Dataset Information

Manufacturing and Characterization of Highly Environmentally Friendly Sandwich Composites from Polylactide Cores and Flax-Polylactide Faces.

ABSTRACT: This work focuses on the manufacturing and characterization of highly environmentally friendly lightweight sandwich structures based on polylactide (PLA) honeycomb cores and PLA-flax fabric laminate skins or facings. PLA honeycombs were manufactured using PLA sheets with different thicknesses ranging from 50 to 500 ?m. The PLA sheets were shaped into semi-hexagonal profiles by hot-compression molding. After this stage, the different semi-hexagonal sheets were bonded together to give hexagonal panels. The skins were manufactured by hot-compression molding by stacking two Biotex flax/PLA fabrics with 40 wt% PLA fibers. The combined use of temperature (200 °C), pressure, and time (2 min) allowed PLA fibers to melt, flow, and fully embed the flax fabrics, thus leading to thin composite laminates to be used as skins. Sandwich structures were finally obtained by bonding the PLA honeycomb core with the PLA-flax skins using an epoxy adhesive. A thin PLA nonwoven was previously attached to the external hexagonal PLA core, to promote mechanical interlock between the core and the skins. The influence of the honeycomb core thickness on the final flexural and compression properties was analyzed. The obtained results indicate that the core thickness has a great influence on the flexural properties, which increases with core thickness; nevertheless, as expected, the bonding between the PLA honeycomb core and the skins is critical. Excellent results have been obtained with 10 and 20 mm thickness honeycombs with a core shear of about 0.60 and facing bending stresses of 31-33 MPa, which can be considered as candidates for technical applications. The ultimate load to the sample weight ratio reached values of 141.5 N·g^-1 for composites with 20 mm thick PLA honeycombs, which is comparable to other technical composite sandwich structures. The bonding between the core and the skins is critical as poor adhesion does not allow load transfer and, while the procedure showed in this research gives interesting results, new developments are necessary to obtain standard properties on sandwich structures.

SUBMITTER: Lascano D

PROVIDER: S-EPMC7865247 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Manufacturing and Characterization of Highly Environmentally Friendly Sandwich Composites from Polylactide Cores and Flax-Polylactide Faces.

Lascano Diego D Guillen-Pineda Rene R Quiles-Carrillo Luis L Ivorra-Martínez Juan J Balart Rafael R Montanes Nestor N Boronat Teodomiro T

Polymers 20210121 3

This work focuses on the manufacturing and characterization of highly environmentally friendly lightweight sandwich structures based on polylactide (PLA) honeycomb cores and PLA-flax fabric laminate skins or facings. PLA honeycombs were manufactured using PLA sheets with different thicknesses ranging from 50 to 500 μm. The PLA sheets were shaped into semi-hexagonal profiles by hot-compression molding. After this stage, the different semi-hexagonal sheets were bonded together to give hexagonal pa ...[more]

PMID: 33494547

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Project description:Polylactide (PLA) materials treated with antimicrobial fillers represent a suitable alternative to the production of medical devices. Their advantage is that they can prevent the growth of microorganisms and the formation of microbial biofilms on the surface and around composites. The work is focused on the evaluation of biocompatibility and biocide effect of PLA composite films filled with vermiculite and graphene oxide modified with silver (Ag+ and Ag nanoparticles), hexadecylpyridinium (HDP) and hexadecyltrimethylammonium (HDTMA) cations and their degradation leachates monitored at 1-3-6-month intervals. The antimicrobial effect of the leachates was detected by microdilution methods on gram-negative (Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis), gram-positive (Staphylococcus aureus, Streptococcus salivarius) bacteria and yeast (Candida albicans). The biocidal effect of composites on biofilm formation on the surface of composites was monitored by Christensen method and autoaggregation and motility tests. The biocompatibility of the composite and the leachates was assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) cytotoxicity assay. The evaluation of the antimicrobial effect of the leachates demonstrated that leachates of PLA composite filled with graphene oxide and Ag+ showed a stronger antimicrobial effect than leachates of PLA composite filled with vermiculite and Ag+ and Ag nanoparticles. The leachates of PLA composites containing vermiculite with HDP and HDTMA cations had a higher antimicrobial effect on G+ bacteria and yeast than G- bacteria. Bacterial growth, biofilm formation, autoaggregation and motility of the tested bacteria were most inhibited by the composite with vermiculite and Ag+ and Ag nanoparticles. Even after a 6-month degradation of this composite, bacterial growth and biofilm formation continued to be strongly inhibited up to 42 and 91%, respectively. The cytotoxic effect was proved only in the leachate of the composite with vermiculite containing HDP after 6 months of its degradation. Tests evaluating the biocompatibility of materials have shown that the vermiculite is the most preferred carrier and can be used in the future to bind other compounds. The study confirmed that PLA composite filled with vermiculite and Ag+ and Ag nanoparticles was the most stable and effective composite with the best biocompatible and biocidal properties.

Dataset Information

Manufacturing and Characterization of Highly Environmentally Friendly Sandwich Composites from Polylactide Cores and Flax-Polylactide Faces.

Publications

Manufacturing and Characterization of Highly Environmentally Friendly Sandwich Composites from Polylactide Cores and Flax-Polylactide Faces.

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