Bio-based Composites Research Articles

Bio-Based Disposable Containers for Food Services

Currently, petrochemical plastics dominate the food service industry due to their good mechanical properties and barrier against heat, water vapor, carbon dioxide, and oxygen. This widespread use is not only harmful to humans but also to the ecosystem as synthetic plastics disrupt ecological balance and deplete petroleum-based oil resources. Researchers and manufacturers are continuously addressing this problem by developing bio-based alternatives that provide numerous advantages including structural flexibility, biodegradability, and effective barrier properties. However, the high cost of production and unavailability of equipment for batch processing impede the potential for widespread manufacturing. Natural fibers mixed with bio-based adhesives derived from plants provide one of the biggest potential sources of bio-based materials for the food container industry. Not only does this address the issue of high raw material cost but it also has the potential to become sustainable once processing steps have been optimized. In this review, the current findings of several research related to the production of bio-based disposable food containers, packaging, and composites made from bio-based materials and bio-based adhesives are critically discussed. Several properties and characteristics important to the production of food service containers and primary packaging, as well as the existing challenges and future perspectives, are also highlighted.

Elucidating intermolecular forces to improve compatibility of kraft lignin in poly(lactic acid).

Owing to its abundant supply from renewable resources, lignin has emerged as a promising functional filler for the development of sustainable composite materials. However, achieving good interfacial compatibility between lignin and synthetic polymers, particularly poly (lactic acid) (PLA), remains a fundamental challenge. To advance the development of high-performance bio-based composites incorporating lignin and PLA, our study has scrutinized to unravel the nuances of interfacial binding interactions with the lignin and PLA composite system. Molecular level and experimental examinations were employed to decipher fundamental mechanisms governing and demonstrating the interfacial adhesion. We synthesized casted films of lignin/PLA and acetylated lignin/PLA at varying weight percentages of lignin (5%, 10%, and 20%) and comprehensively investigated their physicochemical and mechanical properties. The inclusion of acetylated lignin in the composites resulted in improved mechanical strength and Young's modulus, while the glass transition temperature and melting point were reduced compared to neat PLA. Systematic variations in these properties revealed distinct compatibility behaviors between unmodified lignin and acetylated lignin when incorporated into PLA. Molecular dynamics (MD) simulation results elucidated that the observed changes in material properties were primarily attributed to the acetylation of lignin. Acetylated lignin exhibited lower Coulombic interaction energy and higher van der Waals forces, indicating a stronger affinity to PLA and a reduced propensity for intermolecular aggregation compared to unmodified lignin. Our findings highlight the critical role of controlling intermolecular interactions and lignin aggregation to develop PLA composites with predictable performance for new applications, such as functional packaging materials.

Evaluating the load-carrying performance of single-bolted connections of inorganic-bonded bamboo composite

ABSTRACT In the field of civil engineering, the utilization of bio-based composites is a viable solution for promoting environmentally friendly practices. A novel bio-based inorganic-bonded bamboo composite (InorgBam) prepared with roller-pressing impregnation, cold pressing, and molding technology was first introduced, and 72 double-shear specimens were tested to investigate the load-carrying performance of InorgBam single-bolted connections. The failure characteristics of the InorgBam single-bolted connections were evaluated using the European yield model (EYM). By incorporating the existing bilinear and Attiogbe models, the load-displacement relationship of the InorgBam single-bolted connections was foretasted with precision. The effect of bolt diameter and component thickness on load-bearing capacity was compared, and relevant design suggestions were proposed. Prediction equations of load-bearing capacity for timber connections in existing standards were briefly reviewed and compared with the test results to illustrate their applicability for InorgBam connections. Comparison results indicated that the equations for timbers exhibited an adequate safety redundancy for the InorgBam. Finally, a simplified equation was proposed based on nonlinear fitting that aims to provide a convenient approach to design activities for InorgBam bolted connections and promote the structural application of InorgBam material.

Effect of different weft-knitted structures on the mechanical performance of bio-based flexible composites

This work investigates composites from renewable resources that exhibit high flexibility. The effect of three different weft-knitted structures on the tensile properties, flexural properties, tear resistance and puncture impact properties is analyzed in combination with two different flexible matrix materials. Furthermore, the potential of the knitted structures in flexible composites is compared to a woven fabric and comprehensively discussed. The tear resistance and the total absorbed energy in puncture impact tests were unaffected by the matrix material. Among the knitted structures, the highest tensile strength, tear resistance and impact properties were achieved with the interlock structure, whereas the double jersey with tuck stitch structure resulted in the lowest flexural modulus. However, a much higher tensile strength was achieved with the woven fabric, at the expense of a higher flexural modulus. Overall, knitted structures proved promising to be used in bio-based flexible composites for applications requiring high flexibility without the need for high tensile strength.

A case study on the rotomolding behavior of black tea waste and bio-based high-density polyethylene composites: Do active compounds in the filler degrade during processing?

This study verified the possibility of using waste material from the food industry (black tea) as functional filler of rotomolded biobased high-density polyethylene-based composites. As part of the experimental work, the influence of the materials preparation, i.e., dry blending versus twin-screw extrusion, on the effectiveness of the stabilizing antioxidant effect of the black tea was analyzed. The aim of the work was to verify whether, despite the initial degradation of the structure of the lignocellulosic filler, it would be possible to keep its antioxidant capacity and the stabilizing effect on the polyethylene matrix. The research showed that the filler allowed to stabilize the polymeric matrix during the rotomolding process, despite the appearance of numerous defects in the form of pores and a reduction in mechanical properties, more significant for composites prepared by dry blending, obtaining elastic modulus drops of about 50 %. Furthermore, the pre-processing step by melt mixing results in a significant improvement of the composite's thermo-oxidation stability, with increases in the oxidation induction time (OIT), from 25 min for the HDPE to over 70 min for composites with 5 % black tea, and improved rheological behavior, preventing the crosslinking of the matrix, indicative of its thermo-oxidative degradation. The tea brewing process caused the decrease of antioxidant activity of the filler; however, it did not significantly affect the antioxidant behavior, maintaining its influence on the polymeric matrix when the material is prepared via twin-screw compounding, which was proved to provide better stability, increasing OIT by approximately 20 min later when compared to dry blending.

Design of compostable toughened PLA/PBAT blend with algae via reactive compatibilization: The effect of algae content on mechanical and thermal properties of bio‐composites

AbstractA binary blend of polylactic acid (PLA) and poly (butylene adipate‐co‐terephthalate) (PBAT), along with algae in their respective composites, were successfully produced using a melt extrusion process. The produced in‐house coupling agent was used to enhance interfacial adhesion and algae dispersion. The influence of algae content incorporated into the compatibilized binary blend was thoroughly investigated, focusing on the bio‐composites morphology, mechanical, and thermal properties. The addition of PLA‐g‐MA to the binary blend led to notable improvements in the storage modulus, mechanical strength, and thermal properties of the binary blend. Subsequently, the introduction of algae into the compatibilized binary blend further augmented the storage modulus, with an optimum algae concentration of 10 wt%. However, higher algae content led to decreased tensile strength, elongation at break, and impact resilience. The optimal balance of these properties was achieved at an optimal loading of 5–10 wt% of algae into the compatibilized binary blend. The thermal stability of the bio‐composites was notably impacted by algae concentration, with the 10 wt% algae bio‐composite exhibiting increased thermal stability. Increasing algae content correlated with decreased bio‐composite crystallinity. These findings underscore the potential of optimized biobased algae composites for achieving desired mechanical and thermal properties, contributing to the development of sustainable and eco‐friendly polymer bio‐composites.

Investigation of toughening mechanism about core-shell morphology in bio-based polyamide ternary composites

ABSTRACT Bio-based polyamide 56 (PA56) is an environmentally friendly polymer but has not been widely used due to its inherent disadvantages of low impact strength and brittleness. In this paper, polyethylene and maleic anhydride grafted EPDM were used to co-modify PA56. The core-shell structure of PP and EPDM-g-MAH could increase the impact strength of the composites by a factor of 4.5 without significant loss of toughness. The toughness and rigidity of PA56 were balanced while the thermal stability and crystalline properties were maintained in a betterstate. This gives PA56 great potential for the automotive and construction machinery industries.

Investigating the mechanical performance and characteristics of nitrile butadiene rubber date palm fiber reinforced composites for sustainable bio-based materials

The recent focus on enhancing sustainability has emphasized the proper utilization of natural fibers and waste materials. Natural fiber reinforced composites have emerged as a promising solution for future bio-based products. This study aims to investigate the synergistic effects between date palm fiber (DPF) and Nitrile Butadiene Rubber (NBR) in order to develop innovative bio-based composites suitable for diverse industrial applications. The composites were produced through a mixing process using a Brabender internal mixer, followed by rolling. Various reinforcement materials and processing conditions were employed to characterize and analyze the mechanical properties of the composites. These properties included tensile strength, tensile modulus, strain, tear resistance, mechanical hardness, and compression behavior, assessed according to ASTM standards. The results revealed that the composites with a 40 wt% fiber loading exhibited the highest elastic modulus and tear resistance, indicating good compatibility and adhesion between the fibers and rubber. Additionally, the composites displayed increased brittleness and strain with higher fiber content. The mechanical hardness of the composites suggested their potential for various industrial applications, with the best results obtained at a 30 wt% fiber loading. Furthermore, the compression strength of the composites, evaluated using the ASTM D395 standard and a compression molding method, displayed significant improvement at a 40 wt% fiber content, indicating favorable characteristics and potential for industrial applications requiring oil, fuel, abrasion, and heat resistance in the form of bio-based products.

Bio-based conductive polyurethane composites derived from renewable castor oil with enhanced self-healing ability for flexible supercapacitors

To alleviate the pressure on the petrochemical industry and address environmental concerns, the utilization of polyurethane (PU) derived from castor oil (CO) (as an ester polyol replacement of petrochemical-based materials) has garnered significant attention in recent decades. Extending the service life of materials requires imparting self-healing properties to vegetable oil-based polymers, an aspect that has received limited attention in current studies. However, low self-healing efficiency still poses a significant challenge, and non-conductivity also remains an obstacle in current research, crucial for their application in electronic devices. In this work, we present the first series of electrically self-healing biopolymer composites constructed by incorporating carbon nanotube (CNT) networks into crosslinked castor oil-based polyurethane (BPU) through a simple curing process. These materials address the challenges mentioned above and exhibit improved mechanical, electrical, and self-healing capabilities compared to other bio-based self-healing materials. The resulting BPU/CNT composite demonstrated exceptional repeated self-healing capacity, restoring both mechanical properties and electrical performance even after experiencing severe mechanical damage. Notably, this composite served as a conductive substrate in flexible solid-state supercapacitor (FSSC) devices. Consequently, the FSSC derived from the composite conductive substrate achieved an impressive 92.4 % self-healing efficiency even after undergoing 7 cutting/healing cycles. The device remained virtually unchanged even after being bent at a 180° angle with a bending radius of 1.6 mm, indicating excellent repeatability and durability. The exceptional self-healing ability, with ∼98 % electrical recovery at 100 °C for 70 s and 93 % at 80 °C after 6 min, of these composites was attributed to the synergistic interactions of the dynamic exchange reactions of disulfide bonds and dense hydrogen bonds within the BPU matrix, which provide a reversible dynamic polymer network. The healing efficiency of these dynamic bonds was evaluated by adjusting the composition ratio of the long linear chain of pTHF in hybrid polyols of the crosslinked polymer network. Overall, this work highlights a series of green, simple, and highly efficient self-healing polymer composites derived from renewable castor oil, and it establishes an essential framework for future sustainable polymer composite design.

CsxWO3-doped PEG/sweet potato form-stable composites for light-thermal conversion and energy storage

Abstract Cesium tungsten bronze (CsxWO3)-doped PEG/sweet potato form-stable composites are fabricated through a facile two-step method of lyophilization and vacuum impregnation. Abundant starch microsphere enhances the PEG loading capacity above 72 % and also supplies capillary force as well as hydrogen bonding to improve the form-stability of the composites. Here, the latent heat, relative crystallinity (Xc), and light-thermal conversion efficiency of the system with 0.99 wt% CsxWO3 reach to 137.7 J/g, 97.7 %, and 83.5 %, respectively. The light-thermal conversion efficiency increases from 64.3 % to 91.1 % with 2.00 wt% CsxWO3. Besides, the composites exhibit improved thermal stability and excellent thermal reliability. The prepared bio-based composites with low-cost have broad application prospects in the field of energy storage.

Structural features of biobased composite foams revealed by X-ray tomography.

Polymer foams can have heterogeneous and complex internal structures, especially when material blends or particles have been integrated to create composites. It becomes even more challenging to probe and understand foam structure/properties when using non-uniform particles, such as biobased fillers. Optical or SEM imaging can only provide limited information as these are two-dimensional (2D) surface techniques. In this study, 3D X-ray tomography was applied to comprehensively analyze the structural features of biobased polyurethane foams containing porous rice hull fillers. The in-depth characterization at a wide range of length scale enabled us to quantify and obtain statistics of the unique trends in foam pore size and pore orientation corresponding to rice hull particle fraction and particle size. Rice hull particles were found to induce smaller cell formation. In addition, these biobased particles influenced cell expansion and caused cells to have less consistent orientation. Furthermore, after foam samples were subjected to cyclic compressive loading, X-ray tomography showed fractures in large (>100 μm) particles. This helps reveal the premature failing mechanism of composite foams with highly porous and coarse particles. The study elucidates novel microstructural evolution and deformation mechanisms using 3D X-ray tomography. The results offer new insights on internal structures for biobased composites and foams that are not previously possible through the conventional characterization tools.

Preparation of bio-based porous material with high oil adsorption capacity from bio-polyurethane and sugarcane bagasse.

This work presents the fabrication of bio-based porous material for highly efficient removing of oil from oil/water system. The sunflower oil-based polyol was synthesized and then used to replace the petro-polyol in the simultaneous preparation of a sugarcane bagasse-polyurethane composite (SC-PU composite) by inserting sugarcane fiber filler into the PU matrix. The bio-polyol was obtained from sunflower oil with a hydroxyl number of 182 mg KOH g-1, and functionality of 3.5 OH groups per mol. The bio-polyol and the newly designed bio-based SC-PU composite were characterized by NMR, FT-IR and SEM analysis. The effect of several parameters such as bio-polyol/petro-polyol ratio, dosage of adding sugarcane fiber and size of filler particles on oil adsorption capacity of a new sorbent material were also investigated. Oil sorption capacity of the newly designed sorbent was relatively high, up to 15.2 g g-1 when 20% sugarcane bagasse with a particle size of 1 mm was added into the bio-polyurethane matrix. This is nearly four times higher than that of neat PU foam without the biomass filler and lignocellulosic materials. This finding demonstrated the importance of selecting the right components to fabricate a cost-effective, highly renewable and biodegradable sorbent with high oil-water separation efficiency, reducing the use of chemicals from fossil sources.

Establishing the differences between the use of bio-based composites and nanocomposites as matrices in additive manufacturing.

Establishing the differences between the use of bio-based composites and nanocomposites as matrices in additive manufacturing.

Valorization of Tree Bark-Derived Suberin in Applications for the Bio-Based Composites Industry–A Recent Review

Valorization of Tree Bark-Derived Suberin in Applications for the Bio-Based Composites Industry–A Recent Review

Establishing the differences between the use of bio-based composites and nanocomposites as matrices in additive manufacturing.

Establishing the differences between the use of bio-based composites and nanocomposites as matrices in additive manufacturing.

Development of New Bio-Based Building Materials by Utilising Manufacturing Waste

Abstract Over the last decade, research has increasingly focused on reducing the use of natural resources and improving waste management in the construction industry. Various possibilities exist for reducing waste in this sector, ranging from using waste as filler materials to developing new binders and building materials. This study focuses on the development of bio-based building materials using waste from the manufacturing of wood-wool cement boards. The binder and filler materials were obtained from the manufacturing waste and used in this research. The developed materials were tested for their visual appearance, macrostructure, material density, thermal conductivity coefficient and compressive strength. The results showed promising data for the self-bearing bio-based building materials, which had similar thermal properties to other bio-based materials and could be used as thermal insulation materials with a thermal conductivity coefficient of 0.0827–0.1172 W/(mK). The material density of the developed bio-based composites was found to be 430–617 kg/m3. By incorporating manufacturing waste into the production process of bio-based building materials, it becomes evident that overall waste from manufacturing plants can be significantly reduced, and the sustainability aspect of wood-cement board manufacturers can be enhanced.

Experimental study of mechanical, morphological and thermal performance of bamboo-reinforced polylactic acid-based montmorillonite clay hybrid composite

Polylactic acid (PLA) is a promising, sustainable alternative to conventional petroleum-based polymers, but its mechanical and thermal properties limit its applications. This study introduces bamboo powders (BP) and montmorillonite clay particles (MMT) into the PLA matrix to prepare novel bio-based polymer hybrid composites using a unique combination of weight percentages of BP and MMT without chemical solvents through a stir casting process under optimised input parameters followed by compression moulding. Polymer hybrid composites were fabricated with different weight combinations, and their mechanical, morphological, and thermal properties were analysed. Tensile, flexural, and impact tests were performed to examine the mechanical performance, while thermogravimetric analysis and differential scanning calorimetry were used to assess thermal stability and characteristics. Microscopy observations showed a strong interaction between the bamboo, clay, and PLA matrix. The results revealed that the maximum tensile strength and modulus increased by 26.1 % and 40.8 %, respectively, with 10 wt% BP and 4 wt% clay content. Impact strength increased by 48 % with 15 wt% BP and 4 wt% clay content. Moreover, the thermal decomposition temperature, glass transition temperature (Tg), crystallisation temperature (Tc), and melting temperature (Tm) of the hybrid composites improved considerably with 10 wt% BP and 4 wt% clay content, increasing by 4 °C, 2 °C, and 8 °C, respectively. Based on the findings of this study, the controlled processing parameters were optimised to fabricate the bio-based composite with significantly improved mechanical and thermal properties. These properties make the composite suitable for various automotive and structural applications.

Thermal stability analysis and mechanical performance of Mediterranean lignocellulosic fiber reinforced polypropylene sustainable composites

The utilization of the available agro waste to make sustainable materials was recently emphasized to develop better bio-products and sustainable socio-economic environment. This work investigates the effect of reinforcing polypropylene with lemon leaves (LL) and fig leaves (FL) on the overall mechanical performance of the prepared composites considering various reinforcement conditions. The investigations including determining the tensile strength, tensile modulus, elongations at break, flexural and impact properties as well as revealing the thermal characteristics of the fibers to expose their suitability for such bio-based composites. Thermal gravimetric analysis (TGA) and its derivative (DTG) were used to study the thermal stability of fiber composition during manufacturing. The surface morphology of the fibers as well as their polypropylene composites were analyzed using scanning electron microscopy (SEM). Results have revealed that LL positively affects both tensile strength and modulus. The 20 wt% of LL have enhanced the tensile modulus from 1229 MPa to 1321 MPa. However, FL had negative impact on the tensile properties regardless of weight %. FL and LL reduced the flexural strength and impact toughness of PP regardless of weight %. The tensile strength of the 30 wt% lemon leaves-PP composite reaches its highest value at 43.4 MPa. Furthermore, thermal analysis showed that the fibers did not decompose during the manufacturing process. The initial decomposition temperatures of LL and FL were 239 °C and 226 °C, respectively, exceeding the processing temperature of 170 °C. Furthermore, an in-depth comparison of the tensile strength of the studied FL/PP and LL/PP composites with other commonly used PP composites available in the literature was also performed here to demonstrate the potential of Mediterranean fibers and their suitability for green bio-composites.

Vegetal route for synthesis of CQDs/CdS nanocomposites for photocatalytic reduction of CO2 to methanol under visible light

The green pathway for the synthesis of nanoparticles targeting the photoreduction of CO2 to value-added chemicals is a potential approach to control industrial CO2 emission. In this study, we synthesized bio-based CdS(bio) nanorods using plant-based phytochemicals found in Aegle marmelos and carbon quantum dots (CQDs) using orange peels. CQDs (7 nm) were homogeneously incorporated into CdS(bio) nanorods via simple deposition, forming CQDs/CdS(bio) nanocomposites. The catalysts were thoroughly characterized using diffraction, microscopic, spectroscopic, and electrochemical techniques. CQDs/CdS(bio) composites had a diameter and length of 73 nm and 822 nm with 82.25 m2/g specific surface area. CQDs/CdS(bio) composites showed a fourfold increase in both photocurrent density (0.38 μA/cm2) and CO2 adsorption capacity (0.292 mmol/g) compared to CdS(bio) nanorods alone. The conduction band of the composite (−0.92 eV) becomes more negative compared to CdS(bio) (−0.85 eV). Moreover, the composite formation notably improved decay time by 2.35 folds and reduced photoluminescence intensity by 59.23% compared to CdS(bio), indicating enhanced charge separation and reduced charge carrier recombination. Furthermore, the photocatalytic activity of CQDs/CdS(bio) nanocomposites was investigated for CO2 reduction to methanol under visible light (250 W, λ > 420 nm, 2.2 W/m2, 4.2719 ×1018 photons/m2.s) without any sacrificial reagent. The effect of the mass fraction of CQDs on CdS and catalyst loading on photocatalytic CO2 reduction has been investigated. The optimal CQDs/CdS(bio) loading (0.50% w/w) exhibited the maximum methanol yield of 1060.52 μmol/g·h (apparent quantum efficiency 7%) over 5 h. CQDs/CdS(bio) nanocomposites exhibited strong stability (test up to 25 h in five consecutive cycles), retaining the morphological (0.11% variation in size) and structural (4.2% variation in crystallinity index) attributes. This work would provide valuable insights into the development of bio-based CdS-based composites for efficient PCO2RR into valuable chemicals.

High temperature vat photopolymerization 3D printing of fully bio-based composites: Green vegetable oil epoxy matrix & bio-derived filler powder

Additive manufacturing (AM) is a well-established process which allows to generate complex and accurate geometry required in several applications, from medical to automotive area. The exploitation of polymer resin into additive manufacturing needs to overcome the problem of viscosity and reactivity which can be improved by high temperature vat photopolymerization (VPP). Moreover, the concern about climate change and depletion of fossil fuels arises the requirement to move toward bio-derived products which can substitute the commercially available resins without compromise the final properties. In order to close this gap, we have studied vegetable epoxy oil polymer resins as main component for new bio-derived formulations which can be used in vat photopolymerization 3D printing. Furthermore, knowing the limits of the vegetable oils in terms of final properties, the investigation explores the possibility to 3D printing bio-derived composites by adding bio-based fillers, such as wall-nut shell. The UV-curing process was investigated by photo-DSC and photorheology to verify the feasibility of AM. Then, the effect of the presence of the filler on the UV-process was assessed and finally we successfully 3D printed composites of different geometries. The thermo-mechanical properties of the thermoset materials were studied by dynamic analysis and tensile testing. The benefit of the addition of the filler was confirmed and explained by investigating the surface modification of the filler which had an incredible impact on the properties of the composite. Finally, we pursuit the possibility to chemically degrade the thermoset joining the proof-of-concept of circular economy.