Bio-based Composites Research Articles

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.

Use of a commingling process for innovative flax fibre reinforced unidirectional composites

Optimisation of textile preforms play a crucial role in the development of high-performance biobased composites materials. In this context, the main ambition of this work is to quantify and assess the mechanical properties and behaviour of biocomposite materials made from unidirectional commingled preforms based on flax and poly-(propylene) fibres. To the best of our knowledge, there is no literature examining the effect of the commingling process on the ultrastructure and the mechanical properties of flax fibres. At the scale of the elementary fibre, fibre mechanical properties are observed to be stable after commingling. However, repeated drawing in the commingling process leads to increased cellulose crystallinity and a larger fraction of elementary fibres exhibiting quasi-linear tensile behaviour. The composite materials produced with these commingled flax/poly-(propylene) preforms contain few cortical residues and show a remarkable degree of fibre individualisation. Moreover, they exhibit high Young's modulus and a stress at break of 24 GPa and 194 MPa, respectively, for a fibre volume fraction of 36 %. A substantial drop in properties is however noted at high fibre fractions due increased heterogeneity of the materials. Remarkably, the biocomposites achieved unprecedented transverse modulus and stress at break of 2.3 GPa and 16.5 MPa, respectively. Our results validate the potential and interest in commingling processes for designing a new family of plant fibre composite materials.

Bio-based Eucommia ulmoides gum composites for high-performance engineering tire applications

In this work, bio-based Eucommia ulmoides gum (EUG)/natural rubber (NR)/styrene-butadiene rubber (SBR) composites are successfully fabricated through physical blending. The influence of sulfur (S) and EUG content on the crystallization characteristics, static and dynamic mechanical properties of the composites is systematically investigated. Furthermore, the impact of the cross-linking network structure on the crystallization behavior of EUG is examined, and the application of EUG/NR/SBR composites in engineering tires is explored. The results reveal that with the increasing of EUG content, the composites exhibit enhanced wear resistance and cut resistance, as well as reduced heat generation and rolling resistance. Specifically, in comparison with NR/SBR composites, the dynamic temperature rise, wear resistance, and dynamic cutting amount of EUG/NR/SBR (20/40/40) composites decreased by 14.7%, 17.1%, and 11.2%, respectively, while the fatigue life of the composites improves by 33%. This work provides valuable guidance for fabricating and applying high-performance bio-based EUG composites in engineering tires.

Interfacial properties of carbon fiber‐reinforced biobased resin composites by single fiber fragmentation, fiber push‐out, and interlaminar shear strength

AbstractThe present study examines the interfacial properties of carbon fiber biobased resin composites by comparing the test methods such as the single fiber fragmentation test, fiber push‐out test, and interlaminar shear strength test. The composites were fabricated using a cold vacuum‐assisted resin infusion method for the preparation of fiber push‐out and interlaminar shear test specimens. The interfacial adhesion from the three different test methods is analyzed and compared to determine their relative effectiveness in evaluating interfacial adhesion. Plasma treatment is performed on the carbon fibers and the interfacial shear stress is evaluated by conducting the push‐out test. The surface characterization of the carbon fibers is done by scanning electron microscopy and x‐ray photoelectron spectroscopy to investigate the influence of the plasma treatment on the fiber surface. Plasma treatment resulted in significant improvement in the interfacial adhesion between the fiber and matrix.Highlights Analysis and comparison of interfacial adhesion by several test methods. Single fiber fragmentation and push‐out tests with IFSS of 40.5 and 42.2 MPa. Plasma surface treatment improved the IFSS by 88.1%. Surface characterization of treated and untreated fibers by SEM and XPS.

3-D modeling of automatic pressure gelation process for manufacturing gas insulated switchgear spacer using bio-based epoxy composite

In existing power devices, various insulating parts are manufactured with petroleum-based epoxy resin. However, as petroleum-based resources are gradually depleted and environmental problems have emerged, research on replacing petroleum-based products with eco-friendly materials as insulators has been actively conducted. Therefore, in this study, a molding simulation study of the Auto Pressure Gelation (APG) process, one of the leading technologies, was conducted to manufacture a gas insulated switchgear (GIS) spacer using an environmentally friendly bio-based epoxy composite. Using the heat dissipation and degree of cure obtained through the dynamic differential scanning calorimetry (DSC) test, it was applied to the Kamal-Sourour model which is a representative curing dynamics empirical formula. In addition, the viscosity change during the curing process was measured using a rheometer and applied to the cross Castro-Macoskco model. The results obtained were in good agreement with the experimental values. The parameters calculated above and other physical property values were input into Moldflow software, and simulation was performed targeting the three-phase spacer. While changing the temperature setting of the mold, the change and distribution of flow, temperature, and curing degree inside the product were observed during the reactive molding process. As a result, it was found that there was a possibility of clogging of the mold entrance at some set temperatures, and it was possible to suggest improvement directions to solve this problem. Through this series of research process, it is considered that it will be of great help in improving the quality problems of molded products and the process accordingly.

Improvements in Mechanical and Shape-Memory Properties of Bio-Based Composite: Effects of Adding Carbon Fiber and Graphene Nanoparticles.

Shape-memory carbon fiber (CF) polymer composites reinforced with graphene nanoplatelets (GnPs) as a filler based on a bio-based V-fa/ECO copolymer were prepared at different graphene GnPs and CF mass fractions using the hand lay-up and hot-pressing methods. The obtained composite specimens were subjected to flexural, dynamic mechanical, and shape-memory analyses. The obtained results revealed that the flexural strength and modulus were improved by the addition of the GnPs and CF due to the improvement in the interfacial adhesion and fiber reinforcement with up to 3 wt.% GnPs and 60 wt.% CF. Additionally, appreciable improvements in the shape-memory performance were achieved with the addition of the GnPs, where values of up to 93% and 96% were recorded for the shape fixity and recovery, respectively. The shape-memory performance was affected by the fiber mass fraction, with the composites retaining the shape-memory effect albeit with a significant drop in performance at higher fiber mass fractions. Lastly, the specimens at 40 wt.% CF and 3 wt.% GnPs were determined to be the optimum compositions for the best performance of the bio-based SMP composite.