Mechanical characteristics of tire/clay modified epoxy used in fabrication of medical prostheses and artificial human parts
Epoxy is used in many dental and medical applications such as manufacturing prostheses. This polymer is not toxic and is a good candidate for easily forming of artificial hand, leg, etc. In recent years, the recycled waste tire has been concerned as inexpensive modifier for improving the toughness characteristics of many thermoset resins such as epoxy. Herein, the influence of addition of nanoclay on mechanical characteristics of waste tire-modified epoxy was investigated. Mechanical properties i.e. compressive and flexural characteristics, fracture toughness and impact strength of the samples were investigated. The fracture surfaces of the specimens were examined using scanning electron microscope (SEM). Moreover the glass transition temperature (T ) of the samples were measured. Results reveal that nanoclay can improve the g mechanical characteristics of waste tire-modified epoxies.
Synthesis and antibacterial activity of certain random copolyesters from 4,4'- Oxybis(Benzoic acid)
Six new random copolyesters with ethereal linkages were prepared from a potential mesogenic non-linear monomer 4, 4'-oxybis(benzoic acid) by direct poly-condensation with different aliphatic and aromatic diols in pyridine solution. Diphenylchlorophosphate (DPCP) was employed as the condensation agent. Viscosity measurements, FTIR, 1 H and 13 C NMR spectral data were used for investigating their structural features. The thermal phase transition behavior of these polymers was investigated by Differential Scanning Calorimetry (DSC). Agar well diffusion method was employed to study the antibacterial activity of these random copolyesters. All the six random copolyesters showed significant inhibition against the test bacteria. The presence of ether group in the main chain of the polyester enhances the solubility in organic solvents and hence eases processing.
Numerical and experimental investigation on air distributor design of fluidized bed reactor of sawdust pyrolysis
Abstract An improved biomass conversion in a lab-scale fluidized bed reactor (FBR) is achieved by optimizing the air distributor orifice size and number. Two approaches for introducing air were numerically and experimentally examined. These included perforated plate and downward orifice sparger. 3 mm and 5 mm orifice diameters, and 7, 9 and 13 holes were simulated at flow velocities of 2, 4, 6, and 8 times the minimum fluidization velocity, Umf. The simulation results revealed that increasing the orifice number has a positive effect on gas holdup, particularly for the perforated plate, which showed a uniform distribution of bubbles. The sparger configuration produced larger bubbles sizes, which could lead to better recirculation of solid flux, while stagnant particle zones were observed at the lower section of both distributors. A pyrolysis unit is also inserted at the top of freeboard of the FBR. For perforated plate with 6Umf, the pyrolysis process achieved thermal and cold gas efficiencies of 82.91% and 52.03%, respectively, while combustible gases with 41.6%mol CO, 8.7%mol CH 4 and 2.17%mol HC, were obtained. For sparger pipe and 6U mf _sp, 35.33 ppm NOx and 111 ppm SO 2 were measured in flue gas from combustion process at bed region.