High‐performance and cost‐effective melt blended poly(ether ether ketone)/expanded graphite composites for mass production of antistatic materials

Mokhtari, Mozaffar; Archer, Edward; Bloomfield, Noel; Harkin‐Jones, Eileen; McIlhagger, Alistair

doi:10.1002/pi.6226

Cited by 16 publications

(5 citation statements)

References 80 publications

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“…These processes result in a thermally stable carbonaceous char. Neat PEEK presents high amounts of char residues (~51 wt.%) after thermal degradation, consistent with other studies [28,[59][60][61].…”

Section: Thermal Stabilitysupporting

confidence: 91%

High-Performance PEEK/MWCNT Nanocomposites: Combining Enhanced Electrical Conductivity and Nanotube Dispersion

Silva,

Barbosa,

Sousa

et al. 2024

Polymers

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High-performance engineering thermoplastics offer lightweight and excellent mechanical performance in a wide temperature range. Their composites with carbon nanotubes are expected to enhance mechanical performance, while providing thermal and electrical conductivity. These are interesting attributes that may endow additional functionalities to the nanocomposites. The present work investigates the optimal conditions to prepare polyether ether ketone (PEEK)/multi-walled carbon nanotube (MWCNT) nanocomposites, minimizing the MWCNT agglomerate size while maximizing the nanocomposite electrical conductivity. The aim is to achieve PEEK/MWCNT nanocomposites that are suitable for melt-spinning of electrically conductive multifilament’s. Nanocomposites were prepared with compositions ranging from 0.5 to 7 wt.% MWCNT, showing an electrical percolation threshold between 1 and 2 wt.% MWCNT (107–102 S/cm) and a rheological percolation in the same range (1 to 2 wt.% MWCNT), confirming the formation of an MWCNT network in the nanocomposite. Considering the large drop in electrical conductivity typically observed during melt-spinning and the drawing of filaments, the composition PEEK/5 wt.% MWCNT was selected for further investigation. The effect of the melt extrusion parameters, namely screw speed, temperature, and throughput, was studied by evaluating the morphology of MWCNT agglomerates, the nanocomposite rheology, and electrical properties. It was observed that the combination of the higher values of screw speed and temperature profile leads to the smaller number of MWCNT agglomerates with smaller size, albeit at a slightly lower electrical conductivity. Generally, all processing conditions tested yielded nanocomposites with electrical conductivity in the range of 0.50–0.85 S/cm. The nanocomposite processed at higher temperature and screw speed presented the lowest value of elastic modulus, perhaps owing to higher matrix degradation and lower connectivity between the agglomerates. From all the process parameters studied, the screw speed was identified to have the higher impact on nanocomposite properties.

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Section: Thermal Stabilitysupporting

confidence: 91%

High-Performance PEEK/MWCNT Nanocomposites: Combining Enhanced Electrical Conductivity and Nanotube Dispersion

Silva,

Barbosa,

Sousa

et al. 2024

Polymers

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“…The melt compounding of the mixtures was accomplished in a co-rotating twin-screw extruder (Rheomex PTW16/40 OS) with a diameter of 16 mm and L/D 40 operating at a barrel to die temperature range from 365 to 385°C and screw speed of 45 rpm. As explained in previous work, reverse and kneading mixing elements were utilised in an inhouse screw configuration to improve the distribution and dispersion of the EG platelets in the PEEK (Mokhtari et al, 2021).…”

Section: Preparation Of Compositesmentioning

confidence: 99%

Melt-Blended Multifunctional PEEK/Expanded Graphite Composites

et al. 2021

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In this work, antistatic, high-performance composites of poly (ether ether ketone) (PEEK) and concentrations of 0.5–7 vol% expanded graphite (EG) were fabricated via twin-screw extrusion and injection moulding at mould temperatures of 200°C. The morphological, electrical, rheological, thermal, mechanical, and wear properties of the composites were investigated. Scanning electron microscope (SEM) images indicate that distribution and dispersion of EG platelets in the PEEK matrix are enhanced at higher EG loadings. The electrical conductivity of the composites with 5 vol% of EG exhibits a sharp rise in the electrical conductivity range of antistatic materials because of the formation of conductive paths. The formation of a three-dimensional EG network led to a rapid increase in the storage modulus of the melt of the 2 vol% of EG-loaded composite at a frequency of 0.1 rad/s and temperature of 370°C. The neat PEEK and composites containing 0.5–5 vol% EG indicated a cold-crystallisation peak in the first heating scan of a non-isothermal differential scan calorimetry (DSC) test and their crystallinity degrees changed slightly. However, after removing their thermal and stress histories, the EG platelets promoted nucleation and increased the PEEK crystallinity remarkably, indicating that annealing of the PEEK composites can improve their mechanical performance. The neat PEEK exhibits the standard tensile and flexural stress-strain behaviour of thermoplastics, and the composites exhibit elastic behaviour initially followed by a weak plastic deformation before fracture. The addition of 5 vol% of EG to PEEK increased the tensile and flexural modulus from 3.84 and 3.55 GPa to 4.15 and 4.40 GPa, decreased the strength from 96.73 and 156.41 MPa to 62 and 118.19 MPa, and the elongation at break from 27.09 and 12.9% to 4 and 4.6%, respectively. The wear resistance of the composite containing 3 vol% EG was enhanced by 37% compared with the neat PEEK.

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“…This is in contrast to microcompounding (melt−blending), where large shear forces during the compounding process can exfoliate expanded graphite, converting it into a nanoplatelet−like morphology. Mokhtari et al [ 68 ] discussed such exfoliation of expanded graphite through microcompounding.…”

Section: Resultsmentioning

confidence: 99%

Large Enhancement in Thermal Conductivity of Solvent−Cast Expanded Graphite/Polyetherimide Composites

et al. 2022

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We demonstrate in this work that expanded graphite (EG) can lead to a very large enhancement in thermal conductivity of polyetherimide−graphene and epoxy−graphene nanocomposites prepared via solvent casting technique. A k value of 6.6 W⋅m−1⋅K−1 is achieved for 10 wt% composition sample, representing an enhancement of ~2770% over pristine polyetherimide (k~0.23 W⋅m−1⋅K−1). This extraordinary enhancement in thermal conductivity is shown to be due to a network of continuous graphene sheets over long−length scales, resulting in low thermal contact resistance at bends/turns due to the graphene sheets being covalently bonded at such junctions. Solvent casting offers the advantage of preserving the porous structure of expanded graphite in the composite, resulting in the above highly thermally conductive interpenetrating network of graphene and polymer. Solvent casting also does not break down the expanded graphite particles due to minimal forces involved, allowing for efficient heat transfer over long−length scales, further enhancing overall composite thermal conductivity. Comparisons with a recently introduced effective medium model show a very high value of predicted particle–particle interfacial conductance, providing evidence for efficient interfacial thermal transport in expanded graphite composites. Field emission environmental scanning electron microscopy (FE−ESEM) is used to provide a detailed understanding of the interpenetrating graphene−polymer structure in the expanded graphite composite. These results open up novel avenues for achieving high thermal conductivity polymer composites.

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High‐performance and cost‐effective melt blended poly(ether ether ketone)/expanded graphite composites for mass production of antistatic materials

Cited by 16 publications

References 80 publications

High-Performance PEEK/MWCNT Nanocomposites: Combining Enhanced Electrical Conductivity and Nanotube Dispersion

High-Performance PEEK/MWCNT Nanocomposites: Combining Enhanced Electrical Conductivity and Nanotube Dispersion

Melt-Blended Multifunctional PEEK/Expanded Graphite Composites

Large Enhancement in Thermal Conductivity of Solvent−Cast Expanded Graphite/Polyetherimide Composites

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