Polyethylene oxidation products, distribution

Figure 3. Distribution of polyethylene oxidation products as a function of the extent of oxidation (lower scale 02 absorbed upper scale time of reaction). The vertical scale refers to the intensity of the backbone CH2 resonance at 30 ppm. The hydroperoxide decomposes gradually at 110°C the concentrations shown above are the estimated values extrapolated back to zero time assuming first-order decay.

Monofunctional hydroxyl terminated polyethylene oxide chains with degree of polymerization from 5 to 20 are reacted with pMDI, or simply with MDI, to provide surface active agents. The resulting surface active agent is then mixed with pMDI to provide a resin which is dispersible in water, resulting in an oil-in-water emulsion [51]. Such emulsions are stable for brief periods, 1 to 2 hours, before the water reaetion eauses gelation. Emulsifiable pMDI could be used where dispersion in water offers some benefit. For example, neat emulsifiable pMDI could be added directly to the blow line for medium density fiberboard production. Water emulsified pMDI has been used for improving resin distribution in particleboard or OSB manufacture however, this is not common industrial practice. 

TLC has been useful in the analysis of polyethylene oxide compounds. Compounds containing a small, medium or large number of ethylene oxide units are formed, depending on the amount introduced in the reaction. Burgeb [10] has determined the ethylene oxide content and molecular weight distribution of polyethylene oxide condensates with fatty acids, fatty alcohols and alkylphenols, using silica gel and the upper layer of a well shaken mixture of methyl ethyl ketone-water (50 + 50) (Fig. 189). Polymeric products ( condensates ) from reaction of ethylene oxide with fatty amines can be chromatographed in the upper phase of the mixture methyl ethyl ketone-2.5 % ammonium hydroxide... 

The NMR results indicate the following distribution of oxidation products for the polyethylene sample that initially had 17.7 branches per 1000 CH2 groups ketone. 

Oxirane/cyclic acid anhydride alternating copolymers of controlled molecular weight with a narrow molecular weight distribution were found by Aida et al. [188,189] to be formed under mild conditions when copolymerising ethylene oxide and phthalic anhydride in the presence of the (tpp)AlCl-quater-nary phosphonium salt catalyst system. The copolymerisation carried out with (tpp)AlCl alone proceeded very slowly, and the product was not polyethylene terephthalate) but contained ether linkages in considerable amount. The development of the living character and the tendency towards alternation of the copolymerisation when using the aluminium porphyrin catalyst, coupled with a quaternary salt, have been postulated [188,189] to be due to the formation of... 

As can be seen from Table 5.2, nonylphenol ethoxylates have a steeply increasing cloud point for very little addition of ethylene oxide. Most industrial products have a rounded up/down value of ethylene oxide in their nomenclature. Thus, NP9 from one company could be actually NP9.25 and from another could be NP8.75. The cloud point for these two products could be 15° C different and in some applications, such as in solubilisation of a fragrance or flavouring, this could be crucial. This is almost certainly due to the sharp (compared to alcohol-based products) Poisson isomer distribution and also variable polyethylene glycol levels in different manufacturers products. Therefore, it is suggested that product should always be purchased on a cloud point specification and not to an EO number. 

The single largest use of ethylene is for the production of all types of polyethylene, which consumes about half of the total. Other major uses are for the production of ethylene oxide, ethylene dichloride (1,2-dichloroethane), and ethylbenzene enroute to styrene. The remaining 10-15% of production is distributed among a multiplicity of smaller scale products, including vinyl acetate, ethanol, and acetaldehyde. 

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