Polyesters also with polystyrene

It is remarkable that the series of peaks that appear after corona treatment is also observed in corona treatment of other polymers, e.g. polyester, polyethylene, and polystyrene. The nature of the low-molecular weight material thus seems to be independent of the type of polymer, suggesting a rather universal mechanism of formation. This mechanism is still unclear, but a pertinent observation may be that at very short treatment times the surfaces of many polymers indicate a high degree of unsaturation. This is seen in Table II, which shows the ratio 27/29, which is a measure of unsaturation. In corona as well as plasma treatments, the unsaturation increases steeply and then decreases with increasing time or dose. It is thus possible that many polymers initially form some sort of graphite-like structure which then reacts at a slower rate with oxygen. This would explain the similarity in the behavior of these polymers. 

Since the last edition several new materials have been aimounced. Many of these are based on metallocene catalyst technology. Besides the more obvious materials such as metallocene-catalysed polyethylene and polypropylene these also include syndiotactic polystyrenes, ethylene-styrene copolymers and cycloolefin polymers. Developments also continue with condensation polymers with several new polyester-type materials of interest for bottle-blowing and/or degradable plastics. New phenolic-type resins have also been announced. As with previous editions I have tried to explain the properties of these new materials in terms of their structure and morphology involving the principles laid down in the earlier chapters. 

In order to determine the sources of contamination, some water samples, including wastewaters and effluents from different industries were also sampled. Along the Cinca River and in the industrial area of Monzon, industrial effluents from two different industries were selected the first one produced EPS (Expandable polystyrene) treated with flame retardants and ABS (Acrylonitrile-butadiene-styrene), and the second one produced PVC (Polyvinyl chloride). As regards the Vero River, three industries were sampled the first one, a textile industry which produced polyester fibers treated with flame retardants, the second one produced epoxy... 

One of the primary fields of application for P.R.151 is in polystyrene, although there is a slight color change at temperatures above 260°C, at which the pigment partially dissolves. It is also used to a considerable extent in ABS. Cast resins based on methylmethacrylate and unsaturated polyesters are also frequently colored with P.R.151, which is resistant to the peroxide catalysts that are used to harden the plastic. The lightfastness in these media is good it equals step 6-7 on the Blue Scale. 

P.Br.25 also shows excellent lightfastness in polyolefins. Transparent polystyrene samples are heat stable up to 280°C, while specimens reduced considerably with Ti02 withstand up to 240°C. P.Br.25 is also used in polyester, in which it provides an interesting raw material for the manufacture of bottles. 

Petroleum refineries produce a stream of valuable aromatic compounds called the BTX, or benzene-toluene-xylenes (Ruthven 1984). The Cg compounds can be easily separated from the Ce and C compounds by distillation, and consist of ethyl benzene, o-xylene, m-xylene, and / -xylene. Ethyl benzene is the starting material for styrene, which is used to make polystyrene / -xylene is oxidized to make terephthalic acid, and then condensed with ethylene glycol to make polyester for fibers and films. The buyers of / -xylene are the manufacturers of terephthalic acid, such as BP-Amoco, who in turn sell to the fiber manufacturers such as DuPont and Dow. These are big and sophisticated companies that have strong research and engineering capabilities, and are used to have multiple suppliers. The eventual consumers of adsorbents are the public who consider polyester as one of the choices in fabric and garments, in competition with other synthetic and natural fibers. Their purchases are also dependent on personal income and prosperity. In times of recession, it is always possible for a consumer to downgrade to cheaper fibers and to wear old clothes for a longer period of time before new purchases. 

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