Abstract
Some novel phthalimido thiourea stabilizers 1-4 were readily synthesized. Their structure was elucidated by elemental analysis, FTIR, H-1-NMR, and mass spectroscopy. They showed good antimicrobial activity, in particularly the carboxyl derivative, as judged by their high inhibition zone diameter and low minimum inhibition concentration using the agar well diffusion technique. The results reveal the greater stabilizing efficiency of these stabilizers relative to dibasic lead carbonate, Cd-Ba-Zn stearate, and n-OTM reference thermal stabilizers using TG technique in nitrogen. This is well illustrated by the higher initial decomposition temperature and lower rates of both weight loss and discoloration of the polymer during degradation. Moreover, the stabilizing efficiency is influenced by the nature of the substituent group in these stabilizers. While the methyl stabilizer is characterized by a greater efficiency relative to those of the chloro and carboxyl ones, the non-substituted stabilizer lies between these two cases. The good disperse-ability of multi-walled carbon nanotubes (MWCNTs) into the polymeric material was ascertained using FTIR, XRD, SEM, and TEM. The thermal stability of PVC, which stabilized with 4, has been appreciably improved via loading 1 wt% of MWCNTs into its matrices. Further, PVC nanocomposites showed very high inhibition efficiency against Staphylococcus aureus and Escherichia coli.