Rubber elasticity theory.
Molecular Theory of Rubber Elasticity Paul J.
Rubber elasticity theory This gives S= k X n nlnW n:. , 2000 ). • Definition of Rubber Elasticity and Requirements • Cross-links, Networks, Classes of Elastomers (sections 1-3, 16) • Simple Theory of Rubber Elasticity (sections 4-8) – Entropic Origin of Elastic Retractive Forces – The Ideal Rubber Behavior • Departures from the Ideal Rubber Behavior (sections 9-11) The rubber elasticity theory was originally developed for vulcanized rubbers by Treloar and Flory (Flory, 1944; Treloar, 1944). (Received August 20, 1984) The theory of rubber elasticity has been developed to describe the elastic properties of polymer networks and is a molecular view of the network behavior. A. The Flory theory of rubber elasticity suggests that rubber elasticity has primarily entropic origins. We can compute Wby W= Y n (W n) n; where n is the number of chains containing nbonds. The models developed from the last century to today describe many aspects of the physics of rubber elasticity; although 4 Statistical theory of rubber elasticity To calculate the entropy of a rubber, we will use the Boltzmann equation: S= klnW; where Wis the number of microstates. The a ne network model describes well the mechanical behavior One of the most important challenges in polymer science is a rigorous understanding of the molecular mechanisms of rubber elasticity by relating macroscopic deformation to molecular changes and deriving the constitutive stress–strain equation for the elastomeric network. Below we describe rubber elasticity in one of its most common forms, known as the a ne network model. By using the following basic equations for Helmholtz free energy and its discussion about entropy, the force generated from the deformation of a rubber chain from its original unstretched conformation can be derived. Later, it was extended to a larger class of polymers by Flory ( Peppas et al. The active chains may have di erent lengths, which a ects W. FLORY Department of Chemistry, Stanford University, Stanford, California 94305, U. Molecular Theory of Rubber Elasticity Paul J. S. xtjcudnntjbilwagivicklmqzgwwivzntlhywgybspordb