ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The rheological properties of polystyrene have been studied between 90 and 240°C. as a function of molecular weight. Three different methods have been used to obtain the data: rotational viscometer, extrusion-type capillary viscometer, and tensile creep measurements. It has been shown that the nonrecoverable (viscous) deformation is a function of molecular weight whereas the recoverable deformations are, within the investigated molecular weight range, practically independent of chain length. An explanation of this observation is suggested, based on the assumption of a labile network structure, which explains also the effect of “previous history” on the recoverable deformations. The temperature dependence of the recoverable and nonrecoverable deformations is shown to be very similar. Experimental evidence is presented to show that the dependence of the viscosity on shear stress (or rate of shear) is not a simple power relationship but is of the sigmoidal type. It is shown that the creep or compliance function a few degrees below the second-order transition point does not depend on the weight- or number average molecular weight.
Additional Material:
16 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1951.120060403
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