The proportionality constant k depends upon a number of factors for the material. Rubber elasticity may be defined operationally as very large deformability with essentially complete recoverability. On improved network models for rubber elasticity and their applications to orientation hardening in glassy polymers. Elasticity of rubbers is composed from the elastic responses of the chains crosslinked in the network sample. Latex is a natural resource and the elasticity can be increased by heating it with sulfur. Therefore, the elasticity of rubbers is of purely entropic nature. Elasticity, stress, strain, and fracture boundless physics. As a consequence of connectivity and chain flexibility, the network exhibits high elasticity and may be reversibly deformed to. The essential idea of the localization model of rubber elasticity is that that the network chain segments are localized at the network junctions, as in classical elasticity theory, but they also consider the chainsegments to be localized along their contours by a interparticle packing interactions, as in atoms in a. I mean according to the first definition, certainly rubber is more elastic than steel as rubber has tendency to regain its shape even when stretched several times its natural length. Bulletin of the transilvania university of bra sov vol. After a region k to l of partial elastic behaviour, plastic flow continued from l to m. If youre seeing this message, it means were having trouble loading external resources on our website. The elasticity of the single polymer chain, which is the basic unit of the elastomeric solid, is discussed first.
The purpose of this section is to develop some general rules about elasticity, which may them be applied to the four different specific types of elasticity discussed in more detail below. First, we describe experimental results that characterize the elastic behaviour of rubber, in particular of vulcanized natural rubber. Examination of the theories of rubber elasticity using an ideal polymer network. View the table of contents for this issue, or go to the journal homepage for more. Crosslinked polymers and rubber elasticity chapter 9 sperling definition of rubber elasticity and requirements crosslinks, networks, classes of elastomers sections, 16 simple theory of rubber elasticity sections 48 entropic origin of elastic retractive forces the ideal rubber behavior. Chapter 3 rubber elasticity entropydriven elasticity of rubber materials the thermoelastic effects. A new attempt to reconcile the statistical and phenomenological. If the deformation, or strain the ratio of the change in length to the initial length, is.
If youre behind a web filter, please make sure that the domains. While i get what my textbook intends to say, i strongly think that there is a subtle difference between the 2 definitions. Abstract it is argued that one can envisage two extreme regimes in rubber. Rubber elasticity an overview sciencedirect topics. Volume stress f a b volume strain v v the bulk modulus is negative because of decrease in v. A thermodynamic study of an isotropic rubber band under uniaxial stress is presented on the basis of its equation of state. Objects that are very elastic like rubber have high elasticity and stretch easily.
Engineering sciences mechanical properties of rubber an overview al. Molecular aspects of rubber elasticity springerlink. Several studies have been carried out to reuse scraptires in a variety of rubber and plastic products, incineration for production of electricity, or as fuel for cement kilns, as well as in asphalt concrete. Elasticity 4 in general, things are more complicated than this but can be resolved in terms of these basic deformations.
In this chapter we focus on the isothermal phenomenological theory of the elasticity and inelasticity of rubber. This theory provides data for elastic and resistance rubber properties when the rubber is constrained to deformation that are smaller than 300%. It is obtained by chemical crosslinking chains in a melt or in a concentrated solution charles goodyear 18001860. The mechanics of rubber elasticity treloar 1974 journal of. Rubber is one of the most important and fascinating polymeric materials. Equation of state and molecular structure objective to determine the macroscopic thermodynamic equation of state of an elastomer, and relate it to its microscopic molecular properties. In such cases, there is a bulk modulus b of elasticity. Strength enhancement in miscible blends of butyl rubber and. The spring constant associated with a single polymer chain is of importance in a wide range of situations from the development of a simple description of rubber elasticity to understanding flow behavior and other physical deformations of the chain. Several studies have been carried out to reuse scraptires in a variety of rubber and plastic products, incineration for production of electricity. L is proportional to the force applied at least for small deformations. High molecular weight polymers that exhibit rubber like behavior are known as elastomers.
Apr 28, 2016 to understand the molecular properties and theoretical concepts that characterize rubber elasticity. The elementary and more advanced theories of rubber elasticity are discussed. The behavior of the rubber band is compared with both that of an ideal elastomer and that of an ideal gas, considering the generalized joules law as the ideality criterion. If a rubber band stretched 3 cm when a 100g mass was attached to it, then how much would it stretch if two similar rubber bands. Elasticity is a measure of just how much the quantity demanded will be. Published online in wiley interscience terscience rubber elasticity is one of the most fascinating. Abstract a thermodynamic study of an isotropic rubber band under uniaxial stress is presented on the basis of its equation of state.
Find all the books, read about the author, and more. I mean like rubber gloves have a good elasticity while rubber bands not really elastic. Polymer science had developed greatly since the second edition of this text in 1958, and the two main advances the refinements of the. Above the glass transition temperature, the rubber like polymers are in a liquidlike state and the mer or repeat units change their position readily and continuously due to brownian motion. For statistic treating of rubber elasticity, an ideal macromolecule is used. Cavendish laboratory, university of cambridge madingley road. The behavior of the rubber band is compared with both that of an ideal.
Rubber elasticity rubber is one of the most important and fascinating polymeric materials. The bulk modulus is negative because of decrease in v. Elasticity, ability of a deformed material body to return to its original shape and size when the forces causing the deformation are removed. The theory of rubber elasticity edwards 1977 british polymer. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Physics 3 summer 1989 lab 7 elasticity theory all materials deform to some extent when subjected to a stress a force per unit area. Lecture 4 agsm2004 page 22 price elasticity of supply only for pricetaking suppliers monopolists do not have supply cur ves. Treloar, 9780198570271, available at book depository with free delivery worldwide. G treloar oxford classic texts in the physical sciences. The term rubber elasticity refers to the remarkable property of crosslinked rubber.
The nominal stresses are workconjugate to the stretches. University of groningen on improved network models for. University of groningen on improved network models for rubber. Rubber elasticity is the generic term describing the behavior of polymeric solids made up of flexible chains which are joined together to form a threedimensional structure referred to as a network. Publication date 1958 topics elasticity, rubber publisher oxford.
Demonstration as an example of the more complicated behaviour one can get, consider a rod under the action of a. External stress changes the equilibrium endtoend distance of a chain, and it thus adopts a less probable conformation. The rubber bands elasticity, water resistance, and lightness have made it a universal commodity. On the other hand, if it takes a larger force applied to the band to stretch the.
The forces between the atoms due to electrostatic interaction between the charges of the atoms are called interatomic forces. High elasticity is first treated by examining the phenomena at macromolecular scale 6. To a greater or lesser extent, most solid materials exhibit elastic behaviour, but there. The structure of the network obtained by joining the single chains together is described. The rubber sample 3 is stuck between two bolted clamps 2. A detailed study of that eightchain model for rubber elasticity in comparison with experiments.
To understand the molecular properties and theoretical concepts that characterize rubber elasticity. Some principal aspects of these atomistic views of elastic. It is fundamentally different from the restoring force in a spring, which relies on the mechanical stiffness of the material. As a consequence of connectivity and chain flexibility, the network exhibits high elasticity and may be reversibly deformed to several times its. Publishers pdf, also known as version of record publication date. Terms in this set 37 elasticity the property of an object to return to its original dimensions after distorting forces are bber, springs. Elasticity and inelasticity of rubber springerlink. The development of rubber elasticity theory represents one of the most promising attempts to relate our knowledge of the behaviour of a polymeric material on a molecular level with its behaviour on a gross, macroscopic level. For example, a guitar string made of nylon stretches when it is tightened, and the elongation. In rubber the elastic force is due to the thermal interactions of the molecules within the material. Elastic materials have internal forces which restore the size and shape of the object when the stress is removed. It covers all those physical properties which are needed for an understanding of how those properties are created by the chain molecules which form the material. Above the glass transition temperature, the rubberlike polymers are in a liquidlike state and the mer or repeat units change their position readily and continuously due to brownian motion. Rubber band elasticity the concept of elasticity, as used in economics, is quite similar to the concept as applied to.
It is suitable for the nonspecialist and the emphasis is on the physical reality embodied in the mathematical formulations. Today rubber bands are most commonly used to hold multiple items together. This is one of the great classic works on rubber and its very peculiar properties, republished now in paperback for a new generation of readers. The rubber is collected from the latex in a series of steps involving preservation, concentration, coagulation, dewatering, drying, cleaning, and blending. Modifications to the original rubber band patented in england on march 17, 1845 by stephen perry include aerobic bands, bracelets, and projectiles. The theory of rubber elasticity due to flory starts from the two postulates. Concept of elasticity the quantity demanded of a good is affected mainly by changes in the price of a good, changes in price of other goods, changes in income and c changes in other relevant factors. Classical network elasticity theories are based on the concept of flexible volumeless network chains fixed into a network in which there are no. As an additional assumption for the model of elasticity, we. It is obtained by chemical crosslinking chains in a melt or. Thicker nylon strings and ones made of steel stretch less for the same applied force, implying they have a larger k see figure 2. These forces are electrical in nature and these are active if the distance between the two atoms is of the order of atomic size i. Very large deformability with complete recoverability. The spring constant associated with a single polymer chain is of importance in a wide range of situations from the development of a simple description of rubber elasticity to understanding flow behavior and other physical deformations of the.
It is extracted in the form of latex from the bark of the hevea tree. Relation of elastic modulus to crosslink and entanglement. Broad readership in physics, chemistry, polymer science, theoretical and applied mechanics. Elasticity 5 as the stress was further increased, a point y, known as the yield point, at which the stress rapidly dropped, was reached. Introduction we are all familiar with the very useful properties of such objects as rubber bands, solid rubber balls. Elasticity is a measure of just how much the quantity demanded will be affected by a change in price or. If the distorting force exceeds the objects elasticity limit.
On the upper end of the iron bar there is a scaled guide roller 4. Roussel department of chemistry and biochemistry university of lethbridge february 21, 2009 a rubber is a material that can undergo large deformations e. The physics of rubber elasticity third edition by l. High molecular weight polymers that exhibit rubberlike behavior are known as elastomers. Elasticity and kinetics of vulcanized rubber practice. The first is a dilute regime, where crosslinks are the only significant interaction. The physics of rubber elasticity oxford classic texts in the physical sciences 3rd edition. The physical chemistry of polymers 1962 bell laboratories the structure and crosslinks of polymers in rubber have significant impact on its elasticity. Elasticity is a measure of the deformation of an object when a force is applied. Abstract the theory of rubber elasticity relates the elastic modulus of unfilled amorphous rubber to the concentration of elastically effective strands.
Practical course of polymers university of bonn rubber elasticity the device consists of a steel bar 1, which has an iron pin on the lower end. A body with this ability is said to behave or respond elastically. Physics of rubber elasticity by eloisadevries issuu. That is, the elasticity coefficient should increase as the length increases for a given force. My question is why they are have different elasticity than that of latex.
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