Graftability of beaten pulps and acetylated pulps

Ce(IV)-induced polymerization of acrylonitrile with acetylated bagasse and wood pulps, having different acetyl contents, has been investigated. The graft yield is dependent on the acetyl content as well as the origin of the pulp. Increasing the acetyl content of pulps caused a significant decrease in the polymer loading. However, the rate of polymerization of acetylated wood pulp is much higher than that of acetylated bagasse pulp. The ceric consumption during grafting decreases as the acetyl content of the pulp increases. The effect of beating of the pulps, to various degrees of freeness, on their reactivity toward grafting process has also been studied. Generally, the state of cellulose, as defined by its degree of beating, and the origin of the pulp strongly influenced the graft yield. In creasing the beating degree of bagasse pulp resulted in a decrease in graft yield, while beating of wood pulp, to a definite degree, inhibits the polymerization reaction. The consumption of Ce(IV) by the beaten pulps during oxidation is somewhat greater than that consumed by the unbeaten pulps, whereas the consumption during grafting of acrylonitrile onto beaten pulps depends on the initial concentration of ceric solution. Also, the effect of grafting of acrylonitrile onto acetylated wood and bagasse pulps on their strength properties as well as the effect of grafting onto beaten pulps on their properties has been investigated. Grafting of acrylonitrile onto acetylated bagasse pulp decreased its strength properties, but improved its beatability comparatively to those of original pulp (0 acetyl content). On the other hand, grafting of acrylonitrile onto acetylated wood pulp resulted in a great improvement in its strength properties compared to those of grafted unacetylated pulp. Grafted unbeaten pulps gave thinner and weaker paper than the original pulp (without grafting). Beating of bagasse pulp before grafting gave pulp which possessed a higher strength properties, at low °SR, than those of pulp beaten after grafting. Raising the °SR by rebeating the pulp after reaction up to the original value had an adverse effect on the strength. Beating of bagasse pulp before grafting did not accelerate the reaction rate, but it saved some power consumption, since the time required for beating of grafted pulp to a given °SR was lower than that of ungrafted pulp.     

A kinetic study on the reduction of manganese III in presence of citric acid

The rate of reduction of manganese III stabilised by citric acid under variable conditions of Mn(III) concentration, ionic strength, pH and temperature in buffered media was found to obey a second order rate equation, first order with respect to Mn(III) autocatalysed by Mn(II). The reduction was found to proceed to an equilibrium value. The observed rate constants were found to follow a linear relationship with hydrogen ion concentration. Interpretation of results is based on the assumption that there are two reducible species in equilibrium; the aquocomplex and its hydrolysed form. A reaction mechanism is proposed to account for the experimental results. The overall energy (ΔE) and entropy (ΔS) of activation are compared with those for the reduction of Mn(III) in presence of other organic substrates.     

Equilibrium adsorption isotherm and controlled release of antibiotic drug chloroamphenicol from poly(2‐vinyl pyridine/acrylic acid) hydrogels prepared by gamma radiation

High water sorption of 2‐vinyl pyridine (2‐VP)/acrylic acid (AAc) hydrogel were prepared by free‐radical polymerization in aqueous solution of 2‐VP with AAc as comonomer. The amount of ionic monomer (AAc), the irradiation dose of prepared hydrogel, the pH, and the concentration of drug play an important factor on loading, adsorption, and releasing of water‐soluble chloroamphenicol drug. As a result of dynamic swilling tests, the effect of relative content of AAc on the swelling showed that it allowed a non‐Fickian type of water diffusion. The adsorption of the drug onto (2‐VP/AAc) hydrogels was studied by Freundlish adsorption isotherm. The drug concentrations showed an influence on the adsorption of drug which increased with increasing AAc content. From Freundlish adsorption isotherm, the empirical constants, k and n, can be evaluated and showed the ability of hydrogel to be loaded by the drug and the affinity of the drug to be uptake onto the hydrogel respectively. FTIR, TGA, and SEM techniques were used to study the characterization of hydrogel (2‐VP/AAc). Additionally, the release of the drug loaded from hydrogel discs was studied microbiologically to show that hydrophilic structure of the hydrogel has an antimicrobial effect as a dehydration of cytoplasm and unbalance of the cell wall functions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The paradoxical effects of legal intervention over unethical information technology use: A rational choice theory perspective

While the IS literature offers rich insights into the kinds, causes and consequences of unethical information technology use (UITU), we know little about the degree to which legal intervention may mitigate UITU. Our research aims at understanding how legal intervention could mitigate UITU by influencing the cost-benefit analysis in determining the decision to commit such unethical use of IT. Our contributions are twofold. First, we provide testable propositions on the role of legal intervention. Second, we offer an innovative take on intervention – conceived as a multi-mechanism process that adapts to UITU as well as to the way IT users negotiate the IT artifact.     

Variation of the specific surface area and porosity of zinc oxide prepared in various atmospheres

Specific surface area and pore structure studies were carried out on zinc oxide samples prepared from zinc oxalate dihydrate by heating at 330 and 370°C and in various atmospheres of water vapour, oxygen and hydrogen. The variation of S_BET with water vapour pressure for the samples heated at 330°C was found to show a behaviour which can be compared with the Smith-Topley effect. For the samples prepared at 370°C, rapid sintering occurred, and the Smith-Topley effect was not followed in this case. Zinc oxide prepared in an oxygen atmosphere gave higher surface area values than that prepared in a hydrogen atmosphere, which is thought to be due to the oxidation of the carbon impurities on the surface. Analysis of nitrogen adsorption isotherms by the t-method revealed the existence of micropores in the sample prepared at 330°C in vacuo. The rest of the samples have wide pores.     

Competitive Contribution of Catalyst and Adsorption Roles of TiO2 on the Degradation of AO7 Dye During Plasma Treatment

In order to investigate the role of TiO2 during plasma treatment,the degradation of the dye AO7 has been studied by gliding arc discharge in the presence of a TiO2 catalyst(CGAD).The results revealed that the adsorption of the dye on TiO2 is a physical adsorption in accordance with Langmuir isotherm,with a constant of adsorption KL=0.52 mg/L and a maximum adsorption capacity b=18.1 mg/g.The temperature variation of the reaction medium made it possible to consider thermodynamic parameters.Indeed,the adsorption is exothermic(enthalpy:△H 0),and spontaneous(free enthalpy:△G 0).The negative entropy(△S0) confirms the afnity of the dye molecules for TiO2.20 min of CGAD treatment in the presence of an optimal quantity of TiO2(2 g/L enabled us to bleach the solution of AO7(100 μM) completely.The discoloration rate with and without the addition of TiO2 was 100% and 28%,respectively.40 additional minutes of treatment allowed a total abatement of the chemical oxygen demand.The elimination of AO7 molecules during the plasma-catalytic treatment follows Langmuir-Hinshelwood(L-H) model kinetics.According to this model,the speed constant is kr=14.97 mg · L 1· min 1and the adsorption coefcient is KL-H = 0.010 L/mg.The latter being negligible compared to kr,adsorption is therefore weakly performed during the plasma treatment.     

Variation of the specific surface area and porosity of zinc oxide prepared in various atmospheres

Specific surface area and pore structure studies were carried out on zinc oxide samples prepared from zinc oxalate dihydrate by heating at 330 and 370°C and in various atmospheres of water vapour, oxygen and hydrogen. The variation of S_BET with water vapour pressure for the samples heated at 330°C was found to show a behaviour which can be compared with the Smith-Topley effect. For the samples prepared at 370°C, rapid sintering occurred, and the Smith-Topley effect was not followed in this case. Zinc oxide prepared in an oxygen atmosphere gave higher surface area values than that prepared in a hydrogen atmosphere, which is thought to be due to the oxidation of the carbon impurities on the surface. Analysis of nitrogen adsorption isotherms by the t-method revealed the existence of micropores in the sample prepared at 330°C in vacuo. The rest of the samples have wide pores.     

Study of some properties of waste LDPE/waste butyl rubber blends using different compatibilizing agents and gamma irradiation

Blends of waste low‐density polyethylene with waste butyl rubber of equal quantities containing reactive compatibilizing agents, namely: maliec anhydride; glycidyle methacrylate, divinyl benzene, tetraethyleneglycoldimethacrylate and diethyleneglycoldimethacrylate were preparedand exposed to different γ‐irradiation doses up to 400 kGy. The swelling behavior in organic solvent of the gel and soluble fractions and the degree of crosslinking were investigated. The mechanical properties, namely tensile strength and elongation at break were also studied. Thermal properties using thermo gravimetric analysis and differential scanning calorimetry analysis follow analyses have been followed up to follow the change of the structure for the irradiated and nonradiated blends. Results obtained indicated improvement in physical, mechanical and thermal properties on irradiation of the prepared blends which incorporate compatibilizing agents, but with varying degrees. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007