Other Composites

The thermal stability of polystyrene composites reinforced with short sisal fibres was found to be better than that of sisal fibre and the PS matrix [a.288]. The effects of fibre loading, length, orientation and modification on the dynamic mechanical properties of the composites were evaluated. Benzoylation, maleic anhydride coating of the polystyrene and acetylation of the fibres were fibre modifications and treatments that were carried out to improve fibre/matrix adhesion through specific interactions of the macrochains. The Tg values of the composites were lower than that of unreinforced PS, and this effect was attributed to the presence of some residual solvent in the composites entrapped during composite preparation. However, the composites with treated fibres showed better thermal degradation properties than those with untreated fibres. 

Reprinted front [a.289] with permission from Elsevier 

Thermal ageing during heating above the melting point of the polymer matrix caused a decrease in the conductivity of PE/CB composites, but increase of conductivity in composites containing CB-PPy or CB-PANI as filler. The modified fillers created a more perfect and thermally resistant conducting network in the PE matrix. The decomposition temperatures of PE/CB-PPy and PE/CB-PANI composites were higher compared with that of the PE/CB composite as observed by TG. 

Other studies have investigated the decomposition of PMMA utilising TG and calorimetry. One study concentrated on polymer layered silicate nanocomposites 825036 and compared the degradation profiles of PMMA-filled nanocomposites to that of pure PMMA by using TG-DSC-FTIR and GC-MS. The results based on TG and DSC indicated enhanced thermal stability and higher glass transition temperature of filled PMMA nanocomposites with respect to that of pure PMMA. Nonetheless, in both cases the decomposition was described as a two-step reaction. 

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The systems of such type have been developed of all last 10 years. We shall bring some characteristics of one of the last development within the framework of European BRITE project, carried out in LETT This 3D cone-beam tomograph is referred to as EVA Bench or Equipment for Voludensimetry Analysis. It is oriented on NDT of industrial products from ceramics and other composites. One of the main task of this tomograph is achievement of high resolution at study of whole internal volume of researched object. For test sample of the size 10mm spatial resolution in 50mm was obtained [14]. 

Health and safety concerns in the stmctural composite lumber industry are similar to those in the other composite industries. Special care is required in worker awareness, worker protection equipment, dust and vapor control, and general housekeeping. 

Infrared patterns can lead to detection of lack of bonding between surface platings, between coatings and base metal, or within bra2ed honeycombs and other composite materials where bonding is vital. Mote recent developments involve infrared television or image tubes similar to the types used for night vision in military and other appHcations. 

Starch pyrodextrins and British gums have the abiUty, in aqueous dispersion, to form films capable of bonding like or unlike materials. Thus, they have uses as adhesives for envelopes, postage stamps, and other products. These dextrins are used in glass-fiber siting to protect the extmded fiber from abrasion, and as binders for metal core castings, water color paints, briquettes, and many other composite materials (qv). 

Engineering thermoplastics have also been used ia preimpregaated coastmctioas. The thermoplastic is thoroughly dispersed as a coatiauous phase ia glass, other resias, carboa fibers (qv), or other reinforcement. Articles can be produced from these constmctions usiag thermoforming techaiques. For example, the aerospace iadustry uses polyetheretherketoae (PEEK) ia wovea carboa-fiber tapes (26). Experimental uses of other composite coastmctioas have beea reported (27) (see also Composite materials, polymer-matrix). 

Describe some other composite materials that are not addressed in Chapter 1. 

For E-glass-epoxy, the Tsai-Hill failure criterion seems the most accurate of the criteria discussed. However, the applicability of a particular failure criterion depends on whether the material being studied is ductile or brittle. Other composite materials might be better treated with the maximum stress or the maximum strain criteria or even some other criterion. 

This conclusion is unchanged when other composite materials are considered as in Figure 5-35. 

Figure 12-8. Pistons and rings. Lubricated and nonlubricated pistons with PTFE or other composite materials for the piston and rider rings. These designs prevent piston-to-bore contact and provide reliable service life, particularly during possible periods of lubrication interruption. (Used by permission Bui. 85084, 1992. Dresser-Rand Company.)...

There is an increasing interest in explosive bonding as a means of bonding aluminium-steel and other composite cladding systems. 

Conducting polymer composite materials (CPCM) — artificial media based on polymers and conductive fillers, have been known since the early 1940s and widely used in various branches of science and technology. Their properties are described in a considerable number of monographs and articles [1-12]. However, the publications available do not clearly distinguish such materials from other composites and do not provide for specific features of their formation. 

Fig. 17 presents the variation of the terms E((rf/r)n> and Em(rf/r), i in the mesophase layer for a 65 percent E-glass fiber-reinforced epoxy resin, as they have been derived from Eq. (48). It is wortwhile indicating the smooth transition of the Ermodulus to the Em-modulus at the region r == rf. Similar behaviour present all other compositions. 

The most important mercury chalcogenide halides are of the type HgaYjXj (Y = S, Se, Te X = Cl, Br, I). The corresponding sulfide halides have been known for over 150 years (326). Quite a lot of work has been performed concerning the preparation, structures, electronic and optical properties, and phototropic behavior of these compounds. Mercury chalcogenide halides of other compositions have been mentioned in the literature (141). As most of these compounds are not well established, they will not be treated in detail, with the exception of the latest contributions (see Table V). 

The literature also contains other compositions, e. g. solutions of 0.5 to 5 g vanillin in 1 to 20% ethanolic [3, 7, 14, 15, 20) or methanolic [18, 21, 23] sulfuric acid, occasionally also in 80 percent ethanolic [4, 6, 25] or undiluted cone, sulfuric acid [4, 5, 11, 12], where the addition of 3 drops acetic acid is recommended in some cases [3, 14]. 

As described in the introduction, certain cosurfactants appear able to drive percolation transitions. Variations in the cosurfactant chemical potential, RT n (where is cosurfactant concentration or activity), holding other compositional features constant, provide the driving force for these percolation transitions. A water, toluene, and AOT microemulsion system using acrylamide as cosurfactant exhibited percolation type behavior for a variety of redox electron-transfer processes. The corresponding low-frequency electrical conductivity data for such a system is illustrated in Fig. 8, where the water, toluene, and AOT mole ratio (11.2 19.2 1.00) is held approximately constant, and the acrylamide concentration, is varied from 0 to 6% (w/w). At about = 1.2%, the arrow labeled in Fig. 8 indicates the onset of percolation in electrical conductivity. 

An alloy with a specific composition crystallizes its composition may differ from that of the liquid (formation of an intermetallic compound). The composition of the liquid can change during the crystallization process and further intermetallic compounds with other compositions may crystallize. 

The values of the activity coefficients determined at the azeotropic composition can be used to calculate the coefficients in the Wilson equation (or any other of the three-suffix equations) and the equation used to estimate the activity coefficients at other compositions. Horsley (1973) gives an extensive collection of data on azeotropes. 

Stabilization of Ru based oxides by valve metal oxides has not been studied in such detail using photoelectron spectroscopy. The most common compositions, however, with relatively high valve metal content, are not in favor of formation of a solid solution. Studies of the phase formation in Ru/Ti mixed oxides has shown [49] that homogeneous solutions are formed for compositions with Ru < 2% or Ru > 98% (see Section 3.1.1). Therefore electrodes with other compositions are better described as physical mixtures and the electrochemical behaviour is most likely that of a linear superposition of the single components. It has to be considered, however, that the investigations performed by Triggs [49] concern thermodynamic equilibrium conditions. If, by means of the preparation procedure, thermodynamic equilibrium is... 

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