Chap._100019 - It is possible to obtain a crosslinked...

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* Polymer Utilization In order to be useful as a solid material of construction a material must be capable of being manipulated into some desirable shape. Moulding is by-far the most important method for the manupulation of synthetic organic polymers, involving making the material undergo liquid flow (melt or solution) into the required shape and then setting the material (cooling, drying or crosslinking) so that the shape is retained. (few operations and little wastage) Thermoplastics (fusible, soluble) --recycloable Melt process: heating, re-shaping and cooling may be repeated indefinitely (no thermal decompositions) Solution process: after casting polymer solution and then evaporating the solvent. Thermosets (infusible, insoluble) -- cannot recycled polymer chanis are joined together by colvence bonds, cannot be further processes.
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Unformatted text preview: It is possible to obtain a crosslinked polymer in a desirable shape by moulding methods. This is accomplished by carrying out the shaping operations before crosslinking occurs. Two types of intermediates include (i) linear polymers containing reactive sites and (ii) low molecular weight polyfunctional molecules (oligomers) * Polymer Terminology Polymer nomenclature has been largely a matter of custom without any one system being universally accepted. Three nomenclature systems that have been used are based on (i) source (monomer(s) used in its synthesis) poly(ethylene) poly(styrene) poly(vinyl chloride) poly(6-aminocaproic acid) poly(ethylene-co-styrene) poly(ethylene-ter-propylene-ter-1,4-hexadiene) (ii) polymer structure (iii) trade name...
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