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The progress of cure reactions was observed for rubber sheets during the cooling period after their extraction from the mold. The study was performed by considering either motionless air at 125°C and water at 12°C for cooling the rubber previously cured in a mold kept at 160eC. A significant increase in the state of cure was calculated with the help of a numerical model for the vulcanizates, especially in the case of air at 125°C. An improvement in physical properties such as the swellling in toluene, and mechanical properties measured either under static or dynamic conditions, was determined. Some parameters were found of interest, especially the kind of cooling fluid and its temperature, and the state of cure of the vulcanizate at the time of extraction out of the midplane of rubber sheets where the state of cure was lower, cooling in air at 125°C was responsible for a development of the profiles of state of cure through the sample leading to a more homogeneous material.

SynopsisThis paper determines the increase in the state of cure through the rubber mass during the cooling period after the vulcanizate is removed from the mold. The problem is complicated because of the great number of parameters. Some of them, such as the dimension of sample, the state of cure through the rubber a t the time of its removal from the mold, the nature of the fluid, its agitation and temperature, are of interest. This work is concerned with the study of the effect of the temperature of motionless air in which the vulcanizate is cooled. This parameter is important in increasing the state of cure. Although the problem is complicated, it has been resolved by using a model based on a numerical method of calculation with finite differences. This model takes into account not only heat transfer by conduction through the rubber and by convection through rubber-air interface, but also the kinetics for heat evolved in the cure reaction.

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Ni2+ is a highly toxic above 0.07 mg/L and its removal is of high significance. The biosorption of Ni2+ onto medlar male flowers (MMF) was studied in relation with the physical parameters like pH, contact time, biosorbent dosage, Ni2+ concentration and temperature. The interaction biosorbent-Ni2+ was examined by the FTIR technique. The equilibrium was achieved within 40 min and the data were well fitted by the Langmuir and Redlich-Peterson (R-P) models. The maximum Ni2+ uptake capacity was 17.073 mg/g at 25°C and the Ni2+ removal follows a pseudo-second order kinetic with activation energy of 13.3 kJ/mol. The thermodynamic parameters: ΔS°, ΔH° and ΔG° showed that the biosorption was spontaneous and endothermic. MMF was used as a post treatment technique and the biosorption was coupled with the visible light driven Ni2+ reduction over the spinel ZnMn2O4. The effect of the pH, ZnMn2O4 loading and light intensity on the photoactivity was investigated. 77.5% of Ni2+ was reduced after ~140 min under optimal conditions. The Ni2+ removal reached a rate conversion of 96% of with the coupled system biosorption/photocatalysis is very promising for the water treatment.

The combined effect of cadmium and boric acid on the electrodeposition of zinc-nickel from a sulfate has been investigated. The presence of cadmium ion decreases zinc in the deposit. In solution, cadmium inhibits the zinc ion deposition and suppresses it when deposition potential value is more negative than −1.2 V. Low concentration of CdSO 4 reduces the anomalous nature of ZnNi deposit. Boric acid decreases current density and shifts potential discharge of nickel and hydrogen to more negative potential. The combination of boric acid and cadmium increases the percentage of nickel in the deposit. Boric acid and cadmium.

The electrodeposition of nickel with zinc in presence of boric acid was studied in order to determine the influence of the composition of the deposition solution on the properties of the obtained electrodeposits. The Ni / Zn concentrations ratio in solution determines the deposition mechanism and thus, the chemical composition and the electrochemical activity of the electrodeposited alloys. Boric acid decreases current density which minimizes anomalous deposition. The typical results from these acidic media are the formation of Ni-rich alloys (%Ni > 90) by a normal code position mechanism with a better electrochemical activity than Ni for the hydrogen evolution reaction HER reaction.Results show that it is possible to obtain alloys rich in either zinc or nickel, from an acidic solution containing boric acid. For Ni / Zn concentration ratios in the range of 1-3, Zn-rich alloys are obtained despite Zn is the less noble element and even when it is present at lower concentrations than Ni, confirming that at these conditions alloys are deposited by an anomalous deposition mechanism as reported by many researchers (1,2,3). Electrochemical oxidation of these Zn-rich alloys shows the presence of δ and γ phases of Zn-Ni and Ni, in proportions dependent on the electrode position conditions. For the highest Ni/Zn concentrations ratios, in the range between 80 and 1000, the formation of the alloy occurs by a normal deposit mechanism, resulting in Ni-rich alloys (%Ni >90). The electrochemical behaviour of these coatings is different from the zinc-rich coatings and no evidence of the presence of γand δ phases of ZnNi alloy. These Ni-rich alloys show an improvement in their behaviour as a cathode for the HER as compared with Ni and allow proposing them as potentially suitable materials for use as cathode materials in the hydrogen evolution reaction. 10.1149/04524.0079ecst ©The Electrochemical Society ECS Transactions, 45 (24) 79-85 (2013) 79 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252 Downloaded on 2015-03-03 to IP