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Polymer materials concept

While most of the earlier research was done on metals and alloys, more recently a good deal of emphasis has been placed on ceramics and other inorganic compounds, especially functional materials used for their electrical, magnetic or optical properties. A very recent collection of papers on oxides (Boulesteix 1998) illustrates this shift neatly. In the world of polymers, the concepts of phase transformations or phase equilibria do not play such a major role 1 return to this in Chapter 8. [Pg.103]

Hence polysaccharides have been viewed as a potential renewable source of nanosized reinforcement. Being naturally found in a semicrystalline state, aqueous acids can be employed to hydrolyze the amorphous sections of the polymer. As a result the crystalline sections of these polysaccharides are released, resulting in individual monocrystalline nanoparticles [13]. The concept of reinforced polymer materials with polysaccharide nanofillers has known rapid advances leading to development of a new class of materials called Bionanocomposites, which successfully integrates the two concepts of biocomposites and nanometer sized materials. The first part of the chapter deals with the synthesis of polysaccharide nanoparticles and their performance as reinforcing agents in bionanocomposites. [Pg.120]

The concept of reinforced polymer materials with polysaccharides has known rapid advances in the last decade due to following advantages... [Pg.121]

In the following, a number of examples are presented with emphasis on how such amplified imaging device can be built in self-supporting polymer materials. The present photochromic compounds (azobenzene and spiropyran derivatives) are rather common and have been used many times in molecular assemblies without touching upon the concept of image amplification. The most recent references are given(4. - 6). [Pg.211]

Polyolefins are well adapted to the mono-material concept talc-filled polypropylene and LFRT for structural parts, foamed polyethylene and polypropylene for damping, polypropy-lene/EPDM alloys or copolymers for skins. Some other functions need incompatible polymers with specific characteristics such as optical properties. Without claiming to be exhaustive, the other thermoplastic materials are ... [Pg.96]

We have reviewed the material requirements for a viable optical disk and have described two novel materials concepts, each based on the use of an organic dye-polymer interaction. The dyes used in these concepts must be thermally and photochemically stable. In each case the imaging mechanism involves an efficient and rapid conversion of the absorbed electronic energy to heat via internal conversion. [Pg.453]

Everything discussed in the present paper shows that the free-volume concept, although very useful from the qualitative point of view, cannot be used for the quantitative description of many properties of polymer systems. This is especially clear when we consider glass-transition phenomena using the idea of the iso-free-volume state. Many experimental data, discussed above, show that this concept cannot be applied even to polymer materials having the same chemical nature but a different physical structure. From the experimental results Goldstein104 had already concluded that the concept of free-volume cannot be correct. These conclusions were carefully discussed later105. ... [Pg.101]

The feasibility of constructing a miniaturised system including reaction, separation and detection units integrated directly onto the EC-CE microchip device has also been shown and approximates the concept of total analysis system . Furthermore, the low cost of the EC detection in connection with new polymer material can bring a real disposable device. [Pg.860]

Colloidal MIPs enable for the future use of fully synthetic affinity receptors in possibly a vast range of applications. The attractive concept of generating bio-mimetic binding sites in chemically and structurally robust polymer materials was to date possibly but limited by the traditional preparation methods of MIPs. Bulk polymerization of the initial reaction mixture containing monomer, crosslinker, and template, followed by crushing of the formed polymer monolith networks and sieving to find the portion of useful sized polymer particles is not the way of choice for the production of technically widely applicable material. [Pg.141]

In the previous papers of this series, the concepts of mathematical group theory and then ring theory were brought to bear on the nomenclature and structure of multicomponent polymer materials (12,18,19). In each case, no proof of the existence of either a mathematical group or ring was offered, but rather only the notions or concepts were applied. [Pg.605]

The concept of fire hazard of polymer materials is a rather broad one. It includes the tendency of these materials to initiate and develop the combustion (flammability), as well as the negative effects of their exposure to high temperatures, fire or other external thermal actions. [Pg.174]

No doubt, an extensive investigation of the combustion wave structure under different conditions would permit to verify many conceptions of the current flame spread theories, and also to determine the applicability limits of the latter. Even now, since more experimental investigations of the rate of flame spread over polymer material surfaces as a function of various factors are bdng carried out, it is becoming increasingly clear that the mechanism of heat transfer from the flame to the combustible surface can change radically as the size of the combustion zone increases. [Pg.193]

As discussed earlier, while the scale of the fillers is substantially different, nanocomposite materials concepts and technology are very similar to those of conventional composite materials. This is clearly demonstrated in the case of new thermosets for nonlinear optical (NLO) applications, " " where nanocomposite of liquid crystalline thermosets, IPNs, and simple filled thermosets are evaluated. Tripathy et al. discussed four different ways to prepare nonlinear optical polymers. (1) The polymer matrix is doped with NLO moieties in a guest/host system (2) In side-chain polymer systems, NLO polymers with active moieties are covalently bonded as pendant groups (3) In the main chain polymer, the chromo-phores are incorporated as parts of the main polymer backbone to enhance the temporal stability of the NLO properties and (4) Stability of the optical noninearity in sol-gel-based thermosets is related to... [Pg.3037]

The intensive research activities recently focused on late transition metal complexes as polymerization catalysts are justified by decisive improvements in the development of new polymer materials and indicate even more their high potential for future applications. However, up to now they often only dimerize or oligomerize a-olefms due to competing hydride elimination and associative olefin exchange reactions [19]. A new concept of new diimine ligands and complexes bearing 2,6-diphenyl-modified aniline moieties (Fig. 2.5) is stiU focused on sterically demanding substituents in the 2,6-positions, but it aims further towards the facile modification of the steric and electronic properties of the active species. [Pg.31]

During the search for efficient and ecologically justified waste-management concepts, the use of biodegradable polymer materials was repeatedly made a political demand. Next to the arguments of a partial solution to the waste-disposal problem by natural degradation, the conservation of the petrochemical resources, the reduction of C02-emission, and the use of renewable resources are a point of discussion. [Pg.211]

Based on these results, our recent research on polymer electret materials focuses on the understanding of (1) the role of the chemical structure of the polymer, (2) the influence of additives, and (3) the variation of processing parameters on the electret performance. As schematically illustrated in Fig. 7, the objective of our research is to provide concepts and methods to improve substantially the electret performance of polymer materials. [Pg.164]

These compounds are sensitive to electrical field. Microwave frequency losses are due to two phenomena polarisation and conduction. The polarisable materials concept will be examined later with some examples based on conducting polymers. Relaxation-inducing dielectric losses can be caused by interfacial polarisa-... [Pg.376]


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See also in sourсe #XX -- [ Pg.3 , Pg.4 , Pg.5 , Pg.6 ]




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Polymer concept

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