Zytel, what the last generations of Spademans’ were made out of, is a DuPont product that is glass filled nylon. It’s used extensively in the automotive industry for a variety of critical components including water pumps and has much to recommend it. It - a low coefficient of friction and is stable in cold temps, undoubtably important reasons why it was chosen. It is also available in strands for 3-D printing should anyone care to experiment. Most plastic degrades from cross-linking , essentially a degradation of the plastics molecular structure. The biggest culprit- UV exposure. Older plastics didn’t tolerate prolonged exposure to UV very well. Remember those dashboards in the 70’s-80’s that inevitably cracked within 3 years? You rarely see that in more modern cars.