Spherulitic Growth of Poly (Ether Ether Ketone) Crystallized at High Pressure

Abstract

High-pressure crystallized poly (ether ether ketone) (PEEK) samples were prepared with a piston-cylinder apparatus by varying temperature, pressure, crystallization time, and molecular weight, and were investigated using wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The applied etching experiments showed that the chemical resistance of the polymer was significantly improved through the high-pressure treatment. The results also revealed that PEEK spherulites with folded-chain lamellae as substructures and with different characteristics were formed at high pressure. Crystalline elliptical micro-spheres consisting of flake-like lamellae with rugged surfaces were observed on the etched samples with SEM, which may diversify niche applications in functional fillers, carriers, adsorbents, etc. Morphological observations suggested that such micro-spheres might possibly have evolved from a novel dendritic crystal. Furthermore, a granular substructure of the lamellae was observed in these single-phase polymer systems with rigid molecular backbones, which further confirmed the model developed by Strobl for polymer crystallization.

Experimental study and numerical simulation for the interaction between laser and PEEK with different crystallinity

“…For polymers with large, well-developed crystal regions inside (as shown in Figure 5(d)), the scattering phenomenon is relatively strong, and the incident light will be scattered to all directions, resulting in that the integrating sphere that measures reflectivity receiving more energy, and the integrating sphere on the rear side of the sample receives less energy. Among two samples with different crystallinity, the molded product (HC-PEEK), whose crystallinity will be higher and some crystal regions will also occur deformation due to the pressure, 19 is more uneven inside, which will cause the scattering phenomenon to be more notable. Therefore, the reflectance of molded products (HC-PEEK) is slightly higher remelted samples (MC-PEEK), while the transmittance is the opposite.…”

Crystalline structure and morphology of poly(L‐lactide) formed under high pressure

“…Each of the obtained amorphous PLLA was filled in an aluminum container with an inner diameter of 18 mm and depth of 1 mm. The details of the sample assembly and the pressure and temperature calibrations were the same as those described in previous article . After loading the amorphous sample, the pressure was raised to the predetermined level, and then the temperature was raised to the predetermined level.…”