CHARACTERIZATION OF PLASTIC-BONDED EXPLOSIVES BY PYROLYSIS-GAS CHROMATOGRAPHY AND MULTIVARIATE DATA-ANALYSIS .1. SETUP OF THE METHOD

A further development of the procedure based on pyrolysis gas chromato graphy (Py-GC) for the characterization of plastic-bonded explosives ( PBX's) is described. After grinding, the PBX samples were pressed on a pyrolysis wire followed by Py-GC analysis. The peak areas obtained we re normalized and subsequently submitted to multivariate data analysis . The use of principal component analysis (PCA) was tested on five sam ples which differed slightly in composition and age. The results were promising and showed that PCA is a powerful tool for the differentiati on between PBX samples. The pyrolysis conditions were examined and opt imized. A dependency was found between the sample loading (mass) and t he position of the samples in a PCA score plot and indicates that cont rol of the sample loading is important in obtaining reproducible resul ts. For PBX samples an optimum pyrolysis temperature was determined ar ound 540 degrees C, close to the previous selected pyrolysis temperatu re of 610 degrees C. In examining the pyrolysis at lower temperatures it was found that RDX or HMX is pyrolyzed independently from the binde r. It appeared that PBX samples were inhomogeneous despite a thorough mixing of the constituents during preparation.