Journal of Polymer Science Part A-2: Polymer Physics 

About: Journal of Polymer Science Part A-2: Polymer Physics is an academic journal. The journal publishes majorly in the area(s): Polymer & Crystallization. Over the lifetime, 982 publications have been published receiving 21510 citations.

A simple, sensitive graphical method of treating thermogravimetric analysis data

Abstract: Thermogravimetric Analysis (TGA) is finding increasing utility in investigations of the pyrolysis and combustion behavior of materials. Although a theoretical treatment of the TGA behavior of an idealized reaction is relatively straight-forward, major complications can be introduced when the reactions are complex, e.g., in the pyrolysis of cellulose, and when experimental imperfections arise. Consequently, a fairly large number of analytical methods have been proposed for obtaining kinetic parameters from TGA curves. Among the proposed methods are several graphical procedures, mostly involving relatively inaccurate tehniques, such as obtaining slopes on a rapidly changing curve. Included among the proposed procedures is one which permits a linear plot of TGA data. The sensitivity with which such a plot can be used to identify and correct for a variety of experimental complications seems to have escaped even the proponents of the techniques. This paper provides an illustration of the use of this graphical procedure in a hypothetical first-order pyrolysis typical of those occurring in the TGA behavior of cellulose.

Tensile yield‐stress behavior of glassy polymers

Abstract: It is shown that, at the yield stress, glassy polymers exhibit viscous flow which is in agreement with the generalized theory of Eyring. The study of the yield stress over a wide range of temperatures and strain rates provides evidence on the secondary transitions found by other methods. From our measurements we conclude that every secondary transition corresponds to the liberation of one of the degrees of freedom of a segment of the main chain.

A theory of die‐swell

Abstract: An elastic-fluid theory of die-swell for long dies is presented. The theory predicts a swelling ratio De/d asymptotically proportional, for large values of swelling, to the cube root of the recoverable shear evaluated at the die wall. Here the recoverable shear is defined to be half the ratio (first normal stress difference/shear stress). Excellent agreement is shown between predicted De/d and measured De/d for experiments on melts and solutions for which adequate data are available.

Transition in swollen polymer networks induced by intramolecular condensation

Abstract: It is predicted that the net repulsion between the segments of a polymer network and a poor solvent can cause a phase transition marked by a sudden change in the degree of swelling. This is analogous to the “coil–globule” transition recently predicted by Ptitsyn to occur for a macromolecule in solution. The critical conditions for the transition. as well as phase diagrams, are calculated for the gel in free swelling and under uniaxial tension, which facilitates the transition. The transition depends on the gel being formed of chains crosslinked while greatly swollen by a diluent and also having a high degree of crosslinking. It is concluded that it would be difficult to attain the conditions necessary for the transition in the free-swelling case, but that it should be possible for gel under tension.