Elastomer large elastic deformation

The high elasticity or rubber elasticity is a specific state of matter displayed by polymers Large reversible deformation is caused by small tensions. For instance, natural rubber can be stretched reversibly 10-15 times of its original length. Polymeric materials exhibiting high elasticity at room temperature are called elastomers or rubbers. 

The possibility of the existence of the mesophase in a highly elastic state characterized by the capacity of the polymer to exhibit large reversible deformations offers interesting prospects for the creation of new types of liquid-crystalline materials in the form of elastic films and is interesting for elaborating a theory of the viscoelastic behavior of unusual LC elastomers [14]. 

Deformation of Large elastic extensions are possible for elastomeric materials that are amorphous Elastomers and lightly crosslinked. 

The characteristic property of elastomers is their rubber-elastic behavior. Their softening temperature lies below room temperature. In the unvulcanized state, i.e. without crosslinking of the molecular chains, elastomers are plastic and thermo-formable, but in the vulcanized state—within a certain temperature range — they deform elastically. Vulcanization converts natural rubber into the elastic state. A large number of synthetic rubber types and elastomers are known and available on the market. They have a number of specially improved properties over crude rubber, some of them having substantially improved elasticity, heat, low-temperature, weathering and oxidation resistance, wear resistance, resistance to different chemicals, oils etc. 

Polymers that, in contrast to thermosets, have a macromolecule structure with wide-meshed crosslinks are called elastomers. Their characteristic property is their not being flowable up to the temperature range of chemical decomposition, but they are rubbery-elastic and reversibly deformable, to a large extent independent of temperature (e.g., rubber products). 

It will be shown in Chapter 11 that the correlations developed in this monograph can be combined with other correlations that are found in the literature (preferably with the equations developed by Seitz in the case of thermoplastics, and with the equations of rubber elasticity theory with finite chain extensibility for elastomers), to predict many of the key mechanical properties of polymers. These properties include the elastic (bulk, shear and tensile) moduli as well as the shear yield stress and the brittle fracture stress. In addition, new correlations in terms of connectivity indices will be developed for the molar Rao function and the molar Hartmann function whose importance in our opinion is more of a historical nature. A large amount of the most reliable literature data on the mechanical properties of polymers will also be listed. The observed trends for the mechanical properties of thermosets will also be discussed. Finally, the important and challenging topic of the durability of polymers under mechanical deformation will be addressed, to review the state-of-the-art in this area where the existing modeling tools are of a correlative (rather than truly predictive) nature at this time. 

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