ISSN:
0021-8995
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
,
Physik
Notizen:
The permeabilities of nitrogen, oxygen, and carbon dioxide through polyethylene-styrene graft copolymer films were measured by means of a gas permeability apparatus based on a modification of Barrer's high vacuum technique. Polyethylene-styrene grafts were prepared by mutual γ-ray irradiation of low-density polyethylene films in styrene-methanol solution. Densities and thicknesses of the graft copolymer films were determined. It was observed that the gas permeability constants decreased with increasing grafting to minimum values at 20-30% styrene grafting and increased again above 30% grafting. These results are explained in terms of a decrease in the free volume of the amorphous regions of the polyethylene by a “filling in” effect of the grafted polystyrene chains. Above 30% grafting, disruption of the crystallites may occur resulting in increased gas permeation. Activation energies for gas permeation through polyethylene-styrene graft copolymer films were calculated and found to decrease with increasing per cent styrene grafting. For nitrogen permeation, the activation energy decreased from 11.7 kcal/mole for unirradiated polyethylene to 9.5 kcal/mole for a 50.5% graft. Corresponding values for oxygen and carbon dioxide were 10.2-8.2 kcal/mole for a 48.7% graft and 8.4-6.5 kcal/mole for a 50.5% graft.
Zusätzliches Material:
11 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/app.1969.070130409
