Radiochemical polymerization

The first work was carried out by radiochemical polymerization of a mixture of dienic and acrylic monomers on a PVC latex. A parallel study by chemical means leads to equivalent products and the development of a reinforcing resin which satisfied the requirements listed above. At present a resin of this type is manufactured and sold by Pechiney-Saint Gobain under the name Lucovyl H 4010 (10). 

Radiochemical polymerization of A -vinylcarbazole in liquid and solid phase [109]. 

A detailed study of the radiochemical reactions of phenylarsenic compounds has been published by Grossmann. Once again unable to effect isolation of all compounds, he was able, however, to get evidently reliable values for the sums of all compounds with one, two and three phenyl-arsenic bonds, respectively, as well as ionic arsenic and a further organic-soluble fraction which appeared to be a group of polymeric phenylarsenic compounds. Selected data from this work are given in Table 6. 

Type 2 gels are essentially infinite molecular weight molecules Their three-dimensional macroscopic networks comprise structural components that are covalently linked through multifunctional units. This is a very broad class that includes linear polymers that have been chemically or radiochemically cross-linked into a permanent structure as well as networks that have been built up by the step or chain polymerization of difunctional and multifunctional monomers. 

The number of polymer chains attached to zirconium atoms can be measured by treating the reaction mixture with excess tritium oxide giving a radioactive polymer (XXIX). Radiochemical measurements can therefore be used to determine the number of polymer chains attached to metal atoms during the polymerization. 

Analysis of end groups of polymeric chains by chemical, radiochemical and physical methods (IR examination). 

Moreover, we confirmed the results previously ascertained through radiochemical measurements. In fact, the comparison between such data and those obtained by IR measurements on the atactic polymer fraction (Table IV) shows that the ratio between the number of polymeric chains with a —C2H6 end group (corresponding to a chain transfer process depending on the catalyst concentration) and the number of polymeric chains with a vinylidenic end group of polymeric chains (corresponding to the chain transfer process with the monomer) is closely in accordance with the data reported in Fig. 33. 

As an example the carrier addition method 2 is described in more detail in the appendix since this is important for establishing the radiochemical purity of labelled compounds. The other two procedures are similar in principle and are described elsewhere (29). The technique has been used to measure the products of initiator side reactions in azoiso-butyronitrile initiated polymerizations (30—33) and in benzoyl peroxide decomposition (34) and is capable of much wider application than it has so far received. 

Finally the ESR spectrum of Nb(7r-allyl)4/alumina was unaffected by the addition of ethylene gas to the ESR sample tube. It is assumed that polyethylene is produced in this process since polymer can be isolated from larger scale reactions under similar conditions. The accepted mechanism for the ethylene growth reaction postulates a steady-state concentration of a a-bonded transition metal-hydrocarbon species which would be expected to modify the ESR spectrum of the supported complex. A possible explanation for the failure to detect a change in the ESR spectrum may be that only a small number of the niobium sites are active for polymerization. Although further experiments are needed to verify this proposition, it is consistent with IR data and radiochemical studies of similar catalyst systems (41, 42, 43). 

Allen, P. W., G. Ayrey, C. G. Moore and J. Scanlan Radiochemical studies of free-radical vinyl polymerizations. Part II. The polymerization of vinyl monomers in the presence of polyisoprenes use of C14-labeled initiators to determine the mechanism of graft-interpolymer formation. J. Polymer Sci. 36, 55 (1959). 

Preparation of Samples. PVC Latex. Polymerization was performed using chemical initiation (persulfate-metabisulfite) and radiochemical initiation (y-irradiation from 60Co mean dose rate 10,000 rads/hour). Emulsifier was potassium stearate. 

BD-AN. Polymerization was performed chemically (cumyl hydro-peroxide/glucose/pyrophosphate/ferrous sulfate) and by radiochemical initiation (see above). Monomer ratios were VC/BD/AN = 5/3/1. 

A ratio of 4 molecules of carbon dioxide to each ion pair is predicted on the basis of this theory. By direct experiment the M/N ratio is found to be 3.9 to 4.4. In other reactions, as in the polymerization of acetylene a cluster of twenty molecules is assumed in order to account for the experimentally determined M/N ratio. The cluster ion offers a satisfactory explanation of many radiochemical reactions but the size of the cluster is assigned rather arbitrarily, and there may be other ways of accounting for the experimental facts. 

The nature of our concern is best illustrated by a specific example. Blank and Kidwell use a cocaine solution of 100,000 ng/mL for their contamination experiments, to which they add approximately 1 pCi of tritium-labeled cocaine, i.e., approximately one million counts per minute. Therefore, they have approximately a sensitivity of 10 cpm/ng of sample. Decontamination of hair means that residual drug concentration must drop below the endogenous cutoff level of 5 ng/10 mg of hair, i.e., to 50 cpm/10 mg hair. Now if the labeled cocaine has a radiochemical impurity of as little as 0.1%, this corresponds to 1000 cpm or to 100 ng of residual cocaine equivalents. Since self-irradiation of tritium-labeled material tends to form polymeric impurities, and since these are likely to preferentially bind to hair, one incurs a major risk of concluding erroneously that the residual radioactivity represents residual cocaine contamination rather than contamination by polymeric degradation products. 

Table 2. Results of radiochemical study of the relaxation mechanism in polymeric NaPO ...

In a study by Carpenter and co-workers, three polymers (I, III, and IV) were made using TMP to prepare the respective polymeric initiators, as described in Section 3.23P In an effort to produce compliant monofilaments, these polymers were extruded to monofilaments and processed under slightly different conditions from those used in preparing their counterparts in section 3.2.3. One of the polymers (I) was used to prepare a second set of monofilaments for studying the effect of radiation dose, under a typical radiochemical sterilization process (RC-S) on their in vitro breaking strength retention (BSR). 

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