Rizwan Hussain

Thermal degradation of some transition metal (cobalt, nickel and copper) salts of poly(methacrylic acid)

Abstract The thermal stabilities of cobalt, nickel and copper polymethacrylates, synthesized by free radical polymerization of methacrylic acid followed by the replacement of the carboxylic proton with the respective metal ion, have been examined. Various thermoanalytical techniques have been utilized. The results reveal that cobalt and nickel polymethacrylate are much more stable than copper polymethacrylate, although the products are similar. A general mechanism for their thermal degradation has been proposed.

Comparison of the thermal degradations of barium and lead polymethacrylates

Abstract A comparison of the thermal degradations of barium and lead polymethacrylates has been made using thermal volatilization analysis, thermogravimetry and mass spectrometry. Mechanisms of thermal degradation have been suggested.

Thermal degradation of gamma irradiated cobalt, nickel and copper polymethacrylates

Cobalt, nickel and copper polymethacrylates, which have possible applications as radiation shields, were studied for their radiation resistance. The samples were irradiated with 200 kGy to 600 kGy in an oxygen free atmosphere. The changes in degradation pattern, studied by employing various thermoanalytical techniques, are reported and discussed.

Comparison of the thermal degradations of gamma-irradiated lead and barium polymethacrylates

Abstract Barium and lead polymethacrylates, which can be used as radiation shields, were subjected to gamma irradiation at doses ranging from 200 to 600 kGy in an argon atmosphere. The effects of radiation have been assessed by utilizing various thermoanalytical techniques. The changes noted in the thermal degradation patterns have been discussed.

Radiolysis of poly(phenyl methacrylate)

Powdered poly (phenyl methacrylate), synthesized by free-radical bulk polymerization, has been irradiated to doses, between 200 kGy and 600 kGy, of cobalt-60 γ-rays under an argon atmosphere. A G (scission) value of 1·8 has been calculated from the changes in number-average molecular weight as determined by gel permeation chromatography. Energies of activation for the decomposition of irradiated polymers have been calculated from the results of thermogravimetric experiments.

Effects of gamma-irradiation on copolymers of phenyl methacrylate and methyl methacrylate

Abstract The effects of gamma irradiation in an argon atmosphere on copolymers of phenyl methacrylate and methyl methacrylate were, investigated using various thermoanalytical techniques. It is shown that the thermal stability of the copolymers containing higher concentration of methyl methacrylate decreases after being exposed to gamma radiation.

SYNTHESIS AND ELECTRICAL RESISTIVITY OF NICKEL POLYMETHACRYLATE

Synthesis of nickel polymethacrylate was carried out using methanolic solutions of sodium hydroxide and polymethacrylic acid. The electrical resistivity of the pellets made from Ni-polymethacrylate was measured at different voltages and temperatures. Results showed that the electrical resistivity of Ni-polymethacrylate decreases significantly with voltage in high temperature regions but the decrease is insignificant at temperatures nearing room temperature. The activation energy at low temperatures is approximately 0.8 eV whereas at high temperature it is in the range 0.21–0.27 eV.

Current-voltage characteristics of barium polymethacrylate

Current–voltage characteristics of Barium Polymethacrylate (BaPMA) in the form of Al-BaPMA-Al structures have been studied. The currents are measured in the voltage range 10 V–1 kV. At low voltages an ohmic relation is observed and at higher voltages the Poole-Frenkel mechanism is proposed. The mechanism of conduction has been explained on the basis of different current-voltage and current-temperature curves. The activation energy values calculated using Arrhenius relation fall in the range 0.25–2 eV, suggesting a sequence of trapping levels.

Electron transport mechanism in cobalt polymethacrylate (CoPMA)

Electron transport mechanisms in cobalt polymethacrylate have been investigated. The electrical measurements made on the polymer, show that the current-voltage relationship at lower voltages (V<300 V) is ohmic whereas at higher voltages it is exponential. The strong temperature dependence of current on voltage indicates the dominance of a Poole-Frenkel mechanism and the existence of trapping levels. Low activation energy values suggest an electronic conduction mechanism.