Grafted Polyethylenes

Dielectric relaxation measurements of polyethylene grafted with acrylic acid(AA), 2-hydroxyethyl methacrylate (HEMA) and their binary mixture were carried out in a trial to explore the molecular dynamics of the grafted samples [125]. Such measurements provide information about their molecular packing and interaction. It was possible to predict that the binary mixture used yields a random copolymer PE—g—P(AA/HEMA), which is greatly enriched with HEMA. This method of characterization is very interesting and is going to be developed in different polymer/monomer systems. 

Figure 3 (a) Core level spectra of polyethylene (TO/0). (b) Core level spectra of polyethylene grafted with 2 parts TAC at an irradiation dose of 15 Mrad (T2/15). (c) Cls, Nls, and Ols peaks for polyethylene grafted with 1 part TAC at an irradiation dose of 10 Mrad (Tl/10). 

Radiolysis Effects. Radicals formed in solvent (SH) and trunk polymers (PH) are important in the grafting of monomers (MH) with gamma radiation. With polymers such as polyethylene, grafting sites are formed by direct bond rupture (Equation 1). Additional sites are also... 

Although the single amino acids cannot bind the adhesion receptors on cells, they provide other ehemieal functional groups which may improve the adsorption of eell adhesion-mediating molecules on the material surface. Similar efifeet was observed on ion-implanted polyethylene grafted with the Arg-Gly-Asp (RGD)... 

A diblock copolymer consisting of a block of polyethylene grafted with poly(vinyl chloride) and a block of polystyrene, the structure of which is ... 

D. J. Metz, J. Gard and G. Adler Temperature stability and homo-genity of polystyrene-polyethylene grafts. J. Appl. Polymer Sci. 1,371 (1959). 

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 ... 

Ethylene has been separated from ethane by a silver nitrate solution passing countercurrent in a hollow fiber poly-sulfone.165 This separation has also been performed with the silver nitrate solution between two sheets of a polysilox-ane.166 A hydrated silver ion-exchanged Nafion film separated 1,5-hexadiene from 1-hexene with separation factors of 50-80.167 Polyethylene, graft-polymerized with acrylic acid, then converted to its silver salt, favored isobutylene over isobutane by a factor of 10. Olefins, such as ethylene, can be separated from paraffins by electroinduced facilitated transport using a Nafion membrane containing copper ions and platinum.168 A carbon molecular sieve made by pyrolysis of a polyimide, followed by enlargement of the pores with water at 400 C selected propylene over propane with an a-valve greater than 100 at 35°C.169... 

Benzene can be separated over cyclohexane with an revalue of 26 with a polvinyl alcohol-poly(allylamine) blend containing a cobalt(II) complex.213 An a-value of 60 has been obtained by pervaporation with a poly(acrylonitrile-co-methyl methacrylate) membrane.214 Membranes of porous polyethylene grafted with glycidyl methacrylate215 and poly(A,A-dimethylacrylamide-co-methyl methacrylate)216 have also been used in this separation with separation factors of 21-22. This is a separation that would be difficult to do by size and by distillation. The two boil only 2°C apart. The cyclohexane produced by the reduction of benzene is the starting material for nylon. The best solution to the problem is to run the reduction to 100% completion. 

Comparison of Acid with Polyfunctional Monomers as Additives in Polyethylene Grafting. New additives, as well as acid, have been found to accelerate grafting in the presence of ionizing radiation. Much of this recent work has been performed with polyethylene. Only very preliminary studies of these new additives have been carried out with cellulose, however these early results suggest that these latest additives will also be very valuable for copolymerization reactions with cellulose. The more comprehensive polyethylene data will therefore be presented here to act as a guide for what might be predicted when cellulose is used as backbone polymer. 

Research studies [160] conducted with static magnetic susceptibility and EPR spectroscopy methods have made it possible to define the distribution character of Cu(2 + ) ions fixed on polyethylene-graft-polyacrylic acid supports (PE-graft-PAA). 

Nasef, M.M. and Saidi, H. 2004. Structure of polyethylene-graft-polystyrene sulfonic add membranes prepared by radiation-induced grafting. Int J Polym Mater. 53 1027-1043. 

Sanchez-Valdes, S., Picazo-Rada, C.J., and Lopez-Quiuintanilla, M.L. 2001. Polyethylene grafted maleic anhydride to improve wettabdity of liquid on polyethylene films. J Appl Polym Sci. 79 1802-1808. 

Note PAC, poly(acrylic acid) PE-gr-PAC, polyethylene grafted poly(acrylic acid) PVPy, poly(4-vinylpyridine) DP, degree of polymerization. 

This approach is comparatively widely used, for example to evaluate the formation constants of Cu(II) and Ni(II) complexes with polyethylene-grafted-poly(acrylic acid) (PE-gr-PAA) (Table 3-2), Mn(II)-poly(acrylic acid), for studying sorption of low molecular weight compounds by polymers and complexation with modified silica, etc. [35-37]. It was found that one third of the carboxylic groups failed to react with copper ions in the PE-gr-PAA-Cu(II)-system K = 300 L mor, /n,ax = 0.35). For Cu(II) complexes with polystyrene-grafted-poly(vinylpyridine) of different types the values of K andy],. vary from -2500 to 9100 L moL and -0.15 to 0.37, respectively [38]. 

Interesting results were obtained in a study of the topochemistry of Cu(II) complexes on polyethylene-grafted-poly(acrylic acid) [55]. A superposition of two different states of copper was observed. Even at concentrations of bound copper ions 0.1 mmol g more than half are localized in exchange-bonded cluster aggregations, and at concentrations >0.15 mmol g virtually all copper is bonded into aggregations. The local concentrations of Cu(II) in these... 

Table 3-3. The ESR data for isolated ions and dipole-bound aggregations in the polyethylene-grafted-poly(acrylic acid)-Cu(II) system [9,55].

Grafting on polymers to obtain functional groups for binding of metal ions has been reported polyethylene-graft-poly(methylvinylketone)/Schiff base with 2-aminophenol 38 [1,107] or salicylaldehyde hydrazide [108] (for other grafted ligands see [109]). 

Figure 12-10. Oxygen binding for cyclohexene oxidation in the presence of Co-containing catalysts (333 K, without solvent). (1) Co(AcAc)2, (2) polyethylene-grafted -poly(cobalt acrylate), (3) copolymer of styrene with cobalt acrylate, (4), polyethylene-grafted -poly(acrylamide -Co(II)),...

Pig. 6. Ethylene polymerization by heterogenized systems on the base of TiCOC Hg).-A1(C2H5)2C1. Homogeneous system (1). Polymer barrier polyethylene grafted with polydiallylamine (2), polyethylene grafted with polyallylamine (3). polyethylene grafted with polyallyl alcohol (4) polyethylene grafted with polyacrylic acid (5) (toluene, 70°C, Al/Ti=100, pQ jj =10 atm). 

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