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. 2023 Feb 15;16(4):1608.
doi: 10.3390/ma16041608.

A Comparative Study of Different Poly (Lactic Acid) Bio-Composites Produced by Mechanical Alloying and Casting for Tribological Applications

Anzum Al Abir  1 , Bruno Trindade  1
Affiliations

A Comparative Study of Different Poly (Lactic Acid) Bio-Composites Produced by Mechanical Alloying and Casting for Tribological Applications

Anzum Al Abir et al. Materials (Basel). .

Abstract

The aim of this study was to fabricate different self-lubricating poly (lactic acid)-based bio-composites reinforced with mono- and multi-fillers of carbon fibers, graphene nanoparticles, and a soft Sn-based brazing alloy (Sn89-Zn8-Bi3) using a two-step process consisting of mechanical alloying followed by casting. The results showed that the incorporation of the different fillers on the PLA surface by mechanical alloying was quite homogenous. The volume ratio between the PLA and the fillers was 1:0.02, respectively. The PLA sample reinforced with short carbon fibers and graphene nanoparticles presented the highest hardness (84.5 Shore D, corresponding to a 10% increase compared to PLA) and the lowest specific wear rate (1.5 × 10-4 mm3/N·m, one order of magnitude lower than PLA). With regard to the coefficient of friction, the lowest value was obtained for the sample reinforced with graphene (0.43, corresponding to a decrease of 12% compared to PLA).

Keywords: PLA-based bio-composites; casting; friction; hardness; mechanical alloying; wear.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) Optical image of the PLA granules, and (b–f) SEM images of the GNP, SCF, Bi, Zn, and Sn raw materials, respectively.
Figure 2
Figure 2
XRD patterns of the raw materials used in this study. (a) PLA, (b) SCF, (c) GNP, and (d) MA’ed Sn89-Zn8-Bi3 mixture.
Figure 3
Figure 3
DSC curve of raw PLA.
Figure 4
Figure 4
SEM images of the Sn89-Zn8-Bi3 mixture after (a) 5 h, (b) 10 h, and (c) 25 h of MA.
Figure 5
Figure 5
(a) SEM image and (b–e) EDS analysis of the Sn89-Zn8-Bi3 mixture after 25 h of MA.
Figure 6
Figure 6
XRD patterns of the Sn89-Zn8-Bi3 mixture after 5, 10, and 25 h of MA.
Figure 7
Figure 7
(a) Optical micrographs of the PLA granules coated with GNP and Sn89-Zn8-Bi3, (b,c) SEM images of the PLA granules coated with GNP and SCF, and (d) EDS elemental maps of the PLA coated granules shown in (b,c).
Figure 8
Figure 8
(a) XRD peak deconvolution and (b) DSC results from the cast PLA.
Figure 9
Figure 9
FTIR results of the raw and cast PLA.
Figure 10
Figure 10
XRD patterns of the non-reinforced and reinforced cast PLA samples.
Figure 11
Figure 11
Shore D hardness of the non-reinforced and reinforced cast PLA samples.
Figure 12
Figure 12
(a) COF vs time curves of the PLA, PG, PA, and PSG samples and (b) the average COF values of non-reinforced and reinforced cast PLA samples.
Figure 13
Figure 13
Wear profiles and 3D scans of non-reinforced and reinforced cast PLA samples after the tribological tests.
Figure 14
Figure 14
Specific wear rates of the non-reinforced and reinforced cast PLA samples.
Figure 15
Figure 15
SEM images of the wear scars of the non-reinforced and reinforced cast PLA samples after the tribological tests.
Figure 16
Figure 16
Hardness versus specific wear rate and COF of the non-reinforced and reinforced cast PLA samples.
See this image and copyright information in PMC

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