ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Some dynamic mechanical properties of a series of polymethacrylic and polychloroacrylic esters have been measured over a wide temperature range at about 200 c.p.s. using a cantilever vibration method. The sharp changes in dynamic modulus, and the associated mechanical loss maxima, which occur at various temperatures are discussed in relation to the chemical structures of the polymers and in particular to the ester group in their side chains. The main softening region is shown to be influenced by the presence of polar atoms in both the main and the side chains and by the spatial size and flexibility of the side chains. The data further support the recently postulated view that a secondary dispersion occurring just below the main softening region is associated with rearrangements of the —CO.O—group in the side chains. Some new low temperature transitions are reported, one of which at -30°C. is characteristic only of polycyclohexyl methacrylate and polycyclohexyl chloroacrylate; it is suggested that this is associated with intramolecular flexibility within the cyclohexyl ring. Another process occurring at about -150°C. is found for those polymers whose linear side chain alkyl components possess sufficient flexibility to enable them to take up more than one unique spatial configuration; such flexibility is characteristic of the n-propyl, n-butyl, and sec-butyl esters in both series and of the β-chloroethyl, neopentyl carbinyl, and stearyl esters in the polymethacrylic series. Finally, the strengths of the low temperature relaxation processes, defined in terms of the percentage modulus change, are compared and discussed.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1955.120188801
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