Composite Biomaterials Research Articles

Biochar as a UV Stabilizer: Its Impact on the Photostability of Poly(butylene succinate) Biocomposites.

In the present study, biocomposite materials were created by incorporating biochar (BC) at rates of 1, 2.5, and 5 wt.% into a poly(butylene succinate) (PBSu) matrix using a two-stage melt polycondensation procedure in order to provide understanding of the aging process. The biocomposites in film form were exposed to UV irradiation for 7, 14, and 21 days. Photostability was examined by several methods, such as Fourier transform infrared spectroscopy (FTIR), which proved that new carbonyl and hydroxyl groups were formed during UV exposure. Moreover, Differential Scanning Calorimetry (DSC) measurements were employed to record the apparent UV effect in their crystalline morphology and thermal transitions. According to the molecular weight measurements of composites, it was apparent that by increasing the biochar content, the molecular weight decreased at a slower rate. Tensile strength tests were performed to evaluate the deterioration of their mechanical properties during UV exposure, while Scanning Electron Microscopy (SEM) images illustrated the notable surface alternations. Cracks were formed at higher UV exposure times, to a lesser extent in PBSu/BC composites than in neat PBSu. Furthermore, the mechanism of the thermal degradation of neat PBSu and its biocomposites prior to and upon UV exposure was studied by Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS). From all the obtained results it was proved that biochar can be considered as an efficient UV-protective additive to PBSu, capable of mitigating photodegradation.

Risk of rainfall caused leaching from bio-composite material based building façades into the aquatic environment

The increasing focus on sustainability and circularity is driving the global production of environmentally friendly products. The Netherlands started producing new bio-composite materials which are created by reclaiming resources from various sectors of the water industry. These materials can be used for a variety of applications including façade elements in buildings. However, their potential environmental impact, particularly with regard to leaching of potentially harmful substances into surface water, necessitates further evaluation. To address this issue, a systematic environmental risk assessment methodology combined with novel experimental data is presented here. To collect this data, façade panels made of two different bio-composite materials were first subjected to a series of laboratory tests, including analysis in both new and weathered forms, the latter subject to a cyclic UV radiation and high humidity, in order to simulate the effects of aging. Leaching tests were then conducted to determine the potential release of specific chemical substances such as heavy metals and resin compounds, under two different rainfall conditions (every day and more extreme). The data generated this way was used to perform the risk assessment using the existing European ERA framework. The results obtained reveal different leaching behaviour of the new and weathered samples, as well as between the two analysed bio-composite materials, depending on the rain intensity. To overcome the uncertainties caused by the limited input data, a sensitivity analysis was carried out whereby leaching concentrations and rainfall intensities were varied and their influence on the environmental risk was assessed. The results obtained demonstrated that, despite some variability, both materials appear safe to use, i.e., with estimated risks below the established safety threshold. While these findings provide a preliminary indication, they are based on laboratory conditions and assumptions hence further field studies are recommended to obtain more definitive conclusions.

Determination of rare earth elements in synthetic calcium phosphates by high-resolution continuum source electrothermal atomic absorption spectrometry

Ceramic, cement and composite biomaterials have been developed based on hydroxyapatites (HA) and tricalcium phosphates (TCP), which are analogous in phase and chemical composition to the mineral component of bone tissue. The crystal structures of HA and TCP are arranged in isomorphic substitutions. Recently, research has focused on the modification of HA and TCP structures with ions of various metals, including rare earth ions (REEs), with the aim of creating materials with a range of beneficial properties for medical applications. REEs are known to have a number of useful properties, including antibacterial, antitumour, catalytic, magnetic and luminescent properties. The replacement of some of the Ca ions in the structures of HA and TCP with REE ions therefore makes it possible to obtain a material with biocompatibility and biological activity, giving it the required properties depending on the REE used and its concentration. In order to achieve the specified properties, it is necessary to control not only the structure (phase composition, lattice parameters of the powders) and the presence of characteristic functional groups, but also the chemical elemental composition. Modifications of hydroxyapatites and tricalcium phosphates containing from one to several different alloying elements are currently being developed. Various analytical methods are used for this purpose, including X-ray, atomic emission and a number of others. This article is devoted to the study of the analytical capabilities of the method of atomic absorption spectrometry with electrothermal atomization and a continuous spectrum source in relation to the determination of Eu and Yb in hydroxyapatites and tricalcium phosphates. The article considers the optimal conditions and modes of analysis, including temperature-time programs, the use of modifiers, the construction of calibration curves, and other factors that can be adjusted for more precise results. The results demonstrated the possibility of simultaneous determination of both Eu and Yb in the concentration range of 0.09 to 2 wt.%, with a relative standard deviation of less than 6 rel.%.

Hybrid Fiber-Reinforced Biocomposites for Marine Applications: A Review

Highly efficient fiber-reinforced composites find extensive application in diverse industries. Yet, conventional fiber-reinforced composites have significant environmental impacts during both manufacturing and disposal. Environmentally friendly fiber-reinforced composites have garnered significant attention within the framework of sustainable development. Utilizing natural fibers in place of synthetic fibers and progressively decreasing the use of synthetic fibers are the main approaches to achieving a balance between economic progress and environmental quality. Attention is increasingly being drawn to natural fiber-reinforced biocomposites that exhibit outstanding environmental performance, exceptional physical and mechanical capabilities, and biological features. The lightweight and high-strength characteristics of these biocomposites enable them to significantly decrease the weight of structures, making them increasingly popular in many industries. The objective of this review is to evaluate the effectiveness of hybrid fiber-reinforced biocomposites in marine applications, specifically examining their mechanical characteristics, resistance to seawater, and ability to absorb moisture, all while advocating for sustainable material methodologies. To achieve this objective, the paper delineates the distinction between synthetic and natural fibers, examines the benefits of hybrid fiber-reinforced biocomposite materials, and addresses the obstacles and effective approaches in their production and application in seawater. Considering the review analysis, it can be inferred that the use of fiber-reinforced biocomposites in maritime applications shows significant potential and has abundant untapped growth prospects in the future years.

Characterization of three-dimensional printed hydroxyapatite/collagen composite slurry

Nowadays, biomaterial composites for bone tissue engineering are developing rapidly. Many research studies have been done on hydroxyapatite (HA) and collagen because these materials are biomimetic and can be used in human bones. This study aimed to characterize a three-dimensional (3D) printed hydroxyapatite/collagen composite slurry material with a ratio of 99.84 % (w/v) and 0.16 % (w/v). The composite material was printed using 3D printing with a print speed of 10 mm/min and a layer height of 0.5 mm. Characterization layers were investigated using a scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray (EDX), and thermogravimetric analysis (TGA). SEM showed the occurrence of overlapping between layers, which was investigated by the reduction in layer dimensions after printing (layer size 432 μm). Moreover, there were no boundaries between layers; the connection between layers occurred, and porosity and the rough surface were presented. FTIR analyses showed spectrum peaks at 559.36, 628.79, 1022.27, 1562.34, and 1639.49 cm−1 which was confirmed as hydroxyapatite and amide (indicates the presence of spectrum collagen). The XRD pattern peaks show the crystallinity of HA/collagen composite (41 %) and HA (42 %). The Ca/P ratio of the material composite was 1.77. The ratio was osteoconductive, and this characteristic was the main requirement for bone grafts. From TGA, the weight loss occurred between temperatures of 25 °C and 1000 °C with three stages: water absorption (1.844 %), removal of organic content (2.854 %), and decomposition of inorganic compounds (3.517 %).

Preparation and Characterization of Photo-Cross-Linkable Methacrylated Silk Fibroin and Methacrylated Hyaluronic Acid Composite Hydrogels.

Composite biomaterials with excellent biocompatibility and biodegradability are crucial in tissue engineering. In this work, a composite protein and polysaccharide photo-cross-linkable hydrogel was prepared using silk fibroin methacrylate (SFMA) and hyaluronic acid methacrylate (HAMA). SFMA was obtained by the methacrylation of degummed SF with glycidyl methacrylate (GMA), while HA was methacrylated by 2-aminoethyl methacrylate hydrochloride (AEMA). We investigated the effect of the addition of 1 wt % HAMA to 5, 10, and 20 wt % SFMA, which resulted in an increase in both static and cycling mechanical strengths. All composite hydrogels gelled under UV light in <30 s, allowing for rapid stabilization and stiffness increases. The biocompatibility of the hydrogels was confirmed by direct and indirect contact methods and by evaluation against the NIH3T3 and MC3T3 cell lines with a live-dead assay by confocal imaging. The range of obtained mechanical properties from developed composite and UV-cross-linkable hydrogels sets the basis as possible future biomaterials for various biomedical applications.

Surface treatment effects on morphological and property enhancements of poly (3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/Diss fibers (Ampelodesmos mauritanicus) biocomposites

AbstractThe present research investigates the influence of chemical modifications on the surface of Diss fibers (Ampelodesmos mauritanicus) as an effective reinforcing agent for biocomposites based on poly (3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV). The Diss fiber surface underwent three different chemical treatments: alkaline, alkaline/peroxide, and alkaline/silane. Changes in morphology, mechanical properties, thermomechanical behavior, and contact angle measurements of the biocomposite materials were studied according to the following weight ratio PHBV/Diss fibers 80/20. Scanning electron microscopy (SEM) analysis of the fractured surface of the biocomposite samples revealed improved adhesion between Diss fibers and the PHBV matrix after surface modification, compared with the unmodified sample. The study demonstrated that the incorporation of Diss fibers leads to an enhancement in the mechanical performances of PHBV‐based biocomposites. The tensile properties of the modified biocomposites showed a significant increase in Young's modulus compared with the biocomposites with untreated fiber. Similar trends were observed in the data obtained from dynamic mechanical analysis (DMA) and contact angle measurement. Overall, the study highlights the beneficial effects of Diss fibers modification, particularly with the alkali–silane combination, in enhancing the properties of PHBV biocomposites, there by broadening their potential application fields.Highlights The study explores the potential of Diss fibers as an effective reinforcement for PHBV‐based biocomposites. Fully biodegradable biocomposites based on PHBV/Diss fibers are melt‐compounded. Diss fibers are chemically modified by alkaline, alkaline/peroxide, and alkaline/silane. The chemical treatment has considerably enhanced the properties and morphology of the biocomposites, being however much higher for alkaline/silane treatment. The method can be used for specific applications and large‐scale production.

The Role of Methods for Applying Cucurbit[6]uril to Hydroxyapatite for the Morphological Tuning of Its Surface in the Process of Obtaining Composite Materials

In this work, composite materials were obtained for the first time using various methods and the dependences of the resulting surface morphologies were investigated. This involves modifying the surface with cucurbit[n]urils, which are highly promising macrocyclic compounds. The process includes applying cucurbit[6]uril to the hydroxyapatite surface in water using different modification techniques. The first method involved precipitating a dispersion of CB[6] in undissolved form in water. The second method involved using fully dissolved CB[6] in deionized water, after which the composite materials were dried to constant weight. The third method involved several steps: first, CB[6] was dissolved in deionized water, then, upon heating, a dispersion of CB[6] was formed on the surface of HA. The fourth method involved using ultrasonic treatment. All four methods yielded materials with different surface morphologies, which were studied and characterized using techniques such as infrared (IR) spectroscopy and scanning electron microscopy (SEM). Based on these results, it is possible to vary the properties and surface morphology of the obtained materials. Depending on the method of applying CB[6] to the surface and inside the HA scaffold, it is possible to adjust the composition and structure of the target composite materials. The methods for applying CB[6] to the hydroxyapatite surface enhance its versatility and compatibility with the body’s environment, which is crucial for developing new functional composite materials. This includes leveraging supramolecular systems based on the CB[n] family. The obtained results can be used to model the processes of obtaining biocomposite materials, as well as to predict the properties of future materials with biological activity.

Thermal performance of solar dryer using bio-composite insulation material based on date palm waste for drying of hot chili: experimental investigation in Algerian Sahara

This paper investigates the thermal efficiency of solar dryers using different insulation materials, focusing on a bio-composite derived from discarded date palm residues. The current study introduces this sustainable material, created from local palm waste, as insulation material in Solar Air Heaters (SAHs) for agricultural products drying purposes. Thus, two SAH models are designed, fabricated and compared for their thermal efficiencies: the first one used the bio-composite (Model A) as insulation material and the second one is equipped with a polystyrene sheet in the rear insulation (Model B). The thermal performance of these models are assessed, alongside the drying kinetics of Algerian chili at different maturity stages under the climate of Biskra, Algeria. A local product that we aim to promote (Arab chili), widely used in southern Algeria during the harvest period in summer and early spring. It is generally grown using traditional techniques despite its very delicious taste, while (Gazelle’s horn) chili is grown in greenhouses throughout the year. Although the polystyrene-insulated SAH shows slightly better thermal efficiency, the bio-composite model achieves satisfactory drying temperatures, drying chili in 5 hours and 30 minutes.

New Refined Experimental Analysis of Fungal Growth in Degraded Bio-Based Materials

When exposed to different building environmental conditions, bio-composite materials, such as hemp mortars, represent a risk of mold proliferation. This later plays a critical role in the biodeterioration of the materials when their physical properties are locally modified by the natural aging process. The primary objectives of the present work are first to assess the evolution of the surface of contaminated mortar; second, to investigate an accurate DNA extraction method that could be used for both bio-composite mortars and their fiber sources collected in situ; then, to understand the process of the proliferation of mold strains on both hemp shives and hemp mortar; and finally, to compare mold strains present in these phases to show their relationship to mold contamination and their impact on human health. In situ hemp mortar contamination behavior was investigated in the region of Pau (France) two months after hemp mortar application in extreme conditions (high humidity, low temperature, no aeration), which did not match the standard conditions under which hemp mortar must be used. The SEM observations and FTIR and pH analyses highlighted the decrease in pH level and the presence of organic matter on the mortar surface. DNA sequencing results showed that hemp shives were the main source of fungal contamination of hemp mortar. A mold population analysis showed that the most dominant phylum was Ophistokonta, which represented 83.6% in hemp shives and 99.97% in hemp mortar. The Acrostalagmus genus representatives were the most abundant, with 42% in hemp shives and 96% in hemp mortar. The interconnection between the mold strain characteristics (particularly the ability to grow in extreme environments) and the presence of hemp mortar was emphasized.

Damage index correlation in massive granite-porous backfills under hydromechanical triaxial cyclic loading using acoustic emissions and X-ray computed tomography

The characterization accuracy of damage indices in massive and porous composite biomaterials under complex osmotic conditions has long been a challenge in engineering materials science. Establishing correlations between damage indices calculated using different methodologies is crucial to validate and improve defects characterizations. In this study, we investigated the damage index correlation of cylindrical massive granite-porous backfill structural composites under both dry and seepage conditions. A series of triaxial cyclic loading and unloading tests were conducted on specimens under hydromechanical conditions with varying osmotic pressures (0, 1, 3, 5, 7, and 9 MPa) and a confining pressure of 9 MPa involving acoustic emission monitoring and phase-based 3D nondestructive CT scanning. The results revealed the AE energy was lower under osmotic conditions compared to dry conditions. The AE Damage Index (DAE), defined by separating tensile and shear microcracking signals, significantly increased from 0.32 to 0.55 with rising osmotic pressure. 3D mesoscopic fracture visualization provided detailed insights into the fractures in granite and backfill interfaces. The number of small-angle cracks increased with osmotic pressure, and the crack inclination distribution range expanded from 63°- 85° to 49°–80°. The average crack angle showed a significant monotonic decrease with increasing osmotic pressure. An Energy Dissipation Damage Index (DED) was defined, and its correlation with the DAE under dry conditions was modeled using a reciprocal function DED=a/(DAE+bσ3)+c. This novel approach offers insights into the transition points between tensile and shear-dominated failure stages. Furthermore, an exponential function DV=aDAEb(b<0) was used to model the correlation between AE Damage Index and Visual Damage Index (DV) under osmotic conditions. The damage indices derived from different methods can be mathematically correlated, providing a comprehensive evaluation of material damage states. The study found the flow transition between different natural-human medias results in different damage mechanisms, which are all obey the correlation law. These damage mechanisms offered constructive recommendations for engineering applications based on varying ratios of osmotic pressure to confining pressure.

Drying Kinetics and Sorption Isotherms of Biocomposite Materials: Experimental Investigation and Modeling Analysis.

Modern materials science has made significant progress in creating new materials and processes for waste recovery. One such advancement involves the development of a new porous composite material made from clay and an environmentally sustainable eggshell powder. In this study, the dynamic behavior of water vapor during desorption and adsorption processes within this composite material was investigated. The moisture diffusivity coefficient was determined within the clay/eggshell powder composite material. The drying kinetic data were analyzed using various models such as Newton, Page, and Wan and Singh. The static gravimetric vapor adsorption/desorption experiments were conducted at different temperatures (30, 40, 50, 60, and 70 °C) to depict the material's capacity for absorbing and releasing moisture over time. The experimental isotherm data were fitted using different mathematical models (Guggenheim, Anderson, and De Boer, Peleg, Adam and Shove, Oswin, and Modified Henderson). The findings suggest that integrating eggshell powder with clay can significantly influence the behavior and characteristics of the resultant material. The combination of eggshell powder and clay reduces moisture sorption and accelerates the drying process. Consequently, this affects the porosity, permeability, and response to humidity changes.

Self-Assembly Behavior of Collagen and Its Composite Materials: Preparation, Characterizations, and Biomedical Engineering and Allied Applications.

Collagen is the oldest and most abundant extracellular matrix protein and has many applications in biomedical, food, cosmetic, and other industries. Previous reviews have already introduced collagen's sources, structures, and biosynthesis. The biological and mechanical properties of collagen-based composite materials, their modification and application forms, and their interactions with host tissues are pinpointed. It is worth noting that self-assembly behavior is the main characteristic of collagen molecules. However, there is currently relatively little review on collagen-based composite materials based on self-assembly. Herein, we briefly reviewed the biosynthesis, extraction, structure, and properties of collagen, systematically presented an overview of the various factors and corresponding characterization techniques that affect the collagen self-assembly process, and summarize and discuss the preparation methods and application progress of collagen-based composite materials in different fields. By combining the self-assembly behavior of collagen with preparation methods of collagen-based composite materials, collagen-based composite materials with various functional reactions can be selectively prepared, and these experiences and outcomes can provide inspiration and practical techniques for the future development directions and challenges of collagen-based composite biomaterials in related applications fields.

Disintegration and marine biodegradability of biocomposite using Pennisetum setaceum fiber and PLA as matrix

The accumulation of plastics in the environment is a well-recognized issue. To address this, biodegradable materials such polylactic acid (PLA) have been developed. In natural environments such as soil or water, PLA degradation progresses slowly but steadily. To accelerate the degradation of the material, this study investigates the degradation of a biocomposite material using PLA as a matrix and Pennisetum setaceum fiber as reinforcement. Disintegration and marine biodegradability tests, both at the seawater/sediment interface and in marine sediment, were conducted. Different measurement tests were employed to quantify the degradation of PLA and composite samples, focusing on the mass loss and the variation of the mechanical and thermal properties. The results consistently demonstrated greater mass loss and mechanical property deterioration during the disintegration test compared to the marine biodegradability tests. Notably, the composite material exhibits more significant degradation than the pure polymer without fiber. For composite, the addition of fiber increased the degree of biodegradability compared to the plastic matrix.

Sandwich structures in bio-composite material for sustainable acoustic solutions

The use of bio-based materials in acoustic applications has gained a lot of attention recently as a functional and environmentally friendly alternative for synthetic materials. This is because conventional synthetic fibers have a significant impact on the environment and the health risks of people. The focus is now on developing composite systems that minimize environmental harm by using energy and materials more efficiently, and by substituting synthetic or petroleum-based materials with more sustainable options, such as natural fibers. These natural fibers are favoured for their biodegradability, sustainability, and widespread availability, earning them the label of "green materials." Thus, this paper aims to investigate the soundproofing capabilities of a novel sandwich structure composed of hemp fibers and bio-epoxy resin, aiming to broaden the application field of natural fiber composite materials.

A Review of Natural Fibres and Biopolymer Composites: Progress, Limitations, and Enhancement Strategies.

The interest in natural fibres and biopolymers for developing bio-composites has greatly increased in recent years, motivated by the need to reduce the environmental impact of traditional synthetic, fossil fuel-derived materials. However, several limitations associated with the use of natural fibres and polymers should be addressed if they are to be seriously considered mainstream fibre reinforcements. These include poor compatibility of natural fibres with polymer matrices, variability, high moisture absorption, and flammability. Various surface treatments have been studied to tackle these drawbacks, such as alkalisation, silane treatment, acetylation, plasma treatment, and polydopamine coating. This review paper considers the classification, properties, and limitations of natural fibres and biopolymers in the context of bio-composite materials. An overview of recent advancements and enhancement strategies to overcome such limitations will also be discussed, with a focus on mechanical performance, moisture absorption behaviour, and flammability of composites. The limitations of natural fibres, biopolymers, and their bio-composites should be carefully addressed to enable the widespread use of bio-composites in various applications, including electronics, automotive, and construction.

The Effect of Biocomposite Material Composition with Natural Fiber Reinforced Polyester Matrix on Mechanical and Physical Strength

This study was conducted with the aim of determining the effect of natural fiber composition in polymer composites on the flexural strength and density of bio-composites with polyester matrix reinforced with ramie fiber, giant false agave (GFA), bamboo, and sugar cane fibers. Mechanical testing was carried out in the form of flexural strength testing and calculating density as a physical test. The composition of the matrix with fiber reinforcement was set at 70% polyester and 30% natural fiber. The variables used in this study were to create a dominant composition of fiber types in the form of a measured weight amount so as to produce a comparison of which type of natural fiber has a better test value. From the results of the flexural strength test, it was found that the bio-composite dominated by sugar cane fiber had the largest flexural strength value of 261.66 kg/cm2 while the bio-composite dominated by ramie and GFA sequentially produced flexural strengths of 101.465 kg/cm2 and 185.89 kg/cm2. The results of the density calculation show that the highest density was achieved by the bio-composite material with a dominant composition of hemp fiber (70% Polyester: 20% hemp fiber, 5% GFA fiber: 5% sugar cane fiber) of 1.049 g/cm3.

Utilization of banana crop ligno-cellulosic waste for sustainable development of biomaterials and nanocomposites.

Banana (Musa spp.) is a tropical fruit cultivated in over 130 countries, producing significant lignocellulosic biomass. However, much of the agro-industrial waste from banana plants is neglected, contributing to environmental pollution. Around 60 % of the plant's biomass is generated after fruit harvesting, representing an untapped resource. This review examines the potential of banana plant waste for developing biocomposite and biodegradable materials. It covers the extraction and modification of banana fibers for composites, with a focus on the fabrication of nano biocomposites using banana fibers as reinforcement and polysaccharides or proteins as matrices. The review also evaluates the biodegradability and environmental impact of these materials through Life Cycle Assessment studies. Future research directions include refining processing methods, improving fiber-matrix compatibility, and enhancing the durability of banana fiber composites for packaging applications.

Fabrication of high-performance biomedical rare-earth magnesium alloy-based WE43/hydroxyapatite composites through multi-pass friction stir processing

Magnesium-based composites with bioactive ceramic particles addition are promising materials for biomedical implant applications. Nevertheless, the agglomeration of bioactive ceramic particles remains a challenge for fabricating high-performance biomedical magnesium-based composites. Herein, a novel high-performance biomedical rare-earth magnesium alloy-based WE43/hydroxyapatite (HA) composite is successfully fabricated via multi-pass friction stir processing (MP-FSP). Systematic investigations reveal that MP-FSP leads to a uniform distribution of HA particles and efficient elimination of defects. The microstructural analysis shows a significant grain refinement in the WE43 alloy from 49.4 μm to 2.4 μm under triple-passes FSP. The mechanical properties of the composite are enhanced significantly under triple-passes FSP, with yield strength, ultimate tensile strength, and elongation reaching 236.2 MPa, 278.6 MPa, and 14.2% respectively. Corrosion resistance is also improved, with a 30% reduction in the corrosion rate in SBF solution compared to the unprocessed alloy. Moreover, the MP-FSP fabricated composites exhibit superior corrosion-wear resistance, characterized by slight abrasive wear compared to the abrasive wear and severe pitting corrosion observed in the base WE43 alloy. These improvements are attributed to the synergistic effects of grain refinement, dispersion strengthening, enhanced interfacial bonding, and texture modification. Overall, these findings provide significant quantitative insights into the advanced fabrication techniques of magnesium-based composites for biomedical implant applications, highlighting the effectiveness of MP-FSP in enhancing both mechanical and corrosion-related properties.

Investigation of cellulose nanocrystals fabricated via sulfuric acid combined with deep eutectic solvent route

To make full use of tobacco waste in cigarette production and enhance resource utilization efficiency, cellulose nanocrystals (CNCs) were prepared by a method of sulfuric acid combined with a deep eutectic solvent. This method was compared with conventional methods, and the CNCs were thoroughly characterized. The results indicated that the yield of CNCs prepared by the sulfuric acid combined with a deep eutectic solvent method exceeded 26 %, with the highest yield reaching 29.5 %, surpassing the yields from two other methods of 12.5 %, 17.2 %, corresponding to sulfuric acid and sulfuric acid-oxalic acid, respectively. Scanning electron microscopy revealed a laminar morphology of CNCs, in which the CNCs maintained a cellulose type I structure with well-preserved crystallinity. In addition, CNCs prepared by the sulfuric acid combined with a deep eutectic solvent method exhibited good thermal stability, with maximum mass loss at temperature of 342.8 °C during third pyrolysis stage, higher than that of sulfuric acid at 316.7 °C and sulfuric acid-oxalic acid at 335.9 °C. Steady-state rheological testing revealed that the viscosity of the CNCs suspension decreased with an increasing shear rate, which is characteristic of pseudoplastic fluid shear thinning behavior. CNCs prepared by the sulfuric acid combined with DES method reduced the amount of sulfuric acid, and the yield was much higher than that of the other two methods. Moreover, the method using sulfuric acid combined with DES method was simple and safe, and the obtained CNCs had high thermal stability and viscosity, which expands the application prospects in biocomposite material fields.