Controlling degradation

B. Gilg, H. MuUer, and K. Schwarzenbach. Paper presented Advances in Stabili tion and Controlled Degradation of Polymers, New Paltz, N.Y., June... 

The molecular weight may be regulated by controlled degradation of the alkali cellulose in the presence of air. This can be done either before or during etherification. The molecular weight of commercial grades is usually expressed indirectly as viscosity of a 5% solution in an 80 20 toluene-ethanol mixture. 

J. C. Dawson and H. V. Le. Controlled degradation of polymer based aqueous gels. Patent US 5447199,1995. 

Alkali-catalyzed cleavage of glycosidic bonds of glycosaminoglycur-onates occurs by way of -elimination.223 By proper choice of the experimental conditions, it seems possible to achieve a controlled degradation of heparin by -elimination, producing fragments apparently preserving... 

Decker, C. Second International Conference on Advances in the Stabilization and Controlled Degradation of Polymers, Preprints, Luzern, Switzerland, June 1980. 

W.O. Drake, Hindered amine stabilisers as thermal stabilisers or HAS as HATS not just HALS, Proceedings of the 14th International Stability Controlled Degradation, Luzern, Switzerland, 1992, p. 57. 

As pointed out previously, controlled degradation reactions are very difficult with aliphatic or alicyclic hydrocarbons, and most of the relabeling work has been concentrated on aromatic reaction products. Procedures have been extensively described by Pines and co-workers (e.g., 97, 96, also 87, 89-98, 95, 98). For the present purpose, it suffices to note that the 14C contents of the methyl side-chains and the rings in aromatic reaction products are readily estimated by oxidation of the methyl to carboxyl, followed by decarboxylation, while ethyl side-chains may be oxidatively degraded one carbon atom at a time. Radiochemical assays may be made on CO2 either directly in a gas counter, or after conversion to barium carbonate, while other solid degradation intermediates (e.g., benzoic acid or the phthalic acids) may be either assayed directly as solids or burned to CO2. Liquids are best assayed after burning to CO2. 

Processes that control degradation in soils and sediments and transformations during atmospheric transport (Swackhamer and McConnell 1993)... 

The next step in developing controlled degradation polyester is to understand expectations for specific product applications. Some questions to be answered include the following ... 

The possibility of a controlled degradation of polystyrene in copolymer [ethylene styrene] has been examined by selective hydrogenolysis of appended groups, minimizing the cleavage of the main chain [62]. 

Soil Degradation Study. A controlled degradation study will be conducted using soil samples taken from a field that has not been exposed to metolachlor and from a... 

Note 2 A controlled-degradable polymer is a polymer designed to degrade into products at a predictable rate. Such products are usually of lower molecular weight than the original polymer. 

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