HET acid based oligoesters – TGA/FTIR studies

One of the important reactive halogenated dicarboxylic acids used in the synthesis of flame retardant unsaturated polyester resins is 1,4,5,6,7,7-hexachlorobicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid (HET acid). In the present investigation four different oligoesters are synthesized using HET acid as the diacid component and 1,2-ethane diol, 1,2-propane diol, 1,3-propane diol and 1,4-butane diol as the aliphatic diols. Melt condensation technique in vacuum is used for the synthesis of the oligoesters. The number average molecular weights of the oligoesters are determined using end group analysis. The degree of polymerization is estimated to be 3–5. The structural characterization is done using FTIR and NMR (1H and 13C) techniques. In the present investigation, TGA-FTIR studies for the different oligoesters are carried out in nitrogen atmosphere. The materials are heated from ambient to 600 °C at a heating rate of 20 °C/min. The main volatile products identified are CO, HCl, H2O, CO2, hexachlorocyclopentadiene and HET acid/anhydride. The evolution profile of these materials with respect to the structure of the oligoesters is discussed in detail and presented. The importance of β-hydrogens in the diol component and the plausible mechanism for the flame retardant behavior of these oligoesters are presented

Thermal Degradation Studies on PMMA–HET Acid Based Oligoesters Blends

Imparting thermal stability to polymethyl methacrylate (PMMA) without affecting its optical clarity is attempted by incorporating HET acid based oligoesters. Pure PMMA and PMMA containing five and 20 wt% of four different oligoesters are separately prepared using bulk polymerization. The thermal properties of the materials studied using DSC, TG, TG–FTIR and Pyr–GC–MS are presented. The main volatile degradation products identified are CO, HCl, CO2, H2O, hexachlorocyclopentadiene, hexachloroendomethylene tetrahydrophthalic acid/anhydride and methyl methacrylate. A detailed mechanism for the influence of the degradation products of HET acid based oligoesters on the thermal degradation of PMMA is also presented

Discovery of high antibacterial and catalytic activities of biosynthesized silver nanoparticles using C. fruticosus (CF-AgNPs) against multi-drug resistant clinical strains and hazardous pollutants

Our project focused on cost effective, rapid, and novel plant mediated biosynthesis of silver nanoparticles using Convolvulus fruticosus extract (C. fruticosus; CF-AgNPs). The morphology, size, optical and structural properties of synthesized AgNPs were identified by UV–Vis,​ DLS, XRD, FESEM, TEM, FT-IR and, EDX techniques. The synthesis conditions were then optimized using essential parameters like AgNO 3 concentration, pH, temperature and, reaction time. XRD, TEM, and FESEM analysis of the samples showed the cubic crystal structure, spherical-like shaped particles with about 45 nm sizes. The zeta potential displayed the value of −23.7 mV, indicating the high stability of biosynthesized CF-AgNPs. The FT-IR spectra showed the role of the functional groups in C. fruticosus for the formation of AgNPs such as routine compound. The photocatalytic activity of the synthesized CF-AgNPs was evaluated by degradation of basic blue 9 (BB9) and eriochrome black T (EBT) contaminants under UV and sunlight irradiations. The biosynthesized CF-AgNPs exhibited 86.7% and 81.3% degradation activity against BB9 and BB9 pollutants under UV irradiation, respectively. Furthermore, the biosynthesized nanoparticles showed high antibacterial activity against S. aureus (SA-1), E. faecalis (EF-1), A. baumannii (AB-1), E. coli (EC-1), P. mirabilis (PM-1), K. pneumonia (KP-1), and P. aeruginosa (PA-1) strains with MIC values of 0.1, 0.1, 0.1, 0.1, 1, 1, and 0.5 g/ml, respectively. These findings suggest that synthesized silver nanoparticles using C. fruticosus can have applications in various fields such as wastewater treatment and biomedical