The translation of German polymer physics into practical nylon production involved understanding the non-Newtonian behavior of polymer melts. German physicists, including and Hermann Mark (though Mark worked internationally, his training was Viennese-German), applied hydrodynamics to polymer solutions. They described how long nylon molecules align under shear flow—a critical insight for the spinning process.

The trajectory of German nylon physics was profoundly shaped by the Third Reich. Autarky (economic self-sufficiency) drove research into synthetic fibers to replace imported cotton and wool. Perlon was developed not for ladies’ hosiery but for parachutes, tire cords, and ropes for the Wehrmacht. German physicists were compelled to solve practical problems: How does a nylon rope behave under ballistic shock? How does humidity affect polymer chain mobility? This wartime pressure accelerated the study of viscoelasticity , the time-dependent deformation of polymers. The German physicist (later influential in Britain) formulated the Weissenberg effect—the tendency of a polymer solution to climb a rotating rod—demonstrating the normal stress differences that define non-Newtonian fluids.

Kuhn’s work explained why nylon fibers could be stretched and why they retracted. He derived equations for the entropy of a polymer chain, showing that a stretched chain is in a low-entropy state. When released, the chain returns to a random coil (high entropy), a phenomenon known as entropic elasticity . Unlike a metal spring (enthalpic), nylon’s elasticity is fundamentally statistical. This German-led insight transformed materials engineering: it meant that by controlling chain length and crosslinking, one could design fibers with predetermined stretch and recovery properties.

The German school also excelled in polymer optics . Birefringence (double refraction) in drawn nylon fibers was used to measure molecular orientation non-destructively. This marriage of physics and metrology allowed German industry (e.g., BASF, Bayer) to maintain high-quality fiber production long after the war.

After 1945, German polymer physics took a different path from the American. While the US focused on commodity plastics (polyethylene, polypropylene) and bulk rheology, German research retained a deep commitment to molecular kinetics . Scientists at the University of Freiburg and the Max Planck Institute for Polymer Research (founded 1983) advanced the physics of polymer glasses and the reptation model (though the latter is largely credited to de Gennes in France and Edwards in the UK, German experimental work on dielectric relaxation—notably by and H. Wagner —provided crucial data).