Polymer bonded magnets

Fig. 14.144. Basic production steps for polymer-bonded ------ magnets (Strnat, 1976b).

Bonded magnets have many applications a wide variety of shapes can be obtained by compaction, extrusion, injection, etc. One of the basic problems, however, is the high chemical reactivity of the alloys. Instead of polymers, a metallic alloy, such as Sn-Pb solder, or Cu can be useful as a matrix material. Cu-hardened magnets are more stable against oxidation. 

With soluble polymers, it is possible to disperse the magnetic material in a polymeric solution and precipitate the dispersion in a non-solvent. Or else, the solvent can be evaporated in vacuo. This process of manufacture can be conducted at lower temperatures. PEN types are highly suitable as soluble polymers for preparing such resin-bonded magnets, still having good properties. A suitable solvent is NMP, appUed at ca. 190 C. 

Polymer bonded nanocomposites with orientated nanoparticles show high magnetostrictive strain under relatively low magnetic field, and, additionally, a... 

The polymerization can be carried out in a dispersion of the partieles in a monomer solution or in a monomer melt. Monomers are far less viseous and more soluble than polymers. Thus, this route is specially suited for the preparation of nanocomposites with a high density of particles, when the polymer is insoluble or when it does not melt. Polyimide-bonded magnets of rare earth alloys have been prepared in this way. In order to enhance cohesion, the polymer can be grafted to the particle surface by irradiation polymerization. High homogeneity is achieved by sonochemical polymerization. ... 

Yudin V E, Otaigbe J U, Bui T X, Svetlichnyi V M, Polyimide bonded magnets Processing and properties , J Appl Polym Sci, 2003 88 (14) 3151-3158. Korenivski V, GHz magnetic film inductors , J Magn Magn Mater, 2000 215 (SI)... 

Monomer (Section 6 21) The simplest stable molecule from which a particular polymer may be prepared Monosaccharide (Section 25 1) A carbohydrate that cannot be hydrolyzed further to yield a simpler carbohydrate Monosubstituted alkene (Section 5 6) An alkene of the type RCH=CH2 in which there is only one carbon directly bonded to the carbons of the double bond Multiplicity (Section 13 7) The number of peaks into which a signal IS split in nuclear magnetic resonance spectroscopy Signals are described as singlets doublets triplets and so on according to the number of peaks into which they are split... 

Sharkey, W. H. Polymerizations Through the Carbon-Sulphur Double Bond. VoL 17, pp. 73-103. Shimidzu, T. Cooperative Actions in the Nucleophile-Containing Polymers. Vol. 23, pp. 55-102. Slichter, W. P. The Study of High Polymers by Nuclear Magnetic Resonance. VoL 1, pp. 35-74. Small, P. A. Long-Chain Branching in Polymers. VoL 18,pp. 1-64. 

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