/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Science, 23, pp. 847-858, 1979 The origin of residual internal stress in solvent-cast thermoplastic coatings Croll, S. G. Journal of Applied Polymer SynopsisExperiments on polystyrene and poly(isobuty1 methacrylate) coatings cast from toluene have shown that residual internal stress is independent of dried coating thickness and initial solution concentration. A theory is presented that predicts the magnitude of the stress and shows that it has no dependence on thickness or initial solution concentration. Internal strain is calculated from the volume of solvent lost after the coating has solidified. This solidification point is identified with the solvent concentration that is sufficient to depress the glass transition of the polymer to the prevailing experimental temperature. A one-to-one correlation is confirmed between the volume of solvent lost from solution during drying and the volume change of the polymer film.

No abstract

No abstract

No abstract

Crosslinked polymer formation commonly occurs when two or more multi-functional precursors react to form a three-dimensional network. The resulting networks may contain a significant number of topological imperfections such as loops or dangling ends when formed using crosslinkers with high functionality or when crosslinking at high temperatures. We employ molecular dynamics simulations to analyze these topological imperfections in coarse-grained networks generated from precursors consisting of 'chain extenders' composed of two beads (dimers) and a crosslinker of functionality f = 3 or 6 for a wide range of crosslinking temperatures and final conversions. It is shown that these imperfections result in networks in which the number of elastically active chains, the cycle rank and the number of elastically active junctions is smaller than predicted by the Miller-Macosko theory. Such defects must adversely affect the mechanical properties, resistance to solvent swelling and, possibly, the long-term protective properties of polymer networks. 2 1 e      