![]() ![]() The results indicated that the amylose of starch was a key component that influenced the properties of PVA/starch blend hydrogels. ![]() In order to elucidate the effect of component of starch on the properties of PVA/starch hydrogels as well as the formation mechanism of PVA/starch blend hydrogels under irradiation, the two components of starch, amylose and amylopectin, were chosen to blend with PVA to prepare the hydrogels, respectively. The gel strength was improved obviously after adding starch into PVA hydrogels, but the swelling properties decreased slightly due to poor hydrophilicity of starch. The influence of dose, the content of starch in blend systems on the properties of the prepared hydrogels was investigated. (C) 2000 John Wiley & Sons, Inc.read more read lessĪbstract: A series of excellent polyvinyl alcohol (PVA)/starch blend hydrogels were prepared by gamma and electron beam radiation at room temperature. A preliminary biodegradation study confirmed that crosslinked CMC hydrogel can be digested by a cellulase enzyme. It is assumed that high radiation crosslinking of CMC was induced by the increased mobility of its molecules in water and by the formation of CMC radicals from the abstraction of H atoms from macromolecules in the intermediate products of water radiolysis. Hence, it was apparent that a high DS and a high concentration in an aqueous solution were favorable for high crosslinking of CMC. CMC with a DS of 2.2 induced higher crosslinking than that with a DS of 1.32 at lower doses with the same concentration. However, it was found that irradiation of CMC with a relatively high DS, 1.32, led to crosslinking in a 5% aqueous solution, and 20% CMC gave the highest gel fraction. Irradiation of CMC, even with a high DS, 2.2 in solid state, and a low DS, 0.7 in 10% aqueous solution, resulted in degradation. The DS and the concentration of the aqueous solution had a remarkable affect on the crosslinking of CMC. CMC was irradiated in solid-state and aqueous solutions at various irradiation doses. coli, even when the CM-chitosan concentration was only 3 wt%.read more read lessĪbstract: Radiation crosslinking of carboxymethylcellulose (CMC) with a degree of substitution (DS) from 0.7 to 2.2 was the subject of the current investigation. The blend hydrogels exhibited satisfying antibacterial activity against E. The antibacterial activity of the hydrogels against Escherichia coli was also measured via optical density method. The further analyses of FTIR and DSC spectra of the prepared gels after extracting sol manifested that there was a grafting interaction between PVA and CM-chitosan molecules under irradiation. The gel fraction determined gravimetrically showed that a part of CM-chitosan was immobilized onto PVA hydrogel. The mechanical properties and equilibrium degree of swelling improved obviously after adding CM-chitosan into PVA hydrogels. The properties of the prepared hydrogels, such as the mechanical properties, gel fraction and swelling behavior were investigated. Electron spectroscopy analysis of the blend hydrogels revealed that good miscibility was sustained between CM-chitosan and PVA. The fact that discoloration of colored alginate was caused on exposure to ozone suggests a formation of double bond in the pyranose-ring.read more read lessĪbstract: A series of excellent hydrogels were prepared from poly(vinyl alcohol) (PVA) and carboxymethylated chitosan (CM-chitosan) with electron beam irradiation (EB) at room temperature. UV spectra showed a distinct absorption peak at 265 nm for colored alginates, increasing with dose. Little color change was observed on irradiation in the presence of oxygen. The degradation was also accompanied by a color change to deep brown for highly degraded alginate. The free radicals from irradiated water must be responsible for the degradation in solution. Degradation G-values were 1.9 for solid and 55 for solution, respectively. For example, the molecular weight of alginate in 1% (w/v) solution decreased from 6×10 −5 for 0 kGy to 8×10 −3 for 20 kGy irradiation while the equivalent degradation by solid irradiation required 500 kGy. ![]() The degradation in solution was remarkably greater than that in the solid. Degradation was observed both in the solid state and solution. Abstract: Alginates were irradiated as solids or in aqueous solution with Co 60 gamma rays in the dose range of 20 to 500 kGy to investigate the effect of radiation on alginates. ![]()
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