Fabrication and Characterization of PEEK/PEI Multilayer Composites

Abstract

Polyetheretherketone (PEEK)/polyetherimide (PEI) blends (50/50, v/v) keeping the crystal phase of PEEK have been manufactured by alternate PEEK/PEI layer stacking. This strategy avoided the complete miscibility of both polymers, keeping layers of PEEK and PEI unmixed along the sample thickness, as well as promoting the formation of a smooth interfacial layer where PEEK and PEI were mixed. The properties of this interface after processing at molten state and different times was studied by DSC, DMA, and X-Ray synchrotron. These techniques allowed monitoring the evolution of glass transition, where isolated Tg’s for both pristine polymers were observed even after long processing time. PEEK crystallinity slightly decreased during manufacturing, whereas PEEK crystal parameters did not vary. These observations show that, although the interface—the zone where both polymers are mixed—grew, layers with pristine polymers remained even after prolonged processing time. The preservation of the PEEK crystallinity was also observed in the mechanical properties of the multilayer PEEK/PEI films, which were compared with pristine PEEK and PEI films. Multilayer samples processed for shorter times rendered higher young modulus, tensile strength, and strain at break.

Optimization of Processing Conditions and Mechanical Properties for PEEK/PEI Multilayered Blends

“…This reduction is due to the mixture of polymer chains that occurs at the interface, where PEI chains hinder the crystallization of PEEK. However, this effect is less pronounced at 350 C in comparison to that observed at 380 C in our previous research [ 33 ]. The part of the curve corresponding to the cooling ramp confirmed these observations, such as in the lower crystallization enthalpy (28.7 J/g for 120 min vs. 29.9 J/g s for 10 min) or in the small shifts observed in the glass transition.…”

“…Then, the limited interdiffusion of the PEEK/PEI layers was confirmed even after a long processing time. As this is a temperature-driven process, the interpenetration of polymer chains between these layers was much slower than that in our previous work at higher processing temperatures [ 33 ]. These results are in contrast to those obtained at around 400 C by other authors, where only one glass transition was observed in DMA tests due to the high degree of mixture induced on the PEEK/PEI blends at this processing temperature [ 12 , 40 ].…”

“…Depending on the processing conditions, MLP can lead to homogeneous blends, or, as in composite materials, polymer layers can be kept as separate phases. In a previous work [ 33 ], it was shown that this strategy allowed for the crystallinity of PEEK to be retained when a processing temperature of 380 C was used to obtain PEEK/PEI MLPs. At this temperature, there are two limitations: Firstly, PEI has a low viscosity and therefore easily undergoes excessive bleeding.…”

Multilayered Nanocomposites Prepared through Quadruple-Layering Approach towards Enhanced Mechanical Performance

“…The experiments indicated that as the time duration of hot-pressing increased, the bending displacement of the Al/Ni multilayered composite improved first and then declined sharply. Alvaredo-Atienza, et al [ 23 ] fabricated polyetheretherketone (PEEK)/polyetherimide (PEI) multilayered composites by alternating PEEK/PEI layer stacking to avoid the complete miscibility of both polymers, keeping PEEK layers and PEI layers un-mixed along the thickness direction, as well as accelerating the formation of a smooth interfacial layer between PEEK and PEI layers. The results revealed that although the interface between the two pristine polymers remained unchanged after the long processing time, the mechanical properties including the Young modulus, tensile strength, and strain at break of the PEEK/PEI multilayered films were improved compared to the original PEEK and PEI films.…”

Facile Preparation of Light‐Weight Polyetheretherketone/Graphite/FeCo Ternary Heterogeneous Composite Foam with High Compressive Strength and Excellent Integrated Electromagnetic Wave Absorption Performance

“…[35] Polyetheretherketone (PEEK) is the most successful polyaryl ether ketone resin developed so far, thanks to the combined advantages of ether bonds, ketone groups and aromatic groups along the macromolecular backbone, PEEK exhibits superior mechanical capabilities of especially impact toughness, high radiation resistance, and temperature resistance. [36,37] Therefore, PEEK possesses enough excellent properties to be the matrix of EMW absorbing materials. For the composition of the absorbent, the magnetic FeCo alloys are not only soft-magnetic materials with large saturation magnetization, obvious Snoek's limit, high magnetic anisotropy energies, and great coercivity, but also have a size of approximate 1 μm, which are similar to the pores of the PEEK foam, so that the FeCo alloys can completely occupy the pores of the PEEK foam to achieve relatively strong absorption capacity.…”