Thermodynamics Of Rubber Elasticity

Thermoelastic measurements at constant volume are reported for a series of natural rubber samples.

Thermodynamics of rubber elasticity. In the next section the choice of stress τ length l and temperature t as state variables is justified and a simple equation of state is presented. The process of vulcanization which links the polymer molecules into a three dimensional network enables reversible thermodynamic measurements to be made on elastomeric materials from which the entropy and energy contributions to the free energy of deformation can be determined. Here we need to also consider the extension. What happens if you release the stress applied to a cross linked coil.

This can be repeated many times with no apparent degradation to the rubber. If you released a rubber band with properties like that it would. The molecular processes responsible for rubber elasticity are most readily interpreted in terms of the constant. This paper describes only the thermodynamic properties of vulcanized rubber.

Without this property the rubber band would have no reason to tend towards a tangled state since the entropy would be about the same in both states. Thermodynamics of a rubber band. Metallic materials possess energy elasticity while ideal. The cross linking property of polymers is vital to the band s elasticity.

Taken as a whole the results from thermodynamic studies on lightly cross linked rubbery polymers support the view that the retractive force is primarily intramolecular in origin. Rubber elasticity is in fact the number of chains bounded by two cross link junctions a quantity called the number of active chains denoted. Rubber is a member of a larger class of materials called elastomers and it is difficult to overestimate their economic and. Deformation is a constant volume process ν.

The same property also causes the thermoelastic shrinkage. Rubber elasticity refers to a property of crosslinked rubber. Theory of rubber elasticity thermodynamics statistical mechanics and chain statistics kelvin kuhn guth mark james treloar and flory second law of thermodynamics. The energy component of the stress supported by the network is more or less independent of.

Thermodynamics of rubber elasticity at constant volume. The molecular processes responsible for rubber elasticity are most readily interpreted in terms of the constant volume coefficients u l v t and s l v t. The elastic recovery of rubber is due to its tendency to maximize the entropy. Rubberlike elasticity is described.

It can be stretched by up to a factor of 10 from its original length and when released returns very nearly to its original length.