Polymers, radiation crosslinking

As mentioned above, it is the polymer that crosslinks during the radiation cure of hot melts. Various polymer systems have been developed and several of these are now commercial. A brief description of each is summarized below. 

Both radiation and chemical crosslinking can produce amorphous, mechanically stable networks. Radiation crosslinking has a practical advantage in that polymer elec-... 

International Polymer Science and Technology 17,No.ll,1990,p.T/50-l HEAT STABILITY OF RADIATION CROSSLINKED PE FOAM... 

Fig. 5. Equilibrium degree of swelling of radiation-crosslinked PVME gel (Trial 4) at different temperatures. The line added is to guide the eye. Reprinted from Polymer (1991) 33 990 by permission of the publishers, Butterworth Heinemann [46]...

Thus in terms of equilibrium swelling, radiation crosslinked PVME appears to follow the same trends as the gels made of other polymers by other techniques. However, the kinetic properties of these gels could be quite different, as will be discussed in Sect. 5.4.1. 

Peppas N, Merrill E. Poly(vinyl alcohol) hydrogels reinforcement of radiation-crosslinked networks by crystallization. Journal of Polymer Science 1976, 14,441 457. 

Polyethylene is known as one of the typical polymers which crosslink under the influence of ionizing radiation. The radiation-induced crosslinking (the formation of C-C covalent bonds between polymer chains) of polyethylene has long attracted the interest of a large number of research workers, because this polymer has the most simple chemical structure for the fundamental study of radiation effects on polymers, and also because the irradiation with ionizing radiation is a practically important means of modifying the mechanical and thermal properties of polyethylene. 

Polyethylene oxide has been shown to be an excellent mucoadhesive polymer. Low levels of polyethylene oxide are effective thickeners, although alcohol is usually added to water-based formulations to provide improved viscosity stability see Table II. Polyethylene oxide films demonstrate good lubricity when wet. This property has been utilized in the development of coatings for medical devices. Polyethylene oxide can be radiation crosslinked in solution to produce a hydrogel that can be used in wound care applications. 

Comparison of Crosslinking Vs Scission of Polymers Polymer Radiation Heat of Monomer... 

Testing procedure A standardized procedure which requires choice of solvent for extraction. In PE determinations, xylene was used as a solvent." A more complex procedure was used to determine the gel content in radiation crosslinked PVC filled with calcium carbonate. The compound was extracted with tetrahydrofuran, and non-dissolved residue was determined. This residue was then used for determination of chlorine by the Schoniger method. From the amount of chlorine, the concentration of polymer was established. The remainder of the gel content was a filler embedded by gel. " ... 

Major results The total gel content in radiation crosslinked PVC was increased by the addition of calcium carbonate but only due to the inclusion of filler in gel. When filler content in gel was subtracted, the amount of polymer gel formed decreased as... 

Dehydrochlorlnatlon measurements of the radiation cured compounds were conducted at 180°C in oxygen (Table IV). Radiation crosslinking of pure CPE reduces the maximum rate of dehydrochlorlnatlon from 0.27 for the uncrosslinked polymer to... 

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