Linked Life Data

16797663

Source:http://linkedlifedata.com/resource/pubmed/id/16797663

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
2007-1-1
pubmed:abstractText
The last decades have seen the development of sol-gel (SG) process currently used to develop new materials in a wide range of scientific applications. The SG process leads to an oxide macromolecular network through a sol (liquid phase) to gel transition. To optimize this process, the control of the kinetic of the chemical reaction is required. This kinetic can be deduced from the temporal evolution of the viscoelastic parameters. Upto date no complete investigation during the SG formation can be achieved by a unique non-destructive technique. In this paper, we present an ultrasonic technique to measure the viscoelastic parameters (storage G' and loss G'' shear moduli) of the gel material during its formation. By using a suitable model which takes into account the mass loading on the surface, the viscoelastic parameters of these materials are accurately deduced. In order to study the efficiency of this technique, silica gels transition is monitored at various formation temperatures and for different initial hydrolysis molar ratio (h). In addition, the monitoring is performed at different oscillatory shear measurements in the 6-54 MHz frequency range to determine a new characteristic time t(vs) corresponding to the moment when the material is no more a newtonian liquid. This characteristic time is then compared to the gelation time t(g) determined by rheological or acoustic audible range methods. Thus the new characteristic time is also a good criterion to characterize earlier the SG matrix transition. Our AT-cut quartz technique using our model can also be used as a high frequency rheometer for the sol-gel materials.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
1874-9968
pubmed:author
pubmed:issnType
Electronic
pubmed:day
22
pubmed:volume
44 Suppl 1
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
e881-5
pubmed:dateRevised
2009-11-11
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Kinetic study of silica gels by a new rheological ultrasonic investigation.
pubmed:affiliation
Equipe Circuits, Instrumentation et Modélisation Electronique, Université de Cergy, Neuville sur Oise, 95031 Cergy Pontoise Cedex, France.
pubmed:publicationType
Journal Article, Evaluation Studies