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Poly(ether ether ketone) s with terminal propargyl groups (PEEK‐PR) were synthesized from hydroxyl terminated PEEK (PEEKTOH) and characterized. The heat‐triggered polymerization of PEEK‐PR to poly bischromenes having PEEK backbone was confirmed by Fourier transform infrared spectroscopy and differential scanning calorimetric studies. PEEK‐PR was blended with a bisphenol based epoxy resin‐diamino diphenylsulphone system in different proportions and cured to form PEEK‐bischromene‐interpenetrated‐epoxy‐amine networks. Tensile strength and elongation of the cured blends increased up to 10‐phr loading of PEEK‐PR and then declined. Tensile moduli of all formulations were comparable. Fracture toughness increased by a maximum of 33%, and the fractured surface morphology showed a ductile fracture. The blends exhibited slightly lower glass transition temperature to that of the neat epoxy‐amine system. A reference sample of epoxy‐amine was processed with the optimum loading of the precursor polymer, PEEKTOH, and compared its properties with the PEEK‐PR incorporated epoxy systems. In this way, it is found that the incorporation of addition curable propargylated PEEK increases the strength characteristics with adequate thermal stability and fracture toughness for high‐performance structural applications.

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Zinc oxide tetrapod whiskers (T-ZnO) with uniform morphology were processed by thermal evaporation and condensation technique. This was used as filler in epoxy matrix resins to formulate room temperature curable, thermally conducting and high-strength composite adhesive systems. Adhesive compositions with varying extend of T-ZnOs were processed and cured using an ambient temperature curable amine hardener. Adhesive formulations which contain the same extent of conventional irregularly shaped zinc oxide particles were also processed for comparison. Various formulations were evaluated for lap shear strength (LSS), thermal conductivity and morphological examinations. Epoxy-TZnO-based adhesive formulations exhibited higher lap shear strength and thermal conductivity compared to their conventional zinc oxide-based counterparts. Thus, an optimized epoxy-TZnO formulation exhibited 42% improvement in LSS and 77% in thermal conductivity than their zinc oxide counterparts. Fracture morphology revealed a rough texture and uniform distribution of T-ZnO in the epoxy resin system.

Poly Ether Ether Ketone (PEEK) is a very promising engineering thermoplastic material having capability to perform over wide service temperatures from cryogenic to around 300°C. Processing of PEEK is a challenging task, owing to its physical, thermo physical properties and chemical nature. The present paper envisages processing of PEEK by two different techniques viz, 3D printing and extrusion and assessment of properties of respective specimens at 30°C and −196°C. Thermal and mechanical properties and fracture morphological features of PEEK specimen, processed using these techniques are compared. Samples processed by extrusion possessed higher mechanical properties both at 30°C and −196°C. The 3D printed samples, though exhibited inferior strength and modulus, showed significantly higher elongation (150–250%) at 30°C. All samples showed ductile fracture behavior at 30°C. At −196°C, the fracture morphology got transformed in to a pattern typical of brittle materials, as expected. Extruded specimens showed lower thermal expansion coefficient compared to the 3D printed specimens. Thermal expansion characteristics were different in the X, Y and Z directions for 3D printed specimens due to the anisotropy resulting from printing direction which is corroborated by the morphological studies. The results of this investigation enable designing and fabrication of PEEK based structural components of desired geometries for various applications.