Additive Processing of Polymers

Wendel, Bettina; Rietzel, Dominik; Kühnlein, Florian; Feulner, R.; Hülder, Gerrit; Schmachtenberg, Ernst

doi:10.1002/mame.200800121

Cited by 279 publications

(230 citation statements)

References 49 publications

(72 reference statements)

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“…The super-cooling window is the LS processing window defined based on the Differential Scanning Calorimetry (DSC) thermoscan of the powder under test [13], largely used in the LS community [14][15][16][17]. This window is defined as the temperature gap between the onset of the melting event and the onset of the crystallisation event.…”

Section: Super-cooling Windowmentioning

confidence: 99%

Predicting processing parameters in high temperature laser sintering (HT-LS) from powder properties

2016

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New materials for Laser Sintering (LS) are usually developed using a trial and-error approach that consists of a series of builds within LS systems. This strategy is time consuming, costly and focuses only on the optimisation of the processing parameters, ignoring the powder properties of the materials under examination. Being able to predict processing parameters on the basis of the powder material properties would enable a faster development of new materials and new applications, while acknowledging a more in-depth understanding of the mechanisms involved in LS. This paper provides new results into the prediction of processing conditions from the material properties. It is here shown that high temperature polymers such as Poly Ether Ether Ketone (PEEK) and Poly Aryl Ether Ketone (PEK) can be successfully used in LS despite the lack of a super-cooling window. The evaluation of the stable sintering region of PEEK 450PF and the application the energy melt ratio parameter in relation to the mechanical performance of laser sintered PEEK samples are also provided. Lastly, a new method for estimating the powder bed temperature is proposed.

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Section: Super-cooling Windowmentioning

confidence: 99%

Predicting processing parameters in high temperature laser sintering (HT-LS) from powder properties

2016

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“…According to the literature [1,13,27] an ideal polymeric candidate for LS has a DSC thermal scan where melting and crystallisation regions do not overlap, thus identifying a temperature range where the polymer can easily processed. This phenomenon is known as "Super-cooling window" and it is shown in Figure 7.…”

Section: Powder and Pellets Analysismentioning

confidence: 99%

“…A common approach in the LS community is also to recommend polymeric powders exhibiting a wide temperature operating window [1,13], i.e. a temperature interval between the onset temperatures of melting and crystallisation.…”

Section: Introductionmentioning

confidence: 99%

“…a temperature interval between the onset temperatures of melting and crystallisation. This window called "Super-cooling window" [13] is defined on the basis of the thermal properties of melting and crystallisation of the material under test in relation to the temperature at which the material is held during a LS building operation. If the LS processing temperature is lower than the material onset crystallisation temperature and therefore located outside the window, major and localised shrinkage will occur during and just after the laser exposure that, in turn, will lead to deleterious effects on the mechanical properties of the laser sintered parts.…”

Section: Introductionmentioning

confidence: 99%

“…If the LS processing temperature is lower than the material onset crystallisation temperature and therefore located outside the window, major and localised shrinkage will occur during and just after the laser exposure that, in turn, will lead to deleterious effects on the mechanical properties of the laser sintered parts. If the LS processing temperature is higher than the material onset melting temperature, therefore again outside this proposed window, uncontrolled melting will occur all across the powder bed without even the laser exposure [2,13,14]. Any LS processing temperature inside the window instead will lead to controlled and effective sintering without any undesired and detrimental thermal event in the powder.…”

Section: Introductionmentioning

confidence: 99%

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Polymer viscosity, particle coalescence and mechanical performance in high-temperature laser sintering

et al. 2016

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High Temperature Laser Sintering (HT-LS) is an additive manufacturing technology whose potential could be limited by the restricted number of materials optimised for the process. Poly Ether Ether Ketone (PEEK) with different melt viscosity values, PEEK 150PF and PEEK 450PF, have been used in parallel with the commercial grade, Poly Ether Ketone (PEK) HP3, to investigate the role of material viscosity on particle coalescence, parts structure and mechanical performance in HT-LS. The material with lower viscosity, PEEK 150PF, was found to exhibit faster coalescence and lower tensile strength than the grades with higher viscosities, PEEK 450PF and PEK HP3.

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Porous Polymer Monoliths by Emulsion Templating

Pulko

Krajnc

2017

Encyclopedia of Polymer Science and Technology

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Porous polymer monoliths (PPM) are an increasingly important and popular class of materials finding applications in fields such as separation, purification, cell and tissue culturing, storage of liquids and gases, energy storage, structural applications, supports for catalysts and reagents, etc. In contrast to particulate polymer material, monoliths are defined as intractable articles with a homogeneous microstructure. While the method of preparation and the chemical composition largely govern the resulting porous structure, the porous monoliths can be characterized by their pore size profile (micro‐, meso‐, macroporous material), morphology (interconnected or isolated pores, shape of pores), total porosity (pore volume), surface area, and special features, for example, hierarchical porous structure. Meso‐ and micropores mainly contribute to the total surface area of the monolith, whereas macropores, if interconnected, enable the convective mass transfer through the monolith and reduce the overall density of the material. Obtaining PPM with a multimodal pore size distribution is possible via a combination of methods or by a postpolymerization treatment. This is a useful feature allowing the production of materials with tailored porous structure for specific applications where macro‐ and micropores are needed. Generally, the methods for PPM preparation can be divided between templating (two phases are present during the preparation, of which one templates the porosity) and nontemplating (one phase system, eg, phase separation induces pores). This paper introduces the various methods and focuses on the emulsion templating approach. Recently introduced chemistries and combinations of methods as well as new examples of applications are highlighted.

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Additive Processing of Polymers

Cited by 279 publications

References 49 publications

Predicting processing parameters in high temperature laser sintering (HT-LS) from powder properties

Predicting processing parameters in high temperature laser sintering (HT-LS) from powder properties

Polymer viscosity, particle coalescence and mechanical performance in high-temperature laser sintering

Porous Polymer Monoliths by Emulsion Templating

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