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Journal ArticleDOI

Rupture of rubber. I. Characteristic energy for tearing

01 Mar 1953-Journal of Polymer Science (Interscience Publishers, Inc.)-Vol. 10, Iss: 3, pp 291-318
TL;DR: The resistance to tearing of a rubber vulcanizate is usually determined by loading in a specified manner a test-piece of the vulcanizer of standard shape, in which a notch has been produced, either in the molding process or by cutting the testpiece in a standard fashion.
Abstract: The resistance to tearing of a rubber vulcanizate is usually determined by loading in a specified manner a test-piece of the vulcanizate of standard shape, in which a notch has been produced, either in the molding process or by cutting the test-piece in a standard fashion. A wide variety of shapes of test-piece and notch and of methods of loading have been recommended by various authors (see, for example, Buist1).
Citations
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Book
01 Jan 1992
TL;DR: A theory aiming to describe their mechanical behavior must take heed of their deformability and represent the definite principles it obeys as mentioned in this paper, which is not the case in modern physics, since it concerns solely the small particles of matter.
Abstract: Matter is commonly found in the form of materials. Analytical mechanics turned its back upon this fact, creating the centrally useful but abstract concepts of the mass point and the rigid body, in which matter manifests itself only through its inertia, independent of its constitution; “modern” physics likewise turns its back, since it concerns solely the small particles of matter, declining to face the problem of how a specimen made up of such particles will behave in the typical circumstances in which we meet it. Materials, however, continue to furnish the masses of matter we see and use from day to day: air, water, earth, flesh, wood, stone, steel, concrete, glass, rubber, ... All are deformable. A theory aiming to describe their mechanical behavior must take heed of their deformability and represent the definite principles it obeys.

2,644 citations

Book
01 Jan 1971
TL;DR: A concise, self-contained introduction to solid polymers, the mechanics of their behavior and molecular and structural interpretations can be found in this article, which provides extended coverage of recent developments in rubber elasticity, relaxation transitions, non-linear viscoelastic behavior, anisotropic mechanical behavior, yield behavior of polymers and other fields.
Abstract: A concise, self-contained introduction to solid polymers, the mechanics of their behavior and molecular and structural interpretations. This updated edition provides extended coverage of recent developments in rubber elasticity, relaxation transitions, non-linear viscoelastic behavior, anisotropic mechanical behavior, yield behavior of polymers, breaking phenomena, and other fields.

2,335 citations

Journal ArticleDOI
TL;DR: It is reported that polyampholytes, polymers bearing randomly dispersed cationic and anionic repeat groups, form tough and viscoelastic hydrogels with multiple mechanical properties.
Abstract: Hydrogels attract great attention as biomaterials as a result of their soft and wet nature, similar to that of biological tissues. Recent inventions of several tough hydrogels show their potential as structural biomaterials, such as cartilage. Any given application, however, requires a combination of mechanical properties including stiffness, strength, toughness, damping, fatigue resistance and self-healing, along with biocompatibility. This combination is rarely realized. Here, we report that polyampholytes, polymers bearing randomly dispersed cationic and anionic repeat groups, form tough and viscoelastic hydrogels with multiple mechanical properties. The randomness makes ionic bonds of a wide distribution of strength. The strong bonds serve as permanent crosslinks, imparting elasticity, whereas the weak bonds reversibly break and re-form, dissipating energy. These physical hydrogels of supramolecular structure can be tuned to change multiple mechanical properties over wide ranges by using diverse ionic combinations. This polyampholyte approach is synthetically simple and dramatically increases the choice of tough hydrogels for applications.

1,496 citations

Journal ArticleDOI
28 Jul 2017-Science
TL;DR: A bioinspired design for adhesives consisting of an adhesive surface with a flexible matrix to develop an adhesive that has the right level of stick but moves with the surrounding tissues, which is effective in the presence of blood and thus might work during wound repair.
Abstract: Adhesion to wet and dynamic surfaces, including biological tissues, is important in many fields but has proven to be extremely challenging. Existing adhesives are cytotoxic, adhere weakly to tissues, or cannot be used in wet environments. We report a bioinspired design for adhesives consisting of two layers: an adhesive surface and a dissipative matrix. The former adheres to the substrate by electrostatic interactions, covalent bonds, and physical interpenetration. The latter amplifies energy dissipation through hysteresis. The two layers synergistically lead to higher adhesion energies on wet surfaces as compared with those of existing adhesives. Adhesion occurs within minutes, independent of blood exposure and compatible with in vivo dynamic movements. This family of adhesives may be useful in many areas of application, including tissue adhesives, wound dressings, and tissue repair.

919 citations

Journal ArticleDOI
Xuanhe Zhao1
TL;DR: It is shown that tough hydrogels generally possess mechanisms to dissipate substantial mechanical energy but still maintain high elasticity under deformation, and a particularly promising strategy for the design is to implement multiple mechanisms across multiple length scales into nano-, micro-, meso-, and macro-structures of hydrogel.
Abstract: As swollen polymer networks in water, hydrogels are usually brittle. However, hydrogels with high toughness play critical roles in many plant and animal tissues as well as in diverse engineering applications. Here we review the intrinsic mechanisms of a wide variety of tough hydrogels developed over the past few decades. We show that tough hydrogels generally possess mechanisms to dissipate substantial mechanical energy but still maintain high elasticity under deformation. The integrations and interactions of different mechanisms for dissipating energy and maintaining elasticity are essential to the design of tough hydrogels. A matrix that combines various mechanisms is constructed for the first time to guide the design of next-generation tough hydrogels. We further highlight that a particularly promising strategy for the design is to implement multiple mechanisms across multiple length scales into nano-, micro-, meso-, and macro-structures of hydrogels.

880 citations

References
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Journal ArticleDOI
TL;DR: In this article, the surface forces necessary to produce simple shear in a cuboid of either compressible or incompressible material and those required to generate simple torsion in a right-circular cylinder of incompressibly material are derived.
Abstract: The equations of motion, boundary conditions and stress-strain relations for a highly elastic material can be expressed in terms of the stored-energy function. This has been done in part I of this series (Rivlin 1948 a ), for both the cases of compressible and incompressible materials, following the methods given by E. & F. Cosserat for compressible materials. The stored-energy function may be defined for a particular material in terms of the invariants of strain. The form in which the equations of motion, etc., are deduced, in the previous paper, does not permit the evaluation of the forces necessary to produce a specified deformation unless the actual expression for the stored-energy function in terms of the scalar invariants of the strain is introduced. In the present paper, the equations are transformed into forms more suitable for carrying out such an explicit evaluation. As examples, the surface forces necessary to produce simple shear in a cuboid of either compressible or incompressible material and those required to produce simple torsion in a right-circular cylinder of incompressible material are derived.

1,436 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that the load-deformation curves obtained for certain simple types of deformation of vulcanized rubber test-pieces in terms of a single stored energy function can be interpreted on the basis of the theory of large elastic deformations of incompressible isotropic materials.
Abstract: It is shown in this part how the theory of large elastic deformations of incompressible isotropic materials, developed in previous parts, can be used to interpret the load-deformation curves obtained for certain simple types of deformation of vulcanized rubber test-pieces in terms of a single stored-energy function. The types of experiment described are: (i) the pure homogeneous deformation of a thin sheet of rubber in which the deformation is varied in such a manner that one of the invariants of the strain, I 1 or I 2 , is maintained constant; (ii) pure shear of a thin sheet of rubber (i.e. pure homogeneous deformation in which one of the extension ratios in the plane of the sheet is maintained at unity, while the other is varied); (iii) simultaneous simple extension and pure shear of a thin sheet (i.e. pure homogeneous deformation in which one of the extension ratios in the plane of the sheet is maintained constant at a value less than unity, while the other is varied); (iv) simple extension of a strip of rubber; (v) simple compression (i.e. simple extension in which the extension ratio is less than unity); (vi) simple torsion of a right-circular cylinder; (vii) superposed axial extension and torsion of a right-circular cylindrical rod. It is shown that the load-deformation curves in all these cases can be interpreted on the basis of the theory in terms of a stored-energy function W which is such that δ W /δ I 1 is independent of I 1 and I 2 and the ratio (δ W /δ I 2 ) (δ W /δ I 1 ) is independent of I 1 and falls, as I 2 increases, from about 0*25 at I 2 = 3.

1,137 citations

Journal ArticleDOI
01 Mar 1947
TL;DR: In this paper, the authors present a model in which the crack is bounded by the atoms centred on the planes z =±½a, these planes being the boundaries of two semi-infinite elastic solids.
Abstract: The solutions for the problem of an infinite isotropic elastic solid stressed under tension T0 and containing a single internal crack of length c on the plane z=0 are given in a form suitable for the computation of the stresses and displacements at all points. These are used to find the stress distribution on, and the displacements of, the plane situated ½a from the plane containing the crack. The normal stress σz on z=½a (as found above) is plotted as a function f(2uz) of the normal displacement uz and τrz is small compared with σz. A model is used in which the crack is considered to be bounded by the atoms centred on the planes z=±½a, these planes being the boundaries of two semi-infinite elastic solids. Equilibrium is maintained by postulating that an attractive force, f(z), acts between the atoms of these bounding planes when they are z+a apart. It is found that f(z) approximates to the law of force expected from atomic considerations, and the condition for unstable equilibrium of the crack, i.e. a value T0c of T0 such that for T0 T0c the crack spreads (c increases), is found. The surface energy is calculated from the results and the equilibrium condition is found in a form similar to that of Griffith. Agreement is found with the experimental results of Griffith. In the absence of the tension T0, the crack cannot be maintained without an inclusion to prevent closing. Possible physical models are discussed.

101 citations

Journal ArticleDOI
TL;DR: Load-deformation measurements on a number of natural rubber vulcanizates covering a wide range of hardness are reported in this paper, where the mean chain segment lengths obtained from swelling measurements are given.
Abstract: Load-deformation measurements on a number of natural rubber vulcanizates covering a wide range of hardness are reported. For each of the vulcanizates the mean chain segment lengths obtained from swelling measurements are given. The results are consistent with the free-energy of deformation W depending on the strain invariants I 1 and I 2 in such a way that ∂W/∂I 1 is a constant for each vulcanizate and has a value predictable from the kinetic theory, while ∂W/∂I 2 falls as I 2 increases, but is independent of the vulcanizate for each value of I 2.

29 citations