Crosslinked resins and materials

In the manufacturing of composites a certain amount of a waste is generated. Such a waste consists of a crosslinked resin and glass fibers. ORTECH has developed composite recycling process for one of its clients. Fig 7, shows a schematic of this process. Waste composite material is fed into a low speed, high torque shredder where it is shredded into elongated pieces approximately 8cm by 8cm. The shredded material is deposited on a vibrating non-perforated screen where free fibres are separated, picked up an airlift and further... 

IV CROSSLINKED POSS-CONTAINING RESINS AND MATERIALS 106 A. Vinyl Ester, Epoxy, and Phenolic Resins Containing POSS 108... 

Recently, a two-part cross-catalyzed system has been developed that takes advantage of both the acceleration abilities of resorcinol resin and ester [179], The term cross-catalyzed is applied because the phenolic resin contains an accelerator-crosslinker for the resorcinol resin while the resorcinol resin carries an accelerator for the PF, in addition to itself being capable of improving PF cure speed. In each part, the resin carrier for the accelerator is not susceptible to acceleration by the material contained. It is only when the systems are mixed that the accelerators are activated. This system is faster and lower in cost than most of the resorcinol accelerators and gives better bonds (in wood products) than the ester cure alone [179], Another variant of the resorcinol approach utilizes resorcinol-glutaraldehyde resins [180-182],... 

Shellac [124,125] is a natural resin used in very old times for varnishes and moulding compounds. The resin secreted by the lac insect, Kerriar paca, is collected by scraping the shellac-encrusted trees found in southern parts of Asia. It consists of a complex mixture of cross-linked polyesters derived from hydroxy acids, principally aleuritic acid (9,10,16-trihydroxyhexadecanoic acid). From a structural point of view, it appears that this material can be used as a crosslinking agent and/or as a monomer for developing dentrite-like polymers. The question is whether it is possible to produce this material from shellac by controlled hydrolysis. 

Different types of gel materials, such as polysaccharides, proteins and synthetic polymers, are now used to entrap biocatalysts. Among them, photo-crosslinkable resin prepolymer ENTP-4000 as shown in Eig. 7 is more useful compared to others. Entrapment of biocatalysts should be carried out under the illumination of near ultraviolet hght within 3-5 min, by which high temperatures, shifts of pH to extremely alkahne or acidic sides are avoided. ENTP-4000, hydrophobic photo-crosslinkable resin prepolymer, is one of the most suitable prepolymers for entrapment of p-glucosidase. Molecular weight of its main chain is about 4000. 

Oleophilic material occurring, such as resin and fatty acids, especially those which have conjugated double bonds, are most easily oxidized and can also contribute to crosslinking in the system. Such oleophilic material also redistributes, e.g. by sublimation, to cover all hydrophilic surfaces in the material (1) (30). 

The ion-exchange resins used as etherification catalysts are strongly acidic cation-exchange resins. These materials consist typically of polystyrene chains that have been linked with divinylbenzene (DVB), the amount of which determines the degree of crosslinking and regulates the rigidity of the structure schematically presented in Fig. 10.3 [24],... 

Nylons 6/6 and 6 comprise more than 90% of the polyamide market. The two have similar properties but nylon 6 has a lower Tm (223°C). Small amounts of nylons 6/9, 6/10, 6/12, 11, 12, 12/12, and 4/6 are produced as specialty materials. Those with more methylene groups than nylons 6/6 and 6 have better moisture resistance, dimensional stability, and electrical properties, but the degree of crystallinity, Tm, and mechanical properties are lower. Specialty nylons made from dimerized fatty acids find applications as hot-melt adhesives, crosslinking agents for epoxy resins, and thermographic inks. 

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