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The twentieth anniversary of the founding of the Division of High-Polymer Physics of the American Physical Society is an appropriate time to review the progress of polymer physics over the last two decades, and to re-evaluate the hopes of the founders and the present need for the Division. The continuing need for our Division perhaps is best shown by the fact that each of the last two meetings have set new records for the number of papers presented. Much of this progress is due to the officers who have contributed so much of their time and effort to the Division. Those who served in the first decade were recognized in an earlier review. The officers of the last decade are shown in the accompanying table. We are indebted to all these men for their work to keep the Division running, and thus promote the progress of polymer physics.

The acid catalyzed hydrogen exchange reaction of 1 -dimethylaminonaphthalene is greatly retarded by a chloro or nitro group in the 8 position. 1,8 -Bisdimethylaminonaphthalene exchanges hydrogen more slowly than the 1,5 isomer. These observations support a mechanism previously advanced.2. Carbazole and acridane derivatives are less reactive in hydrogen exchange than the corresponding diphenylamine derivatives. The role of steric factors is discussed.3. N-Methylacridane also exhibits a base catalyzed exchange reaction which is thought to involve the methylene hydrogen atoms. Chicago, Illinois

Current theories of polymer flow processes often sacrifice realistic molecular models for simplicity of their mathematical equations. An analysis of what might happen to molecules of more realistic sizes and shapes under shear flow, shows the importance of the rapid Brownian motion of chain segments, the elastic deformations of polymer random coils, and the dissipation of this elastic random coil energy by the relatively slow slippage of the chains past each other at a few entanglements where steric hindrance causes long relaxation times. This makes the energy loss depend on the time at each local deformation, and not on the overall shear rate. At high shear rates this model leads to “cluster flow” and low loss cyclic deformations, rather than the high loss processes of steady‐state shear. This model gives reasonable qualitative explanations for many anomalous flow properties, and it has predicted new effects that have since been observed.

The effect of temperature and time of application of load on the growth and the apparent ``tensile strength'' of fabrics was studied with a number of new tests. The results gave considerable information about the mechanism of failure of mechanical fabrics at low loads in service which could not be obtained with standard textile tests. A ``fatigue'' test was developed which measured the lives of samples at elevated temperatures when subjected to a constant average load and a superimposed cyclic stress. The change in life with temperature on this test is enormously greater than the change of tensile strength with temperature. Over a considerable range the logarithm of the life under a given load is a linear function of the reciprocal of the absolute temperature, showing that the failure depends on a viscous or plastic flow within the fibers. Calculated activation energies for this flow process increase for different fibers in the order rayon, cotton, Nylon. The construction of the fabric affects the absolute life, but not the calculated activation energy. When creep is negligible, a loaded cord contracts when the temperature is raised, analogous to the Joule effect in rubber.