Full Factorial Study Research Articles

Drug transport across nylon 610 films: influence of synthesis variables.

Nylon 610 is a hydrophilic polymer with considerable potential as a membrane for drug microencapsulation. To better understand drug transport through such membrane, the influence of the solvents and monomers used in the synthesis of nylon films were examined using a full factorial study. Nylon 610 films were synthesized by an interfacial polycondensation reaction using hexamethylenediamine (HD) in the water phase and sebacoyl chloride (SC) in the organic phase, which was a solvent blend of chloroform and trichlorotrifluoroethane at ratios of 1:1, 1:4, and 4:1. Monomer concentrations studied were 0.2, 0.4, and 0.6 M with respect to their appropriate phase, while the monomer ratios were 1:1, 3:1, and 1:3. The molecular weight, porosity, thickness, and crystallinity of the films were characterized. The transport of potassium chloride, hydrocortisone, and m-cresol was studied at 25 degrees C as a function of the synthesis variables. Potassium chloride was selected to measure the porosity of the membrane. Hydrocortisone and m-cresol, a known solvent for nylon 610, were used to study pore and solution-diffusion transport, respectively. The molecular weight of the films was proportional to the chloroform concentration. As the molecular weight increased, film thickness, porosity, and hydrocortisone permeability increased. As the molecular weight decreased, film thickness and porosity decreased, while m-cresol permeability increased. These results can be explained on the basis of HD ability to readily partition into a good solvent such as chloroform permitting high molecular weight polymer to form before precipitation.

Factors affecting the strength of alkali-activated slag

The effect of several factors on the strength of alkali activated slags has been investigated. The most important factors were found to be: the type of alkaline activator, the means of adding activator, the dosage of alkali, the type and fineness of slag, SiO 2/Na 2O ratio (modulus, Ms) when using waterglass solution, curing temperature, liquid/slag or water/slag ratio and additive. Some of these factors are interdependent and the effect of changing more than one is usually not additive. The optimum range for each factor is suggested through reviewing previous work and our recent results of a full factorial range strength study. The interaction of factors is considered and discussed throughout the paper, hoping to gain a better understanding of the processing of alkali-activated slag (AAS) cement and concrete.

Optimisation procedure for the silanisation of silicas for reversed-phase high-performance liquid chromatography : I. Elimination of non-significant variables

The reaction between chlorosilanes and silica to produce reversed-phase bonded phases for chromatographic separations in influenced by many variables. A full factorial study involving most of the possible variables would require in excess of two million individual experiments. The application of Plackett-Burman statistcs reduces the number to twenty-four experiments. These data can then be further extended and precision improved.