The phase structure and mechanical properties of polyamide 6 (PA 6) / poly(butylene terephthalate) (PBT) blends
Polimery 1999, No 1, 30
PBT/PA 6 blends covering the whole concentration range, were prepared in a laboratory extruder equipped with a mixing die (L = 2D,D = 19 mm), at a screw speed of 50 rpm. Scanning electron microscopy (SEM) was used to study the morphology of the blends. Glass transition temperature and melting point were determined by DSC and DMTA (Table 1). The breaking stress, elongation at break, hardness, MFR, and limiting viscosity number were studied in relation to blend composition (Table 2). The blends were extracted with a formic acid solution. The extracts were analyzed by FTIR (Fig. 9). SEM photomicrographs (Figs. 6, 11, 12) and DSC and DMTA thermograms showed the blends to be heterogeneous. When the components were mixed in the molten state, they were likely to undergo mechanical degradation and recombination; PBT/PA 6 block copolymers were found to form by segmental exchange, where by compatibility was enhanced in the system (Fig. 10).