Saroj Sharma

Alternating Copolymers of Limonene with Methyl Methacrylate: Kinetics and Mechanism

The radical copolymerization of limonene (optically active) with methyl methacrylate in xylene at 80±0.1°C for 1 hr, initiated by benzoyl peroxide (BPO) yield alternating copolymer(s), under the inert atmosphere of nitrogen, as evidenced by reactivity ratios r1 (MMA)=0.07 and r2 (limonene)=0.012 using the Kelen–Tüdos method. The kinetic expression is Rα[I]0.5[MMA]1.0[Lim.]−1.0. The decrease in the rate of polymerization with increase in concentration of limonene is due to penultimate unit effect. The overall energy of activation is calculated as 49 kJ/mole. FTIR of the copolymer(s) shows the characteristic frequencies at 1732.40 and 2951.40 cm−1 due to –OCH3 of MMA and aromatic C–H stretching of limonene, respectively. 1H NMR spectra shows peak at 3.8–4.1 δ and 5.3–5.6 δ due to –OCH3 of MMA and trisubstituted olefinic protons [–CH=CH–CH2–] of limonene, respectively.

Preparation of heterogeneous bipolar membranes and their performance evaluation for the regeneration of acid and alkali

A cost effective bipolar membrane has been prepared by the solution casting method for the hydrolysis of inorganic and organic salts using a bipolar electrodialysis technique. Two types of heterogeneous–heterogeneous composite bipolar membranes (BPM) have been prepared. The first one is prepared by the dispersion of cation exchange resin powder in polystyrene solution and cast on a commercially available anion exchange membrane. The second type of BPM has been prepared by the dispersion of anion exchange resin powder in polystyrene solution and then cast on a commercially available cation exchange membrane. Both the BPMs have been prepared without using the interfacial layer required for water splitting. Both the BPMs exhibited low ionic resistance, moderate to high water uptake, high ion-exchange capacity, high ionic conductivity, appropriate stability and high water splitting efficiency during the bipolar electrodialysis process. Water splitting efficiency of the prepared BPMs was also tested in a four compartment bipolar electrodialysis cell for converting sodium chloride and sodium formate/sodium acetate into their corresponding acids and sodium hydroxide. During hydrolysis of 0.5 M sodium chloride 87–90% current efficiency and 5.23–3.78 kW h kg−1 power consumption values were observed for the two different types of BPMs. Similarly, during hydrolysis of 0.5 M sodium formate 92–94% current efficiency and 4.25–3.85 kW h kg−1 power consumption values were observed for both types of BPMs. The performance of BPMs slightly reduced during hydrolysis of 0.5 M sodium acetate solution due to the slower ionization of sodium acetate. The performance of the BPMs is comparable with commercial BPMs.

Studies on the Effects of Salt and Surfactant in Wet Phase Separation of Polysulfone

This study investigates the effect of additives in the nonsolvent water in terms of cloud point during the phase inversion of Polysulfone (PS) in dimethyl formamide (DMF). The exponential pattern is observed with PS concentration (0.2 to 0.6% (w/w)). It needs a low amount of water to get the cloud point at low temperature. The cloud point varied with the nature of water matrix and depended on the amount of salt, as well as the PS amount. The presence of salts (sodium chloride and sodium sulfate) lowers the cloud point of the solution. The network distribution of the particles at the cloud point is disturbed in the presence of salt. The requirement is more for Sodium lauryl sulfate (SLS) added water to reach the cloud point in the low range of PS solution up to 0.3% PS (w/w). The morphological and distribution pattern of PS particles are very different compared to PS particles produced from pure water. XRD study of PS particles produced from the mixed water system reflects relatively more amorphous character with respect to PS particles from pure water. The presence of both surfactant and salts in water systems also influences the cloud point in synergistic manner.

Sodium Styrene Sulfonate-co-Methyl Methacrylate-Based Proton Conducting Membranes for Electrochemical Energy Applications

ABSTRACT The present investigation reports one-pot synthetic approach to develop cation exchange membranes (CEMs) via free radical polymerization which avoids the post functionalization step that involves use of hazardous chemicals. The CEM is composed of sodium styrene sulfonate (StSO3Na), methyl methacrylate, divinyl benzene, and polyvinyl chloride which is prepared by varying relative amount of vinyl monomers. The membranes shown improved ion-exchange capacity, water uptake, ionic conductivity, and stabilities (mechanical, chemical, and thermal). Among different CEMs, CEM-1 has shown significantly improved performance with 8.54 × 10−2S.cm−1 proton conductivity and 2.71 meq. g−1 proton exchange capacity.