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Wood–plastic composites (WPCs) represent composite materials that employ shredded wood combined with a thermoplastic substance, such as polylactic acid (PLA), to establish structural cohesion within the product profile. This amalgamation of materials results in a robust structure designed to fulfill specialized roles under the influence of pressure and temperature. Given the nature of the constituent materials, the resultant product can be classified as a biocomposite. The creation of such biocomposites entails a rigorous process necessitating the fine-tuning of specific parameters and suitable technologies. The foundational materials employed in this process must be both natural and biodegradable. However, it is noteworthy that natural components like fibers exhibit anisotropic behavior, wherein their mechanical attributes are contingent on the direction of the applied force. Consequently, predicting their performance during biocomposite production proves challenging. The principal objective of this study was to conduct a comparative analysis of wood-based composites incorporating PLA thermoplastic binding agents. The intention was to discern variations in density profiles arising from distinct measurement methodologies. Two measurement methods were used for the measurement: X-ray and spectrum desaturation. Additionally, the study sought to investigate the impact of introducing PLA additives at 25% and 50% concentrations on the fabrication of WPC from wood chips. The properties of these composites were assessed by considering the inherent traits of the composite materials. [ABSTRACT FROM AUTHOR]

The development of the paper industry has led to the discharge of a large amount of papermaking waste liquid containing lignosulfonate. These lignin black liquids cause a lot of pollution in nature, which runs counter to the current environmental protection strategy under the global goal. Through the development and use of lignosulfonate in papermaking waste liquid to increase the utilization of harmful substances in waste liquid, we aim to promote waste liquid treatment and reduce environmental pollution. This paper proposes a new strategy to synthesize novel glue-free biocomposites with high-performance interfacial compatibility from papermaking by-product sodium lignosulfonate/chitosan (L/C) and waste bamboo. This L/C bamboo biocomposite material has good mechanical properties and durability, low formaldehyde emissions, a high recovery rate, meets the requirements of wood-based panels, and reduces environmental pollution. This method is low in cost, has the potential for large-scale production, and can effectively reduce the environmental pollution of the paper industry, promoting the recycling of biomass and helping the future manufacture of glue-free panels, which can be widely used in the preparation of bookcase, furniture, floor and so on. [ABSTRACT FROM AUTHOR]

The present investigation seeks to assess the impact of fillers on the mechanical characteristics of entirely biodegradable composites, introducing an advanced solution to fulfil long-term durability demands within point-of-purchase (POP) industries. The inclusion of calcium carbonate (CaCO3) fillers on the various properties of the flax fibre-reinforced composites, after accelerated irradiation in an ultraviolet (UV) radiation exposure has been investigated in the present study. Different types of flax fibre-reinforced poly lactic acid (PLA) biocomposites (with and without filler) were fabricated. The mechanical (tensile and flexural), and physical properties of the specimens were assessed after 500 h of exposure to accelerated UV irradiation of 0.48 W/m2 at 50 °C and were compared with those of the unexposed specimens. The results indicate that the presence of the inorganic filler significantly improved the performance of the biocomposites compared to the unfilled biocomposites after UV exposure. After adding 20% of fillers, the tensile strength was increased by 2% after UV degradation, whereas the biocomposite without filler lost 18% of its strength after UV exposure. This can be attributed to the change in the photo-degradation of the PLA due to the presence of the CaCO3 filler, which acts as a safeguard against UV light penetration by creating a protective barrier. The scanning electron microscopy (SEM) images of the degraded specimen surface show substantial difference in the surface topography of the composites with and without fillers. [ABSTRACT FROM AUTHOR]

The dynamic development of the food industry and the growing interest of consumers in innovative solutions that increase the comfort and quality of life push the industry towards seeking pioneering solutions in the field of food packaging. Intelligent and active packaging, which affects the quality and durability of food products and allows one to determine their freshness, is still a modern concept. The aim of our study was to obtain two types of films based on chitosan and starch with micellar nanostructures containing extracts from turmeric rhizomes and hibiscus flowers. The presence of spherical nanostructures was confirmed using a scanning electron microscope. The structural and optical properties of the obtained composites were characterised by Fourier-transform infrared (FTIR), UltraViolet-Visible (UV-VIS), and photoluminescence (PL) spectroscopy. Scanning electron microscopy (SEM) analysis confirmed the presence of spherical micellar structures with a size of about 800 nm in the obtained biocomposites. The presence of nano-/microstructures containing extracts affected the mechanical properties of the composites: it weakened the strength of the films and improved their elongation at break (EAB). Films with nano-/microparticles were characterised by a higher water content compared to the control sample and lower solubility, and they showed stronger hydrophilic properties. Preliminary storage tests showed that the obtained biocomposites are sensitive to changes occurring during the storage of products such as cheese or fish. In addition, it was found that the film with the addition of turmeric extract inhibited the growth of microorganisms during storage. The results suggest that the obtained bionanocomposites can be used as active and/or intelligent materials. [ABSTRACT FROM AUTHOR]

Poly(glycerol sebacate) (PGS) is a novel polymeric material intended for applications in tissue engineering (TE). This study involves synthesizing the PGS prepolymer (pPGS) and subsequent manufacturing of porous PGS-based scaffolds with an addition of hydroxyapatite (HAp) by means of thermally induced phase separation followed by thermal cross-linking and salt-leaching (TIPS-TCL-SL). The study aims to investigate the effect of the apatite filler content on properties and morphology of porous PGS/HAp scaffolds. The emphasis is put on the mechanical behavior of the material characterized by means of compression tests and dynamic thermal mechanical analysis (DMTA). In addition to the reference polymer scaffold, the composites with filler contents of 10, 20 and 30 wt% have been examined. Our research revealed that the HAp content does not affect the mechanical properties in a directly proportional manner. The 30 wt% addition of HAp resulted in frayed structure and decrease in the mechanical parameters in comparison to other tested specimens. On the other hand, an addition of 10% did not sufficiently boost the properties. Therefore, a 20% addition of HAp was concluded to have superior mechanical properties in comparison to other analyzed specimens. A similar relationship results from the DMTA studies. Moreover, the strain sweep and frequency sweep tests confirmed the stability of the mechanical parameters in various conditions, as well as the elastomeric nature of the materials. Finally, the material did not exhibit cytotoxicity against standard L929 fibroblasts and cells readily populated the scaffolds. [Display omitted] [ABSTRACT FROM AUTHOR]

In the past couple of decades, there has been significant rise in interest towards formulation and application of biomaterials for the purpose of bone-tissue engineering as well as environmental bioremediation. Hydroxyapatite is a bioceramic which has gained much attention in this regard, because it resembles the mineral composition of bone and can be used as bone substitute, teeth filler, or as a coating material on orthopedic and dental implants, etc. On the other side, chitosan is a natural biopolymer that is renowned for its bioactivity, biodegradability, and biocompatibility. Chitosan and hydroxyapatite-based biocomposites have been created and studied for their capacity for biomineralization, mechanical performance, and porous interconnected structure, all of which are highly desired for tissue engineering applications. Together with defluoridation usage, hydroxyapatite has also been identified as a possible material for dye and heavy metal removal, because of its high capacity for adsorption, a low water solubility, and a high level of stability in both oxidizing and reducing conditions. However, due to significant pressure drop, it cannot be employed in powder form or in a fixed bed design. Hence, adding hydroxyapatite to a chitosan matrix improves mechanical strength and increases stability, overcoming its drawbacks. The objective of this review paper is to provide an in-depth analysis of the literature on chitosan-hydroxyapatite based biocomposites having different formulations such as scaffold, hydrogel, nanocomposite, film, powder, etc., and the potential applications of these composites in two important research fields, namely tissue engineering and wastewater bioremediation.

Rice husk biochar was added to polylactic acid (PLA) to create a biocomposite filament suitable for the extrusion-based 3D printing process of fused deposition modelling (FDM). Taguchi L16 was used for experiment design, and the significance of process parameters was determined using variance analysis (ANOVA). For a 0.3-mm layer thickness, the addition of 5 wt.% biochar resulted in ultimate tensile strength and a modulus of elasticity of 36 MPa and 1103 MPa, respectively. The addition of biochar had a negative influence on flexural strength. The maximum flexural modulus was obtained with 3 % biochar, 100 % infill density, and 0.1 mm layer thickness. Particularly, 1 % biochar resulted in a considerable increase in impact strength, while a subsequent rise in biochar resulted in a decrease, probably due to the agglomeration effect. For 3D printed neat PLA, the average tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength observed were 19 MPa, 550 MPa, 54 MPa, 1981 MPa, and 25 KJ/m2, respectively. Additionally, considering the output of each test, a multicriteria decision-making model, namely, TOPSIS, has been utilized for ranking the mechanical performance. In order to optimise the mechanical properties of three-dimensional printed objects, the study suggests a layer thickness of 0.2 mm, an infill density of 100 %, and raster angle of 0° as the FDM process parameters.

Nylon/polyamide (PA6) is a major cause of ocean plastic pollution because of its extended use in commercial fishing activities. Recovery of this nylon from oceans and its use in manufacturing new materials or composites is urgently required to promote sustainability and circularity. In this work, unlike higher-density mineral fillers, lignin from the forestry industry was converted into biocarbon, which was used as a lightweight filler to manufacture recycled-ocean nylon (RN)-based composites. Biocarbon is a highly stable, competitive, and sustainable filler for high-performance engineering plastics such as nylon. Lignin was pyrolyzed at 600 °C followed by further treatment at 1200 °C (with and without cobalt (II) nitrate catalyst) to induce graphitization in the produced biocarbon. Among the three types of biocarbon samples, such as pyrolyzed at 600 °C, 1200 °C and 1200 °C catalyzed lignin biocarbon, the catalyzed biocarbon showed the maximum electrical conductivity. Catalyzed lignin biocarbon pyrolyzed at 1200 °C showed an increase of 85% in electrical conductivity compared to commercial mineral graphite. The biocomposites consisting of 600 °C biocarbon were manufactured by injection molding at different filler contents up to 40 wt.%. The biocomposites consisting of 40% of pyrolyzed lignin at 600 °C showed increased flexural strength, flexural modulus, and heat deflection temperature by 41, 76 and 76%, respectively, compared to neat RN. Improved properties of the prepared biocarbons and biocomposites showed the potential of RN-based composites in the automotive industries.

This paper deals with the study of the degradation of polylactic acid (PLA) material structures and biocomposite systems with a PLA matrix containing ground natural particulate waste fillers, buckwheat husks and egg shells. Waste fillers were used without difficult cleaning operations to describe the effect of the raw waste material on PLA. Biocomposites with raw waste materials are increasingly coming to the forefront in car interiors and packaging products. The prepared material systems were exposed to controlled climatic ageing simulating long-term solar radiation and cyclic outdoor conditions. The degradation of the biocomposite systems was evaluated via thermal (differential scanning calorimetry) and mechanical properties (tensile and flexural tests, Charpy impact toughness). In addition to evaluating the degradation of the material structures using standardized tests, the influence and effect of controlled climatic ageing was visually assessed using SEM images (electron microscopy) of the surfaces and fracture surfaces of the test specimens. [ABSTRACT FROM AUTHOR]

Recently, new brake pads have been developed using sustainable materials that are not harmful to the environment. In this study, the effect of using blue-colored Cupressus arizonica cones was determined as a friction modifier in brake pad composites. Four different samples were prepared by grinding the cone material. The samples’ physical and chemical properties and performances were compared, and finally, their microscopic analyses were visualized by scanning electron microscopy. Maximum friction coefficient and minimum wear rate are required for brake pads. The maximum friction coefficient of 0.39 and the minimum wear rate of the samples containing Cupressus arizonica were obtained in the 0.124X10-7 cm³ /Nm BCA3 sample. When the brake pads developed from lignocellulosic biomass were compared, it was determined that the BCA3 sample met the most reasonable performance values. [ABSTRACT FROM AUTHOR]

Spearing mantis shrimps are aggressive crustaceans using specialized appendages with sharp spikes to capture fishes with fast movement. Each spike is a biological tool that has to combine high toughness, as required by the initial impact with the victim, with high stiffness and strength, to ensure sufficient penetration while avoid breaking.We performed a multimodal analysis to uncover the design strategies of this harpoon based on chitin. We found that the spike is a slightly hooked hollow beam with the outer surface decorated by serrations and grooves to enhance cutting and interlocking. The cuticle of the spike resembles a multilayer composite: An outer heavily mineralized, stiff, and hard region (with average indentation modulus and hardness of 68 and 3 GPa), providing high resistance to contact stresses, is combined with a less mineralized region, which occupies a large fraction of the cuticle (up to 50%) and features parallel fibers oriented longitudinally, enhancing stiffness and strength. A central finding of our work is the presence of a tiny interphase (less than 10 μm in width) based on helical fibers and showing a spatial modulation in mechanical properties, which has the critical task to integrate the stiff but brittle outer layer with the more compliant highly anisotropic parallel-fiber region.We highlighted the remarkable ability of this helicoidal region to stop nanoindentation-induced cracks.Using three-dimensional multimaterial printing to prototype spike-inspired composites, we showed how the observed construction principles can not only hamper damage propagation between highly dissimilar layers (resulting in composites with the helical interphase absorbing 50% more energy than without it) but can also enhance resistance to puncture (25% [ABSTRACT FROM AUTHOR]

This research work investigates the effects of the concentration and treatment of chopped false banana (Ensete ventricosum) fibres on the mechanical properties of a polypropylene matrix. The chopped false banana fibres (FBFs) were modified using Aloe Vera gel following treatment with 5% NaOH for 12 h at room temperature, with 1% acetic acid used to neutralise the remaining NaOH. FBF-reinforced polypropylene composite plates were then manufactured with 10, 20, 30, and 40 wt.% of chopped FBF. The mechanical properties were investigated using the compressive, impact, and three-point bending tests. Regarding the mechanical properties of the FBF-reinforced polypropylene composites, it was found that they have a maximum average compressive strength of 17.2 MPa. A maximum bending strength of 12.109 MPa was found for the Aloe Vera gel-treated composite with 30 wt.% of FBF. The maximum average compressive strength for this composite was 17.19 MPa. A maximum bending strength of 9.97 MPa for untreated composites was recorded for the composite with 10 wt.% of FBF. Finally, Aloe Vera-treated FBF-reinforced composites have better mechanical properties than untreated ones. The mechanical properties of Aloe Vera-treated FBF-reinforced polypropylene composites, as determined via impact, compressive and flexural tests, were superior for composites with 30 wt.% of FBF. [ABSTRACT FROM AUTHOR]

Sustainability is a key factor in the development of new materials for plant pots, given the significant environmental impact of traditional plastic-based pots. Researchers have paid attention to developing biodegradable and sustainable alternatives to petroleum-based pots. In this study, two novel bioplastic formulations are developed, which incorporated soy-based by-product fractions to produce plant pots with self-fertilizing capability while also being cost-competitive. A 3D-printing process, fused filament fabrication, is used to produce plant containers from the filaments of soy-based new materials. Further, a small-scale greenhouse experiment is conducted to compare the performance of the soy-based 3D-printed bioplastic pots with pure polylactic acid (PLA) 3D-printed pots and traditional plastic pots, by growing a fruit-bearing plant (tomato) and a flowering plant (zinnia). Plant growth properties and root circling are analyzed, and the results show that the soy-based pots performed comparably to traditional plastic pots, especially in dry conditions, and also reduced root circling. While a more in-depth analysis is necessary, these initial findings suggest that using soy-based fractions and 3D-printing technology could provide a sustainable approach to developing plant pots, which could reduce the environmental impact of plastic-based containers and improve plant health. [ABSTRACT FROM AUTHOR]

The effect of the chemical treatment of paper mill sludge fibers and polypropylene molecular weight were studied relative to the physical, mechanical, and morphological properties of a novel cellulosic biocomposite. Paper mill sludge fibers were treated with acetic anhydride, and succinic anhydride was mixed with maleic anhydride polypropylene (MAPP) and coupling agent (0 and 3%). The ratio of fibers and polymer materials was considered 30 to 70, which was manufactured by the hot-pressing method at 180 °C. Water absorption, volume swelling, and contact angle were examined on each specimen according to ASTM standards, while Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) explored the efficiency of chemical modification of fibers and the morphology of biocomposites, respectively. The results showed that chemical treatment of fibers reduced the water absorption and volumetric swelling. Both tensile and flexural strength were increased with chemical treatment using the coupling agent. Comparison of fibers treated with succinic acid and acetic acid showed that the succinic acid enhanced the mechanical properties better than the acetic acid treatment. Finally, FTIR analysis showed that the hydroxyl groups decreased, and SEM images indicated the interface between fibers and polypropylene improved via chemical treatment of sludge fibers.

Bioderived poly(lactic acid) (PLA) is a promising alternative for fossil-based polymers, but its poor hydrophilicity, high brittleness, and low heat-resistance are problems for its utilization. In this work, bleached softwood kraft pulp (BSKP) fiber was adopted to modify PLA with MAPP as the coupling agent, with BSKP accounting for 10 wt% to 50 wt%. Internal mixing (IM) was applied to mix the PLA/fiber blend instead of screw grinding. The thermal and mechanical properties of the composites were assessed. The IM process was proven qualified for its effective dispersion of BSKP fibers in the PLA matrix. At a fiber loading of 50 wt%, IM-processed composites acquired satisfactory tensile strength (50.49 MPa, slightly higher than PLA) and Young's modulus (2.56 GPa, 45.8% higher than PLA). The pulp fillers matched PLA matrix well for the characteristic temperatures in thermal decomposition. The BSKP/PLA composites were thermally strengthened by pulp fibers characterized by higher content of residues. The fibers improved the interfacial crystallinity of PLA in the composites (i.e., from 5.22% to 11.86%). The increased crystallinity resulted in enhanced stiffness or weaker damping performance of the composites. In conclusion, natural plant fibers are a feasible option to modify PLA for extended applications.

Abstract As an emerging science, tissue engineering and regenerative medicine focus on developing materials to replace, restore or improve organs or tissues and enhancing the cellular capacity to proliferate, migrate and differentiate into different cell types and specific tissues. Renewable resources have been used to develop new materials, resulting in attempts to produce various environmentally friendly biomaterials. Poly (lactic acid) (PLA) is a biopolymer known to be biodegradable and it is produced from the fermentation of carbohydrates. PLA can be combined with other polymers to produce new biomaterials with suitable physicochemical properties for tissue engineering applications. Here, the advances in modified PLA as tissue engineering materials are discussed in light of its drawbacks, such as biological inertness, low cell adhesion, and low degradation rate, and the efforts conducted to address these challenges toward the design of new enhanced alternative biomaterials.

Chitons are herbivorous invertebrates that use rows of ultrahard magnetite-based teeth connected to a flexible belt (radula) to rasp away algal deposits growing on and within rocky outcrops along coastlines around the world. Each tooth is attached to the radula by an organic structure (stylus) that provides mechanical support during feeding. However, the underlying structures within the stylus, and their subsequent function within the chiton have yet to be investigated. Here, we investigate the macrostructural architecture, the regional material and elemental distribution and subsequent nano-mechanical properties of the stylus from the Northern Pacific dwelling Cryptochiton stelleri. Using a combination of μ-CT imaging, optical and electron microscopy, as well as elemental analysis, we reveal that the stylus is a highly contoured tube, mainly composed of alpha-chitin fibers, with a complex density distribution. Nanoindentation reveals regiospecific and graded mechanical properties that can be correlated with both the elemental composition and material distribution. Finite element modeling shows that the unique macroscale architecture, material distribution and elemental gradients have been optimized to preserve the structural stability of this flexible, yet robust functionally-graded fiber-reinforced composite tube, providing effective function during rasping. Understanding these complex fiber-based structures offers promising blueprints for lightweight, multifunctional and integrated materials.

This study explores the synthesis and characterization of chitosan/gelatine films incorporating nickel ferrite (NiFe2O4) and cobalt ferrite (CoFe2O4) nanoparticles. The magnetic nanoparticles exhibit superparamagnetic behaviour, making them attractive for various applications, including biomedical uses. The X-ray diffraction analysis confirmed the successful synthesis of NiFe2O4 and CoFe2O4 nanoparticles, and the scanning electron micrographs illustrated well-dispersed ferrite nanoparticles within the biopolymer network, despite the formation of some aggregates attributed to magnetic interactions. Magnetization loops revealed lower saturation magnetization values for the composites, attributed to the chitosan/gelatine coating and the dielectric studies, indicating increased dielectric losses in the presence of ferrites, particularly pronounced in the case of NiFe2O4, suggesting interactions at the interface region between the polymer and ferrite particles. The AC conductivity shows almost linear frequency dependence, associated with proton polarization and conduction processes, more significant at higher temperatures for samples with ferrite particles.

The use of wheat middlings (WM) and rice husks (RH) as biofillers for mixing with poly(lactic acid) (PLA) matrix to produce new 3D-printable biocomposites was assessed. Filaments containing 10 and 20 wt.% agro-waste-derived biofillers were manufactured and, for the sake of comparison, filaments of neat PLA were also produced. The obtained filaments were characterized via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), showing potential for further application in additive manufacturing processing. Three-dimensionally printed specimens were thus produced and characterized via: DSC, also evaluating the specific heat capacity (CP) of specific 3D-printed specimens; dynamic mechanical analysis (DMA), also applied for determining the coefficient of linear thermal expansion (CLTE) measured on 3D-printed specimens in two different directions (X and Y); and tensile tests. The latter testing campaign was carried out along three printing directions (X, Y, and Z axes) to test the intrinsic biocomposite features (X-printed samples) as well as interbead and interlayer adhesion (Y- and Z-printed specimens, respectively). All samples demonstrated acceptable properties. The inclusion of a cost-free natural material leads to a strong reduction of the whole material cost. Implementing this new class of composite material to an additive manufacturing technique can significantly reduce the environmental impact of 3D-printed products.

In the context of sustainable materials, this study explores the effects of accelerated weathering testing and bacterial biodegradation on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/rapeseed microfiber biocomposites. Accelerated weathering, simulating outdoor environmental conditions, and bacterial biodegradation, representing natural degradation processes in soil, were employed to investigate the changes in the mechanical, thermal and morphological properties of these materials during its post-production life cycle. Attention was paid to the assessment of the change of structural, mechanical and calorimetric properties of alkali and N-methylmorpholine N-oxide (NMMO)-treated rapeseed microfiber (RS)-reinforced plasticized PHBV composites before and after accelerated weathering. Results revealed that accelerated weathering led to an increase in stiffness, but a reduction in tensile strength and elongation at break, of the investigated PHBV biocomposites. Additionally, during accelerated weathering, the crystallinity of PHBV biocomposites increased, especially in the presence of RS, due to both the hydrolytic degradation of the polymer matrix and the nucleating effect of the filler. It has been observed that an increase in PHBV crystallinity, determined by DSC measurements, correlates with the intensity ratio I1225/1180 obtained from FTIR-ATR data. The treatment of RS microfibers increased the biodegradation capability of the developed PHBV composites, especially in the case of chemically untreated RS. All the developed PHBV composites demonstrated faster biodegradation in comparison to neat PHBV matrix.

The low carbon footprint, biodegradability, interesting mechanical properties, and relatively low price are considered some of the reasons for the increased interest in polylactic acid-based (PLA-based) filaments supplied with natural fillers. However, it is essential to recognize that incorporating natural fillers into virgin PLA significantly impacts the printability of the resulting blends. The complex inter-relationship between process, structure, and properties in the context of fused deposition modeling (FDM)-manufactured biocomposites is still not fully understood, which thus often results in decreased reliability of this technology in the context of biocomposites, decreased accuracy, and the increased presence of defects in the manufactured biocomposite samples. In light of these considerations, this study aims to identify the optimal processing parameters for the FDM manufacturing process involving wood-filled PLA biocomposites. This study presents an optimization approach consisting of Grey Relational Analysis in conjunction with the Taguchi orthogonal array. The optimization process has identified the combination of a scanning speed of 70 mm/s, a layer height of 0.1 mm, and a printing temperature of 220 °C as the most optimal, resulting in the highly satisfactory combination of good dimensional accuracy (Dx = 20.115 mm, Dy = 20.556 mm, and Dz = 20.220 mm) and low presence of voids (1.673%). The experimentally determined Grey Relational Grade of the specimen manufactured with the optimized set of process parameters (0.782) was in good agreement with the predicted value (0. 754), substantiating the validity of the optimization process. Additionally, the research compared the efficacy of optimization between the integrated multiparametric method and the conventional monoparametric strategy. The multiparametric method, which combines Grey Relational Analysis with the Taguchi orthogonal array, exhibited superior performance. Although the monoparametric optimization strategy yielded specimens with favorable values for the targeted properties, the analysis of the remaining characteristics uncovered unsatisfactory results. This highlights the potential drawbacks of relying on a singular optimization approach.

The main advantage of green composites is their biodegradability, but this biodegradability can also be considered a drawback if the degradation appears during the service life of the component. Therefore, the study of the mechanical behavior of green composites after hygrothermal aging tests is necessary to analyze their degradation process. This study aims to comprehensively analyze the hygrothermal aging behavior and aging mechanism of flax-fiber-reinforced polylactic acid (PLA) biocomposites. The fully biodegradable composites are manufactured by compression molding. In addition, the influence of atmospheric-pressure plasma treatment on the mechanical properties of the biocomposite is studied. Specimens are exposed to water vapor and 40 °C environmental conditions in a stove for up to 42 days. Several specimens of each type are taken out at regular intervals and tested to examine the water absorption, mechanical properties, and thermal characterization. The results show that the stiffness was significantly reduced after 24 h due to matrix degradation, while the strength was reduced only after three weeks.

This paper delves into the development of biocomposite (BC) packaging material from tapioca starch (TS), flax seed gel (FS), and Siam weed (SW) extract, considering the increased demand for sustainable, eco-friendly packaging materials. The BCs—BC1 (40 mL), BC2 (80 mL), and BC3 (120 mL), prepared by varying the concentration of SW—were subjected to morphological, structure, thermal, and optical characterisations. The BC with a fragmented, agglomerated morphology shows cellulosic peaks in the X-ray diffraction pattern, indicating the C-type crystalline structure in TS. Thermogravimetric analysis confirmed the BC’s safe use up to 300 °C, with a minimal 40% weight loss. Differential scanning calorimetry plots identified heat absorption during gelatinisation, with an endothermic peak at 300 °C marking a phase transition. The Fourier transform infrared (FTIR) and UV–visible spectra revealed functional groups that attribute antibacterial potential to the BC. The optical analyses show greater absorption and fewer emissions, resulting in the increased enthalpy responsible for the microbial activities. Antibacterial studies demonstrated BC2’s efficacy against Staphylococcus aureus, while the stability against humidity and the minimal weight loss underscored the BC’s robust thermal stability. FTIR spectra of post-heating at 80 °C confirmed the structural integrity, positioning the BC as a promising material for eco-friendly packaging solutions.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biobased and biodegradable polymer. This polymer is considered promising, but it is also rather expensive. The objective of this study was to compound PHBV with three different organic fillers considered waste: human hair waste (HHW), sawdust (SD) and chitin from shrimp shells. Thus, the cost of the biopolymer is reduced, and, at the same time, waste materials are valorised into something useful. The composites prepared were characterised by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile strength and scanning electron micrograph (SEM). Tests showed that chitin and HHW did not have a reinforcing effect on tensile strength while the SD increased the tensile strength at break to a certain degree. The biodegradation of the different composites was evaluated by a soil burial test for five months. The gravimetric test showed that neat PHBV was moderately degraded (about 5% weight loss) while reinforcing the polymer with organic waste clearly improved the biodegradation. The strongest biodegradation was achieved when the biopolymer was compounded with HHW (35% weight loss). The strong biodegradation of HHW was further demonstrated by characterisation by Fourier-transform infrared spectroscopy (FTIR) and solid-state nuclear magnetic resonance (NMR). Characterisation by SEM showed that the surfaces of the biodegraded samples were eroded.

The fiber-filled polymer composite is one of the best materials which provides a symmetrical superior strength and stiffness to structures. With the strengthening of people’s environmental protection and resource reuse consciousness, the development of renewable materials, especially natural fiber-filled polymer composites, is receiving great attention. This study investigated the mechanical properties of polymer composites incorporating waste materials from the food processing industry and agricultural sources. Waste vegetal fiber-filled polymer biocomposites (WVFFPBs) with varying fiber types and 3D printing orientations were systematically fabricated. Subsequently, the tensile tests were executed to comprehensively assess the anisotropic mechanical behaviors of the WVFFPBs. The results demonstrated that WVFFPBs performed excellent anisotropic mechanical properties compared to pristine matrix samples as print orientation changed. As the printing angle increased from 0° to 90°, the tensile mechanical properties of the WVFFPBs displayed a decreasing trend. Moreover, the print orientation–anisotropic mechanical behavior relationship of 3D-printed WVFFPBs was revealed through the analysis of the material manufacturing characteristics and damage features.

editorial

The main objective of this study is to review the applicability of rapeseed straw (RSS) as a sustainable filler material in polylactic acid (PLA)-based biocomposites. The effect of different RSS particle sizes and concentrations (0–20 wt%) on the mechanical, morphological, thermal, and water absorption properties was investigated. The composites were fabricated by melt compounding using a twin-screw extruder followed by injection molding. The mechanical properties were analyzed through tensile and flexural tests and Charpy impact tests. The morphology of the samples was investigated by scanning electron microscopy (SEM). The thermal properties and the crystallinity of the composites were determined through differential scanning calorimetry (DSC). Mechanical properties revealed an increasing stiffness of PLA as a function of RSS loading, albeit at the cost of strength. SEM images have shown a limited interfacial adhesion between PLA and the straw, which was suggested to be responsible for the decreased strength values. Based on the DSC measurements, the RSS fibers facilitated the nucleation in the composites, thereby decreasing the cold crystallization temperature of PLA. The conducted experiments demonstrated that environmentally friendly and economically attractive biocomposites can be fabricated by substituting part of the PLA with RSS as a lignocellulosic by-product.

Abstract Spearing mantis shrimps are aggressive crustaceans using specialized appendages with sharp spikes to capture fishes with fast movement. Each spike is a biological tool that has to combine high toughness, as required by the initial impact with the victim, with high stiffness and strength, to ensure sufficient penetration while avoid breaking. We performed a multimodal analysis to uncover the design strategies of this harpoon based on chitin. We found that the spike is a slightly hooked hollow beam with the outer surface decorated by serrations and grooves to enhance cutting and interlocking. The cuticle of the spike resembles a multilayer composite: An outer heavily mineralized, stiff, and hard region (with average indentation modulus and hardness of 68 and 3 GPa), providing high resistance to contact stresses, is combined with a less mineralized region, which occupies a large fraction of the cuticle (up to 50%) and features parallel fibers oriented longitudinally, enhancing stiffness and strength. A central finding of our work is the presence of a tiny interphase (less than 10 μm in width) based on helical fibers and showing a spatial modulation in mechanical properties, which has the critical task to integrate the stiff but brittle outer layer with the more compliant highly anisotropic parallel‐fiber region. We highlighted the remarkable ability of this helicoidal region to stop nanoindentation‐induced cracks. Using three‐dimensional multimaterial printing to prototype spike‐inspired composites, we showed how the observed construction principles can not only hamper damage propagation between highly dissimilar layers (resulting in composites with the helical interphase absorbing 50% more energy than without it) but can also enhance resistance to puncture (25% increase in the force required to penetrate the composites with a blunt tool). Such findings may provide guidelines to design lightweight harpoons relying on environmentally friendly and recyclable building blocks. Key Points –The heavily mineralized biological appendages of the mantis shrimp are a constant source of inspiration for developing new engineering materials. –We use characterization methods of material science to investigate a biological harpoon based on chitin. –Several morphological, compositional, microstructural, and biomechanical features are highlighted, allowing the spikes of the mantis shrimp to be remarkable lightweight, tough, and stiff harpoons.

Biodegradable plastic-based items play an essential role in ensuring the sustainability of the food packaging industry due to their high biodegradability and minimized use of fossil fuels. The incorporation of low-cost waste biomass into bio-based polymers to produce biodegradable composites supports the circular economy model and reduces landfilling and carbon footprint challenges associated with petroleum-based plastics. This work discusses the utilization of waste almond shell powder (ASP) up to 50 wt.% with poly(butylene succinate-co-butylene adipate) (PBSA) to develop sustainable biocomposites through injection moulding for rigid packaging applications. At a lower angular frequency (0.1 s − 1), the complex viscosity of the PBSA/50%ASP biocomposite was reduced by ∼65% after adding 5 wt.% compatibilizer, as confirmed by a rheological analysis. The heat deflection temperature, flexural strength, and tensile and flexural moduli of the PBSA/50% ASP biocomposite with 5 wt.% compatibilizer were improved by ∼24, 125, 368, and 385%, respectively, compared to pristine PBSA. These improvements are attributed to the high stiffness and load-bearing capacity of ASP and the enhanced interfacial adhesion and particle dispersion caused by the compatibilizer, as corroborated by SEM analyses. Hence, the formulated biocomposites show a suitable structure-property-processing co-relationship for injection moulding of single-use products.

Hydroxyapatite doped with magnesium and zinc in chitosan matrix biocomposites have great potential for applications in space technology, aerospace, as well as in the biomedical field, as a result of coatings with multifunctional properties that meet the increased requirements for wide applications. In this study, coatings on titanium substrates were developed using hydroxyapatite doped with magnesium and zinc ions in a chitosan matrix (MgZnHAp_Ch). Valuable information concerning the surface morphology and chemical composition of MgZnHAp_Ch composite layers were obtained from studies that performed scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), metallographic microscopy, and atomic force microscopy (AFM). The wettability of the novel coatings, based on magnesium and zinc-doped biocomposites in a chitosan matrix on a titanium substrate, was evaluated by performing water contact angle studies. Furthermore, the swelling properties, together with the coating's adherence to the titanium substrate, were also analyzed. The AFM results emphasized that the composite layers exhibited the surface topography of a uniform layer, and that there were no evident cracks and fissures present on the investigated surface. Moreover, antifungal studies concerning the MgZnHAp_Ch coatings were also carried out. The data obtained from quantitative antifungal assays highlight the strong inhibitory effects of MgZnHAp_Ch against C. albicans. Additionally, our results underline that after 72 h of exposure, the MgZnHAp_Ch coatings display fungicidal features. Thus, the obtained results suggest that the MgZnHAp_Ch coatings possess the requisite properties that make them suitable for use in the development of new coatings with enhanced antifungal features. [ABSTRACT FROM AUTHOR]

Astragalus residue powder (ARP)/thermoplastic starch (TPS)/poly(lactic acid) (PLA) biocomposites were prepared by fused-deposition modeling (FDM) 3D-printing technology for the first time in this paper, and certain physico-mechanical properties and soil-burial-biodegradation behaviors of the biocomposites were investigated. The results showed that after raising the dosage of ARP, the tensile and flexural strengths, the elongation at break and the thermal stability of the sample decreased, while the tensile and flexural moduli increased; after raising the dosage of TPS, the tensile and flexural strengths, the elongation at break and the thermal stability all decreased. Among all of the samples, sample C—which was composed of 11 wt.% ARP, 10 wt.% TPS and 79 wt.% PLA—was the cheapest and also the most easily degraded in water. The soil-degradation-behavior analysis of sample C showed that, after being buried in soil, the surfaces of the samples became grey at first, then darkened, after which the smooth surfaces became rough and certain components were found to detach from the samples. After soil burial for 180 days, there was weight loss of 21.40%, and the flexural strength and modulus, as well as the storage modulus, reduced from 82.1 MPa, 11,922.16 MPa and 2395.3 MPa to 47.6 MPa, 6653.92 MPa and 1476.5 MPa, respectively. Soil burial had little effect on the glass transition, cold crystallization or melting temperatures, while it reduced the crystallinity of the samples. It is concluded that the FDM 3D-printed ARP/TPS/PLA biocomposites are easy to degrade in soil conditions. This study developed a new kind of thoroughly degradable biocomposite for FDM 3D printing. [ABSTRACT FROM AUTHOR]

The management of diabetic foot osteomyelitis (DFO) is extremely challenging with high amputation rates reported alongside a five-year mortality risk of more than fifty percent. We describe our experience in using adjuvant antibiotic-loaded bio-composite material (Cerament) in the surgical management of DFO and infected Charcot foot reconstruction. We undertook a retrospective evaluation of 53 consecutive patients (54 feet) who underwent Gentamicin or Vancomycin-loaded Cerament application during surgery. The feet were categorised into two groups: Group 1, with infected ulcer and DFO, managed with radical debridement only (n = 17), and Group 2, requiring reconstruction surgery for infected and deformed Charcot foot. Group 2 was further subdivided into 2a, with feet previously cleared of infection and undergoing a single-stage reconstruction (n = 19), and 2b, with feet having an active infection managed with a two-stage reconstruction (n = 18). The mean age was 56 years (27–83) and 59% (31/53) were males. The mean BMI was 30.2 kg/m2 (20.8–45.5). Foot ulcers were present in 69% (37/54) feet. At a mean follow-up of 30 months (12–98), there were two patients lost to follow up and the mortality rate was 11% (n = 5). The mean duration of post-operative systemic antibiotic administration was 20 days (4–42). Thirteen out of fifteen feet (87%) in group 1 achieved complete eradication of infection. There was a 100% primary ulcer resolution, 100% limb salvage and 76% bony union rate within Group 2. However, five patients, all in group 2, required reoperations due to problems with bone union. The use of antibiotic-loaded Cerament resulted in a high proportion of patients achieving infection clearance, functional limb salvage and decrease in the duration of postoperative antibiotic therapy. Larger, preferably randomised, studies are required to further validate these observations. [ABSTRACT FROM AUTHOR]

The effect of the chemical treatment of paper mill sludge fibers and polypropylene molecular weight were studied relative to the physical, mechanical, and morphological properties of a novel cellulosic biocomposite. Paper mill sludge fibers were treated with acetic anhydride, and succinic anhydride was mixed with maleic anhydride polypropylene (MAPP) and coupling agent (0 and 3%). The ratio of fibers and polymer materials was considered 30 to 70, which was manufactured by the hotpressing method at 180 °C. Water absorption, volume swelling, and contact angle were examined on each specimen according to ASTM standards, while Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) explored the efficiency of chemical modification of fibers and the morphology of biocomposites, respectively. The results showed that chemical treatment of fibers reduced the water absorption and volumetric swelling. Both tensile and flexural strength were increased with chemical treatment using the coupling agent. Comparison of fibers treated with succinic acid and acetic acid showed that the succinic acid enhanced the mechanical properties better than the acetic acid treatment. Finally, FTIR analysis showed that the hydroxyl groups decreased, and SEM images indicated the interface between fibers and polypropylene improved via chemical treatment of sludge fibers. [ABSTRACT FROM AUTHOR]

Bioderived poly(lactic acid) (PLA) is a promising alternative for fossilbased polymers, but its poor hydrophilicity, high brittleness, and low heatresistance are problems for its utilization. In this work, bleached softwood kraft pulp (BSKP) fiber was adopted to modify PLA with MAPP as the coupling agent, with BSKP accounting for 10 wt% to 50 wt%. Internal mixing (IM) was applied to mix the PLA/fiber blend instead of screw grinding. The thermal and mechanical properties of the composites were assessed. The IM process was proven qualified for its effective dispersion of BSKP fibers in the PLA matrix. At a fiber loading of 50 wt%, IMprocessed composites acquired satisfactory tensile strength (50.49 MPa, slightly higher than PLA) and Young's modulus (2.56 GPa, 45.8% higher than PLA). The pulp fillers matched PLA matrix well for the characteristic temperatures in thermal decomposition. The BSKP/PLA composites were thermally strengthened by pulp fibers characterized by higher content of residues. The fibers improved the interfacial crystallinity of PLA in the composites (i.e., from 5.22% to 11.86%). The increased crystallinity resulted in enhanced stiffness or weaker damping performance of the composites. In conclusion, natural plant fibers are a feasible option to modify PLA for extended applications. [ABSTRACT FROM AUTHOR]

The high incidence of osteochondral defects has increased the interest in the development of improved repairing alternatives, with tissue engineering being considered a promising approach. The hierarchical, complex structure of osteochondral tissue requires the design of a biomimetic multilayered scaffold. Here, a multilayered and multiphasic 3D macroporous structure was achieved at subzero temperature by the Michael addition reaction of amino functionalities of collagen with acryloyl groups of a bifunctionalized poly(ε-caprolactone). This green approach has been successfully applied to crosslink layers of different composition, both for their efficient sequential formation and connection. Polyethylenimine functionalized nano-hydroxyapatite (nHApLPEI) was added to the bottom layer. The resulting hybrid cryogels were characterized by morphology, equilibrium swelling ratios, compressive strength analysis, and MTS assay. They presented good stability, integrity, and biocompatibility. The results revealed that the properties of the prepared constructs may be tuned by varying the composition, number, and thickness of the layers. The Young modulus values were between 3.5 ± 0.02 and 10.5 ± 0.6 kPa for the component layers, while for the multilayered structures they were more than 7.3 ± 0.2 kPa. The equilibrium swelling ratio varied between 4.6 and 14.2, with a value of ~10.5 for the trilayered structure, correlated with the mean pore sizes (74–230 µm). [ABSTRACT FROM AUTHOR]

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This paper aims to apply a generic model for the transition to a product classified as a Product-Service System in the bike sharing case. For theoretical foundation, a systematic literature review was conducted, and then, the model was developed and validated with PSS experts and statistical analysis. Considering the need of PSS products to be aligned with the Tripple Botton Line, a Life Cycle Analysis (LCA) was performed to measure the environmental and human health impacts of a bike. Aiming to design an action plan and mitigate these impacts, the generic model was applied. The results contribute to (i) the theoretical development of the literature by proposing a generic model validated and applicable in other cases, and (ii) with the practical development, since with the application of the LCA and the model, it was possible to identify an alternative to mitigate the impacts of the most polluting part of a bike: the aluminum frame. Thus, this study proposes substituting aluminum with a polymeric biocomposite: a blend between polypropylene and bamboo fiber. Given the theoretical modeling of this work, future studies can focus on the practical validation of this blend through mechanical testing. [ABSTRACT FROM AUTHOR]

The development of novel polymeric composites, especially those based on conductive polymers has attracted a considerable attention due to their applications in a wide range of fields. This study focuses on one of these biocomposites based on polyaniline Pani and a biopolymer (microcrystalline cellulose MCC), synthesized by in-situ polymerization of aniline using ammonium persulfate (APS) as oxidant at room temperature. Firstly, different amounts of MCC were dispersed in HCl solution with aniline monomer under stirring. Then a mixture of APS/HCl solution was introduced into the first aniline-MCC-HCl mixture. The obtained materials as well as Pani and MCC were characterized using powder X-ray diffraction (XRD), Argon adsorption–desorption (BET/DFT), thermal analysis, fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Thus, a correlation between interesting structural/textural/morphological data of these materials will be established. The results confirm the formation of Polyaniline-MCC composite under well determined conditions which has a more compact homogeneous morphology and a higher thermal stability than those of Pani and MCC. Furthermore, these materials are used for the catalytic degradation of toxic anionic dye namely Methyl Orange (MO) from aqueous media under UV light irradiation. The optimum values were 0.1 g L− 1 of photocatalyst, 30 ppm of MO solution, and pH solution of 5.6, which allowed reaching 97% within 70 min with high stability after four continuous runs. The photodegradation kinetics of MO onto composite followed the pseudo-first order model. [ABSTRACT FROM AUTHOR]

A green biocomposite (BTF-i-ACS) consisting of banana trunk fibers (BTF)-infused acidified chitosan (ACS) was prepared. The biocomposite was characterized by means of Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). The results of characterization indicated that BTF are widely immobilized in ACS without any chemical interaction. The biocomposite was used for the removal of Cd2+ from aqueous media. The effect of pH, contact time and initial concentration was evaluated. Contact time of 120 min and pH ~ 6.50 were selected for the removal of Cd2+ at ambient temperature (27 ± 1 °C). The percentage removal of Cd2+ was found to be 92.67%. The data best fitted pseudo-second order kinetics and Freundlich isotherm model indicating that the rate-limiting step might be chemisorption involving sharing or transfer of electrons between Cd2+ and biocomposite.

Recent investigations proposed alternatives for utilization of Açaí (Euterpe oleracea Mart.) fruit wastes, seeds, and lignocellulosic fibers. However, Açaí leaves may also be obtained without harvesting the palms and could be used in higher value-added products. Alkali reaction (1% and 5% of NaOH), different temperatures (70°C, 80°C, and 100°C), and bleaching were combined to produce fibres from the Açaí leaves. Scanning electron microscopy, X-ray diffraction, and thermogravimetry were used to evaluate the effect of treatments on fibers, whereas X-ray diffraction and calorimetry were employed to characterize Portland cement pastes containing fibers. Results indicated that Açaí leaves could be transformed into short-length fibers with improved degrading temperature. Alkali treatment at 5% sodium hydroxide (90°C) and bleaching increased fibers’ crystallinity and showed efficiency in removing non-cellulosic components. Cement paste evaluation also indicated that fibers treated at 5% NaOH solution caused fewer changes in calorimetric profile and therefore present a greater potential for cement-based composites.

This study investigated the effects of poly(butylene-succinate) (PBS) and cassava pulp (CP) at two particle sizes (250 and 400 µm) on the properties of PBS/CP biocomposites. The PBS/CP biocomposites with different ratios (PBS100/CP0, PBS90/CP10, PBS80/CP20, PBS70/CP30, and PBS60/CP40) were prepared using a twin-screw extruder and formed using a ram extruder. The physical, mechanical, and biodegradable properties of these biocomposites were studied. The results showed that the melt flow index of biocomposites significantly decreased with an increase in the CP content as observed in both CP particle sizes. It was also observed that using 400 µm CP in PBS80/CP20 led to a higher melt flow index as compared to using 250 µm CP. The PBS/CP biocomposites were shown to improve Young's modulus and hardness. Nevertheless, tensile strength, elongation at break, and impact strength of the PBS/CP biocomposites decreased with an increase in the amount of CP (in both particle sizes). The addition of 250 µm CP provided good particle dispersion and compatibility in the biocomposite matrix. An increase in the CP content of up to 40% showed that the biocomposites had more brittle fracture although they were also the best biodegradable as indicated by natural soil burial test for 42 days. A biocomposite from PBS/CP could be useful in commodity packaging, outdoor plant pots, and injection molding as eco-friendly, strong and biodegradable materials.

In recent decades, scientists have started to search for more sustainable and environmentally friendly materials. It is known that building materials are among the most used materials and have a visible negative effect on the environment. The development of environmentally friendly composites in buildings offers different solutions to decrease energy consumption. The aim of the present study is to investigate a new biocomposite material fabricated with natural date palm fibers (DPFs), cement, and sand. The main objective is to assess the thermal insulation characteristics as well as the water absorption and mechanical performance of this material for building industry. The percentage by weight of DPF in the studied specimens ranged from 0% to 30% for two fiber sizes. The characteristics of these specimens were determined experimentally in terms of flexural and compression strength as well as thermal conductivity. The results confirmed that the thermal conductivity decreases with the addition of DPF. Also, the compressive strength of the composite decreases with the weight reduction. Thus, DPF has a positive effect on the thermo-mechanical properties of the considered material. Consequently, it considerably improves the mortar insulating capacity.

The present study focuses on the development of biodegradable composites to replace synthetic polymer-based composites for potential lightweight structural applications in the automobile, aeronautical, marine, and packaging industries. Initially, PLA and NFBF/PLA films are prepared by solution casting, and from these films, composite laminates are prepared by film sequencing and compression (hot-press) molding methods. First, the critical buckling load (Pcr) of composites is analyzed, and then, the influence of compressive load on natural frequency is studied. The critical buckling load-bearing capacity of PLA is enhanced with the reinforcement of NFBF (natural fiber braided yarn fabric). The composite with three layers of NFBF registered the highest critical-buckling load (Pcr) of 374.19 N, and this value is 172.13% high compared to the virgin PLA. Similarly, the natural frequency of the NFBF composites approaches minimum when the applied load is equal to the corresponding Pcr. However, a significant increase in the fundamental frequency is noticed when the applied load is higher than the Pcr.

Alginate based biofilms are widely used for designing edible food packaging while its application for developing inedible waterproof food packaging has not been studied enough. Both, cellulose fiber and alginate are attractive natural materials that could be used for developing natural fiber-based food packaging. In this research the cellulose/alginate biocomposites were produced by eco-friendly technique bi-layer lamination of prepared cellulose (C) fiber plates with sodium (SA) and calcium alginates (CA) containing glycerol as plasticizer. The morphology, moisture content, solubility in water, water vapor permeability (WVP), surface hydrophobicity and mechanical characteristics of prepared cellulose/alginates biocomposites were evaluated and compared. The biocomposite surface morphology evaluation showed that all analyzed samples had smooth surfaces without cracks. Moreover, obtained results showed that plasticizer is essential in developing biocomposites with improved characteristics. The concentration of glycerol had a positive effect on gloss, flexibility, moisture content, solubility in water and negative effect to surface hydrophobicity of C/SA and C/CA biocomposites. It was observed that samples had partly hydrophobic surfaces which contact angles varies from 37° to 63°. Mechanical characteristics revealed that the most promising are C/CA biocomposites that could be further modified for waterproof food packaging developing.

For the past few decades environmental concerns had been influencing the researchers to employ natural fibers and polymers from renewable resources as a replacement for petroleum-based resins and synthetic fibers. In this work, materials from renewable resources were used to prepare the composites. Modified epoxidised soybean oil as resin was employed to prepare the composites with chicken feather fibers as the reinforcing agent by compression molding technique. Epoxidised soybean oil (ESO) was modified by reacting with methacrylic acid and methacrylic anhydride to form resin. Rosin acid derivative was synthesized to serve as the crosslinker for replacement of the petroleum based divinylbenzene (DVB). For comparison, divinylbenzene (DVB) was also employed to copolymerize with the same resin. Chemical structure of rosin derivative was verified by 1H-NMR spectroscopy. FT-IR study showed the interaction between resin, chicken feather fiber (CFF) and rosin derivatives. The morphological features of the composites were evaluated by scanning electron microscopy (SEM), where it indicated a uniform interaction among the components of the composites. Different experimental results showed that the composites with higher amount of rosin acid derivative showed better properties. Results demonstrated that rosin acid derivative can serve as a substitute for petroleum-based rigid compounds for preparing biocomposites.

In pursuit of new biobased materials for a sustainable world, glasswort (Salicornia europaea) was utilized in this study as a natural fiber to develop a biocomposite material. Glasswort (GW) reinforced high-density polyethylene (HDPE) composites at different GW percentages were prepared with a high-speed thermo-kinetic mixer. The effect of GW on HDPE composites was thoroughly investigated with Fourier transform infrared (FTIR) spectroscopy, tensile and flexural tests, dynamic mechanical analysis, water contact angle measurements, and scanning electron microscopy (SEM). A new method was also developed by seawater immersion of samples to conduct microbiological analysis. The method included bacteria population count with respect to time. Biointegration was reported to increase as 25% for 20 wt% GW-filled HDPE. The tensile modulus of HDPE increased up to 20% with GW inclusion. The unique properties of this novel composite material proved that GW can be a promising natural fiber for polymer composites.

New research directions regarding novel materials and manufacturing processes are continuously developed all around the world. In particular, replacement products and materials exhibiting a high degree of recyclability and environmentally friendly are sought after in most activity fields. The goal of finding and eventually employing such materials in the immediate future is very important, if considering the massive invasion of plastic products, known as having an extremely long-term biodegradability and a still limited recycling capacity. “Liquid wood” is a material with potential to replace some plastic materials, due to its properties superior to other plastics and to its biodegradability. To this end, it is very important to know the properties of “liquid wood” and its processing possibilities, comparatively with plastic materials. The “liquid wood” granules considered for analysis are: arboform, arbofill and arboblend trademarks. The constituents of arboform granules are: lignocellulosic fibers (a combination of cellulose, lignin and wood polyoses); lignin, polyesters, as natural polymers; natural resins/ waxes: aromatic and aliphatic ketones, carbonic acids, alcohols, lactones and polycycles in monomeric, polymeric and oligomeric form. The arboblend granules contain biopolymers like polyester, polyhydroxialkanoate, ingeo TM, lignin, cellulose, starch, organic additives, natural resins or waxes and natural reinforcing fibers. Arbofill granules are mostly made of polypropylene or polyethylene as petrochemical polymers, reinforced with flax, hemp or wood fiber (natural fiber). As noticed, irrespective of the form of the “liquid wood” to be used for 3D printing, all have a significant content of lignin, therefore the experiments made for lignin are applicable. To obtain products for use in industry or even in everyday human activity, the material known as “liquid wood” has already been processed by injection molding in molds, by rotation and compression, compression, extrusion, thermoforming. The chemical methods employed involve hydroximethylation and epoxidation reactions, already used for obtaining lignin nanoparticles. As to the physical methods applied, a first one consists in the irradiation, in the ultrasonic field, of powder lignin (i.e., the sonicity method). A second physical way for obtaining “liquid wood” nanoparticles was by using laser ablation of the “liquid wood” in different liquid mediums. Generation of “liquid wood” nanoparticles through laser ablation has been experimentally and theoretically investigated. The dispersed ablation product resulted from the interaction of a nanosecond pulsed laser (Quantel Brilliant, 1064 nm, 10 ns) with an “liquid wood” target immersed in different liquid media has been studied through specific experimental techniques for morphological (atomic force microscopy – AFM, dynamic light scattering – DLS, transmission electron microscopy – TEM) and structural analysis (X-ray diffraction – XRD, Raman spectroscopy). The visible emitting regions of the plasma resulted from the interaction of a nanosecond pulsed laser with target material have been investigated through ICCD fast imaging. Additionally, a Langmuir probe has been used to study the transient charged particles cloud. A non-differentiable hydrodynamic model has been established according to our own experimental data.

The most important reason why natural fibers are not sufficiently involved in applications is the large scattering of their properties. In addition, it is very difficult to find one kind of natural fiber which has perfect mechanical properties like synthetic fibers. Here, we aimed to find solutions by developing a hybrid composite according to the expectations in the field of application. With this method, desired mechanical properties can be designed, and the weak properties can be improved. To be able to examine this method, we used two different fibers which have different mechanical characteristics. The mechanical properties were measured with three-point bending and impact resistance tests. According to the results, the flexural strength of the jute-reinforced composites (JC) has been improved by 44–71% using luffa fiber hybridization method. On the other hand, it has been observed that the impact resistance of the same specimens of JC has been improved by 51–83%. These results revealed that it is possible to improve the mechanical properties of the composites with hybridization. In conclusion, our study shows that bio-composites can be designed according to the requirement of the application. Hence, the application areas of bio-composites can be widened with increased usage rates.