Other Resin Technologies

Perhaps the best evidence for the superior quality of the composite comes from our comparative studies with other polyamine composites and polystyrene resins. Ramsden et al. synthesized a silica-polyamine composite by reacting 3-chloropropyl trimethoxy silane with PEI, and then reacting the resulting polyamine silane with silica gel. We reproduced this synflietic approach with the same silica used in our pro-cedme (Fig. 1). The material produced had a density of 0.31 g/mL versus 0.49 g/mL for WP-1. A scanning electron micrograph of the two materials revealed a much smoother surface for WP-1 relative to the material produced by the method of Ramsden (Fig. 4). 

Most significantly, we tested the two materials in exactly the same manner using a computer-controlled copper sulfate load, water rinse, acid strip, water rinse, base regenerate, and water rinse cycle. The results of these tests are summarized in Figme 5. The Ramsden composite coliunn plugged after about 400 cycles, owing to 

We also cycle tested a polystyrene chelator resin for material lifetime. Here, the column held its capacity. However, after about 1200 cycles the particles degraded. 

The flow capacities of both the Ramsden materials and the polystyrene chelator resin were less than half that of the WP-1 for the fast flow rates at which these tests were done (two column volumes per minute). More important, after 3000 cycles there 

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PhenoHc-based resins have almost disappeared. A few other resin types are available commercially but have not made a significant impact. Inorganic materials retain importance in a number of areas where synthetic organic ion-exchange resins are not normally used. Only the latter are discussed here. This article places emphasis on the styrenic and acryHc resins that are made as small beads. Other forms of synthetic ion-exchange materials such as membranes, papers, fibers (qv), foams (qv), and Hquid extractants are not included (see Extraction, liquid-liquid Membrane technology Paper.). 

It is not tme either that vinyl is the problem in municipal recycling because it contaminates other resins. Contamination occurs whether or not vinyl is present. Other resins are just as much a contamination problem as vinyl. Except for commingled plastics apphcations, different plastic materials caimot be mixed successfiJly in most recycled products apphcations. This is why it is cmcial to separate efficientiy one plastic from another. Because of the chlorine that is present in it, vinyl lends itself very weU to automated sorting technology. 

The forecasts made in 1985 (77) of 8—8.5% worldwide aimual growth have not materialized. The 2 x lOg + /yr engineering plastic production reported for 1985—1986 has remained fairly constant. Whereas some resins such as PET, nylon-6, and nylon-6,6 have continued to experience growth, other resins such as poly(phenylene oxide) have experienced downturns. This is due to successhil inroads from traditional materials (wood, glass, ceramics, and metals) which are experiencing a rebound in appHcations driven by new technology and antiplastics environmental concerns. Also, recycling is likely to impact production of all plastics. 

Terephthalic Acid (Dimethyl Terephthalate). Terephthalic acid (TPA) and dimethyl terephthalate (DMT) are precursors for polyethylene terephthalate (PET), which in turn is used in the production of polyester fibers and film polyester thermoplastic PET bottles, and other resins. In 1999 the total U.S. production was more than 9 billion lb. In the past, the relative ease of producing high-quality DMT gave it the largest share of the terephthalate market. The trend is now toward TPA, as the result of technological advances that permit better purification of TPA and the use of the acid directly in polymer formation. The capacity is about 3 to 1 split in favor of TPA process. 

To assess the feasibility and to verify if the ED operations of the EDBM2C configuration could be expensive because of the NaOH and energy consumption, the authors recently published a work comparing this method with different methods used for deacidification of clarified passion fmit juice [18]. They compared EDBM with other physicochemical technologies, ion-exchange resins, and electrodialysis with homopolar membranes (Figure 21.25), as well as the conventional chemical method based on the precipitation of calcium citrate obtained by addition of calcium hydroxide or carbonate to the clarified juice. 

Ethyl lactate is used as a solvent or co-solvent in liquid formulations and recently as a co-solvent in emulsions and microemulsion technologies. It has also been used as a solvent for nitrocellulose, cellulose acetate, cellulose ethers, polyvinyl and other resins. It has been applied topically in the treatment of acne vulgaris,where it accumulates in the sebaceous glands and is hydrolyzed to ethanol and lactic acid, lowering the skin pH and exerting a bactericidal effect. 

Johns et al. (2000) reported an anion exchange technology using Amberlite or Dowex or other resins to isolate phytoestrogens from plant protein materials. Carbonate or bicarbonate was used as a counterion to avoid chlorides or alkali in the final product. Protein slurry was passed through the column at pH 6-8. The bound isoflavones were released with alcohols, organic solvents or acid or base solution. The protein isolate produced was essentially free of isoflavones. 

While the initial concern for formaldehyde emissions in the hardwood plywood industry was in the wall paneling sector there is a strong and decided movement by many manufacturers to apply new low emitting adhesive technology to other hardwood plywood products. Low emitting UF products are nearing the emission characteristics of certain other resin systems assumed to be likely substitutes. 

The separate phases will be rich in one component but may have the other present as a minor component. In order to control compatibility the elastomer may have reactive end groups to enhance interfacial adhesion. A common example in epoxy-resin technology is the carboxy-terminated butadiene-acrylonitrile copolymer (CTBN). The structure is shown in Scheme 1.47. In this resin the solubility in the epoxy resin is conferred by the acrylonitrile group, and an increase in the fraction present decreases the upper critical solution temperature, with 26% acrylonitrile conferring total miscibility of CTBN with a DGEBA-based epoxy resin (Pascault et al, 2002). 

While polyester is the most economical choice for the resin in PC, epoxy resins, PMMA, and PV are also being used. Of course, larger amounts of these and other resins will be used as construction engineers recognize the advantages of PC technology. 

Tukker A, de Groot H, Simons L, Wiegersma S. Chemical recycling of plastic waste PVC and other resins. European Coimnission, Final Report, STB-99-55 Final. TNO Institute of Strategy, Technology and Policy, Delft 1999. 

Various technologies, methods, and applications are encompassed by the field of epoxies and other resins. These range from molecular design... 

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