High-performance co-polyesters for material-extrusion 3D printing: A molecular perspective of weld properties

Costanzo, Andrea; Cavallo, Dario; McIlroy, Claire

doi:10.1016/j.addma.2021.102474

Cited by 10 publications

(15 citation statements)

References 49 publications

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“…Once the glass transition temperature is reached, this diffusion/relaxation/re-entanglement process is arrested. This was captured in the model via a simple Williams–Landel–Ferry (WLF) dependence of the polymer relaxation times (Equation (2)), as in previous work [ 26 , 27 ],

where the shift factors C 1 and C 2 are obtained from time–temperature superposition as described above. At this point, we probed the state of the weld region (i.e., the surface of the deposited filament) via three molecular features: the degree of alignment, the degree of entanglement, and the degree of interdiffusion (not reported here).…”

Section: Discussionmentioning

confidence: 99%

“…The thickness of the adhesion surface between the adjacent layers, required to correctly evaluate the stress experienced by the sample, was measured using a stereoscope. Figures of the adopted geometry for mechanical testing are provided in previous works [ 26 , 27 ].…”

Section: Methodsmentioning

confidence: 99%

“…Lower printing temperatures limit the time interval above the glass transition temperature and consequently the diffusion of the chains. At the same time, high deposition rates generate greater shear stresses on the polymer melt, favouring the alignment of the chains in the direction of the nozzle movement [ 27 ]. Polymer molecular features, in particular the average molar mass and its distribution, can also affect the final properties of the products.…”

Section: Introductionmentioning

confidence: 99%

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The Role of Molar Mass in Achieving Isotropy and Inter-Layer Strength in Mat-Ex Printed Polylactic Acid

et al. 2022

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There has been extensive research in the field of material-extrusion (Mat-Ex) 3D printing to improve the inter-layer bonding process. Much research focusses on how various printing conditions may be detrimental to weld strength; many different feedstocks have been investigated along with various additives to improve strength. Surprisingly, there has been little attention directed toward how fundamental molecular properties of the feedstock, in particular the average molar mass of the polymer, may contribute to microstructure of the weld. Here we showed that weld strength increases with decreasing average molar mass, contrary to common observations in specimens processed in more traditional ways, e.g., by compression molding. Using a combination of synchrotron infra-red polarisation modulation microspectroscopy measurements and continuum modelling, we demonstrated how residual molecular anisotropy in the weld region leads to poor strength and how it can be eradicated by decreasing the relaxation time of the polymer. This is achieved more effectively by reducing the molar mass than by the usual approach of attempting to govern the temperature in this hard to control non-isothermal process. Thus, we propose that molar mass of the polymer feedstock should be considered as a key control parameter for achieving high weld strength in Mat-Ex.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Role of Molar Mass in Achieving Isotropy and Inter-Layer Strength in Mat-Ex Printed Polylactic Acid

et al. 2022

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“…Generally, fused deposition modeling (FDM) printable polymers must fulfill certain requirements regarding viscosity, surface energy, thermally induced shrinkage etc, allowing not all thermoplastics to be printed in this way [18]. On the other hand, since interdiffusion of neighboring strands in FDM and similar techniques necessitates crossing the glass transition temperature, it is clear that materials with higher glass temperature necessitate higher printing temperatures [19].…”

Section: Introductionmentioning

confidence: 99%

Investigating inexpensive polymeric 3D printed materials under extreme thermal conditions

Storck

Ehrmann²,

Uthoff

et al. 2022

Mater. Futures

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3D printing is nowadays used for many applications far beyond pure rapid prototyping. As tools to prepare custom-made objects which may be highly complex, different 3D printing techniques have emerged into areas of application where the mechanical, thermal, optical and other properties have to meet high requirements. Amongst them, applications for space, e.g. for microsatellites, make extreme demands regarding the stability under high temperatures. Nevertheless, polymeric 3D printed materials have several advantages for space application in comparison with metal objects. Here we thus investigate the impact of temperatures up to 85 °C and 185 °C, respectively, on typical 3D printing materials for fused deposition modeling (FDM) or stereolithography (SLA). The materials are found to differ strongly in terms of mechanical properties and dimensional stability after the treatment at higher temperature, with SLA resins and co-polyester (CPE) showing the best dimensional stability, while acrylonitrile-butadiene-styrene (ABS) and SLA resin after long UV post-treatment have the best mechanical properties.

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“…In another study, further high-temperature polymers were tested, such as polyetherimide (PEI) ULTEM 9085, PEI-modified ULTEM 1010, or poly(ether ketone ketone) (PEKK), and also found suitable for similar thermal conditions [ 24 ]. These materials, however, can only be printed in specialized, large, and expensive FDM printers, which are not as abundantly available as common FDM printers for more usual polymers [ 25 ]. For the latter, however, only a few reports exist on the mechanical and dimensional stability under thermal cycling or at elevated temperatures in general.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Low-Cost FDM-Printed Polymers for Elevated-Temperature Applications

Storck

Ehrmann²,

Güth

et al. 2022

Polymers

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While fused deposition modeling (FDM) and other relatively inexpensive 3D printing methods are nowadays used in many applications, the possible areas of using FDM-printed objects are still limited due to mechanical and thermal constraints. Applications for space, e.g., for microsatellites, are restricted by the usually insufficient heat resistance of the typical FDM printing materials. Printing high-temperature polymers, on the other hand, necessitates special FDM printers, which are not always available. Here, we show investigations of common polymers, processible on low-cost FDM printers, under elevated temperatures of up to 160 °C for single treatments. The polymers with the highest dimensional stability and mechanical properties after different temperature treatments were periodically heat-treated between -40 °C and +80 °C in cycles of 90 min, similar to the temperature cycles a microsatellite in the low Earth orbit (LEO) experiences. While none of the materials under investigation fully maintains its dimensions and mechanical properties, filled poly(lactic acid) (PLA) filaments were found most suitable for applications under these thermal conditions.

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High-performance co-polyesters for material-extrusion 3D printing: A molecular perspective of weld properties

Cited by 10 publications

References 49 publications

The Role of Molar Mass in Achieving Isotropy and Inter-Layer Strength in Mat-Ex Printed Polylactic Acid

The Role of Molar Mass in Achieving Isotropy and Inter-Layer Strength in Mat-Ex Printed Polylactic Acid

Investigating inexpensive polymeric 3D printed materials under extreme thermal conditions

Investigation of Low-Cost FDM-Printed Polymers for Elevated-Temperature Applications

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