Rizwan Hussain | University of the Punjab (original) (raw)
Address: Islamabad, Islamabad, Pakistan
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Papers by Rizwan Hussain
Polymer International, 2007
A series of blocked diisocyanates has been synthesized from toluene diisocyante (TDI), isophorone... more A series of blocked diisocyanates has been synthesized from toluene diisocyante (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), 4,4′-diphenylmethane diisocyanate (MDI) and 2-butoxyethanol. The synthesis of blocked diisocyanate adducts was confirmed by Fourier transform infrared, 1H NMR, electron impact mass spectrometry and nitrogen analysis. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and carbon dioxide evolution were used to determine the minimum de-blocking temperatures. De-blocking temperatures determined by these three techniques were found to be in the order DSC > TGA > CO2 evolution. The effect of different metal catalysts on thermal de-blocking reaction of the blocked diisocyanates was studied, using the carbon dioxide evolution method. It was found that iron(III) oxide has the maximum catalytic activity on de-blocking. The solubility of the blocked diisocyanate adducts was determined in different solvents. The study revealed that at 30 °C blocked IPDI and HDI adducts show better solubility than adducts based on TDI and MDI. Isocyanate-terminated prepolymers of blocked diisocyanates and hydroxyl-terminated polybutadiene (HTPB) were prepared. The storage stability and gelation times of the prepolymers were studied. Results showed that all the diisocyanate-HTPB compositions are stable at 50 °C for more than three months. However, aliphatic diisocyanate-HTPB compositions require greater gelation time than aromatic diisocyanate-HTPB compositions at their respective de-blocking temperatures. Copyright © 2007 Society of Chemical Industry
Composites Science and Technology, 2010
AgO is considered to be a prime source for producing high-energy zinc-silver batteries, and Ag2O ... more AgO is considered to be a prime source for producing high-energy zinc-silver batteries, and Ag2O is always accompanied with AgO during the production of AgO. The presence of Ag2O in AgO decreases the potential of the battery. Determination of AgO purity is a tedious job for the analytical chemist. It usually involves laborious and lengthy wet chemistry processing and very expensive analytical technique such as XRD, SEM, XPS spectroscopy etc. We have developed and standardized a simple, fast and economical method based on thermo-gravimetry for the determination of AgO in AgO/Ag2O. This method is being applied successfully for the purity determination of AgO during its production.
Polymer International, 2007
A series of blocked diisocyanates has been synthesized from toluene diisocyante (TDI), isophorone... more A series of blocked diisocyanates has been synthesized from toluene diisocyante (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), 4,4′-diphenylmethane diisocyanate (MDI) and 2-butoxyethanol. The synthesis of blocked diisocyanate adducts was confirmed by Fourier transform infrared, 1H NMR, electron impact mass spectrometry and nitrogen analysis. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and carbon dioxide evolution were used to determine the minimum de-blocking temperatures. De-blocking temperatures determined by these three techniques were found to be in the order DSC > TGA > CO2 evolution. The effect of different metal catalysts on thermal de-blocking reaction of the blocked diisocyanates was studied, using the carbon dioxide evolution method. It was found that iron(III) oxide has the maximum catalytic activity on de-blocking. The solubility of the blocked diisocyanate adducts was determined in different solvents. The study revealed that at 30 °C blocked IPDI and HDI adducts show better solubility than adducts based on TDI and MDI. Isocyanate-terminated prepolymers of blocked diisocyanates and hydroxyl-terminated polybutadiene (HTPB) were prepared. The storage stability and gelation times of the prepolymers were studied. Results showed that all the diisocyanate-HTPB compositions are stable at 50 °C for more than three months. However, aliphatic diisocyanate-HTPB compositions require greater gelation time than aromatic diisocyanate-HTPB compositions at their respective de-blocking temperatures. Copyright © 2007 Society of Chemical Industry
Composites Science and Technology, 2010
AgO is considered to be a prime source for producing high-energy zinc-silver batteries, and Ag2O ... more AgO is considered to be a prime source for producing high-energy zinc-silver batteries, and Ag2O is always accompanied with AgO during the production of AgO. The presence of Ag2O in AgO decreases the potential of the battery. Determination of AgO purity is a tedious job for the analytical chemist. It usually involves laborious and lengthy wet chemistry processing and very expensive analytical technique such as XRD, SEM, XPS spectroscopy etc. We have developed and standardized a simple, fast and economical method based on thermo-gravimetry for the determination of AgO in AgO/Ag2O. This method is being applied successfully for the purity determination of AgO during its production.