Radiation grafting method

FIGURE 12.13 Stability of PVDF- -PSSA having the same G% and prepared with two different radiation-grafting methods. 

The direct radiation grafting of a vinyl monomer onto a polymer by the mutual method. 

The dose and dose rate of irradiation are important factors in any radiation grafting system. In the direct method the total dose determines the number of grafting sites, while the dose rate determines the number of grafting sites, and the dose rate determines the length of the grafted branches. The length of the branches is also con-... 

A number of methods have been used to prepare graft copolymers in the past few decades including both conventional chemical and radiation-chemical methods [20,86,87]. In the latter case, graft copolymerization is usually initiated by creating active radical sites on existing polymer chains. The advantages of radiation-chemical methods are (i) ease of preparation as compared to... 

Trapped radicals on samples with different storage conditions and reaction conditions are usually determined by ESR. Modification of PVC by radiation-grafting technique is an attractive method to improve the mechanical strength, printing ink adhesion, and adhesive receptance. Wang... 

Radiation grafting is an extremely valuable one-step method for directly modifying the properties of polymers (y,2). The technique has been used with a wide variety of naturally occurring macromolecules such as wool (3) and cellulose (4) and also with many synthetic polymers, particularly the polyolefins (2, 5, 6) ... 

The commonly used separator material now is the surface treated polypropylene. The surface treatment helps in making the polypropylene permanently wettable. Surface treatments involve the grafting of a chemical such as acrylic acid to the base fibers to impart wettability and is accomplished using a variety of techniques such as UV or cobalt radiation. Another method of imparting wettability to the polypropylene is a sulfonation treatment where the base fiber material is exposed to fuming sulfuric acid. The separator surface is designed to be made hydrophilic to the electrolyte. 

The most common material used is cellophane, which is a cellulose film, which acts as a membrane and is capable of resisting zinc penetration. The cycle life of cells utilizing this material is severely limited due to the hydrolysis of the cellophane in alkaline solution. Various methods have been tried to stabilize cellulose materials, such as chemical treatment and radiation grafting to other polymers, but none have, as of now proved economically feasible. The most successful zinc migration barrier material yet developed for the nickel—zinc battery is Celgard microporous polypropylene film. It is inherently hydrophobic so it is typically treated with a wetting agent for aqueous applications. 

C. Aymes-Chodur, N. Betz, M.C. Porte-Durrieu, Ch. Baquey, A. Le Moel, A FTIR and SEM study of PS radiation grafted fluoropolymers Influence of the nature of the ionizing radiation on the film structure, Nucl. Instrum. Methods Phys. Res. B 151 (1999) 377-385. 

Seko, N., Tamada, M. and Yoshii, F. (2005) Current status of adsorbent for metal ions with radiation grafting and crosslinking techniques. Nuclear Instruments and Methods in Physics Research, Section B Beam Interactions with Materials and Atoms, 236(1-4), 21-29. 

Radiation grafting [83, 84, 85, 86, 87, 88, 89] is a very versatile and widely used technique by which surface properties of almost all polymers can be tailored through the choice of different functional monomers. It covers potential applications of industrial interest and particularly for achieving desired chemical and physical properties of polymeric materials. In this method, the most commonly used radiation sources are high-energy electrons, y-radiation, X-rays, U.V.-Vis radiation and, more recently, pulsed laser [90], infrared [91], microwave [92] and ultrasonic radiation [93]. Grafting is performed either by pre-irradiation or simultaneous irradiation techniques [94, 95]. In the former technique, free radicals are trapped in the inert atmosphere in the polymer matrix and later on the monomer is introduced into... 

Another method of immobilization, using radiation graft copolymerization, has been studied by Hoffman, Gaussen, Garnnett and other researchers in the... 

Methods for Enhancing Ultraviolet and Radiation Grafting of Monomers to Cellulose and Derivatives to Improve Properties of Value to Conservation... 

Both UV and ionizing radiation grafting procedures were modifications of previously reported methods (7,13). Monomers were purchased from Monsanto Chemicals (Australia) Limited and Polysciences Incorporated. Inhibitor was removed prior to reaction by passing the monomer down a column of activated alumina (13). All solvents were AR grade and used without further purification. 

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