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 preparation of isotactic and syndiotactic 1,4-polypentadienes with a cis content of at least 70%-75% using i-Bu2AlH/Ti(i-OPr)4 and AlEtCl2/thiophene/Co(acetylacetonate)2 catalysts, respectively, is reported. Physical characterization of the vulcanizates, prepared by a common recipe, involving infrared analysis, DTA, simple stress-strain and swelling measurements, and dynamic mechanical measurements over a frequency range of 2 decades and temperature range of -60°C to +20°C indicated that no isomerization had taken place during vulcanization and that stereoregularity of the polymer chains affected the resultant cure: the isotactic form was found to have a greater crosslink density than the syndiotactic form. Master curves covering an extended frequency range were constructed from the reduced dynamic mechanical data and the calculated quantities - thermal expansion coefficients of free volume and the fractional free volumes at the glass transition temperatures - agree with the accepted values. Glass transition temperatures of the isotactic and syndiotactic polymers are -37°C and -42°C, respectively, and for their vulcanizates, -33°C and -40°C, respectively.
Zusätzliches Material:
9 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/app.1970.070140321
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