This cure temperature differential

This cure temperature differential can be advantageously employed to prepare B-stageable films or tapes from a mixture of aliphatic/aromatic BZ and thiol [s]. Upon mixing at room temperature or slightly above,the aliphatic components immediately react, while the aromatic benzoxazine rings remain unreacted. Figure 5 illustrates how 1H NMR can be used to monitor the sequential nature of the reaction by observing the peaks responsible for the methylene protons on the carbon between the oxygen and nitrogen of the oxazine (BZ-1),shown later. In the case of the aromatic amine, these protons are observed in the region between 5.0 and 5.4 ppm. In the aliphatic BZs, the signal is farther downfield,below 5 ppm.