Bio-based Composite Materials Research Articles

Fabrication of Bio-Based Composite Materials forAntimicrobial Cotton Fabric With Microbial Anti-Adhesive Activity.

The development of multifunctional cotton fabrics that are stain-resistant, antimicrobial, and easy to clean has sparked scientific interest as well as practical usefulness, owing to its medical and healthcare applications. The purpose of this study was to fabricate self-cleaning and antimicrobial cotton for final use by soaking the cotton fabric in nonfluorinated hybrid formulations based on quaternary chitosan-silane using the sol-gel process. The fluorine-free cotton fabric demonstrated high self-cleaning behavior and outstanding bacterial killing efficacy against E. coli and S. aureus bacteria, without altering the desired textile properties of cotton fabric. Remarkably, cotton textiles using the hybrid formulations HTACC-VTES (N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride-vinyltriethoxy silane) and TMCC-VTES (N, N, N-trimethyl chitosan chloride-vinyltriethoxy silane) demonstrated promising water contact angles of 147° and 142° respectively, indicating a move toward superhydrophobicity. In FTIR spectra, both treated cotton textiles had an absorption peak at 1208 cm-1 (SiOC bending), indicating a stronger interaction between silane binding agents and the cotton substrate. The treated cotton fabric with desirable features retains its stability and endurance after 12 cycles of washing for antibacterial tests and 15 cycles for wettability tests. The manufactured cotton fabric has several potential applications, such as in personal hygiene items and medical applications.

Structural dynamics of individual plant fibres: a contribution to the understanding of damping properties of bio-based composites

The field of bio-based composites faces challenges in understanding the physical mechanisms providing excellent compromise between stiffness and damping. Potential sources of damping, including the matrix, the fibre, and the interfaces (fibres/fibres and fibres/matrix) are identified in the literature. To better understand damping at the composite scale, it is necessary to understand the dissipation causes at each scale of the material. However, the mechanical characteristics of individual plant fibres, such as modulus and damping, can be uncertain due to the complexity of measuring their properties at such small scale (10 µm diameter, a few mm long). To address this knowledge gap, this work proposes a method based on dynamic response of individual plant fibres. By exciting the fibre with a piezoelectric actuator and using high-speed camera image processing to evaluate displacements along the fibre, it becomes possible to determine intrinsic dynamic properties such as the loss factor and storage modulus. Controlled environment tests are conducted to investigate the influence of external parameters such as temperature and pressure on the measurement results. By utilizing this method, the aim is to obtain a better understanding of the damping properties of plant fibres and ultimately improve design choices for bio-based composite materials.

MXene quantum dots modified pitaya peel-based composite phase change material with excellent thermal properties for building energy efficiency applications

Bio-based materials have attracted much attention because their application in the construction field is conducive to energy saving and emission reduction. In this paper, a bio-based composite phase change material (CPCM) was prepared by utilizing pitaya peel as a bio-based material, MXene quantum dots (MQDs) as a modified material, and polyethylene glycol (PEG) as a phase change medium. MXene quantum dots dispersed in the pitaya peel-based porous carbon skeleton enhanced the three-dimensional thermal conductivity network of the porous carbon skeleton somewhat improved the thermal conductivity (0.676 W/mK) of the polyethylene glycol/MXene quantum dots-modified pitaya peel-based porous carbon foam (PPF) composite phase change material (PEG/PPF@M). It is worth noting that PEG/PPF@M has excellent thermal stability and its enthalpy is basically unchanged after 100 cycles, which proves the recyclable stability of PEG/PPF@M in practical applications. PEG/PPF@M has great potential for thermal management of buildings and electronic components. Overall, a novel multifunctional CPCM was prepared in this study using a simple process method, which can not only be applied in electronic products to improve the service life of electronic components, but also in the field of construction to realize energy saving and emission reduction, as well as the recycling and reuse of waste.

Damage and fracture studies of continuous flax fiber-reinforced composites 3D printed by in-nozzle impregnation additive manufacturing

Additive manufacturing (AM) of continuous yarn-reinforced biobased composites presents multi-functional properties and low environmental impact of this technology. Few studies focused on the mechanical damage mechanisms of continuous biobased composites obtained by AM processes, while it is a topic of high interest for the mastery of mechanical behaviors and optimization of the materials for high requirement applications. This study aims to assess the damage and fracture modes of continuous flax yarn-reinforced PLA manufactured by AM, with different yarn orientations. The additively manufactured biobased composites were characterized by tensile test, 3D microscopy and micro-tomography to link the process-structure-properties relationships regarding the damage and fracture modes. The results showed that the 0° manufactured composite had a significant enhancement of tensile properties compared to other configurations. The damage mechanism presented fiber rupture with polymer transverse cracks at 0°, while the 45° and 90°-oriented composites showed premature fiber/matrix interface debonding. This study aims to find the relationship between damage mechanisms, deposition strategy, and anisotropy of the additively manufactured long vegetal fibers-reinforced biobased composite materials. The results bring a new understanding of the anisotropy and defects in printed composite materials regarding their mechanical behaviors during damage.

Bio-based eutectic composite phase change materials with enhanced thermal conductivity and excellent shape stabilization for battery thermal management

Organic phase change materials (PCMs) are commonly used for battery thermal management. Organic petroleum-based PCMs such as paraffin have an adverse effect on environment. Fatty acids as environmentally friendly bio-based PCMs, have enormous potential in sustainable development strategies. Nevertheless, the application of fatty acids in battery thermal management (BTMS) is restricted by the leakage of liquid PCM, poor thermal performance and the improper phase change temperature. We proposed a novel bio-based eutectic composite phase change materials (CPCM) with enhanced thermal conductivity and excellent shape-stabilization, composed of ethylene-vinyl acetate (EVA), Aluminum nitride (AlN), and the eutectic PCM of Lauric acid (LA) and Stearic acid (SA). Significantly, the screened eutectic PCM of LA-SA possesses a suitable phase change temperature(37.03 °C) corresponding to the battery operating temperature, and long-term thermal cycling stability of up to 100 cycles. And the cross-linked structure of EVA effectively encapsulated the eutectic PCM, whose mass only lost below 4% after being heated at 80 °C for 24 h. Simultaneously, the introduction of AlN can greatly improve their heat transfer ability and mechanical properties. LA-SA/EVA/AlN composites with 5 wt% AlN has adequate latent heat of 107.94 J.g−1 and high thermal conductivity of 0.726 W.(m·K)−1 as well as with low flexural strength of 1.72 MPa. Additionally, the proposed CPCM with 5 wt% AlN achieved the maximum temperature of battery below 45 °C during 4C discharging test. It suggested that the CPCM incorporated with AlN is capable effective cooling battery and dissipate energy inside PCM rapidly.

Regulating natural galactomannan into composite hydrogels for improved adhesion, anti-swelling capability and efficient dye pollution removal

Constructing bio-based composite hydrogel materials are receiving much interest, while regulating the interactions of the hydrogel components and integrating functions for multi-application meet various challenges. Herein, composite hydrogels were prepared by cross-linking of poly-acrylamide (PAM) and poly-N-[3-(Dimethylamino) propyl] acrylamide (PDMAPAA), assisted by natural galactomannan (GM) regulation. Even distribution and compatibility of GM in the three-dimensional materials were proved by a series of chemical and morphological characterizations, which favored the improvement of mechanical properties (~80 kPa) and flexibility. Besides, the hydrogels were well-connected with double networks of noncovalent intermolecular hydrogen bonding interactions and hydrophobic interactions, in addition to covalent-linked polymers. Due to great amount of inner hydrogen bond linkages, the hydrogels present satisfying anti-swelling capabilities (<15 %), exhibiting high potential for application in water treatment. Meanwhile, abundant surface functional groups provided possibilities to form interactive layer with the various substrates surface, exhibiting highly adhesive properties. Significant dyes adsorption capabilities were revealed on the hydrogels according to the electrostatic attraction with Congo red and hydrogen bond interactions with Brilliant green respectively. Thus, the proposed composite hydrogels integrated multi-functions due to the tuning the surface groups and cross-linking interactions, which provided deeper understanding on bio-based materials on fields of water treatment and environmental protection.

Mechanical and Dynamic Mechanical Characterization of Epoxy Composites Reinforced with Casuarina Leaf Bio Fibre

This study investigates the influence of casuarina leaf biofibre on the mechanical and morphological characteristics of epoxy resin composites. Composites were prepared using the hand-layup method, incorporating varying volume fractions of the biofibre (4%, 8%, 12%, 16%, 20% and 24% v/v). Mechanical and dynamic mechanical tests were carried out to assess the impact of the biofibre on the composite material. Mechanical testing revealed significant enhancements in tensile strength of 29.2 MPa, particularly at a biofibre volume fraction of 12% and the composite with the highest impact and flexural strengths measured at 2621 J/m2 and 41.1 MPa, respectively for the 16%v/v fibre loading. Dynamic mechanical analysis (DMA) results demonstrated improved viscoelastic properties attributed to the presence of the biofibre. Scanning electron microscopy (SEM) examination of tensile tested samples provided insights into interfacial bonding and filler dispersion within the composite matrix. Overall, the findings highlight the potential of casuarina leaf biofibre to enhance specific mechanical properties and viscoelastic behaviour of epoxy casuarina composites. Optimizing the biofibre volume fraction offers possibility to tailor composite properties for specific application requirements. This research advances the development of bio-based composite materials, contributing valuable insights for the creation of sustainable and high-performance engineering materials.

Preparation and characterization of Baijiu Jiuzao cellulose nanofibers-kafirin composite bio-film with excellent physical properties

Jiuzao is the main solid by-products of Baijiu industry, which contain a high amount of underutilized cellulose and proteins. In recent years, cellulose nanofibers mixed with proteins to prepare biodegradable bio-based film materials have received widespread attention. In this study, we propose a novel method to simultaneously extract kafirin and cellulose from strong-flavor type of Jiuzao, and modify cellulose to prepare cellulose nanofibers by the TEMPO (2,2,6,6-tetramethylpiperidine-1-oxide) oxidation-pressure homogenization technique, and finally mix kafirin with cellulose nanofibers to prepare a new biodegradable bio-based composite film. Based on the analysis of one-way and response surface experiments, the highest purity of cellulose was 82.04 %. During cellulose oxidation, when NaClO was added at 25 mmol/g, cellulose nanofibers have a particle size of 80–120 nm, a crystallinity of 65.8°. Finally, kafirin and cellulose nanofibers were mixed to prepare films. The results showed that when cellulose nanofibers were added at 1 %, the film surface was smooth, the light transmittance was 60.8 %, and the tensile strength was 9.17 MPa at maximum, which was 104 % higher than pure protein film. The contact angle was 34.3°. This paper provides new ideas and theoretical basis for preparing biodegradable bio-based composite film materials, and improves the added value of Jiuzao.

Development of New Lignin-Based Coatings with Ultraviolet Resistance for Biobased Composite Materials.

Nowadays, there is a challenge in searching for more sustainable alternatives to decrease the environmental impact of composite materials. In this work, we fabricate new composites based on a biobased-content epoxy system, lignin, and flax fiber; considering these materials could be promising due to their high renewable content of around 40%. In addition, another key requirement for composites, besides being sustainable, is that they present improved properties such as UV resistance. Therefore, throughout this work, priority was given to improving UV resistance in addition to taking into account sustainability. In order to carry out a complete characterization of the materials developed, the mechanical properties, brightness, and thermal, rheological, and fire behavior of these kinds of materials were analyzed by using vacuum-assisted resin infusion processes. By way of conclusion, it should be noted that the manufactured composite with the optimized formulation showed improved UV resistance using lignin and that it could be applied on internal and external walls according to the railway fire regulations.

Greening the composite industry: Evaluating Lantana camara Verbenaceae fiber as a promising substitute for lightweight polymer matrix composites

Presently, researchers are engaged in investigations with the aim of developing novel products that exhibit biodegradability and subsequent environmental friendliness. As products, biofiber-based composites are gaining popularity in various industries. Consequently, this investigation successfully identified a unique cellulosic stem fiber from Lantana camara L. (Verbenaceae) plant. As the fiber was unique, sustainable, and abundantly available throughout all seasons, it was selected for the comprehensive characterization investigation to find its potential use as a lightweight bio-based composite material substitute for synthetic fibers. Physiochemical examination revealed that the Lantana camara Verbenaceae fiber had a greater cellulose concentration (61.23±8.42 %) and density (1167±60 kg/m3), measured to be very less compared to synthetic fiber, making a perfect choice for producing lightweight composites with higher strength. The presence of cellulose Iβ and the ordered character of the crystallites were verified by Fourier transform infrared spectroscopy and X-ray diffraction method. Thermogravimetric study showed the maximum degradation temperature of 323 °C, a thermal stability of 242 °C, and a kinetic activation energy of 66.11 kJ/mol. The maximum tensile strength, strain-to-failure percent, and Young’s modulus were observed for 50-mm-length fibers. Detailed analysis of the longitudinal section of the fiber from atomic force microscopy and scanning electron microscopy study revealed that the fiber had a rough surface, which improves the bonding behavior when reinforced. The aforementioned properties showed that L. camara L. fibers are an excellent, greener alternative reinforcement for composite materials, allowing for the cleaner, more sustainable components.

Application and performance evaluation of recycled building materials in civil engineering

The concept of renewable materials has received extensive advocacy and promotion in the ongoing development of the construction industry. Furthermore, emerging renewable building materials, such as bio-based composite materials, are continually evolving and gradually being incorporated into civil engineering applications. This paper focuses on the application and performance assessment of recycled building materials in civil engineering. As a crucial component of environmental protection and sustainable development, recycled building materials possess vast potential for application. In this article, the characteristics of common materials such as recycled concrete, recycled steel, and recycled glass are introduced, and their mechanical performance, durability, and other vital attributes are evaluated. Finally, the feasibility and challenges of recycled building materials are analyzed, along with discussions on sustainable development strategies and policy support. The comprehensive research results demonstrate the significant role of recycled building materials in promoting sustainable development in civil engineering, warranting increased support and promotion at the policy and societal levels.

Experimental and numerical estimation of thermal conductivity of bio-based building composite materials with an enhanced thermal capacity

The paper tackles the important problem of estimating and predicting the thermal conductivity of bio-based building materials that can help decarbonize the building sector. Knowledge and the possibility to optimize their insulating properties is the first criterion for determining the ability of their use in the building sector. The novel yet not well-studied hemp shives and magnesium binder composites with improved thermal mass by microencapsulated phase change material (PCM) were considered. The samples of composites without PCM having different densities as well as with different amounts of microencapsulated PCM and the same density were manufactured and tested experimentally in different states, i.e., dry and after conditioning at relative humidity (RH) of 50, 75, and 90 %, and in the case of samples with PCM also at different average measurement temperatures selected with respect to the phase change range of the PCM. A novel method of predicting bio-based composites' effective thermal conductivity tensor was also developed. The method is based on the numerical solution of the heat conduction equation at the micro-scale considering real composite microstructure. The method was tuned using micro-computed tomography (μCT) data with the microstructure of composites without PCM and then applied to predict the thermal conductivities of composites with PCM, utilizing computational domains with an artificially distributed PCM in the binder. The experimental testing of composites without PCM revealed an apparent effect of increasing thermal conductivity with rising sample density and RH applied during conditioning. With an increase in density from 394 to 576 kg/m3, their thermal conductivities varied from 0.105 to 0.159 W/m/K for the dry state and from 0.157 to 0.241 W/m/K for RH 90 %. A similar effect of sample state and RH was observed for composites with microencapsulated PCM, which had the highest thermal conductivity, equal to 0.265 W/m/K, for the lowest PCM amount and RH 90 %. Moreover, a decrease in composites' effective thermal conductivity with an increase in PCM fraction was observed, except for the lowest PCM fraction, for which it increased. It also rose with increasing the average measurement temperature. The developed micro-scale-based numerical method allowed for predicting the thermal conductivities of composites with accuracies below 4.1 and 7.2 % for composites without and with PCM, respectively, except for the composite with the lowest amount of PCM, which behaved differently. Thus, its suitability for designing and optimizing bio-based composites was shown.

Bio-based composite phase change material utilizing wood fiber and coconut oil for thermal management in building envelopes

Bio-based materials are attracting substantial attention for their eco-friendly attributes within the construction field, where they facilitate energy saving and emissions reduction. However, the performance of it, such as thermal properties, needs to be improved. Fully utilizing bio-based materials, we developed a novel composite phase change material (PCM), A-WF/CO/h-BN, with high thermal storage properties designed for application in building envelopes. It incorporates coconut oil (CO) as the PCM featuring an optimal phase change temperature. Hexagonal boron nitride (h-BN) was chosen to enhance the thermal conductivity. Acetylated wood fiber (A-WF) was employed as the supporting material. The prepared A-WF/CO/h-BN sample exhibits excellent and rapid heat storage and exothermic capabilities. In the experiment of thermal performance evaluation, the cold end of the A-WF/CO/h-BN sample is cooler than that of the A-WF when both hot ends are heated. Results indicate that the proposed A-WF/CO/h-BN sample can effectively delay the heat transfer and inhibit the temperature rise and fall. For these superior properties, when the A-WF/CO/h-BN sample is applied in building envelopes, it can minimize the heat transfer from the envelope to the interior and inhibit indoor temperature fluctuation. Thus, it can reduce building energy consumption and carbon emissions while achieving indoor thermal comfort.

Development and thermal property analysis of biobased binary composite heat storage materials

Natural aliphatic dibasic acids are a type of bio-based material that shows promising potential as green phase change thermal storage materials due to their favorable thermophysical properties. However, these materials have been found to have issues with subcooling, low thermal conductivity, and poor temperature matching. In this study, three aliphatic dibasic acids, namely adipic acid (AA), sebacic acid (SA), and azelaic acid (ZA), were selected for further investigation. Three biobased eutectic systems, AA-SA (melting point: 118.3 °C), ZA-SA (melting point: 96.2 °C), and AA-ZA (melting point: 98.4 °C), were then prepared based on the calculation of Schrader's equation and experimental screening. The eutectic systems were thoroughly characterized, revealing thermal conductivities ranging from 0.4 to 0.5 W·m−1·K−1, with all systems exhibiting a subcooling of around 20 °C. Based on the principle of optimal overall performance, the AA-SA system was selected for modification. By incorporating Expanded graphite (EG) as a highly thermally conductive additive and nucleating agent, the AA-SA/EG composite phase change material (CPCM) was successfully prepared. This modification effectively reduced the supercooling degree of the bio-based phase change materials (PCM) and significantly improved its thermal conductivity by a factor of four. The resulting AA-SA/EG CPCM demonstrated excellent temperature suitability and has the potential to contribute to the application of bio-based phase change materials in waste heat recovery and solar energy systems. This study provides valuable insights into the development and optimization of bio-based phase change materials, contributing to the sustainable utilization of renewable resources for thermal energy storage applications.

Characterization and Implementation of Cocoa Pod Husk as a Reinforcing Agent to Obtain Thermoplastic Starches and Bio-Based Composite Materials.

When the cocoa pod husk (CPH) is used and processed, two types of flour were obtained and can be differentiated by particle size, fine flour (FFCH), and coarse flour (CFCH) and can be used as a possible reinforcement for the development of bio-based composite materials. Each flour was obtained from chopping, drying by forced convection, milling by blades, and sieving using the 100 mesh/bottom according to the Tyler series. Their physicochemical, thermal, and structural characterization made it possible to identify the lower presence of lignin and higher proportions of cellulose and pectin in FFCH. Based on the properties identified in FFCH, it was included in the processing of thermoplastic starch (TPS) from the plantain pulp (Musa paradisiaca) and its respective bio-based composite material using plantain peel short fiber (PPSF) as a reinforcing agent using the following sequence of processing techniques: extrusion, internal mixing, and compression molding. The influence of FFCH contributed to the increase in ultimate tensile strength (7.59 MPa) and higher matrix-reinforcement interaction when obtaining the freshly processed composite material (day 0) when compared to the bio-based composite material with higher FCP content (30%) in the absence of FFCH. As for the disadvantages of FFCH, reduced thermal stability (323.57 to 300.47 °C) and losses in ultimate tensile strength (0.73 MPa) and modulus of elasticity (142.53 to 26.17 MPa) during storage progress were identified. In the case of TPS, the strengthening action of FFCH was not evident. Finally, the use of CFCH was not considered for the elaboration of the bio-based composite material because it reached a higher lignin content than FFCH, which was expected to decrease its affinity with the TPS matrix, resulting in lower mechanical properties in the material.

3D Printing with Bamboo: An Early-Stage Exploration towards Its Use in the Built Environment

Along with the circular bioeconomy principles, alternative ways of utilizing biomass waste streams are considered viable approaches to reaching sustainability goals. Accordingly, a growing body of literature is exploring new materials utilizing biomass in 3D-printing applications. This article presents early-stage research that initially investigates the usability of bamboo fibers and dust with bio-based binders in 3D printing towards its use in the design and production of the built environments. The research delves into solutions through a material tinkering approach to develop a bio-based composite material that can be used in fused deposition modeling (FDM). It includes mechanical strength analyses of printed specimens to understand the effects of different infill designs on the structural performance of objects printed using bamboo-based composite. Then, it demonstrates a design-to-production workflow that integrates a mechanically informed infill pattern within a self-supporting wall design that can be produced by 3D printing with bamboo. The workflow is presented with a partial demonstrator produced through robotic 3D printing. The article concludes with discussions and recommendations for further research.

Insights into effect of lignocellulosic biomass framework types on bio-based shape stable composite phase change materials

The utilization of biomass waste as framework materials to inhibit the leakage of phase change material (PCMs) has gained widespread attention. In this work, three new kinds of shape stable composite phase change materials (sscPCMs) were prepared which combined with stearic acid (SA) and peanut shell powders (PSP), poplar wood powders (PWP), and corn straw powders (CSP), respectively. The influence of lignocellulosic biomass types on the thermal energy storage performance of sscPCMs was studied by comparing three types of sscPCMs. The research results indicated that SA/CSP exhibited superior properties in terms of load capacity and thermal energy storage performance. According to leakage experiments the load capacity of SA/PSP, SA/PWP and SA/CSP was 31.67 %, 44.69 %, and 50.09 %, respectively. The phase change latent heat of SA/PSP, SA/PWP, and SA/CSP was 55.78, 84.27 and 98.47 J/g, respectively. In addition, the relationship between biomass component content and load rates was studied. The results showed that there was a positive correlation between the loading rates of SA and the ratio of holocellulose (cellulose + hemicellulose) to lignin. The results provided a promising approach for the selection of lignocellulosic biomass framework materials.

Potential of Plantain Pseudostems (Musa AAB Simmonds) for Developing Biobased Composite Materials.

A plantain pseudostem was harvested and processed on the same day. The process began with manually separating the sheaths (80.85%) and the core (19.14%). The sheaths were subjected to a mechanical shredding process using paddles, extracting 2.20% of lignocellulosic fibers and 2.12% of sap, compared to the fresh weight of the sheaths. The fibers were washed, dried, combed, and spun in their native state and subjected to a steam explosion treatment, while the sap was subjected to filtration and evaporation. In the case of the core, it was subjected to manual cutting, drying, grinding, and sieving to separate 12.81% of the starch and 6.39% of the short lignocellulosic fibers, compared to the fresh weight of the core. The surface modification method using steam explosion succeeded in removing a low proportion of hemicellulose and lignin in the fibers coming from the shims, according to what was shown by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC), achieving increased σmax and ε from the tensile test and greater thermal stability compared to its native state. The sap presented hygroscopic behavior by FT-IR and the highest thermal stability from TGA, while the starch from the core presented the lowest hygroscopic character and thermal stability. Although the pseudostem supplied two types of fibers, lower lignin content was identified in those from the core. Finally, the yarns were elaborated by using the fibers of the sheaths in their native and steam-exploded states, identifying differences in the processing and their respective physical and mechanical properties.

Valorization of Winery By-Products as Bio-Fillers for Biopolymer-Based Composites.

Grape seeds (GS), wine lees (WL), and grape pomace (GP) are common winery by-products, used as bio-fillers in this research with two distinct biopolymer matrices-poly(butylene adipate-co-terephthalate) (PBAT) and polybutylene succinate (PBS)-to create fully bio-based composite materials. Each composite included at least 30 v% bio-filler, with a sample reaching 40 v%, as we sought to determine a composition that could be economically and environmentally effective as a substitute for a pure biopolymer matrix. The compounding process employed a twin-screw extruder followed by an injection molding procedure to fabricate the specimens. An acetylation treatment assessed the specimen's efficacy in enhancing matrix-bio-filler affinity, particularly for WL and GS. The fabricated bio-composites underwent an accurate characterization, revealing no alteration in thermal properties after compounding with bio-fillers. Moreover, hygroscopic measurements indicated increased water-affinity in bio-composites compared to neat biopolymer, most significantly with GP, which exhibited a 7-fold increase. Both tensile and dynamic mechanical tests demonstrated that bio-fillers not only preserved, but significantly enhanced, the stiffness of the neat biopolymer across all samples. In this regard, the most promising results were achieved with the PBAT and acetylated GS sample, showing a 162% relative increase in Young's modulus, and the PBS and WL sample, which exhibited the highest absolute values of Young's modulus and storage modulus, even at high temperatures. These findings underscore the scientific importance of exploring the interaction between bio-fillers derived from winery by-products and three different biopolymer matrices, showcasing their potential for sustainable material development, and advancing polymer science and bio-sourced material processing. From a practical standpoint, the study highlighted the tangible benefits of using by-product bio-fillers, including cost savings, waste reduction, and environmental advantages, thus paving the way for greener and more economically viable material production practices.

Preparation of a long-term mildew resistant and strong soy protein adhesive via constructing multiple crosslinking networks

Developing strong soy protein-based adhesive (SPA) to replace harmful formaldehyde-based resins in the wood-based panel industry is a hot research. However, the lack of long-term antibacterial and antifungal properties of SPA significantly impacts its durable bonding performance and limits application. The commonly used anti-mold agents often decrease the protein compatibility and strength. Inspired by the robust and resilient dissipative matrix found in slug mucus, a green and sustainable adhesive with long-term antibacterial, antifungal properties, and excellent bonding performance was prepared using classic self-assembly and building toughened crosslinked networks. Specifically, caffeic acid and L-arginine were grafted onto tubuchitosan via acylation to prepare a chitosan with strong cationic graft modification (CCL), which combined with self-made triglycidylamine as a crosslinking agent to synergically strengthen the adhesive network. The SPA demonstrated excellent antibacterial properties against Staphylococcus aureus (20 mm) and Escherichia coli (19 mm). The prepared plywood and liquid/cured adhesive showed effective antifungal periods of 30, 80, and 120 days, respectively. Moreover, the incorporation of CCL significantly enhanced the dry and wet shear strengths of the prepared plywood to 2.73 MPa and 1.86 MPa, respectively. And a dry shear strength of 2.10 MPa and a wet shear strength of 1.53 MPa maintained even after a 30-day antifungal observation period, which still meet the interior use plywood requirement (≥0.7 MPa). The corresponding plywood after placing 30 days (1.46 MPa) is obviously higher than E0 level (0.05 mg/m3, GB18580-2017, Climate chamber method) of melamine-urea–formaldehyde resin (0 MPa after ten days). This study provides a straightforward and effective strategy for developing high performance and durable bio-based composite material, including adhesive, film, hydrogel.