Polyaryletherketone Based Blends: A Review

This review aims to report the status of the research on polyaryletherketone-based thermoplastic blends (PAEK). PAEK are high-performance copolymers able to replace metals in many applications including those related to the environmental and energy transition. PAEK lead to the extension of high-performance multifunctional materials to target embedded electronics, robotics, aerospace, medical devices and prostheses. Blending PAEK with other thermostable thermoplastic polymers is a viable option to obtain materials with new affordable properties. First, this study investigates the miscibility of each couple. Due to different types of interactions, PAEK-based thermoplastic blends go from fully miscible (with some polyetherimides) to immiscible (with polytetrafluoroethylene). Depending on the ether-to-ketone ratio of PAEK as well as the nature of the second component, a large range of crystalline structures and blend morphologies are reported. The PAEK-based thermoplastic blends are elaborated by melt-mixing or solution blending. Then, the effect of the composition and blending preparation on the mechanical properties are investigated. PAEK-based thermoplastic blends give rise to the possibility of tuning their properties to design novel materials. However, we demonstrate hereby that significant research effort is needed to overcome the lack of knowledge on the structure/morphology/property relationships for those types of high-performance thermoplastic blends.

Influence of dodecyl surfactants on the cross-linking, plasticization and damping behavior of epoxy novolac resins

A series of modified epoxy novolac resins (ENRs) were prepared by incorporating dodecyl chain surfactants with polar groups such as amine, carboxylic acid, phenol, resorcinol and benzene sulfonic acid. Except for the case of benzene sulfonic acid, no macrophase separation is seen in any of the modified ENRs. The addition of these dodecyl surfactants to ENR hinders the cross-linking reaction as revealed from their dynamic and isothermal DSC curing measurements and reduced glass transition temperatures (T_g). The cross-link density evaluated from the storage modulus (E') in the rubbery region using DMTA measurements is found to be low with the addition of surfactants in agreement with their plasticization behavior. The stiffness of the materials obtained at low temperatures showed a moderate increase for ENRs with carboxylic acid and phenol surfactants. Upon heating, their storage modulus drops at low temperatures compared to ENR supporting the mechanism of plasticization in them. This high value of E' for the plasticized material in the glassy phase is different from the generally known behavior. Such unusually high storage modulus together with increased 'd' spacing from the XRD results seems to indicate 'partial segmental confinement' of epoxy chains. It is believed that high damping obtained in these two materials is due to 'partial segmental confinement' of epoxy chains because of interaction with lauric acid and phenolic surfactants and the associated internal and interfacial friction in them. Dielectric relaxation measurements support the plasticization process based on the high dielectric loss and ionic conductivity in the surfactant modified ENR, as compared to the pristine ones.

The effect of an organophosphonite antioxidant on poly(ether ether ketone)/poly(ether imide) blend as studied by quasi-isothermal modulated differential scanning calorimetry and dynamic mechanical thermal analysis methods

In the present study, the effect of P-EPQ, an organophosphonite antioxidant, on the glass transition and the viscoelastic behavior of optimized poly(ether ether ketone) (PEEK)/poly(ether imide) (PEI; PEEK/PEI: 50/50) blend has been reported. For this, P-EPQ was added in various proportions to the PEEK/PEI blend and was studied by quasi-isothermal modulated differential scanning calorimetry (Qi-MDSC) and dynamic mechanical thermal analysis (DMTA) methods. The Qi-MDSC results clearly indicate a significant decrease in the glass transition temperature of the blend up to 1 wt% P-EPQ addition. The DMTA measurements revealed a decrease in tan δ peak temperature upon antioxidant addition in agreement with calorimetric results. The shift factors obtained using the time–temperature superposition of DMTA data exhibit Williams–Landel–Ferry behavior, and the fractional free volume of the blend increases with increase in antioxidant addition (up to 1 wt%). The “master curve” of storage modulus predicts high modulus for the blend with 1 wt% antioxidant, revealing its suitability for high-impact applications.