Thermokinetic analysis of two-step curing reactions in melt: Part II. Investigation of polymeric model systems

Thermo-controlled two-step curing reactions in melt are of particular interest for reactive polymeric systems. These reaction types are e.g. observed in thermal curing polyurethane (PUR) powder coatings. Illustrated by the uretdione/OH-reaction we describe the formal kinetic analysis of two-step curing processes in melts. The two reaction steps (allophanate- and uretdione reaction) can be separated applying special reaction conditions. The curing reaction of polymeric model systems was monitored by non-isothermal DSC measurements with different heating rates. On the basis of these data the kinetic parameters (activation energies, pre-exponential factors and reaction orders) were determined and analyzed with the aid of formal kinetic analysis. Our investigations are of particular interest in view of the simulation of curing processes of low temperature powder coatings. In this way, time consuming curing experiments can be minimized.