Summary: The swelling properties of photochemically crosslinked poly(n‐butyl acrylate) (PABu) networks in isotropic and anisotropic solvents were investigated experimentally. The purpose of this study was to examine the swelling kinetics of PABu networks in isotropic solvents and to compare the results obtained which those observed in the case of the low molecular weight liquid crystal 4‐cyano‐4′‐n‐pentyl‐biphenyl known as 5CB. The phase diagrams were established in terms of composition and temperature for isotropic solvents, as toluene, acetone, cyclohexane, and methanol, and 5CB, using the plateau values corresponding to equilibrium states of swelling. The polymer networks were prepared via free radical polymerization/crosslinking processes by ultraviolet (UV) radiation of initial mixtures made up from a monomer, a crosslinker, and a photoinitiator. PABu networks with several crosslinking densities were formed using different quantities of difunctional monomer hexanedioldiacrylate (HDDA). Immersion of these networks in excess solvent allows measuring the solvent uptake by determination of the weight in isotropic solvents and diameter in an anisotropic solvent (5CB). Swelling data were rationalized by calculating weight and diameter ratios considering swollen to dry network states of the samples.
Inhibition efficiencies (IE) process in polyvinylpyrrolidone (PVP) which is influenced by independent factors, concentration and size of PVP, temperature, time of immersion, and perchloric acid concentration was investigated in this paper. The relationship between factors and their responses is established by the concept of response surface methodology (RSM) explicitly through regression statistical analysis and probabilistic analysis is used in this work. The concept is a combination of mathematical and statistical techniques allowing the modeling and problems analysis by experimental design. In this study, the results based on statistical analysis showed that the quadratic models for the inhibition efficiencies (IE) were significant at the value of probability P < 0.0001 and the coefficient of multiple regressions R2=0.9997, for further validation of the model, R2Adj=0.9993 indicated a good model. The observed experimental values were in good agreement with predicted ones and the model washighly significant with Q2= 0.9884. The optimal conditions of inhibition efficiencies (IE) obtained are 104.301% for a concentration of 3.55×10−3 mol/L, temperature of 20.15°C, immersion time of 2h, size of PVP 58000 g/mol, and acid concentration of 0.5 mol/L.
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