Radiation grafting blends

Several authors have discussed the ion exchange potentials and membrane properties of grafted cellulose [135,136]. Radiation grafting of anionic and cationic monomers to impart ion exchange properties to polymer films and other structures is rather promising. Thus, grafting of acrylamide and acrylic acid onto polyethylene, polyethylene/ethylene vinyl acetate copolymer as a blend [98], and waste rubber powder [137,138], allows... 

Conversion of a membrane material or membrane from one developed for aqueous-inorganic salt separations to one for use In aqueous-organic or organic-organic separations often requires modifications such as copolymerization, polymer blending or radiation grafting onto the membrane surface. These approaches are often difficult, are not fully understood and are not always entirely successful. 

McHerron and Wilkes ° have shown that PS does not offer any protection against radiation cross-linking into PS/PVME blends while these blends are miscible. On the contrary, a significant amoimt of radiation grafting occurs between both polymers. 

Valenza, A., Carianni, G., Mascia, L., Radiation grafting functionalization of poly(vinylidene fluoride) to compatibilize its blends with polyolefin ionomers. Polymer Engineering and Science 1998,38(3), 452 60. 

The butadiene and butadiene-acrylic monomer systems polymerize when irradiated on PVC or vinyl chloride copolymer latex. The structure of the polymer obtained may be grafted if it can be proved that the copolymer properties are different from the blend properties. To elucidate the structure we studied a copolymer obtained by polymerizing butadiene-acrylonitrile on a PVC homopolymer lattice. Owing to practical reasons and to exclude the secondary effect of catalytic residues we used y radiation. However, we shall observe in a particular case the properties of peroxide-initiated graft copolymer. 

Multi-polymer Materials. The literature for multi-polymer materials is extensive but is less than that for blends and grafts composed of two polymers. A ternary graft copolymer, semi-IPN is described by Rogers and Ostler (43, 44) an original crosslinked polyethylene graft-poly-(potassium acrylate) was swelled with styrene and radiation polmerized. The authors comment that most of the grafting of polymer 3 was on polymer 2, the poly (potassium acrylate). This reaction sequence can be described ... 

Peroxy radicals are known to be formed on exposure of irradiated PMMA to O. Thus in the presence of some oxidative degradation would take place but its nature is most likely different from that of the degradation in the absence of Oj. The addition of benzene and many free radical scavengers e.g., allyl thiourea) also protects PMMA against radiation-induced degradation. PMMA undergoes grafting by direct irradiation, post-irradiation by trapped free radicals or on irradiation in a blend [Chapiro, 1962]. 

K. El-Salmawi, M. Zaid, S. Ibraheim, A. El-Naggar, A. Zahran, Sorption of dye wastes by poly (vinyl alc(4iol)/poly (carboxymethyl cellulose) blend grafted through a radiation method, J. Appl. Polym. Sci. 82 (1) (2001) 136-142. 

In some cases, lack of noticeable influence of electron beam radiation on the values of tensile and Charpy impact strengths of 24-23-21-15-17 LDPE-HDPE-PP-PS-PET blends (based on recycled polymers) compatibilized with 1% trimethylol propane trimethylacrylate (TMPTMA) were found. Zenkiewicz et al. ° explained this lack of influence by the protective action of aromatic rings of PS and PET that hindered cross-linking. In the same article, the addition of 10% of styrene-ethylene/butylene-styrene elastomer grafted with maleic anhydride (SEBS-g-MA) led to the great increase of both tensile and Charpy impact strengths. 

Methods for the incorporation of the graft nnit may include irradiation of the base polymer and mixing with the comonomer, or reaction as solids or solntions with free radical agents and blending techniques (see Chain polymerization, Radiation-cured adhesives). 

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