Effect of Colorants and Process Parameters on the Properties of Dope-Dyed Polylactic Acid Multifilament Yarns

Sustainability in the Development of Natural Pigment-Based Colour Masterbatches and Their Application in Biopolymers

This article is focused on the development and characterization of a series of biodegradable and eco-friendly colour masterbatches (MBs), based on natural pigments and biodegradable polylactic acid (PLA) and polybutylene succinate (PBS). Four commercial natural pigments were used, spirulina, curcumin, beetroot and chlorophyllin, to develop the colour masterbatches using a twin-screw extruder. The natural pigment-based MBs were added at 2, 4 and 6 wt%, as additives to study the effect on the properties of injected biodegradable parts (PLA and PBS). The injected samples were characterized in terms of their mechanical (tensile and Charpy impact tests) and visual properties (according to CieLab). In addition, the ageing of the coloured material was followed by colorimetric analysis after its exposure under a Xenon lamp. The mechanical results showed that the addition of coloured masterbatches in different percentages (2-6 wt%) did not significantly change the properties of the materials with respect to the as-received ones. A noticeable colour difference in the injected samples was observed after the first 50 h of artificial light exposure. Regarding environmental concerns, the study showed that the carbon footprint of natural pigments and electricity consumption during extrusion and pelletizing were lower.

Hydrophilic Modification of Polylactic Acid Fiber and the Usage of Natural Dye for Multi-Levered Improvement of the Fabric Staining Depth and the Stability Effect

Polylactic acid (PLA) fiber is a degradable material with good environmental friendliness for textile applications. However, the main problems of difficult dyeing of PLA fibers were: high crystallinity to the adsorption of dyes, more ester and methyl groups producing non-hydrophilic problems, long chains making dyes difficult to penetrate, and producing a low dyeing rate. Here, we attempted to change the crystallinity of the PLA fiber to a lower degree from hydrophobic to hydrophilicity property variation, destroy the long chain structure to grant more staining sites, and improve the PLA fiber staining depth and the resilience dyeing effect with deep eutectic solvent (DES) treatment and natural dyes. We discovered that a controlled DES treatment process could make PLA fibers less crystallized, help amorphous areas form, and break up long chains, which lead to more dye sites. After DES treatment, the crystallinity decreased from 56.12 to 29.86%, and the instantaneous water contact angle decreased from 108.79 to 64.39°. The DES-treated PLA fabric exhibited a higher K/S value of 15.14 for natural dyes under specific conditions. The fabric, which had remarkable fastness characteristics and wash resistance, could endure frequent laundering and fulfill the demands of everyday use. Moreover, the fabric had good antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans and possessed a certain level of biocompatibility with fibroblasts. This DES treatment and natural dye combination method offered a new strategy for improving PLA fabric staining depth and color fastness, making it a promising option for low-carbon environmental protection in the textile industry.

Experimental and Numerical Study of Printing Strategy Impact on the Mechanical Properties of Sustainable PLA Materials

This article is focused on a mechanical properties investigation of three types of sustainable poly lactic acid materials manufactured using the fused filament fabrication process. The purpose of this work was to study the impact of printing strategies on the mechanical properties and predict mechanical behavior under tensile loading using finite element analysis. The testing of mechanical properties was conducted according to the ISO 527 standard. The numerical simulations were conducted in Simufact Forming 2022 software. Analysis of the experimental data showed a dependance of mechanical properties on the used printing strategy. The Clear PLA samples printed in the XY plane exhibited a 43% reduction in tensile strength and a 49% reduction in elongation compared to samples printed from the same material in YZ plane. The experimental results show the influence of the printing orientation on the mechanical properties of 3D-printed samples.

Dye-Doped Polymeric Microplastics: Light Tools for Bioimaging in Test Organisms

Ecosystems around the world are experiencing a major environmental impact from microplastic particles (MPs 0.1 µm-1 mm). Water, sediments, and aquatic biota show the widespread presence of this pollutant. However, MPs are rarely used in laboratory studies as they are scarcely available for purchase or expensive, especially if one wishes to trace the particle with a dye or fluorescent. Furthermore, existing preparation techniques have limited application in biological studies. In this work, we propose a new, easy, and cheap way to prepare fluorescent MPs. The protocol is based on the osmosis method in order to obtain spherical polymeric particles of P(S-co-MMA), with 0.7-9 micron diameter, made fluorescent because dye-doped with rhodamine B isothiocyanate (RITC) or fluorescein isothiocyanate (FITC). The dye loading was studied and optimized, and the MPs-dye conjugates were characterized by UV-vis FTIR and XPS spectrometry and scanning electron microscopy (SEM). Furthermore, preliminary tests on aquatic organisms demonstrated the possible use of these fluorescent MPs in bioimaging studies, showing their absorption/adsorption by duckweeds (Lemna minuta) and insect larvae (Cataclysta lemnata).