POLYMER DIFFUSION IN SEMICRYSTALLINE POLYMERS .1. POLY(ETHER IMIDE) POLY(ARYL ETHER KETONE KETONE)

The transport of poly(ether imide) (PEI) into amorphous and semicrysta lline matrices of poly(aryl ether ketone ketone) (PEKK) has been chara cterized quantitiatively. Diffusion measurements were performed by an infrared attenuated total reflectance technique and the semicrystallin e morphology investigated both before and after transport via DSC, TEM , SEM, WAXS, SAXS, and microtomy/FTIR. Fickian interdiffusion occurs w hen these polymers are in contact as melts. Two distinct time scales o f sorption kinetics are observed during PEI transport into PEKK with a stable semicrystalline morphology. The early time transport is Fickia n mutual diffusion although the amount of PEI imbibed remains far belo w that expected for complete miscibility in the PEKK amorphous phase. The mutual diffusivity activation energy increases from 9 kcal/mol in amorphous PEKK to 30 kcal/mol for the early time regime in semicrystal line PEKK. The suppression of the PEKK matrix mobility significantly h inders transport. The existence of slower transport in a later-time, k inetics regime is identified with a time scale over which macromolecul es explore bottlenecks between crystalline obstacles. The competitive evolution of PEKK spherulites during mutual diffusion both significant ly retards the transport kinetics and diminishes the total sorption of PEI.