Effect of zinc oxide nanoparticles as cure activator on the properties of natural rubber and nitrile rubber

Zinc oxide (ZnO) nanoparticles were synthesized by homogeneous precipitation and calcination method and were then characterized by transmission electron microscopy and X‐ray diffraction analysis. Synthesized ZnO was found to have no impurity and had a dimension ranging from 30–70 nm with an average of 50 nm. The effect of these ZnO nanoparticles as cure activator was studied for the first time in natural rubber (NR) and nitrile rubber (NBR) and compared with conventional rubber grade ZnO with special reference to mechanical and dynamic mechanical properties. From the rheograph, the maximum torque value was found to increase for both NR and NBR compounds containing ZnO nanoparticles. ZnO nanoparticles were found to be more uniformly dispersed in the rubber matrix in comparison with the conventional rubber grade ZnO as evident from scanning electron microscopy/X‐ray dot mapping analysis. The tensile strength was observed to improve by 80% for NR when ZnO nanoparticles were used as cure activator instead of conventional rubber grade ZnO. An improvement of 70% was observed in the case of NBR. The glass transition temperature (T_g) showed a positive shift by 6°C for both NR and NBR nanocomposites, which indicated an increase in crosslinking density. The swelling ratio was found to decrease in the case of both NR and NBR, and volume fraction of rubber in swollen gel was observed to increase, which supported the improvement in mechanical and dynamic mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Interdiffusion Between Ti3SiC2–Ti3GeC2 and Ti2AlC–Nb2AlC Diffusion Couples

In this work, we report on the interdiffusion of Ge and Si in Ti₃SiC₂ and Ti₃GeC₂, as well as that of Nb and Ti in Ti₂AlC and Nb₂AlC. The interdiffusion coefficient, D _int, measured by analyzing the diffusion profiles of Si and Ge obtained when Ti₃SiC₂–Ti₃GeC₂ diffusion couples are annealed in the 1473–1773 K temperature range at the Matano interface composition (≈Ti₃Ge_0.5Si_0.5C₂), was found to be given by
D _int increased with increasing Ge composition. At the highest temperatures, diffusion was halted after a short time, apparently by the formation of a diffusion barrier of TiC. Similarly, the interdiffusion of Ti and Nb in Ti₂AlC–Nb₂AlC couples was measured in the 1723–1873 K temperature range. The D _int for the Matano interface composition, viz. ≈(Ti_0.5,Nb_0.5)₂AlC, was found to be given by
At 1773 K, the diffusivity of the transition metal atoms was ≈7 times smaller than those of the Si and Ge atoms, suggesting that the former are better bound in the structure than the latter.     

1,3,5‐trihydroxy benzene as a surface modifier of carbon black and its effect on the filler–rubber interaction

A surface‐modified rubber‐grade carbon black has been prepared by treating it with 1,3,5‐trihydroxy benzene (phluroglucinol) in aqueous solution at different molar concentrations. This modified carbon black has been used as one of the compounding ingredients with natural rubber. An attempt has been made to establish a concentration optimum for the modifier. Improved physicomechanical properties like hardness, heat buildup, hysteresis loss, and improved dynamic mechanical properties are observed for the compounded rubber. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2272–2278, 2003     

Effect of meta‐dihydroxy benzene as a surface modifier on filler–filler and filler–polymer interaction of carbon black polymer composite

In the present context an attempt was made to use polyhydroxybenzene on rubber‐grade carbon black to suitably modify the surface morphology and hence to achieve improved thermomechanical and mechanical dynamic properties. FTIR studies clearly point out the presence of excess hydroxyl group in the modified black. The improvement in mechanical properties is attributed to higher crosslink density through hydrogen bonding and oxygen bridge participation during the covulcanization reaction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2025–2033, 2002     

Real-time inferencing of solid–liquid phase equilibria in solution polymerization of polyethylene

An algorithm for the real-time prediction of multi-component solid–liquid equilibrium (SLE) in a polyethylene (PE) process flowsheet has been attempted. While most of the available literature assumes the polymer to possess a single average molecular weight and lump the entire polymer as a single component, the present work proposes to consider a polydispersed multi-component fraction, characterized by the pseudo-component approach. The SLE model has been used to study the effects of monomer and polymer polydispersity in solution polymerization process. At first, it has been validated on the solubility data of n-alkanes in n-hexane, polyethylene in M-xylene and on wax precipitation from a mixture of n-paraffins. The SLE model is based on perturbed chain SAFT (PC–SAFT) equation of state (EOS). An algorithm for the real-time prediction of SLE phase boundaries in solution polymerization has been subsequently presented. A simulation experiment on the polyethylene flowsheet highlighted the potential of real-time inferencing for industrial applications.     

Simulating thermal power plant processes on a message passing environment

Simulators play a very important role in the operation of thermal power plants and also in the design of control systems for these plants. To cater to this requirement elaborate methodologies have been developed to simulate thermal power plant processes in an interactive way. Due to the intensive computations involved, such simulators use one or more high through-put computers known as the simulation computers. This paper puts forward a method where parallel processing on a low latency message passing environment has been used to simulate thermal power plant processes following a modular approach. This eliminates the need of an expensive high through-put simulation computer, thus cutting down the hardware cost associated with a simulator and increasing the system reliability manifold.