جستجوی مقالات مرتبط با کلیدواژه "گلیسرول" در نشریات گروه "مهندسی شیمی، نفت و پلیمر"

Carbon dioxide (CO2) separation from flue gases as a green-house gas produced from the combustion of fossil fuels is one of the main concerns in controlling the green-house gas emissions. Among the various technologies employed for gas separation, membrane technology due to its many advantages has attracted more attentions. A new blend membranes were prepared by solution casting/solvent evaporation method from poly(ether-b-amide) (Pebax) – as a backbone structure – and glycerol as an additive in the membrane matrix. CO2 and N2 permeability rates were measured at pressures of 2-10 bar and temperature of 25 °C. Afterwards, the CO2/N2 gas permeation properties were determined. Moreover, the effect of different glycerol loadings (0-25 wt%) in the membrane matrix and also the effect of feed pressure on CO2 permeability and CO2/N2 selectivity were investigated. Morphological characteristics of the prepared membranes were determined by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) analyses. The achieved results showed that by addition of glycerol to Pebax matrix, CO2 permeability was decreased somewhat but the CO2/N2 selectivity was considerably increased. At pressure of 10 bar, CO2/N2 selectivity of the blend membrane with 15 wt% glycerol was 172% higher than that of pure Pebax, while the CO2 permeability declined only by about 23%. Therefore, the blend membrane containing 15 wt% glycerol with a good CO2 permeability and a high CO2/N2 selectivity was selected as the optimum membrane. The FE-SEM observations revealed the compatibility and homogeneity of glycerol in the Pebax matrix. The XRD analysis determined that the addition of glycerol decreases the membrane crystallinity and the d-spacing between the polymer chains. The DSC results revealed that the insertion of glycerol in the membrane structure decreased the glass transition temperature. The FTIR spectra showed no new absorption band except for those for the constituent species, which suggests a physical interaction between Pebax and glycerol.

In this research, wheat, corn and potato thermoplastic starch films were prepared through melt mixing method and the effect of starch type and glycerol plasticizer content on their tensile and moisture sorption properties was investigated. The results depicted that by increasing glycerol content at studied range, the tensile strength and elastic modulus of film of all three starch types decreased significantly, while their percentage of elongation at break first raised up to certain amount and then followed a decreasing trend. Also among three thermoplastic starches, potato thermoplastic starch films had the highest tensile strength and elastic modulus and the lowest percentage of elongation at break values due to having higher amount of amylopectin content than other two thermoplastic starches. For all of three thermoplastic starches, increasing glycerol content increased moisture absorption of films so that by increasing glycerol weight percentage from 25 to 35 , the moisture absorption of wheat, corn and potato thermoplastic starch films conditioned at relative humidity of 84% for 7days, increased from 26.8, 29.9 and 36.8 to 30.8, 34.6 and 41.7 respectively. Indeed at the same environment relative humidity and glycerol content, the potato thermoplastic starch films had higher moisture absorption than wheat and corn thermoplastic starch films. The data of moisture sorption isotherm curves for the three thermoplastic starch films was modeled by Peleg model. The obtained correlation coefficients explained the suitability of this model for prediction of changes of moisture absorption of films versus water activity.