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. 2021 Mar 6;13(5):810.
doi: 10.3390/polym13050810.

Polyamide 12 Materials Study of Morpho-Structural Changes during Laser Sintering of 3D Printing

Gražyna Simha Martynková  1   2 , Aleš Slíva  3 , Gabriela Kratošová  1 , Karla Čech Barabaszová  1 , Soňa Študentová  4 , Jan Klusák  4 , Silvie Brožová  5 , Tomáš Dokoupil  6 , Sylva Holešová  1
Affiliations

Polyamide 12 Materials Study of Morpho-Structural Changes during Laser Sintering of 3D Printing

Gražyna Simha Martynková et al. Polymers (Basel). .

Abstract

The polyamide (PA)-12 material used for additive manufacturing was studied in aspects of morphology and their structural properties for basic stages received during 3D laser printing. Samples were real, big-scale production powders. The structure of polymer was evaluated from the crystallinity point of view using XRD, FTIR, and DSC methods and from the surface properties using specific surface evaluation and porosity. Scanning electron microscopy was used to observe morphology of the surface and evaluate the particle size and shape via image analysis. Results were confronted with laser diffraction particles size measurement along with an evaluation of the specific surface area. Fresh PA12 powder was found as inhomogeneous in particle size of material with defective particles, relatively high specific surface, high lamellar crystallite size, and low crystallinity. The scrap PA12 crystallinity was about 2% higher than values for fresh PA12 powder. Particles had a very low, below 1 m2/g, specific surface area; particles sintered as twin particles and often in polyhedral shapes.

Keywords: 3D print; PA12; morphology; structure.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Scanning electron microscopy (SEM) images of experimental samples (a) fresh polyamide (PA)-12 and detail of crack; (b) scrap PA12 and crack detail with melted bridges on the edge of crack in detail; (c) recycled PA12 particle with observed polyhedrons and (d) renewed with detail sample. Images captured at 25 kV in COMPO mode. This is a figure. Schemes follow the same formatting.
Figure 1
Figure 1
Scanning electron microscopy (SEM) images of experimental samples (a) fresh polyamide (PA)-12 and detail of crack; (b) scrap PA12 and crack detail with melted bridges on the edge of crack in detail; (c) recycled PA12 particle with observed polyhedrons and (d) renewed with detail sample. Images captured at 25 kV in COMPO mode. This is a figure. Schemes follow the same formatting.
Figure 2
Figure 2
Log-normal (a) and cumulative (b) particles size distribution (PSD) of experimental samples. The mode diameter (dm) values are noted in the graph.
Figure 3
Figure 3
Example SEM image of analyzed material. Particle size image analysis, where all shapes are approximated as round circle-equivalent or oval.
Figure 4
Figure 4
Example of normal probability plots for fresh PA12 sample (a) width; (b) length measurement.
Figure 5
Figure 5
X-ray diffraction (XRD) patterns of all studied samples in range 3–45° 2Θ with evaluated α and γ phases of polyamide 12 and detail of studied main γ-PA diffractions in range 18–25° 2Θ.
Figure 6
Figure 6
Charts explaining the tendency of selected calculated and measured parameters of material structure of samples with demonstration of lamellar structure ordering of PA12 regarding mean crystallite size Lc.
Figure 7
Figure 7
Fourier transform infrared (FTIR) spectra of PA 12 samples: fresh PA 12, scrap PA 12, recycled PA 12, and renewed PA 12.
Figure 8
Figure 8
DSC thermograms of PA12 samples: fresh PA12, scrap PA12, recycled PA12, and renewed PA12.
See this image and copyright information in PMC

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