I mean like rubber gloves have a good elasticity while rubber bands not really elastic. The elementary and more advanced theories of rubber elasticity are discussed. The elasticity of the single polymer chain, which is the basic unit of the elastomeric solid, is discussed first. Physics of rubber elasticity by eloisadevries issuu. Elasticity is a measure of just how much the quantity demanded will be. 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. Examination of the theories of rubber elasticity using an ideal polymer network.
High elasticity is first treated by examining the phenomena at macromolecular scale 6. External stress changes the equilibrium endtoend distance of a chain, and it thus adopts a less probable conformation. The structure of the network obtained by joining the single chains together is described. The first is a dilute regime, where crosslinks are the only significant interaction. Abstract a thermodynamic study of an isotropic rubber band under uniaxial stress is presented on the basis of its equation of state.
L is proportional to the force applied at least for small deformations. Bulletin of the transilvania university of bra sov vol. Elasticity 5 as the stress was further increased, a point y, known as the yield point, at which the stress rapidly dropped, was reached. Rubber is one of the most important and fascinating polymeric materials. The behavior of the rubber band is compared with both that of an ideal. Several studies have been carried out to reuse scraptires in a variety of rubber and plastic products, incineration for production of electricity. Abstract it is argued that one can envisage two extreme regimes in rubber. 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. Elasticity is a measure of the deformation of an object when a force is applied. If the deformation, or strain the ratio of the change in length to the initial length, is. High molecular weight polymers that exhibit rubber like behavior are known as elastomers.
Some principal aspects of these atomistic views of elastic. Roussel department of chemistry and biochemistry university of lethbridge february 21, 2009 a rubber is a material that can undergo large deformations e. 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. Latex is a natural resource and the elasticity can be increased by heating it with sulfur. Lecture 4 agsm2004 page 22 price elasticity of supply only for pricetaking suppliers monopolists do not have supply cur ves. The theory of rubber elasticity edwards 1977 british polymer. It is obtained by chemical crosslinking chains in a melt or in a concentrated solution charles goodyear 18001860. 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. As an additional assumption for the model of elasticity, we. Strength enhancement in miscible blends of butyl rubber and.
Find all the books, read about the author, and more. Apr 28, 2016 to understand the molecular properties and theoretical concepts that characterize rubber elasticity. To a greater or lesser extent, most solid materials exhibit elastic behaviour, but there. 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. The rubber sample 3 is stuck between two bolted clamps 2. On the other hand, if it takes a larger force applied to the band to stretch the. Relation of elastic modulus to crosslink and entanglement. 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. For example, a guitar string made of nylon stretches when it is tightened, and the elongation. Elasticity of rubbers is composed from the elastic responses of the chains crosslinked in the network sample. Introduction we are all familiar with the very useful properties of such objects as rubber bands, solid rubber balls.
The nominal stresses are workconjugate to the stretches. Rubber elasticity rubber is one of the most important and fascinating polymeric materials. 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. Volume stress f a b volume strain v v the bulk modulus is negative because of decrease in v. 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. The rubber is collected from the latex in a series of steps involving preservation, concentration, coagulation, dewatering, drying, cleaning, and blending. It is obtained by chemical crosslinking chains in a melt or. Terms in this set 37 elasticity the property of an object to return to its original dimensions after distorting forces are bber, springs. 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. As a consequence of connectivity and chain flexibility, the network exhibits high elasticity and may be reversibly deformed to. If the distorting force exceeds the objects elasticity limit. 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 rubberlike polymers are in a liquidlike state and the mer or repeat units change their position readily and continuously due to brownian motion. Elasticity and inelasticity of rubber springerlink.
Demonstration as an example of the more complicated behaviour one can get, consider a rod under the action of a. It is extracted in the form of latex from the bark of the hevea tree. Published online in wiley interscience terscience rubber elasticity is one of the most fascinating. The physics of rubber elasticity third edition by l. Learn vocabulary, terms, and more with flashcards, games, and other study tools. As a consequence of connectivity and chain flexibility, the network exhibits high elasticity and may be reversibly deformed to several times its. 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.
It is suitable for the nonspecialist and the emphasis is on the physical reality embodied in the mathematical formulations. To understand the molecular properties and theoretical concepts that characterize rubber elasticity. A thermodynamic study of an isotropic rubber band under uniaxial stress is presented on the basis of its equation of state. Broad readership in physics, chemistry, polymer science, theoretical and applied mechanics. Engineering sciences mechanical properties of rubber an overview al. 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. The term rubber elasticity refers to the remarkable property of crosslinked rubber. Cavendish laboratory, university of cambridge madingley road. Rubber band elasticity the concept of elasticity, as used in economics, is quite similar to the concept as applied to. 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. Modifications to the original rubber band patented in england on march 17, 1845 by stephen perry include aerobic bands, bracelets, and projectiles. Elasticity, ability of a deformed material body to return to its original shape and size when the forces causing the deformation are removed. A new attempt to reconcile the statistical and phenomenological. Publishers pdf, also known as version of record publication date.
On the upper end of the iron bar there is a scaled guide roller 4. The forces between the atoms due to electrostatic interaction between the charges of the atoms are called interatomic forces. Therefore, the elasticity of rubbers is of purely entropic nature. Elasticity is a measure of just how much the quantity demanded will be affected by a change in price or. In this chapter we focus on the isothermal phenomenological theory of the elasticity and inelasticity of rubber.
That is, the elasticity coefficient should increase as the length increases for a given force. 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. Chapter 3 rubber elasticity entropydriven elasticity of rubber materials the thermoelastic effects. The theory of rubber elasticity due to flory starts from the two postulates. If youre behind a web filter, please make sure that the domains. High molecular weight polymers that exhibit rubberlike behavior are known as elastomers. Today rubber bands are most commonly used to hold multiple items together. 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. Very large deformability with complete recoverability. View the table of contents for this issue, or go to the journal homepage for more. 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. Rubber elasticity may be defined operationally as very large deformability with essentially complete recoverability. Elasticity, stress, strain, and fracture boundless physics.
My question is why they are have different elasticity than that of latex. The physical chemistry of polymers 1962 bell laboratories the structure and crosslinks of polymers in rubber have significant impact on its elasticity. While i get what my textbook intends to say, i strongly think that there is a subtle difference between the 2 definitions. 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 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. Abstract the theory of rubber elasticity relates the elastic modulus of unfilled amorphous rubber to the concentration of elastically effective strands. University of groningen on improved network models for. Molecular aspects of rubber elasticity springerlink. In such cases, there is a bulk modulus b of elasticity. Elasticity and kinetics of vulcanized rubber practice. Publication date 1958 topics elasticity, rubber publisher oxford. This theory provides data for elastic and resistance rubber properties when the rubber is constrained to deformation that are smaller than 300%. If youre seeing this message, it means were having trouble loading external resources on our website. The proportionality constant k depends upon a number of factors for the material.
Classical network elasticity theories are based on the concept of flexible volumeless network chains fixed into a network in which there are no. Treloar, 9780198570271, available at book depository with free delivery worldwide. Physics 3 summer 1989 lab 7 elasticity theory all materials deform to some extent when subjected to a stress a force per unit area. A body with this ability is said to behave or respond elastically. For statistic treating of rubber elasticity, an ideal macromolecule is used. On improved network models for rubber elasticity and their applications to orientation hardening in glassy polymers. The bulk modulus is negative because of decrease in v. First, we describe experimental results that characterize the elastic behaviour of rubber, in particular of vulcanized natural rubber. G treloar oxford classic texts in the physical sciences. Rubber elasticity an overview sciencedirect topics.
Thicker nylon strings and ones made of steel stretch less for the same applied force, implying they have a larger k see figure 2. Elastic materials have internal forces which restore the size and shape of the object when the stress is removed. University of groningen on improved network models for rubber. It is fundamentally different from the restoring force in a spring, which relies on the mechanical stiffness of the material.
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