Radiation chemical yield copolymers

In order to have a uniform exposure to electrons over the entire wafer, a standard transmission microscope (RCA EMV-3) was used. The apertures were opened and the 40 kv beam spread out over a circle larger than the wafer itself. The coated wafer was introduced into the microscope via the film cassette drawer (below the fluorescent screen). Charge density was measured with a Faraday Cup. Each polymer was irradiated at doses of 2, 5, 10, and 20 yC/cm. The radiation chemical yield was measured from plots of 1/Mjj versus the incident dose. A sample plot is shown in Figure 1, in this case for itaconic acid-MMA copolymers. The slope of such a plot is given by ... 

An Interpretative review of the reactions initiated by macrocellulosic free radicals with vinyl monomers to yield block and graft copolymers of fibrous cellulose was made. Macrocellulosic radicals are usually formed by interactions with radiation or chemical redox systems. Important factors in these heterogeneous reactions are lifetimes and accessibilities of the radicals and interactions of solutions of monomer with fibrous cellulose. Changes in organochemical, macromolecular, and morphological structures in cellulosic fibers through formation of copolymers are made. 

The interest in radiation grafting lies in the fact that it is on route to the production of an almost unlimited range of new materials by an easy and clean method. If can be carried out in gels, in semi-solid substances and even in the bulk or on the surface of shaped products. At the time of these early findings, chemical grafting methods were scarce and were conducted in dilute solutions with very low yields of graft copolymers. This explains why these studies produced such a strong impact on radiation research. 

Another method of graft copolymer synthesis is a combination of microwave-based and conventional synthesis, i.e. using both microwave radiation as well as a chemical free radical initiator (e.g. ceric ammonium nitrate) together. This process is referred to as microwave assisted synthesis [47]. Although it yields a higher percentage grafting than the microwave initiated synthesis, the rehability of the synthesis process is low. 

The only way to apply chemically bonded thin perfluorosulfonic acid layer onto the surface of an inert support is to graft perfluorinated functional monomers onto perfluorinated polymers. Some features of radiation-induced graft copolymerization of PFAVESF onto fluoropolymers were investigated. The studies showed that neither irradiation of a fluoropolymer-PFAVESF mixture (direct grafting) or interaction of PFAVESF with previously irradiated fluoropolymers (preirradiation grafting) yielded the grafted copolymers. It was assumed that this is connected with the low activity of PFAVE in radical polymerization. A special method has been developed for the synthesis of grafted copolymer. Previously irradiated fluoropolymer powders were used to prevent waste of PFAVESF. 

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