Increased strength in carbon-poly(ether ether ketone) composites from material extrusion with rapid microwave post processing

Ai, Jia-Ruey; Liu, Siyuan; Vogt, Bryan D.

doi:10.1016/j.addma.2022.103209

Cited by 8 publications

(9 citation statements)

References 65 publications

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“…An initial interpretation for this phenomenon was densification of the long-annealed monoliths due to an increasing crystallinity. Thermal annealing is often utilized to increase the crystallinity of polymers to augment mechanical strength. ,− Furthermore, crystalline regions are inherently denser than amorphous polymer due to the close packing of chains on a crystalline lattice . The use of an annealing temperature very close to the PEEK melting temperature ( T m ≈ 343 °C) should primarily promote the growth of spherulites, supporting the densification of the sample through increased crystallinity as the source of the contraction.…”

Section: Resultsmentioning

confidence: 99%

Multiple Molecular-Level Processes in the Evolution of Residual Strain in 3D Printed Poly(ether ether ketone)

Riggins,

Dadmun

2024

ACS Appl. Polym. Mater.

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The processing that occurs during material extrusion (ME) 3D printing imparts residual stress in printed parts, which is released during annealing and manifests as an irreversible thermal strain. Our group seeks material-based solutions that control the release of residual stress through molecular-level processes, decrease the magnitude of observed strain, and produce structures that can be annealed without loss of structural fidelity. This work describes an examination of the release of residual stress in 3D printed monoliths made from poly(ether ether ketone) (PEEK) filaments using nanographene sheets as an additive, in situ illumination with an appropriate wavelength light source, and thermal annealing close to the melting temperature. The extent of strain release of the PEEK monoliths is far suppressed relative to that of those made from poly(lactic acid) for all formulations. Moreover, there is a consistent pattern of a transition from positive-to-negative residual strains with annealing time that is independent of the annealing temperature and material formulation. This is interpreted to indicate that multiple competing processes drive the development of residual stress in the ME-printed PEEK samples. Short time relaxation of molecular alignment compels macroscopic expansion, while increased polymer crystallization at longer times forces macroscopic contraction due to densification. These results, therefore, provide crucial insight into molecular-level processes that guide macroscopic structural changes and will inform the development of PEEK annealing protocols to form robust structures by ME without sacrificing structural integrity.

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Section: Resultsmentioning

confidence: 99%

Multiple Molecular-Level Processes in the Evolution of Residual Strain in 3D Printed Poly(ether ether ketone)

Riggins,

Dadmun

2024

ACS Appl. Polym. Mater.

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“…In particular, Joule heating is typically conducted under a processing timescale similar to RTA, 100 suggesting that systematic investigations with RTA can inform the appropriate ramp rate and soaking temperature with different atmospheres. As another example with similar temperature profiles to RTA, microwave heating with high heating rates has been used for polymer synthesis, 101 pyrolysis, 102,103 self-assembly, [104][105][106][107] and additive manufacturing, [108][109][110] where there are material-specific responses to microwaves that RTA cannot simulate. We note that photothermal annealing is usually performed in much shorter timescales (ms), but the chemistry and characterization developed for RTA may inspire further tuning of materials and processing conditions.…”

Section: Synergy With Other Flash Heating Processing Methodsmentioning

confidence: 99%

Recent advances and emerging opportunities in rapid thermal annealing (RTA) of polymers

Katsumata

Senger

Pagaduan

2023

Mol. Syst. Des. Eng.

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“…It absorbed more microwave radiation, causing the majority of the crystals to melt, which reduced the melt strength and increased the average size of the pores. 27 Moreover, with a further increase in irradiation power, the compression modulus of TBC-100 continued to increase (2.9 MPa). This phenomenon was probable due to the collapse of pore structure due to the very low viscosity of TBC at 100% power, where the thickened wall originated from the collapse of the adjacent bubble, resulting in a condensing of the final foam materials.…”

Section: Mechanical Properties Of Tbc Composite Foamsmentioning

confidence: 95%

Microwave-Induced Construction of Flame-Retardant TPU Foams with Adjustable Sensitivity for Piezoresistive Sensing

Tang,

Han,

Xia

et al. 2024

Ind. Eng. Chem. Res.

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CNTs feature ultrahigh electrical conductivity and multiwall structure, contributing to the favorable interaction with microwaves, and accordingly evoke drastic energy conversion to the form of heat upon microwave irradiation. Herein, CNTs were ball milling assembled at the surface of expandable thermoplastic polyurethane/black phosphorus (e-TPU/ BP) beads, where BP was used as a flame retardant, and served as the "interfacial sensitizer", resulting in exceptional selective heating to inducing bubble formation in a continuous conductive network of TBC composite foams under the microwave field setting. The sinter-molded TBC composite foam possesses a high sensitivity of 550 kPa −1 over 0−0.4 MPa of compressive stress with an ultralow CNT content of 0.5 wt %, stability of over 1000 cycles, and durability of 5000 s. Moreover, BP also provided excellent flame retardant and antidripping properties at 2 wt % loading. Therefore, by utilizing the intense response of CNTs to microwaves, a universal approach was developed not only for foam molding but also for the functionalization of thermoplastic materials.

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Increased strength in carbon-poly(ether ether ketone) composites from material extrusion with rapid microwave post processing

Cited by 8 publications

References 65 publications

Multiple Molecular-Level Processes in the Evolution of Residual Strain in 3D Printed Poly(ether ether ketone)

Multiple Molecular-Level Processes in the Evolution of Residual Strain in 3D Printed Poly(ether ether ketone)

Recent advances and emerging opportunities in rapid thermal annealing (RTA) of polymers

Microwave-Induced Construction of Flame-Retardant TPU Foams with Adjustable Sensitivity for Piezoresistive Sensing

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