ISSN:
0022-3832
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
A pyrolytic dehydrogenation technique originally proposed by Szwarc has been employed for the preparation of polyhydrocarbons from p-xylylene, pseudocumene, and durene. With particular emphasis on poly-p-xylylene, the structure and physical properties of the polymers were investigated. Poly-p-xylylene may be obtained in two modifications: a transparent form and opaque form. The transparent form of poly-p-xylylene exhibits uniaxial, negative birefringence. The opaque form on purification by chloroform extraction melts at 412°C. Heat treatment of either modification appears to result in an irreversible, polymorphic transition. Poly-p-xylylene may be stretched at temeratures above 150°C. to reveal a well-defined x-ray fiber diagram, having an identity period of one. Sulfonation of poly-p-xylylene yields a product having one sulfonic acid group per benzene ring. The product swells anisotropically but does not dissolve in water. This observation, as well as the observation that the rate of dissolution of poly-p-xylylene in high boiling solvents is dependent upon the presence of oxygen, suggest that the polymer is crosslinked to a small but finite extent. The polymer derived from pseudocumene is also crosslinked but contains up to ca. 21% of a chloroform-extractable component. The number-average molecular weight of the chloroform soluble component is 23,900.
Zusätzliches Material:
14 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1954.120136802
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