Poly(ether ether ketone)‐bischromenes: Synthesis, characterization, and influence on thermal, mechanical, and thermo mechanical properties of epoxy resin

Abstract

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.

Toughening of Epoxy Systems with Interpenetrating Polymer Network (IPN): A Review

“…Toughening of epoxies with thermoplastics, studied since the early 1980s, has been considered to be an effective way to improve the toughness of epoxy resins without a significant decrease in desirable properties such as stiffness and strength, thermal stability, chemical and creep resistance, and processability [ 25 ]. Several thermoplastics have been studied to toughen epoxies such as polysulfone (PSF), poly(ether sulfone) (PES), poly(ether imide) (PEI), polyamides (PA), poly(ether ether ketone) (PEEK), poly(phthalazinone ether) [ 35 , 36 , 37 , 38 ]. The effect of several parameters have been investigated in literature such as (1) toughener content, (2) structure and molecular weight of toughener components, (3) type of curing agent for epoxy or (4) synthesis parameters, to study the resultant mechanical properties of the thermoplastic modified epoxy systems.…”

“…The fracture toughness measured at room temperature increased (from 50% to 63%) by increasing the content of PPO from 10 to 25 wt % ( Figure 4 a) [ 44 ]. Similarly, an increasing behavior of fracture toughness as a function of toughener content (i.e., PEEK-PR) was also observed, with the highest value of 33% increase in fracture toughness [ 38 ]. However, the highest fracture toughness (1.33 MPa·m 1/2 ) was observed by adding PEEK-TOH in the epoxy system, which was associated with its improved interaction with the epoxy resin via polar hydroxyl groups ( Figure 4 b) [ 38 ].…”

“…Similarly, an increasing behavior of fracture toughness as a function of toughener content (i.e., PEEK-PR) was also observed, with the highest value of 33% increase in fracture toughness [ 38 ]. However, the highest fracture toughness (1.33 MPa·m 1/2 ) was observed by adding PEEK-TOH in the epoxy system, which was associated with its improved interaction with the epoxy resin via polar hydroxyl groups ( Figure 4 b) [ 38 ]. Likewise, polymethyl methracrylate (PMMA) and polycarbonate (PC) were reported to use as toughening agents for epoxy resin [ 45 ].…”

“…In summary, the effect of several parameters on the mechanical properties (i.e., fracture toughness and impact strength) of the toughened epoxy system has been investigated in literature. The increase in toughener content typically lead towards the gradual increase in fracture toughness of epoxy resin, which is attributed to the formation of IPN structure and phase separated morphologies [ 23 , 38 , 44 ]. However, beyond a certain concentration of toughener, the fracture toughness of modified epoxy system tends to reach a plateau, which is associated to the fact that there is no further interactions between the epoxy and toughener [ 11 ].…”

Facile strategy and mechanism of greatly toughening epoxy resin using polyethersulfone through controlling phase separation with microwave‐assisted thermal curing technique

“…However, TRRs generally have poor toughness due to highly crosslinked structure . In order to improve toughness without degrading heat resistance of TRRs, engineering thermoplastics with good heat resistance, such as polyethersulfone (PES), polysulfone, polyetheretherketone, and polyetherimide have been utilized to toughen thermosetting resins, and many valuable achievements in theoretic and industrial aspects have been obtained.…”