That’s a very correct way to define the operating window. In PMB production, 160 °C is usually the practical minimum where polymer swelling and dispersion can still proceed at a reasonable rate, while 190 °C is the absolute upper limit beyond which thermal degradation of both bitumen and polymer becomes a real risk. In most plants, around 180 °C is indeed the optimal compromise: viscosity is low enough for good mixing and pumping, polymer swelling is fast and complete, but oxidation and polymer chain scission are still under control. Staying close to this temperature gives stable curing kinetics and better long-term storage stability.