Abandoned farmlands are increasing due to socio-economic changes and land marginalization, and they require sustainable land management practices. Biocrusts are a common cover on the topsoil of abandoned farmlands and play an important role in improving soil stability and erosion resistance. The critical functions of biocrusts are known to mostly rely on their biofilaments and extracellular polymeric substances (EPS), but how these components act at microscopic scale is still unknown, while rheological methods are able to provide new insights into biocrust microstructural stability at particle scale. Here, bare soil and two representative types of biocrusts (cyanobacterial and moss crusts) developed on sandy (Ustipsamments) and sandy loam (Haplustepts) soils in abandoned farmlands in the northern Chinese Loess Plateau were collected at a sampling depth of 2 cm. Changes in the rheological properties of the biocrusts were analyzed with respect to their biofilament network and EPS contents to provide possible explanations. The rheological results showed that compared with bare soil, storage and loss moduli were decreased by the biocrusts on sandy soil, but they were increased by the biocrusts on sandy loam soil. Other rheological parameters tau max, gamma L, gamma YP, and Iz of biocrusts on both soils were significantly higher than those of bare soil, showing higher viscoelasticity. And the moss crusts had about 10 times higher rheological property values than the cyanobacterial crusts. Analysis from SEM images showed that the moss crusts had higher biofilament network parameters than the cyanobacterial crusts, including nodes, crosslink density, branches, branching ratio and mesh index, and biofilament density, indicating that the biofilament network structure in the moss crusts was more compact and complex in contrast to the cyanobacterial crusts. Additionally, EPS content of the moss crusts was higher than that of the cyanobacterial crusts on both soils. Overall, the crosslink density, biofilament density, and EPS content of the biocrusts were significantly and positively correlated with their gamma YP and Iz. The interaction between crosslink density and biofilament density contributed 73.2 % of gamma YP, and that between crosslink density and EPS content contributed 84.0 % of Iz. Our findings highlight the biocrusts-induced changes of abandoned farmland soil rheological properties in drylands, and the importance of biocrust biofilament network and EPS in maintaining abandoned farmland soil microstructural stability to resist soil water/wind erosion and degradation, providing a new perspective for sustainable management of abandoned farmlands.

Poly(butylene adipate-co-terephthalate) (PBAT) is a biodegradable polymer derived from fossil-based raw materials. Combined with poly(lactic acid) (PLA), a major material used in 3D printing, PBAT provides mechanical properties that are particularly attractive for applications requiring flexible 3D-printed objects. However, blends with high PBAT content in fused filament fabrication (FFF) are currently not well-documented, and optimal printing parameters remain unclear for advancing this field. This study aims to address this gap by first exploring the extrusion of filaments at different temperatures, followed by analyzing the printing conditions for PBAT/PLA blends to enhance their spectrum of applications. Using a commercial blend, Ecovio (R) (86 mol% PBAT), this paper demonstrates the feasibility of employing high PBAT content in the additive manufacturing process. Printing parameters such as nozzle temperature and speed were assessed based on the visual quality and mechanical properties of the specimens. The results indicate that extruding at 120 degrees C yields smoother filaments with adequate diameter for FFF applications. Regarding 3D-printing analysis, variations in parameters did not significantly impact elongation at break. However, increasing the nozzle temperature from 180 to 210 degrees C and the printing speed from 50 to 80 mm/s resulted in a 29% increase in tensile strength and a 77% increase in the modulus of elasticity of the 3D-printed specimens which is attributed to better interlayer adhesion. Therefore, high PBAT content blends can improve the performance of 3D-printed materials, and parameters must be optimized to exploit their effectiveness fully across various industrial uses.Highlights Extrusion temperature variations minimally affect PLA/PBAT thermal properties. Higher nozzle temperature and speed significantly improve mechanical properties. Optimal printing conditions for high PBAT blends enable flexible materials. PBAT blends show potential for enhanced 3D printing performance in all sectors.

The escalating global crisis of plastic waste necessitates innovative and sustainable approaches to its management. This study explores a novel method; the transformation of discarded plastic materials into high quality 3D printing filaments, offering a promising solution to this pervasive environmental challenge. This review paper delves into the prospects of leveraging plastic waste recycling for the production of 3D printing filaments, thereby advancing the cause of sustainable additive manufacturing. The investigation encompasses a comprehensive examination of the recycling process, encompassing waste collection, sorting, and filament extrusion. The outcomes of this study underscore the substantial potential of recycling plastic waste for 3D printing filaments as a sustainable alternative to conventional manufacturing. This review also delves into the polymer degradation phenomenon, assessment of properties of recycled polymers, and environmental impact assessment, conducting a comparative analysis with traditional filament production methods. This paper advances the application of recycling plastic waste for 3D printing filaments, offering a tangible and immediate response to the global plastic waste crisis.

Lignocellulosic waste materials are among the most abundant raw materials on Earth, and they have been widely studied as natural additives in materials, especially for polymer composites, with interesting results when it comes to improving physiochemical properties. The main components of these materials are cellulose, hemicellulose, and lignin, as well as small amounts of other polysaccharides, proteins, and other extractives. Several kinds of lignocellulosic materials, mainly fibers, have been evaluated in polymer matrices, and recently, the use of particles has increased due to their high surface area. Garlic is a spice seed that generates a waste husk that does not have applications, and there are no reports of industrial use of this kind of lignocellulosic material. Additive manufacturing, also known as 3D printing, is a polymer processing technique that allows for obtaining complex shapes that are hard to obtain with ordinary techniques. The use of composites based on synthetic polymers and lignocellulosic materials is a growing field of research. In the present work, the elaboration and evaluation of 3D-printed polypropylene-garlic husk particle (PP-GHP) composites are reported. First, the process of obtaining a filament by means of a single extrusion was carried out, using different GHP contents in the composites. Once the filament was obtained, it was taken to a 3D printer to obtain probes that were characterized using differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) was performed with the aim of evaluating the thermal behavior of the 3D-printed PP-GHP composites. According to the obtained results, the crystallization process and thermal stability of the PP-GHP composites were modified with the presence of GHP compared with pristine PP. Dynamic mechanical analysis (DMA) showed that the addition of GHP decreased the storage modulus of the printed composites and that the Tan delta peak width increased, which was associated with an increase in toughness and a more complex structure of the 3D-printed composites. X-ray diffraction (XRD) showed that the addition of GHP favored the presence of the beta-phase of PP in the printed composites.

Agricultural waste is a renewable source of lignocellulosic components, which can be processed in a variety of ways to yield added-value materials for various applications, e.g., polymer composites. However, most lignocellulosic biomass is incinerated for energy. Typically, agricultural waste is left to decompose in the fields, causing problems such as greenhouse gas release, attracting insects and rodents, and impacting soil fertility. This study aims to valorise nonedible tomato waste with no commercial value in Additive Manufacturing (AM) to create sustainable, cost-effective and added-value PLA composites. Fused Filament Fabrication (FFF) filaments with 5 and 10 wt.% tomato stem powder (TSP) were developed, and 3D-printed specimens were tested. Mechanical testing showed consistent tensile properties with 5% TSP addition, while flexural strength decreased, possibly due to void formation. Dynamic mechanical analysis (DMA) indicated changes in storage modulus and damping factor with TSP addition. Notably, the composites exhibited antioxidant activity, increasing with higher TSP content. These findings underscore the potential of agricultural waste utilization in FFF, offering insights into greener waste management practices and addressing challenges in mechanical performance and material compatibility. This research highlights the viability of integrating agricultural waste into filament-based AM, contributing to sustainable agricultural practices and promoting circular economy initiatives.

Biodegradable Poly (butylene succinate) (PBS) composites with natural polymers have been widely developed, the compatibility of PBS and natural polymers is often the first consideration in terms of performance. In this work, PBS/silk sericin composite monofilaments (content of silk sericin is 6 wt%) with gamma -methacryloxypropyl- trimethoxysilane (KH570) as the coupling agent were fabricated by reactive melt -mixing, spinning, and stretching. The effect of KH570 content (1 - 3 wt%) on the morphology, mechanical property and biodegradation was studied. The reaction between the hydroxyl groups of silk sericin and -Si-OH of KH570 was analyzed by Fourier transform infrared spectroscopy. The cross- morphology of the monofilaments obtained from SEM and EDS images indicates that the dispersion of silk sericin is improved with the increase of KH570 content. Compared with unmodified composite monofilaments, the composite monofilament with 2 wt% KH 570 shows the best mechanical performance (102% and 80% improvement in tensile strength and elongation at break respectively). The incorporation of silk sericin, which possesses skin -friendly properties, imparts composite monofilaments with advantages in the fields of clothing, headgear, shoe uppers and other related applications. Otherwise, the silk sericin can enhance the biodegradability velocity of PBS/silk sericin composite monofilaments. And the weight loss of the composite monofilaments buried in soil can be adjusted by the synergistic effect of silk sericin and KH570.