The present study is an investigation of the properties of poly(vinyl alcohol),which would be a better contact lens mate- rial than conventional HEMA in some ways.A transparent PVA hydrogel was prepared from a PVA sol...The present study is an investigation of the properties of poly(vinyl alcohol),which would be a better contact lens mate- rial than conventional HEMA in some ways.A transparent PVA hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent,DMSO,by the freezing-thawing method.The water content,visible light transmittance,mechanical and swelling properties of the hydrogels were evaluated as a function of PVA concentration and number of freeze-thaw cycles.The results show that the properties of PVA hydrogels depend on the polymer concentration,the number of freeze-thaw cycles and the addition of the organic solvent.展开更多
Using the simulation test facility designed on the basis of similitude principle, the authors of the paper carry out a series of simulation tests and study the influence of effective factors on the stress in the freez...Using the simulation test facility designed on the basis of similitude principle, the authors of the paper carry out a series of simulation tests and study the influence of effective factors on the stress in the freezing pipes during hoth periods of active freezing and excavating-lining. They obtain preliminarily the regularity of stress variation and discuss the causes of freezing pipe fracture.展开更多
基金Projects 50575106 supported by the National Natural Science Foundation of ChinaBG2007046 by the High Technology Project of Jiangsu Province
文摘The present study is an investigation of the properties of poly(vinyl alcohol),which would be a better contact lens mate- rial than conventional HEMA in some ways.A transparent PVA hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent,DMSO,by the freezing-thawing method.The water content,visible light transmittance,mechanical and swelling properties of the hydrogels were evaluated as a function of PVA concentration and number of freeze-thaw cycles.The results show that the properties of PVA hydrogels depend on the polymer concentration,the number of freeze-thaw cycles and the addition of the organic solvent.
文摘Using the simulation test facility designed on the basis of similitude principle, the authors of the paper carry out a series of simulation tests and study the influence of effective factors on the stress in the freezing pipes during hoth periods of active freezing and excavating-lining. They obtain preliminarily the regularity of stress variation and discuss the causes of freezing pipe fracture.
