Investigation of Blends of Poly(Ether Ketone Ketone) with Polyphenylenesulfone

Polymer–polymer composites based on poly(ether ketone ketone) and polyphenylenesulfone have been investigated for the first time. It has been shown that the blends exhibit a single relaxation vitrification transition up to the 50 : 50 composition, which evidences good compatibility of poly(ether ketone ketone) and polyphenylenesulfone in the amorphous phase. Slight phase separation has been observed at the 50 : 50 and 30 : 70 ratios, reflected in significant broadening of the glass transition regions in the differential scanning calorimetry and dynamic mechanical analysis curves. It has been shown that an increase in the content of polyphenylenesulfone leads to an increase in the glass transition temperature and the heat deflection temperature. Furthermore, polyphenylenesulfone has prevented the crystallization of poly(ether ketone ketone), which has been accompanied by an increase in the crystallization temperature and a decrease in the degree of crystallinity. It has been revealed that the introduction of polyphenylenesulfone leads to a gradual decrease in the mechanical parameters measured at low strain, the changes of which have followed the additivity rule. On the contrary, the strain has been more sensitive to the phase structure; it has been significantly decreased upon the appearance of the phase separation, more pronounced at the 50 : 50 composition.