Due to their hexagonal crystal structure,magnesium alloys have relatively low workability at room temperature.In this study,the hot workability behavior of cast-extruded AZ31B magnesium alloy is studied through hot co...Due to their hexagonal crystal structure,magnesium alloys have relatively low workability at room temperature.In this study,the hot workability behavior of cast-extruded AZ31B magnesium alloy is studied through hot compression testing,numerical modeling and microstructural analyses.Hot deformation tests are performed at temperatures of 250℃ to 400℃ under strain rates of 0.01 to 1.0 s^(−1).Transmission electron microscopy is used to reveal the presence of dynamic recrystallization(DRX),dynamic recovery(DRY),cracks and shear bands.To predict plastic instabilities during hot compression tests of AZ31B magnesium alloy,the authors use Johnson–Cook damage model in a 3D finite element simulation.The optimal hot workability of magnesium alloy is found at a temperature(T)of 400℃ and strain rate(ε)of 0.01 s^(−1).Stability is found at a lower strain rate,and instability is found at a higher strain rate.展开更多
Controlled release of TDI and hence the cure characteristics of several blocked TDI with HTPB are reported. The reactions were followed through viscosity measurements as a function of time and temperature under the ca...Controlled release of TDI and hence the cure characteristics of several blocked TDI with HTPB are reported. The reactions were followed through viscosity measurements as a function of time and temperature under the catalytic influence of triethylamine. The effect of nature of substituents present on the end capping substrate, temperature, solvent, basicity of catalyst and kinetics thereon have been studied.展开更多
The present paper deals with the use of a new polymeric flame retardant material, polyphenylene sulphide (PPS) for plastics. Incorporation of 15—20% PPS into nylon-6 has provided UL V-0 rating for the system and ther...The present paper deals with the use of a new polymeric flame retardant material, polyphenylene sulphide (PPS) for plastics. Incorporation of 15—20% PPS into nylon-6 has provided UL V-0 rating for the system and there is enhancement in tensile and flexural properties. The results obtained on the thermal, crystallization and flow characteristics of the nylon-PPS system upto a loading of 40% PPS are also discussed.展开更多
Cure characteristics of hydroxyl terminated polybutadiene (HTPB) prepolymer with avariety of blocked toluene diisocyanate (TDI) in the presence of triethylamine (TEA) andchloroacetic acid catalyst are reported. Phenol...Cure characteristics of hydroxyl terminated polybutadiene (HTPB) prepolymer with avariety of blocked toluene diisocyanate (TDI) in the presence of triethylamine (TEA) andchloroacetic acid catalyst are reported. Phenol, thiophenol, p-chloropheno1, p-nitrophenol,p-cresol, resorcinol, naphthols, caprolactam and butylated-hydroxytoluene were used as blockingagents. Viscosity measurements have been carried out using a mixture of HTPB and blocked TDIin cyclohexanone in the presence of the catalysts at 50℃ and 60℃ using Haake rotational vis-cometer. Viscosity measurements have also been carried out with 50% solids such as ammonium sulphate along with HTPB and TDI adduct.展开更多
文摘Due to their hexagonal crystal structure,magnesium alloys have relatively low workability at room temperature.In this study,the hot workability behavior of cast-extruded AZ31B magnesium alloy is studied through hot compression testing,numerical modeling and microstructural analyses.Hot deformation tests are performed at temperatures of 250℃ to 400℃ under strain rates of 0.01 to 1.0 s^(−1).Transmission electron microscopy is used to reveal the presence of dynamic recrystallization(DRX),dynamic recovery(DRY),cracks and shear bands.To predict plastic instabilities during hot compression tests of AZ31B magnesium alloy,the authors use Johnson–Cook damage model in a 3D finite element simulation.The optimal hot workability of magnesium alloy is found at a temperature(T)of 400℃ and strain rate(ε)of 0.01 s^(−1).Stability is found at a lower strain rate,and instability is found at a higher strain rate.
文摘Controlled release of TDI and hence the cure characteristics of several blocked TDI with HTPB are reported. The reactions were followed through viscosity measurements as a function of time and temperature under the catalytic influence of triethylamine. The effect of nature of substituents present on the end capping substrate, temperature, solvent, basicity of catalyst and kinetics thereon have been studied.
文摘The present paper deals with the use of a new polymeric flame retardant material, polyphenylene sulphide (PPS) for plastics. Incorporation of 15—20% PPS into nylon-6 has provided UL V-0 rating for the system and there is enhancement in tensile and flexural properties. The results obtained on the thermal, crystallization and flow characteristics of the nylon-PPS system upto a loading of 40% PPS are also discussed.
文摘Cure characteristics of hydroxyl terminated polybutadiene (HTPB) prepolymer with avariety of blocked toluene diisocyanate (TDI) in the presence of triethylamine (TEA) andchloroacetic acid catalyst are reported. Phenol, thiophenol, p-chloropheno1, p-nitrophenol,p-cresol, resorcinol, naphthols, caprolactam and butylated-hydroxytoluene were used as blockingagents. Viscosity measurements have been carried out using a mixture of HTPB and blocked TDIin cyclohexanone in the presence of the catalysts at 50℃ and 60℃ using Haake rotational vis-cometer. Viscosity measurements have also been carried out with 50% solids such as ammonium sulphate along with HTPB and TDI adduct.
