The investigation of catalyst effect on curing kinetics of HTPB-TDI binder system by differential scanning calorimetry (DSC)

DSC method was used to investigate the curing kinetics of HTPB-TDI curing reaction like the other articles.1-3 In this investigation, four heating rates (5, 10, 20, 40 ̊C/min ) were used to examine curing behavior of HTPB-TDI binder system, that just one of them (10 ̊C/min) is demonstrated in figure 1-a. In the presence of catalyst (DBTDL), it’s clear that the curing reaction has two different stages as two distinctive peaks has been observed (Figure 1-a). Two stages curing behavior exists in both catalytic and non-catalytic modes, but the different peaks are more obvious in the presence of catalyst. Peak separation and two-peak presence may be due to reduced activation energy as a result of using DBTDL catalyst. By calculating of the activation energy required for the formation of polyurethane, it is understood that activation energy for the non-catalyst state is about 36 kJ/mol more than the catalytic state. Since the use of the catalyst has reduced the activation energy, the rate of reaction has increased, and consequently, the released heat of reaction has increased. As shown in Figure 1-b, the amount of heat released decrease is more sensitive to heating rate for catalytic mode. It means that, when catalyst has been used in binder system, effect of heating rate on the released heat is negligible and therefore it may be predicted that the physical and mechanical properties will not mainly changed as the heat released during curing reaction is approximately constant.

کلیدواژه ها:

DSC ، Heating rate ، Catalyst ، Released heat.