Resin efficiency, improvement

AlCl efficiency (based on g resin/g catalyst) can be markedly improved by polymerizing dry feeds (<10 ppm H2O) with an AlCl /anhydrous HCl system. Proceeding from 250 ppm H2O down to 10 ppm H2O, catalyst efficiency improves from 30.6 to 83.0 (26). Low levels of tertiary hydrocarbyl chlorides have been shown to gready enhance the activity of AlCl, while yielding resins with narrow molecular weight distributions relative to systems employing water or HCl (27). 

Eigure 13.57 discusses in some detail the use of mobile-phase modifiers to prevent adsorption on PDVB resins. These concepts are very valuable in developing methods. Eor example, note how the observed column efficiencies improve for paraben analysis in the order of methanol < acetonitrile < 50/50 methanol/acetonitrile < THE. Eurthermore, when THE is used the chromato-... 

Chemical and Related Savings. Improvement in resin efficiency when the finish is applied at low wet pick-up can be expected due to the reduction or elimination of migration during drying. 

If the reactants are applied uniformly, the absence of migration allows a lower average level of treatment to assure a given level of performance in the finished fabric. Experimental evidence for such an improved efficiency has been reported by several investigators (4, 13, 14). Results in our laboratories have confirmed a higher resin efficiency for polyester-cotton blend fabrics treated at low wet pick-up by controlled applica-... 

Although the tailored sensitizers and resins presumably improve DUV performance, systems based on the DQN design have a sensitivity limit imposed by the quantum efficiency of the sensitizer to photoproduct conversion that... 

Initial work to process PVC resin into manufactured products led many investigators to believe that the polymer was not a useful one. Some of the performance shortcomings of PVC were overcome by the advent of plasticizers and development of copolymers, both of which were responsible for the subsequent commercial growth of PVC. Although resins with improved stability and processing characteristics have since been developed, the tremendous growth of vinyl plastics is in no small measure due to the development of effective heat stabilizers as well as efficient processing equipment. 

Alkanolamines are used as cross-linking and hardener accelerators in epoxy resins applications. Improved thermal and oxidative stability of polyvinyl alcohol, poly(phenylene ether), polystyrene, polypropylene, and polyethylene polymers are achieved by the addition of small amounts of the alkanolamines. Diethanolamine and morpholine act as initiators for the preparation of poly (alkyl methacrylate) in bulk or solution polymerization. The ethanolamines are efficient initiators for the preparation of polyvinyl chloride. Alkanolamines promote cross-linking of styrene copolymers with polystyrene or polyvinyl alcohol. Addition of alkanolamines to phenolic formaldehyde or urea formaldehyde resins affords improved electrical properties and increased water solubility. 

The aliphatic resins have good compatibility with natural rubbers and polyisobutylene. The degree of unsaturation, which has an impact on aging and radical cross-linking efficiency, is characterized by the bromine number. Recently an increasing number of aromatically modified C5 resins with improved adhesive properties in natural rubber and block copolymers are available. Some are hydrogenated to improve aging properties. 

Methyl methacrylate is often used in combination with styrene to improve light transmission and uv stabiUty in fiame-retardant glazing appHcations. Phosphate ester (triethyl phosphate) additives are also included to supplement fiame-retardant efficiency benzophenone uv stabilizers are required to prevent yellowing of these uv-sensitive resins. 

Reactant for /-butyl phenolic resins. Magnesium oxide reacts in solution with /-butyl phenolic resin to produce an infusible resinate (Fig. 36) which provides improved heat resistance. The resinate has no melting point and decomposes above 200°C. Although oxides of calcium, lead and lithium can also be used, they are not as efficient as magnesium oxide and also tend to separate from solution. Where clear adhesive solutions are required epoxide resins, zinc-calcium resinates or zinc carbonate can be used. 

Resin consumption is low because of the highly efficient use of the capacity of the resin for the enantiomer during each cycle, as well as the material stability of the resin. The above benefits of the ChiraLig M technology result in improved economics for the large-scale separation. 

Recovery of phenylalanine from aqueous solutions by cation-exchange resins has been reported by Carta and co-workers (Borst et al., 1997). It might be possible to improve the efficiency of resin treatment by raising the operating temperature, to, say, 65 °C. 

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