Formation of Fiber Fragments during Abrasion of Polyester Textiles.

Fiber fragments are one of the dominant types of microplastics in environmental samples, suggesting that synthetic textiles are a potential source of microplastics to the environment. Whereas the release of microplastics during washing of textiles is already well studied, much less is known about the release during abrasion processes. The abrasion of textiles may induce fibrillation of fibers and therefore result in the formation of much finer fiber fragments. The aim of this study was to investigate the influence of abrasion of synthetic textiles on the formation of microplastic fibers and fibrils. Fleece and interlock textile swatches made of polyester were abraded using abrasion tests with a Martindale tester. The microplastic fibers and fibrils formed during abrasion were extracted from the textiles and characterized in terms of number, length, and diameter. The microplastic fibers demonstrated the same diameter than the fibers found in the textiles (fleece: 12.3 µm; interlock: 12.7 µm), while fibrils with a much smaller diameter (fleece: 2.4 µm; interlock: 4.9 µm) were also found. The number of fibrils formed during abrasion in both textiles was higher than the number of microplastic fibers. The majority of the extracted microplastic fibers had a length between 200 and 800 µm, while most fibrils were between 30 and 150 µm, forming two distinct fiber fragment morphologies. The number of microplastic fibers formed during abrasion was 5 to 30 times higher than the number of microplastic fibers that could be extracted from non-abraded samples. The number of fibrils increased after abrasion by more than a factor of 200 for both fabric types. The fibrils formed during abrasion have diameters that fall within the inhalable size for airborne particles. The potential release of fibrils into air during wear of textiles thus raises questions about the human exposure to these materials. Since the Martindale tester can simulate a daily application scenario of textiles over a prolonged period only in a limited way, future studies are needed to establish the correlation between the test results with a real-world scenario.

Systematic Study of Microplastic Fiber Release from 12 Different Polyester Textiles during Washing.

Microplastic fibers (MPFs) have been found to be a major form of microplastics in freshwaters, and washing of synthetic textiles has been identified as one of their main sources. The aim of this work was to use a panel of 12 different textiles of representative fibers and textile types to investigate the source(s) of the MPF during washing. Using standardized washing tests, textile swatches tailored using five different cutting/sewing methods were washed up to 10 times. The MPF quantity and fiber length were determined using image analysis. The 12 textiles demonstrated great variability in MPF release, ranging from 210 to 72,000 MPF/g textile per wash. The median MPF length ranged from 165 to 841 µm. The number of released MPF was influenced by the cutting method, where scissor-cut samples released 3-21 times higher numbers of MPF than the laser-cut samples. The textiles with mechanically processed surfaces (i.e., fleece) released significantly more (p-value < 0.001) than the textiles with unprocessed surfaces. For all textiles, the MPF release decreased with repeated wash cycles, and a small continuous fiber release was observed after 5-6 washings, accompanied by a slight increase in the fiber length. The decrease in the number of MPF released is likely caused by depletion of the production-inherited MPFs trapped within the threads or the textile structure. The comparison of MPF release from laser-cut samples, which had sealed edges, and the other cutting methods allowed us to separate the contributions of the edge- and surface-sourced fibers from the textiles to the total release. On an average, 84% (range 49-95%) of the MPF release originated from the edges, highlighting the importance of the edge-to-surface ratio when comparing different release studies. The large contribution of the edges to the total release offers options for technical solutions which have the possibility to control MPF formation throughout the textile manufacturing chain by using cutting methods which minimize MPF formation.

Porous, Water-Resistant Multifilament Yarn Spun from Gelatin.

Sustainability, renewability, and biodegradability of polymeric material constantly gain in importance. A plausible approach is the recycling of agricultural waste proteins such as keratin, wheat gluten, casein or gelatin. The latter is abundantly available from animal byproducts and may well serve as building block for novel polymeric products. In this work, a procedure for the dry-wet spinning of multifilament gelatin yarns was developed. The process stands out as precipitated gelatin from a ternary mixture (gelatin/solvent/nonsolvent) was spun into porous filaments. About 1000 filaments were twisted into 2-ply yarns with good tenacity (4.7 cN tex(-1)). The gelatin yarns, per se susceptible to water, were cross-linked by different polyfunctional epoxides and examined in terms of free lysyl amino groups and swelling degree in water. Ethylene glycol diglycidyl ether exhibited the highest cross-linking efficiency. Further post-treatments with gaseous formaldehyde and wool grease (lanolin) rendered the gelatin yarns water-resistant, allowing for multiple swelling cycles in water or in detergent solution. However, the swelling caused a decrease in filament porosity from ∼30% to just below 10%. To demonstrate the applicability of gelatin yarn in a consumer good, a gelatin glove with good thermal insulation capacity was fabricated.

Bio-based modification of polyhydroxyalkanoates (PHA) towards increased antimicrobial activities and reduced cytotoxicity.

With the increased occurrence of bacteria resistance to conventional antibiotics, the development of novel antimicrobials is urgently needed. Traditional biomaterials used for delivering these agents often struggle to achieve sustained release while maintaining non-cytotoxic properties. In this study, we present an innovative approach using bacterial polyhydroxyalkanoates (PHA) as a carrier for antimicrobial delivery, specifically designed for wound healing applications. Octenidine dihydrochloride (OCT), a widely used antimicrobial agent, served as our model drug. To achieve the desired balance of OCT release and low cytotoxicity, we introduced a novel bio-derived additive, 3-hydroxy-pentadecanoic acid (3OHC15), extracted from bacteria. This additive significantly improved the hydrophilicity of PHA films, resulting in enhanced and sustained release of OCT. Importantly, the additive did not adversely affect the material's tensile strength or thermal properties. The increased OCT release led to improved antibacterial activity against both Gram-negative and -positive strains. Most notably, the incorporation of 3OHC15 in PHA mitigated the cytotoxic effects of the released drug on human fibroblasts, ensuring biocompatibility. This work represents a novel strategy in the design of biomaterials for the delivery of bioactive compounds, achieving a critical balance between efficacy and cytocompatibility, and marks a significant advancement in the field of antimicrobial delivery systems.

Effects of Nanoscale Morphology on Optical Properties of Photoluminescent Polymer Optical Fibers.

Bicomponent photoluminescent polymer optical fibers (PL-POFs) have been melt-spun and in-situ drawn to different extents. The results suggest that scattering in the sheath can effectively increase the photoluminescent dye excitation probability in the fiber core. The core/sheath PL-POFs are made of a semi-crystalline fluoropolymer sheath of low refractive index (RI) and an amorphous cycloolefin polymeric core of high RI, which is doped with a luminescent dye. The axial light emission, as well as the guiding attenuation coefficients of the core/sheath PL-POFs, have been measured using a side-illumination set-up. The incident blue laser is down-converted to red light, which is re-emitted and partially guided by the core. The axial light emission is measured at the fiber tip as a function of the distance from the illumination position to the integrating sphere. It is demonstrated that the presence of a semi-crystalline sheath significantly enhances the axial light emission and that it also lowers the attenuation coefficient, compared to the emission and guiding properties of PL core-only fibers. Additionally, the attenuation coefficient has been found to be lower in more strongly drawn PL-POFs. Wide-angle X-ray diffraction and small-angle X-ray scattering experiments reveal structural differences in differently drawn PL-POFs that can be linked to the observed differences in the optical properties.

Structure-Property Relationship in Melt-Spun Poly(hydroxybutyrate-co-3-hexanoate) Monofilaments.

Poly(hydroxybutyrate-co-3-hexanoate) (PHBH) is a biodegradable thermoplastic polyester with the potential to be used in textile and medical applications. We have aimed at developing an upscalable melt-spinning method to produce fine biodegradable PHBH filaments without the use of an ice water bath or offline drawing techniques. We have evaluated the effect of different polymer grades (mol% 3-hydroxy hexanoate, molecular weight etc.) and production parameters on the tensile properties of melt-spun filaments. PHBH monofilaments (diameter < 130 µm) have been successfully melt-spun and online drawn from three different polymer grades. We report thermal and rheological properties of the polymer grades as well as morphological, thermal, mechanical, and structural properties of the melt-spun filaments thereof. Tensile strengths up to 291 MPa have been achieved. Differences in tensile performance have been correlated to structural differences with wide-angle X-ray diffraction and small-angle X-ray scattering. The measurements obtained have revealed that a synergetic interaction of a highly oriented non-crystalline mesophase with highly oriented α-crystals leads to increased tensile strength. Additionally, the effect of aging on the structure and tensile performance has been investigated.

Systematic development of extraction methods for quantitative microplastics analysis in soils using metal-doped plastics.

The inconsistency of available methods and the lack of harmonization in current microplastics (MPs) analysis in soils demand approaches for extraction and quantification which can be utilized across a wide variety of soil types. To enable robust and accurate assessment of extraction workflows, PET MPs with an inorganic tracer (Indium, 0.2% wt) were spiked into individual soil subgroups and standard soils with varying compositions. Due to the selectivity of the metal tracer, MPs recovery rates could be quickly and quantitatively assessed using ICP-MS. The evaluation of different methods specifically adapted to the soil properties were assessed by isolating MPs from complex soil matrices by systematically investigating specific subgroups (sand, silt, clay, non-lignified and lignified organic matter) before applying the workflow to standard soils. Removal of recalcitrant organic matter is one of the major hurdles in isolating MPs for further size and chemical characterization, requiring novel approaches to remove lignocellulosic structures. Therefore, a new biotechnological method (3-F-Ultra) was developed which mimics natural degradation processes occurring in aerobic (Fenton) and anaerobic fungi (CAZymes). Finally, a Nile Red staining protocol was developed to evaluate the suitability of the workflow for non-metal-doped MPs, which requires a filter with minimal background residues for further chemical identification, e.g. by µFTIR spectroscopy. Image analysis was performed using a Deep Learning tool, allowing for discrimination between the number of residues in bright-field and MPs counted in fluorescence mode to calculate a Filter Clearness Index (FCI). To validate the workflow, three well-characterized standard soils were analyzed applying the final method, with recoveries of 88% for MPs fragments and 74% for MPs fibers with an average FCI of 0.75. Collectively, this workflow improves our current understanding of how to adapt extraction protocols according to the target soil composition, allowing for improved MPs analysis in environmental sampling campaigns.

Earthworms ingest microplastic fibres and nanoplastics with effects on egestion rate and long-term retention.

Microplastic fibres (MPFs) and nanoplastics (NPs) have the potential to be hazardous to soil organisms. Understanding uptake into organisms is key in assessing these effects, but this is often limited by the analytical challenges to quantify smaller-sized plastics in complex matrices. This study used MPFs and NPs containing inorganic tracers (In, Pd) to quantify uptake in the earthworm Lumbricus terrestris. Following seven days exposure, tracer concentrations were measured in earthworms and faeces. Earthworms exposed to 500 µg MPFs/g soil retained an estimated 32 MPFs in their tissues, while at 5000 µg MPFs/g earthworms retained between 2 and 593 MPFs. High variation in body burdens of MPFs was linked to soil retention in earthworms and reduced faeces production, suggesting egestion was being affected by MPFs. NPs uptake and elimination was also assessed over a more extended time-period of 42 days. After 1 day, NPs were no longer detectable in faeces during the elimination phase. However, some retention of NPs in the earthworms was estimated, not linked to retained soil, indicating not all NPs were eliminated. MPFs and NPs uptake can be quantified in earthworms and both particle types can be retained beyond the depuration period, suggesting the potential for longer-term accumulation.

Fitting of 2D WAXD data: Mesophases in polymer fibers.

This data article presents fitting results of wide-angle x-ray diffraction (WAXD) patterns of melt-spun polymer fibers from amorphous materials (polycarbonate (PC), cyclo-olefin polymer (COP), copolyamide (coPA), polyethylene terephthalate glycol (PETG)) and semi-crystalline materials (polyethylene terephthalate (PET), poly-3-hydroxybutyrate(P3HB)). The data was fit using the fitting algorithms, previously described in the publication by Perret and Hufenus 'Insights into strain-induced solid mesophases in melt-spun polymer fibers' [1]. Fitting results of WAXD data and details about azimuthal, equatorial, meridional or off-axis profiles are presented in sections 1.1-1.2. SAXS patterns of fibers, melt-spun from amorphous materials, are shown in section 1.3. Fiber production parameters are given in section 2.1, and a description of the WAXD measurements and fitting details, e.g., the chosen fitting parameters, are given in section 2.2.

Melt-Spun Photoluminescent Polymer Optical Fibers for Color-Tunable Textile Illumination.

The increasing interest in luminescent waveguides, applied as light concentrators, sensing elements, or decorative illuminating systems, is fostering efforts to further expand their functionality. Yarns and textiles based on a combination of distinct melt-spun polymer optical fibers (POFs), doped with individual luminescent dyes, can be beneficial for such applications since they enable easy tuning of the color of emitted light. Based on the energy transfer occurring between differently dyed filaments within a yarn or textile, the collective emission properties of such assemblies are adjustable over a wide range. The presented study demonstrates this effect using multicolor, meltspun, and photoluminescent POFs to measure their superimposed photoluminescent emission spectra. By varying the concentration of luminophores in yarn and fabric composition, the overall color of the resulting photoluminescent textiles can be tailored by the recapturing of light escaping from individual POFs. The ensuing color space is a mean to address the needs of specific applications, such as decorative elements and textile illumination by UV down-conversion.

Flexible Phase Change Material Fiber: A Simple Route to Thermal Energy Control Textiles.

A flexible hollow polypropylene (PP) fiber was filled with the phase change material (PCM) polyethylene glycol 1000 (PEG1000), using a micro-fluidic filling technology. The fiber's latent heat storage and release, thermal reversibility, mechanical properties, and phase change behavior as a function of fiber drawing, were characterized. Differential scanning calorimetry (DSC) results showed that both enthalpies of melting and solidification of the PCM encased within the PP fiber were scarcely influenced by the constraint, compared to unconfined PEG1000. The maximum filling ratio of PEG1000 within the tubular PP filament was ~83 wt.%, and the encapsulation efficiencies and heat loss percentages were 96.7% and 7.65% for as-spun fibers and 93.7% and 1.53% for post-drawn fibers, respectively. Weak adherence of PEG on the inner surface of the PP fibers favored bubble formation and aggregating at the core-sheath interface, which led to different crystallization behavior of PEG1000 at the interface and in the PCM matrix. The thermal stability of PEG was unaffected by the PP encasing; only the decomposition temperature, corresponding to 50% weight loss of PEG1000 inside the PP fiber, was a little higher compared to that of pure PEG1000. Cycling heating and cooling tests proved the reversibility of latent heat release and storage properties, and the reliability of the PCM fiber.

Melt-Spun Fibers for Textile Applications.

Textiles have a very long history, but they are far from becoming outdated. They gain new importance in technical applications, and man-made fibers are at the center of this ongoing innovation. The development of high-tech textiles relies on enhancements of fiber raw materials and processing techniques. Today, melt spinning of polymers is the most commonly used method for manufacturing commercial fibers, due to the simplicity of the production line, high spinning velocities, low production cost and environmental friendliness. Topics covered in this review are established and novel polymers, additives and processes used in melt spinning. In addition, fundamental questions regarding fiber morphologies, structure-property relationships, as well as flow and draw instabilities are addressed. Multicomponent melt-spinning, where several functionalities can be combined in one fiber, is also discussed. Finally, textile applications and melt-spun fiber specialties are presented, which emphasize how ongoing research efforts keep the high value of fibers and textiles alive.

Long-term assessment of nanoplastic particle and microplastic fiber flux through a pilot wastewater treatment plant using metal-doped plastics.

In recent years, several studies have investigated the flux of particulate plastic through municipal waste water treatment plants (WWTP). Challenges related to time consuming analytical methods have limited the number of sampling points and detection limits have hampered quantification of nanoplastic and microplastic fiber fluxes through WWTPs. By synthesizing nanoplastic particles and microplastic fibers labeled with a rare metal (Pd and In, respectively) which can be measured as a proxy for the plastic itself, we have circumvented major analytical pitfalls associated with (micro)plastic measurements. In this study, we spiked the labeled materials to a pilot WWTP mimicking the activated sludge process (nitrification, de-nitrification and secondary clarification). Using a mass flow model for WWTP sludge, we assessed the behavior of particulate plastic in relation to the removal of organic matter. Triplicate samples were collected from the mixed liquor and from the effluent at least twice weekly over the entire experimental run time of 40 d. Our findings show that in discrete grab samples during steady state conditions, at least 98% of particulate plastics were associated with the biosolids. A positive correlation between total suspended solids (TSS) and plastic concentrations was observed in the sludge as well as in the effluent. Because of the strong association between particulate plastic and TSS, TSS removal is likely a good indicator of plastic removal in a full scale WWTP. Therefore, additional process steps in a full-scale WWTP which further reduce the TSS load will likely retain nanoplastic particles and microplastic fibers effectively and consequently increase the removal rates.

X-ray data about the structural response of melt-spun poly(3-hydroxybutyrate) fibers to stress and temperature.

Mechanical properties of as-spun, aged and stress-annealed melt-spun poly(3-hydroxybutyrate) (P3HB) fibers are presented in section 1.1. Section 1.2 presents tables with stress/temperature conditions and exposure times during in-situ laboratory WAXD and SAXS experiments, and section 1.3 presents azimuthal profiles of the corresponding WAXD patterns with extracted orientation factors of the α-crystals. Section 1.4 presents the extracted long-spacings, coherence lengths and crystal sizes from SAXS patterns. The corresponding fits of meridional and transversal SAXS profiles are shown in sections 1.5 and 1.6, respectively. In-situ synchrotron measurements during tensile drawing of differently pre-annealed P3HB fibers are presented in section 1.7. A detailed description of the tensile, SAXS/WAXD measurements and analysis is given in the experimental section 2. The laboratory SAXS/WAXD measurements during stress annealing were performed with a Bruker Nanostar U diffractometer (Bruker AXS, Karlsruhe, Germany) and a heating stage H+300 (Bruker AXS, Germany). Different weights were attached to the fibers during heating to apply stress. The synchrotron measurements during tensile drawing were performed at the cSAXS beamline at the Swiss Light Source of the Paul Scherrer Institute in Switzerland. The fibers were drawn with a TS 600 tensile stage (Anton Paar GmbH, Austria) using a 5 N load cell. For more information see 'Structural response of melt-spun poly(3-hydroxybutyrate) fibers to stress and temperature' [1].

Antistatic Fibers for High-Visibility Workwear: Challenges of Melt-Spinning Industrial Fibers.

Safety workwear often requires antistatic protection to prevent the build-up of static electricity and sparks, which can be extremely dangerous in a working environment. In order to make synthetic antistatic fibers, electrically conducting materials such as carbon black are added to the fiber-forming polymer. This leads to unwanted dark colors in the respective melt-spun fibers. To attenuate the undesired dark color, we looked into various possibilities including the embedding of the conductive element inside a dull side-by-side bicomponent fiber. The bicomponent approach, with an antistatic compound as a minor element, also helped in preventing the severe loss of tenacity often caused by a high additive loading. We could melt-spin a bicomponent fiber with a specific resistance as low as 0.1 Ωm and apply it in a fabric that fulfills the requirements regarding the antistatic properties, luminance and flame retardancy of safety workwear.

Mechanistic understanding of microplastic fiber fate and sampling strategies: Synthesis and utility of metal doped polyester fibers.

The increased use of synthetic textiles in the last decades, coupled with recent emphasis on the accumulation of (micro)plastic across multiple environmental compartments, has garnered interest into how microplastic fibers are released into the environment. In particular, polyester textiles washed in the home have shown to release microplastic fibers but challenges with microplastic fiber analysis, including time and difficulty of sample preparation and measurement, has limited mechanistic studies on fiber fate and transport studies. In this study, we provide a method to synthesize fibers with an embedded inorganic (In) fingerprint which can be used as a tracer for ease of analysis and show the utility of this approach to assess the affinity for heteroaggregation between microplastic fibers and other particles in a heterogeneous suspension, as well as approximate the fate of microplastic fibers in batch studies using activated sludge from a municipal wastewater treatment plant (WWTP). Total In content in the fibers was measured to be 0.2 % by weight, which was low enough to not change fiber dynamics for fate and transport studies (e.g. density, etc.) but provided sensitive detection limits by ICP-MS. Fiber length was 510 µm ±â€¯410 µm and 30 µm in diameter. The incorporated metal remained stable inside the polymer when suspended in water and in activated sludge, with < 0.1 % In leaching over two months. In batch experiments, the majority of fibers were associated with the sludge ( > 99.9 %), with a mass balance of > 95 % recovery achieved on average across batches. Fiber removal linearly increased with contact times of up to 10 min, suggesting interactions between plastics and organic matter is a metric that should be considered closely in this and other environmental contexts for fate and transport.

X-ray data from a cyclic tensile study of melt-spun poly(3-hydroxybutyrate) P3HB fibers: A reversible mesophase.

Wide-angle x-ray diffraction (WAXD) patterns that show mesophases in core-sheath bicomponent fibers and amorphous fibers are presented in section 1.1 of the article. Section 1.2 presents molecular dynamics simulations and scattered intensity calculations of stretched P3HB chains. Sections 1.3-1.6 summarize WAXD and small-angle x-ray scattering (SAXS) data analysis from a tensile study of melt-spun P3HB fibers. Azimuthal profiles are extracted from 2D WAXD patterns at various angular regions and the positions of equatorial reflections and corresponding d-spacings are summarized. Additionally, the extracted structural parameters from SAXS images are summarized. The tensile stress calculations, crystal orientation calculations, applied intensity corrections, calculations of long spacings, coherence lengths and lamellar diameters are explained in the methods subsections 2.3.1-2.3.7. WAXD and SAXS measurements of P3HB fibers were recorded on a Bruker Nanostar U diffractometer (Bruker AXS, Karlsruhe, Germany). The recorded WAXD/SAXS patterns were analyzed with the evaluation software DIFFRAC.EVA (version 4.2., Bruker AXS, Karlsruhe, Germany) and python codes. For more information see 'Tensile study of melt-spun poly(3-hydroxybutyrate) P3HB fibers: Reversible transformation of a highly oriented phase' (Perret et al., 2019).

Body-monitoring with photonic textiles: a reflective heartbeat sensor based on polymer optical fibres.

Knowledge of an individual's skin condition is important for pressure ulcer prevention. Detecting early changes in skin through perfusion, oxygen saturation values, and pressure on tissue and subsequent therapeutic intervention could increase patients' quality of life drastically. However, most existing sensing options create additional risk of ulcer development due to further pressure on and chafing of the skin. Here, as a first component, we present a flexible, photonic textile-based sensor for the continuous monitoring of the heartbeat and blood flow. Polymer optical fibres (POFs) are melt-spun continuously and characterized optically and mechanically before being embroidered. The resulting sensor shows flexibility when embroidered into a moisture-wicking fabric, and withstands disinfection with hospital-type laundry cycles. Additionally, the new sensor textile shows a lower static coefficient of friction (COF) than conventionally used bedsheets in both dry and sweaty conditions versus a skin model. Finally, we demonstrate the functionality of our sensor by measuring the heartbeat at the forehead in reflection mode and comparing it with commercial finger photoplethysmography for several subjects. Our results will allow the development of flexible, individualized, and fully textile-integrated wearable sensors for sensitive skin conditions and general long-term monitoring of patients with risk for pressure ulcer.