Composites polymeric

To define a polymeric composite, it is necessary to specify, for each constituent material 

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Lately, polymeric composite materials have found a wide recognition thanks to their unique qualities /1,2/. But use of the materials for construction, is limited, because lack of reliable diagnostic facilities. The non-destructive control method (NC), based on the acoustic emission phenomenon (AE), might offer a prospective solution to the situation. 

One of the primary tasks in connection with the use of AE method is to identify defects by the AE parameters. For identification of nature of the destruction centre in the polymeric composites it is necessary to consider the peculiarities of their heterogeneous structure, that is presence of at least two different components (filler and connector), and also boundary transitional layers. 

Ghassemieli, E. and Nassehi, V., 2001a. Stiffness analysis of polymeric composites using the finite element method. Adv. Poly. Tech. 20, 42-57. 

Table 4. Generic Names of Polymeric Compositions Used in Soft Contact Lenses ...

D. McCall and Biiefing Panel, Report of the Research Briefng Panel on High Peformance Polymers and Polymeric Composites, National Research Council, Washington, D.C., Aug. 10,1984, pp. 11-12, 16-19. 

Sharpe, L.H. In Akovali, G. (Ed.), The Interfacial Interactions in Polymeric Composites. 

Wool, R.P., Polymer Interfaces, Structure and Strength. Hanser Publishers, Munich, 1995. Ishida, H. In Akovali, G. (Ed.), The Interfacial Interactions in Polymeric Composites. Kluwer Academic, Dordrecht, 1993, p. 169. 

Development of an assortment of polymeric composite materials, decisions concerning their possible scope of applicability and service conditions involve research into a very broad circle of problems ... 

The method used for predicting the different physical and mechanical characteristics of crystalline or glassy polymeric composites is somewhat different. Most frequently it has been proposed (cf., e.g. [118]) to introduce an extra term into the relationship between some characteristic and the composition of the material based, more often than not, on the principle of additivity of the filler and matrix characteristics and taking into account their relative volumes in the composite. This extra term is the product of the interphase volume by a characteristic other than the characteristics of either the matrix or the filler. 

Lipatov et al. [116,124-127] who simulated the polymeric composite behavior with a view to estimate the effect of the interphase characteristics on composite properties preferred to break the problem up into two parts. First they considered a polymer-polymer composition. The viscoelastic properties of different polymers are different. One of the polymers was represented by a cube with side a, the second polymer (the binder) coated the cube as a homogeneous film of thickness d. The concentration of d-thick layers is proportional to the specific surface area of cubes with side a, that is, the thickness d remains constant while the length of the side may vary. The calculation is based on the Takayanagi model [128]. From geometric considerations the parameters of the Takayanagi model are related with the cube side and film thickness by the formulas ... 

The behavior of the physico-mechanical characteristics of polymeric composites is easily traceable in the table given in [144] which presents the results of experiments with polyamide matrices filled with resite particles of different shape. The filler concentrations were adjusted so that the integral contact surface area in the filler-matrix system remained the same. 

According to Nielsen [217] the elongation at rupture of a filled polymeric composition may be approximately described by the following expression... 

We have already noted in an earlier section that treatment of filler with a finishing agent also increases its abrasive attack on the parts of the processing equipment [271], At the same time it has been shown indirectly in [297,298] and directly by microscopic inspection in [294] that a synthesized polymer film remains on the polymerization-modified filler after the processing treatment, that is, there is always a medium which protects the molding equipment from the abrasive attack of the filler. In view of these observations, the polymeric composites with PMF are comparable, in terms of abrasive activity, with unfilled polymers [226, 227],... 

Lipatov, Y. S. Relacation and Viscoelastic Properties of Heterogeneous Polymeric Compositions. Vol. 22, pp. 1 —59. 

IV. SELF-DOPED POLYMERS, POLYMERIC COMPOSITES, AND HYBRID MATERIALS... 

The second problem relates to the role that interfaces play in mediating chemical reactions in the synthesis of composite materials. This problem has three parts, which are illustrated here for polymeric composites. 

Polymers, ceramics, and composite materials. In addition to continued growth in support for research on polymers and polymeric composites, a new thmst is recommended to establish six to eight centers for the chemical engineering of ceramic materials and composites over the next 5 years, funded at a total annual level of 4 million per year. Cross-disciplinary pioneers should also be supported in this area. 

There is currently considerable interest in processing polymeric composite materials filled with nanosized rigid particles. This class of material called "nanocomposites" describes two-phase materials where one of the phases has at least one dimension lower than 100 nm [13]. Because the building blocks of nanocomposites are of nanoscale, they have an enormous interface area. Due to this there are a lot of interfaces between two intermixed phases compared to usual microcomposites. In addition to this, the mean distance between the particles is also smaller due to their small size which favors filler-filler interactions [14]. Nanomaterials not only include metallic, bimetallic and metal oxide but also polymeric nanoparticles as well as advanced materials like carbon nanotubes and dendrimers. However considering environmetal hazards, research has been focused on various means which form the basis of green nanotechnology. 

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