ISSN:
0032-3888
Schlagwort(e):
Chemistry
;
Chemical Engineering
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
,
Physik
Notizen:
Experimental results for thermal conductivity and flow birefringence on liquid poly (dimethyl siloxane), PDMS, under a shearing strain are discussed. An increase in thermal conductivity with increasing shear rate is attributed to an increased degree of orientation in a direction at 45° to the flow direction for simple shear. A mathematical model is set up. It is based on the assumption that the macromolecules do not change their time-average shape and otherwise behave as rigid, thin cylinders which can be influenced by convection and external fields and are endowed with rotational Brownian motion. The model predicts that thermal conductivity will reach a maximum value at moderate rates of strain and begin to decrease eventually reaching a minimum value (the transverse thermal conductivity of the basic element) at very high rates of strain when the molecules are completely aligned in the flow direction. Liquids studied were a 12,500 centipoise PDMS in the pure state and in solution in methyl ethyl ketone, MEK, as well as a 65,000 centipoise solution in MEK.
Zusätzliches Material:
5 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pen.760150510
