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Semi-interpenetrating polymer networks based on liquid natural rubber

1994-12-01T00:00:00Z

Title: Semi-interpenetrating polymer networks based on liquid natural rubber Authors: Pillai, V Bhoothalingam; Francis, D Joseph Abstract: Semi-interpenetrating polymer networks based on liquid natural rubber polyurethane and linear polystyrene have been synthesized under different experimental conditions. The Semi-IPNs are found to be tough films and their physical, mechanical and thermal properties have been evaluated and compared with that of the homopolymer polyurethane and corresponding Full-IPNs. The density, shore-A Hardness and tensile strength of the Semi-IPNs indicated an increasing trend while percentage elongation at break decreases with increase in polystyrene content and also with increase in NCO/OH ratio. Crosslink density measurements indicated a possible phase inversion process for similar variations. These properties are found to be higher for Full-IPNs than Semi-IPNs except elongation at break, which is lower than Semi-IPNs. A marginal improvement in the thermal stability of Full-IPNs than the Semi-IPNs has been observe. Page(s): 355-358

Preparation of lime-rich sinter from waste limestone chips for steel making

1994-12-01T00:00:00Z

Title: Preparation of lime-rich sinter from waste limestone chips for steel making Authors: Pandey, O P; Gupta, R C Abstract: Lime-rich sinters using waste limestone chips have been made for use in steel making as a fluxing material. The yield and shatter strength of the sinter was examined as determined by sinter mix composition (viz. limestone, iron ore and coke breeze). The dissolution behaviour of such lime sinter was studied to observe its quick slag formation behaviour over molten steel bath. The present investigation has shown the feasibility of preparing lime-rich agglomerates of higher basicity from limestone chips using coke breeze as a cheap energy source. Page(s): 350-354

Catalysed combustion of ammonium perchlorate, polystyrene and their composite propellants

1994-12-01T00:00:00Z

Title: Catalysed combustion of ammonium perchlorate, polystyrene and their composite propellants Authors: Dubey, B L; Nath, Narendra; Tripathi, Awadhesh; Tiwari, Neeta Abstract: he combustion behaviors of ammonium perchlorate (AP), polystyrene (PS) and (AP+PS) propel-lant have been studied thermogravimetrically using Ni_1-xCu_xCr₂ O₄ (0≤x≤1) phases as catalysts. Catalyst NiCr₂0₄ is found to be the most efficient amongst all the phases for thermo oxidative degradation of PS. The phase, Ni_0.5Cu_0.5Cr₂O₄ facilitates thermal decomposition of AP and propellant to a greater extent as compared to other phases. Effect of catalyst in the enhancement of the combustion/burning rate of propellant is found to be through AP. The condensed phase reactions occurring at lower temperatures also affect the exothermic gaseous phase reactions at higher temperatures during the combustion of propellant. Page(s): 341-349

X-Ray photoelectron spectroscopic investigation of metalized (Pt, Pd, Rh and Ru) titania systems

1994-12-01T00:00:00Z

Title: X-Ray photoelectron spectroscopic investigation of metalized (Pt, Pd, Rh and Ru) titania systems Authors: Viswanathan, B; Mary, U D; Viswanath, R P Abstract: Detailed X-ray photoelectron spectroscopic study of noble metal supported titania systems after pretreatments in oxygen or hydrogen atmospheres showed considerable variations in the surface metal concentrations. The observed variations are rationalized in terms of thermodynamic parameters like surface free energy or standard heat quantities like heat of formation, heat of vaporization or sublimation. Page(s): 335-340