Technology of Recycling

A solvent-fi ee adhesive was used for laminating vinyl sheet to wood. A new technology of recycling waste carpets and textiles was developed based on coating individual yam fibers by an adhesive containing solvent The high surface contact area produced materials with excellent mechanical properties. 

Within the scope of the mechanical recycling, three basic areas were discussed (1) the fundamentals of recycling, (2) the technology of recycling, and (3) the pertinent aspects of recycling specific polymers or their mixtures. Thus, basic properties of polymers found most... 

This book is intended to focus on the state of the art in recycling, the most recent technologies of recycling, and some recent scientific research in the field. 

Polyurethane is pulverized to iacrease its bulk density, mixed with 30—80% of a thermoplastic mol ding material, gelled, and then granulated to give coated urethane foam particles 0.1 to 0.15 mm in size (48). The particle bulk density is three times that of the polyurethane, while the volume is 15% less. This material may be injection molded or extmsion molded into products (49). Other technologies for recycling polyurethanes have also been reported. 

The obvious destination for nickel waste is in the manufacture of stainless steel, which consumes 65% of new refined nickel production. Stainless steel is produced in a series of roasting and smelting operations. These can be hospitable to the various forms of nickel chemical waste. In 1993, 3 x 10 t of nickel from nickel-containing wastes were processed into 30 x 10 t of stainless steel remelt alloy (205,206) (see Recycling, nonferrous metals). This quantity is expected to increase dramatically as development of the technology of waste recycle coUection improves. 

The recycling option is being utilized outside the United States. Whereas the technology of this option has been completely demonstrated ia the United States, the economics have not been favorable. Moreover, concerns have been raised as to the diversion of the plutonium to weapons use. Thus, the throwaway option is the only one ia use ia the United States as of this writing. 

Much of the technology used in the reclamation of metals from metal-bearing wastes was developed by the mining iadustries. The primary means of recycling metal from metal and alloyed scrap is via pyrometaHurgy (see Metallurgy). 

Research Trends. Research since the late 1970s appears to have centered on further process modifications and optimization of conventional processes, reduction in pollution, evaluation of potentially more efficient processing technology, increased use of less expensive softwood sources to extend the available hardwood suppHes, and accommodation of recycled newspaper pulp (see Recycling, paper). 

Transesterification has a number of important commercial uses. Methyl esters of fatty acids are produced from fats and oils. Transesterification is also the basis of recycling technology to break up poly(ethylene terephthalate) [25038-59-9] to monomer for reuse (29) (see Recycling, plastics). Because vinyl alcohol does not exist, poly(vinyl alcohol) [9002-89-5] is produced commercially by base-cataly2ed alcoholysis of poly(vinyl acetate) [9003-20-7] (see Vinyl polymers). An industrial example of acidolysis is the reaction of poly(vinyl acetate) with butyric acid to form poly(vinyl butyrate) [24991-31-9]. 

Urethanes Technology 15, No.6, Dec. 1998/Jan. 1999, p.32-3 COMMERCIAL EVALUATION OF RECYCLING PROCESS BEGINS IN JOINT-VENTURE UNIT... 

This paper reviews recycling technologies of PMMA waste, its applications and its markets. It relates in detail experimentation on thermal and oxidative depolymerisation of PMMA scrap, under nitrogen and oxygen atmospheres, at different heating rates by thermogravimetry and differential scanning calorimetry techniques. 15 refs. 

Hague, 31 st March-2nd April 1992, p.247-51. 43C6 PROGRESS IN THE TECHNOLOGIES FOR RECYCLING OF PU SCRAPS... 

This paper discusses in depth advanced technologies for recycled materials from solid waste streams. Chemical depolymerisation, thermal depolymerisation, pyrolytic liquefaction, pyrolytic gasification, partial oxidation, and feedstock compatibility are all explained. The economic feasibility of the methods are considered. 

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