Preparation of β-cyclodextrin-ester network and new organo-modified LDH as dual additives of PVA: Thermal, dynamic-mechanical and migration study

A new ternary nanocomposite based on poly(vinyl alcohol) (PVA) by using a beta - cyclodextrin-ester network and organo-modified layered double hydroxides (MLDH) was prepared by water solution casting method. beta-cydodextrin-ester network (beta-CDE) was synthesized by using the reaction of beta-cyclodextrin with 3,3',4,4'-benzophenone tetracarboxylic dianhydride in the basic media. The interlayer basal spacing of LDH was modified by using a bio based modifier containing three carboxylic groups (TA) through the regeneration method (MLDH). As a potential adjuvant, the MLDH, combined with and without beta-CDE, was used in a PVA system. The morphology, thermal and thermo-mechanical properties of all the PVA systems as well as migration of modifier from PVA/MLDH and ternary PVA/CDE-MLDH nanocomposites were investigated. In the presence of the beta-CDE, the MLDH showed a synergistic effect on improving all of the investigated properties of PVA. Based on TGA results, it can be concluded that adding both of the beta-CDE network and MLDH into PVA matrix increased the char yields from 3.1 (in the neat PVA) to 6.1 (in the PVA/CDE-MLDH nanocomposite) in inert atmospheres. The temperature at 5 mass% loss (T-5) increased from 188.1 degrees C to 197.7 degrees C in PVA/CDE-MLDH nanocomposite containing 4 mass% of each the beta-CDE and MLDH in comparison to the neat PVA. Dynamic mechanical analysis revealed that the storage modulus and thermal stability were improved by incorporation of both MLDH and beta-CDE into PVA. Migration results indicate that migration of TA from PVA matrix for PVA/CDE-MLDH is much lower than that for PVA/MLDH.