayers of OZnAl-LDH and PMA chains. In the high temperature range, PMA/ZnAl-LDH has 39 wt% residues at 400 °C, which is 26 wt% higher than pure PMA. This is because the char with inorganic compounds is much stronger in retaining the polymer than that without inorganic compounds.