ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
We have made precise measurements of the unperturbed radius of gyration 〈S2〉1/20 of polystyrene and polymethylmethacrylate molecules in the melt over the temperature range 120 °C–240 °C by small-angle neutron scattering. Contrary to most previous reports, based on dilute solution measurements, we find that neither polymer exhibits a significant change in dimensions with temperature, and we deduce temperature coefficients, κ=d ln〈S2〉0/dT, of (0.0±0.1)×10−3 K−1 for polystyrene and (0.1±0.1)×10−3 K−1 for polymethylmethacrylate. These κ values are close to those given by thermoelastic measurements, but are difficult to reconcile with predictions obtained from the rotational isomeric state model.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.465528
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