Plastic and elastic properties

Proc. First International Particle Technology Forum, vol. 2, AIChE, Denver, 1994, p. 178), whereas surface energy can be characterized by inverse gas chromatography and other adsorption techniques. Particle yield pressures and elastic moduli of the powder feeds can also be determined by uniaxial compaction experiments which monitor deformation and pressure throughout the compaction cycles. In addition, rate effects are investigated, as plastic and elastic properties can be rate-dependent for some materials. 

The CG catalysts produce highly processable polyolefins with a unique combination of narrow MWD and long chain branches. Ethylene-octene copolymers produced with CG catalysts have useful properties across a range of densities and melting indexes. These novel copolymer families are called polyolefin plastomers (POP) and polyolefin elastomers (POE). POPs possess plastic and elastic properties while POEs containing greater than 20 wt% octene comonomer units have higher elasticity. 

Other nanoindentation-based techniques have been developed in recent years that, instead of applying a static load and determining material stiffness from the unloading curve, employ an oscillating force [157]. Such is the case of the continuous stiffness module (GSM), which enables us to determine the contact stiffness throughout the whole experiment during loading, and thus has proved to be a useful technique in the study of polymer s plastic and elastic properties [158]. 

On warming to the temperature range 160-200°C, eu-polyoxjTnethylene softCTS and in this state shows both plastic and elastic properties. Since dficompoaition takes place at 170 220°C, the elasticity interval is very small. Iki-polyo miethylenje passes obtained by Staudinger, sintered at 175 C m an open melting-point tube, decomposed with evolution of... 

Hardness is a measure of a material s resistance to deformation. In this article hardness is taken to be the measure of a material s resistance to indentation by a tool or indenter harder than itself This seems a relatively simple concept until mathematical analysis is attempted the elastic, plastic, and elastic recovery properties of a material are involved, making the relationship quite complex. Further complications are introduced by variations in elastic modulus and frictional coefficients. 

The viscoelasticity is a combination of viscous and elastic properties in a plastic with... 

Viscoelasticity A combination of viscous and elastic properties in a plastic with the relative contribution of each being dependent on time, temperature, stress, and strain rate. It relates to the mechanical behavior of plastics in which there is a time and temperature dependent relationship between stress and strain. A material having this property is considered to combine the features of a perfectly elastic solid and a perfect fluid. 

The main considerations of mechanical properties of metals and alloys at low temperatures taken into account for safety reasons are the transition from ductile-to-brittle behavior, certain unconventional modes of plastic deformation, and mechanical and elastic properties changes due to phase transformations in the crystalline structure. 

Methods for characterizing the elastic, plastic, and brittle properties of compacts of organic materials have been developed by Hiestand and coworkers [29-33]. These indices of tableting performance measure the mechanical properties of compacted materials. 

The unique cellular morphologies of foams play a key role in determining their deformation mechanisms [51. They also allow the development of very simple alternative equations based on the mechanical models of beam theory (a branch of civil engineering) combined with scaling concepts, to estimate both the thermoelastic properties and the strengths of foams. Such simple relationships have been developed for foams manifesting elastomeric, elastic-plastic and elastic-brittle responses to mechanical defonnation. While much of this work has focused on the responses of foams to compressive defonnation because of the special importance of this deformation mode in many applications of foams, the responses of foams to tensile and shear deformation have also been considered within this theoretical framework. 

While Heckel plots are able to distinguish between plastic and fragmenting mechanisms, they do not readily distinguish between plastic and elastic deformation. The data presented in Table 11.4 would suggest that microcrystalline cellulose and starch 1500 have very similar properties, yet the elastic nature of starch and its derivative products is well documented in the literature. Additional methods are, therefore, required to measure elasticity. 

Because the fibers in mat are randomly oriented, mat-reinforced materials have essentially the same strength and elastic properties in all directions in the plane of the plate, that is, they are essentially isotropic in the plane. Consequently, the usual engineering theories and design methods employed for isotropic engineering materials may be applied. It is only necessary to know strength, modulus of elasticity, shearing modulus, and Poisson s ratio of the combined mat and resin. These can be obtained from standard stress-strain measurements made on specimens of the particular combination of fiber and plastic under consideration. 

Mechanical hardness is a complicated function of compressibility, plasticity, and elasticity and is not really an intrinsic property in polycrystalline materials but depends on the microstructure. 

Plasticizers are auxiliary agents used in the industrial processing of plastics. By lowering the intermolecular forces between the molecular chains, they endow high polymeric substances with certain desirable physical characteristics, e.g. reduced brittleness, higher plasticity, increased elastic properties, lower hardness and, where necessary, increased adhesion. 

A typical load-displacement curve is shown in Fig. 2. The loading portion of the curve results from both plastic and elastic deformation response of the contact, while the unloading portion of the curve is related to the elastic recovery of the contact. If the indenter geometry and materials properties are known, the modulus can be obtained by fitting the unloading curve to determine the contact stiffness at maximum load (i4, 17). In this case,... 

The theory relevant for the study of mechanical properties of such objects is taken from solid mechanics. This theory is based on, among other things, fundamental mechanics, and it contains theoretical analyses of dynamic properties of various kinds of objects bars, plates and other geometric configurations with plastic or elastic properties. Within this theory we have massive knowledge about, say, stress-strain relations of various idealized objects. This knowledge is presented in a mathematical form and is about model objects which are idealized to such a degree that a mathematical analysis is feasible. The research object is represented by such a model object. 

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