Wanting to determine if a particular lot of PBT (15% glass-filled) has had any degradation occur. Melt flow index, melt point (DSC), and TGA show no major difference btwn suspect material and ok material. FTIR shows very minor differences at 1470, 1264, and 917 cm-1. Processing is likely the source of the differences the engineers are seeing, but any suggestions to completely rule out material differences would be greatly appreciated! Thanks in advance for your help!