ISSN:
0449-2978
Schlagwort(e):
Physics
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
Random copolymers of N-n-butyl-, N-n-octyl-, or N-n-octadecylacrylamide with acrylonitrile were prepared in tert-butanol at 60°C. to test the effect of amide homologs as internal plasticizers. At room temperature under high deformations all samples showed brittle failure; at 100°C. flexible and resilient copolymers were obtained. At low deformations, torsional stiffness values Tf followed the equations of Wood, Fox, and Dimarzio and Gibbs, the latter two modified by use of mole fraction instead of weight fraction. Mole fraction appeared to function better than weight fraction for these special cases where wi 〉 2mi and where modulus-temperature curves were broad. Because literature values for the glass (or brittle) temperatures of homologs of poly-n-alkyl acrylates, methacrylates, n-alkyl styrenes and alkenes, and estimated values for poly-N-n-alkylacrylamides, plotted as a function of the logarithm of the number of single bonds in repeat units, extrapolate to an average value of -111°C. at a chain length of eighteen carbon atoms, and because side-chain melting points of linear eighteen carbon side-chain homologs appear to have a common value of 48-50°C. regardless of structure, it was concluded that similar glass and melting transitions are obtained when the side chain reaches eighteen carbon atoms in any series of homologs. Transitions for longer side-chain lengths then approach the limit of a polyethylene graft, where Tg is -81°C. and Tm is 137°C.
Zusätzliches Material:
5 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1966.160040612
