Sustainable Structural Materials Research Articles

Performance Evaluation of Carbon Fiber Fabric-Reinforced Formaldehyde-Free High-Strength Plywood.

Plywood is lightweight, strong, and durable, making it a widely used material in building decoration and furniture areas. In this study, formaldehyde-free, high-strength plywood was prepared through the incorporation of carbon fiber fabrics (CFFs) as reinforcement layers and their bonding with maleic anhydride polyethylene (MAPE) films. Various tests were performed to assess the impact of the carbon fiber fabric positioning on the physical and mechanical properties of plywood, including tensile shear strength, flexural strength, water absorption, thickness swelling, and electro-thermal properties. The results revealed that the plywood with CFFs exhibited significantly higher mechanical properties than plywood without CFFs. Particularly, the addition of CFFs increased the tensile strength of the plywood by nearly 54.43%, regardless of the CFFs' position. The symmetric placement of CFFs near the bottom and upper layers of the plywood resulted in a maximum modulus of rupture of 85.6 MPa. These findings were validated by numerical simulations. Scanning electron microscopy analysis of the plywood microstructures revealed that MAPE penetrated both the vessels and xylem of the wood veneers and the pores of the CFFs, thereby improving the mechanical properties of the plywood. Plywood reinforced with CFFs exhibited increased water absorption and thickness swelling after immersion. Additionally, the placement of CFFs influenced the electro-thermal properties of the plywood. Plywood with CFFs positioned near the bottom and upper surfaces exhibited superior thermal conductivity. Overall, this study presents a feasible method for developing high-performance, formaldehyde-free plywood and sustainable wood-based structural materials with potential applications in geothermal flooring.

Influential reinforcement parameters, elemental mapping, topological analysis and mechanical performance of lignocellulosic date palm/epoxy composites for improved sustainable materials

The value of biomaterials for green products has begun to develop more ecofriendly and renewable sustainable materials for a better circular economy and to reduce carbon footprints. This work presents integrated investigations of the lignocellulosic date palm/epoxy composites at various reinforcement condition parameters for sustainable structural materials where elemental mapping, topological analysis, and mechanical performance have been performed. Mapping energy dispersive X-ray spectroscopy was utilized to assess the composite composition properly. Elemental mapping and a scanning electron microscope were employed to evaluate the chemical composition of the composites. The mechanical performance of the produced composites was also explored in terms of ultimate tensile strength, tensile modulus, elongation at break, and impact energy properties. The effects of fiber loading, fiber length, and fiber width (as long fiber, short fiber, and long-thin fiber) were investigated for the date palm fiber/epoxy composites. Results have revealed that the composite behavior was affected by several influential reinforcement parameters. The energy dispersive X-ray spectroscopy maps by C–K, O–K, Si–K, K-K, and Ca-K demonstrated that the composites contain mainly carbon, silicon, and oxygen. It was evident that the modulus of elasticity property of short fiber composites exhibits an increasing trend with higher fiber content, even at 35 wt%. Moreover, the enhancement of tensile strength for the short fiber size composites reached 72.5 %. However, such tensile strength of thin fiber size/epoxy composites achieved 135.7 % at 25 wt% indicating superior development of this mechanical property. The long date palm fiber composites demonstrated the best value of modulus of elasticity and the maximum impact energy of 15.3 kJ/m2 attained at 25 wt%, which is about 112.5 % enhancement. Scan electron microscope was capable of confirming that broken fibers were not separated from the matrix indicating the good adhesion between the fiber and the matrix that supports their good mechanical performance.

Structure-property correlations study in biochar-enhanced polyamide composites for sustainable materials development

This study explores the synthesis and characterization of polyamide/biochar composites via in situ polymerization of 12-aminolauric acid with varying biochar concentrations. The motivation behind this research is to enhance the properties of polyamide 12 (PA12) by integrating biochar, a sustainable material derived from biomass, to improve both performance and environmental impact. A detailed structure-property correlation analysis was conducted to assess the effects of biochar on PA12's morphology, mechanical behavior, crystallinity, thermal stability, viscoelastic performance, and environmental sustainability. Key findings include successful PA12 synthesis, confirmed by FTIR and 1H NMR spectroscopy. Increased biochar content led to a decrease in molecular weight and an increase in crystallinity from 27 % to 38 %, suggesting enhanced nucleation effects. SEM analysis showed excellent dispersion and compatibility of biochar within the PA12 matrix, leading to significant improvements in tensile strength (from 38 ± 1 MPa to 54 ± 2 MPa) and modulus (from 745 ± 30 MPa to 2055 ± 65 MPa). Rheological tests demonstrated shear-thinning behavior, facilitating effective extrusion-based 3D printing of a complex object with 50 wt% biochar. A life cycle assessment revealed substantial environmental benefits, including a net reduction of 1.83 kg·CO₂ equiv.·kg⁻1 due to the use of biochar derived from wood pyrolysis. These findings highlight the potential of PA12/biochar composites as environmentally sustainable structural materials, combining enhanced functional properties with significant ecological advantages.

Green and sustainable fabrication of DES-pretreated high-strength densified wood

Wood is a sustainable, benign, and high-performing green structural material readily available in nature that can be used to replace structural materials. However, insufficient mechanical performance (compared to metals and plastic), moisture sensitivity, and susceptibility to microorganism attack make it challenging to use wood as it is for advanced engineering applications. We here present an efficient approach to fabricating densified wood with minimal time and waste generation, demonstrating high mechanical strength, and decreased water penetration on the surface. Wood slabs were treated with deep eutectic solvents (DESs) to solubilize the lignin, followed by in-situ regeneration of dissolved lignin in the wood. Then, the slabs were densified with heat and pressure, turning the wood into a functionalized densified material. Lignin regeneration and morphological changes were observed via two-photon microscopy and Scanning Electron Microscopy (SEM), respectively. The final product is less susceptible to water absorption on the surface and has enhanced flexural strength (> 50% higher), surface hardness (100% increased), and minimal set recovery compared to natural wood. The improved mechanical performance is due to regenerated lignin which acts as a glue and fills spaces present within the interconnected cellulose network inside the wood, forming a highly dense composite during densification. Such enhancement in the properties of DES-densified wood composite makes it a favorable candidate for advanced structural and engineering applications.

Simultaneously Strengthening and Toughening All-Natural Structural Materials via 3D Nanofiber Network Interfacial Design.

Constructing structural materials from sustainable raw materials is considered an efficient way to reduce the potential threat posed by plastics. Nevertheless, challenges remain regarding combining excellent mechanical and thermal properties, especially the balance of strength and toughness. Here, we report a 3D nanofiber network interfacial design strategy to strengthen and toughen all-natural structural materials simultaneously. The introduced protonated chitosan at the interface between the surface oxidized 3D nanonetwork of bacterial cellulose forms the interfacial interlocking structure of nanonetworks, achieving a robust physical connection and providing enough physical contact sites for chemical crosslinking. The obtained sustainable structural material successfully integrates excellent mechanical and thermal properties on the nanoscale of cellulose nanofibers, such as light weight, high strength, and superior thermal expansion coefficient. The relationship between structural design and comprehensive mechanical property improvement is analyzed in detail, providing a universal perspective to design sustainable high-performance structural materials from nanoscale building blocks.

Simultaneously Strengthening and Toughening All‐Natural Structural Materials via 3D Nanofiber Network Interfacial Design

AbstractConstructing structural materials from sustainable raw materials is considered an efficient way to reduce the potential threat posed by plastics. Nevertheless, challenges remain regarding combining excellent mechanical and thermal properties, especially the balance of strength and toughness. Here, we report a 3D nanofiber network interfacial design strategy to strengthen and toughen all‐natural structural materials simultaneously. The introduced protonated chitosan at the interface between the surface oxidized 3D nanonetwork of bacterial cellulose forms the interfacial interlocking structure of nanonetworks, achieving a robust physical connection and providing enough physical contact sites for chemical crosslinking. The obtained sustainable structural material successfully integrates excellent mechanical and thermal properties on the nanoscale of cellulose nanofibers, such as light weight, high strength, and superior thermal expansion coefficient. The relationship between structural design and comprehensive mechanical property improvement is analyzed in detail, providing a universal perspective to design sustainable high‐performance structural materials from nanoscale building blocks.

Unveiling ductile, rare-earth-free structural materials: A DFT exploration of MnTi and MnZr

This paper presents a theoretical exploration of the electronic, structural, and mechanical attributes inherent in three rare-earth-free intermetallic compounds, namely, MnTi, MnZr, and MnHf. Employing density functional theory (DFT) calculations with the Implementation of projector augmented wave (PAW); our investigation adopts the supercell approach to meticulously determine the structural and mechanical properties of these materials. The findings reveal that MnTi and MnZr exhibit intrinsic ductility, positioning them as viable contenders for applications demanding high-strength structures. In contrast, MnHf demonstrates mechanical instability. This study provides promising insights into the mechanical characteristics of MnTi and MnZr, underscoring their potential as sustainable structural materials, given the abundance and non-toxic nature of their constituents. The research findings presented herein contribute to the understanding of rare-earth-free intermetallics, offering valuable information for applications in materials science and engineering.

Lignocellulosic abaca fibre-reinforced thermoplastic composites as future sustainable structural materials: a bibliometric analysis and literature review

Lignocellulosic abaca fibre-reinforced thermoplastic composites as future sustainable structural materials: a bibliometric analysis and literature review

Fire-retardant anti-microbial robust wood nanocomposite capable of fire-warning by graded-penetration impregnation

Wood, renowned for its sustainability, specific strength, and thermal insulation, stands as a highly sought-after sustainable structural material. However, the inherent flammability, decay susceptibility, and inadequate mechanical strength hinder its practical applications in high-rise buildings. Here, we report a groundbreaking solution to fabricate multi-functional fire-retardant wood (M-FRW) through a coupled delignification/impregnation procedure followed by densification treatment. The GO/BA created a hybridized network on the M-FRW surface, while BA molecules penetrated the wood cell. As-created M-FRW exhibits a superior flame retardancy due to the physical barrier and catalytic charring effect of GO/BA, as reflected by an ultrahigh limiting oxygen index value of >75 % and an 85 % reduction in the peak of heat release rate compared to natural wood. Furthermore, the GO/BA layer of M-FRW has a sensitive fire alarm response and ultralong alarm time (∼11280 s). More impressively, M-FRW exhibits an exceptional ability to inhibit decay fungi, mold fungi, and common bacteria due to the superimposed anti-microbial effect of GO and BA. Additionally, M-FRW shows desirable mechanical and thermal insulation properties. This work provides a facile strategy to fabricate a multi-functional advanced wood nanocomposite, making them hold great potential for various engineering applications, such as intelligent buildings.

Assessment of Density and Anatomical Features of Young and Old Bambusa vulgaris (Schrad. ex J.C. Wendl.) Culm Heights as Sustainable Structural Material in Ghana

This study sought to assess the density and anatomical features of young and old Bambusa vulgaris Schrad. ex JC Wendl. culm heights and, therefore, evaluate their influence on the utilization potential of the culm as a sustainable structural material. Bambusa vulgaris culm of 2-year and 4-year-old were harvested and prepared to the required length of 6 meters for the study. Basic density and anatomical features were carried out. The results showed that the basic density of old bamboo ranges from 652.91 kg/m³ to 729.06 kg/m³, while the young bamboo ranges from 342.33 kg/m³ to 509.52 kg/m³. The vascular bundle arrangement was found to be in Type III and Type IV for the culm heights of both young and old bamboo. The average vascular bundle radial diameter ranged from 761.13 μm to 890.78 μm for the old culm and 727.16 μm to 844.83 μm for the young culm. The average vascular bundle tangential diameter ranged from 499.44 μm to 533.49 μm for the old culm and 425.56 μm to 483.56 μm for the young culm. The radial diameter of the metaxylem vessel of the old culm ranged from 216.81 μm to 54.74 μm, while 214.23 μm to 73.86 μm were for the young culm. Parenchyma tissues ranged from 35%– to 70% for the old bamboo culm and 45% to 75% for the young bamboo culm. Vessel proportion ranged from 6%–12% for the old culm while the young culm ranged from 5%–11%. Fiber proportion ranged from 22% to 54% for the old culm and 19% to 44% for the young culm. Old bamboo had better vascular bundle properties than that of young bamboo. The density is significantly correlated positively to the anatomical properties. Old bamboo is more suitable to be used as the engineered composite material due to its better anatomical features across the culm wall thickness.

Fabrication of High-Performance Densified Wood via High-Pressure Steam Treatment and Hot-Pressing.

The fabrication of sustainable structural materials with high physical properties to replace engineering plastics is a major challenge for modern industry, and wood, as the most abundant sustainable natural raw material on the planet, has received a great deal of attention from researchers. Researchers have made efforts to enhance the physical properties of wood in order to replace plastics. However, it is also difficult to meet practical demands at a low cost. Herein, we report a simple and efficient top-down strategy to transform bulk natural basswood into a high-performance structural material. This three-step strategy involves partial removal of hemicellulose and lignin via treating basswood by boiling an aqueous mixture of NaOH and Na2SO3, and a high-pressure steam treatment (HPST) was applied to delignified wood followed by hot-pressing, which allowed the wood to absorb moisture uniformly and quickly. HPST-treated dense delignified wood (HDDW) has a tensile strength of ~420 MPa, which is 6.5 times better than natural basswood (~65 MPa). We systematically investigated the various factors affecting the tensile strength of this wood material and explored the reasons why these factors affect the tensile strength, as well as the intrinsic connection between the moisture absorbed through HPST and the increased tensile strength of HDDW. Through our experiments, we realized the enhancement mechanism of HDDW and the optimal experimental conditions for the fabrication of HDDW.

Development of eco-friendly and robust structural materials via binder-free lamination of waste biomass with help of finite element method

To alleviate the environmental pressure, it is of great significance to develop the green and sustainable structural materials by utilization of waste biomass. In this work, an eco-friendly, high-strength, superhydrophobic, and thermally stable material was fabricated through a scalable binder-free lamination method using waste biomass (e.g., wood residues, crop straw, and waste paperboard). The waste biomass was separated and molded into fiber mats by a clean pulping process, and then laminated without adhesives. The finite element method (FEM) was adopted to visually observe fracture behaviors and detect the weakest zones. The utilization of FEM to enhance the mechanical strength is unique in productions of traditional biomass composites. The weakest zones were reinforced by the H2O2 spraying approach, and the flexural strength (FS) was improved from 80.12 to 120.35 MPa. The moisture content (MC) in the mat was used for regulating the softening of cellulosic fibers. In virtue of the water-induced plasticization, the laminated materials showed a high internal bonding strength (IBS) of 2.24 MPa and excellent FS of 134.81 MPa. Being benefitted from the silica modification, the materials exhibited a superhydrophobic surface with the high water contact angle (154.1°), good dimensional stability (a thickness swelling of 14.8%), and superior mechanical stability (remained 94.3% FS after two months of ultraviolet radiation). This work provides a new strategy to develop green and sustainable structural materials for buildings, furniture, and related applications.

Strong and fire-resistant bamboo enabled by densification and boron nitride/graphene oxide nanocoating

Bamboo is an abundant and fast-growing nature material, which has been used in furniture and buildings. Its strength and fire-resistance are two critical issues for its wide applications. Herein, a high-strength and flame-retardant structural bamboo is obtained by constructing a boron nitride (BN)/graphene oxide (GO) composite nanocoating on the surface of delignified and densified bamboo (D-bamboo), abbreviated as BN/GO@D-bamboo. The two-dimensional BN nanosheets can form a layered structure on the surface of bamboo, providing bamboo with thermal dissipation and physical barrier for significantly improving its fire resistance. As a result, compared with natural bamboo and D-bamboo, the ignition time of BN/GO@D-bamboo is prolonged by 67% and 49%, the maximum heat release rate and total heat release are reduced by 59% and 40%, respectively, the smoke generation is also significantly reduced, showing an excellent flame retardancy and smoke suppression. On the other hand, GO in the composite nanocoating can form hydrogen bonding with the cellulose of bamboo, which in turn endows the coating with strong adhesion (5 B grade). Consequently, the axial tensile strength, bending strength and radial compressive strength of the BN/GO@D-bamboo are significantly improved compared with natural bamboo. Given the excellent flame retardancy and mechanical robustness of BN/GO@D-bamboo, it is expected to be a new generation high-performance sustainable structural material.

High-strength and ultra-tough supramolecular polyamide spider silk fibers assembled via specific covalent and reversible hydrogen bonds

Achieving ultra-high tensile strength and exceptional toughness is a longstanding goal for structural materials. However, previous attempts using covalent and non-covalent bonds have failed, leading to the belief that these two properties are mutually exclusive. Consequently, commercial fibers have been forced to compromise between tensile strength and toughness, as seen in the differences between nylon and Kevlar. To address this challenge, we drew inspiration from the disparate tensile strength and toughness of nylon and Kevlar, both of which are polyamide fibers, and developed an innovative approach that combines specific intermolecular disulfide bonds and reversible hydrogen bonds to create ultra-strong and ultra-tough polyamide spider silk fibers. Our resulting Supramolecular polyamide spider silk, which has a maximum molecular weight of 1084 kDa, exhibits high tensile strength (1180 MPa) and extraordinary toughness (433 MJ/m3), surpassing Kevlar's toughness 8-fold. This breakthrough presents a new opportunity for the sustainable development of spider silk as an environmentally friendly alternative to synthetic commercial fibers, as spider silk is composed of amino acids. Future research could explore the use of these techniques and fundamental knowledge to develop other super materials in various mechanical fields, with the potential to improve people's lives in many ways. Statement of significance• By emulating synthetic commercial fibers such as nylon and polyethylene, we have successfully produced supramolecular-weight polyamide spider silk fibers with a molecular weight of 1084 kDa through a unique covalent bond-mediated linear polymerization reaction of spider silk protein molecules. This greatly surpasses the previous record of a maximum molecular weight of 556 kDa. • We obtained supramolecular polyamide spider silk fibers with both high-tensile strength and toughness. The stress at break is 1180 MPa, and the toughness is 8 times that of kevlar, reaching 433 MJ/m3. • Our results challenge the notion that it is impossible to manufacture fibers with both ultra-high tensile strength and ultra-toughness, and provide theoretical guidance for developing environmentally friendly and sustainable structural materials that meet industrial needs.

Fatigue and Impact Properties of Kenaf/Glass-Reinforced Hybrid Pultruded Composites for Structural Applications.

To address the weight, cost, and sustainability associated with fibreglass application in structural composites, plant fibres serve as an alternative to reduce and replace the usage of glass fibres. However, there remains a gap in the comprehensive research on plant fibre composites, particularly in their durability for viable structural applications. This research investigates the fatigue and impact properties of pultruded kenaf/glass-reinforced hybrid polyester composites tailored for structural applications. Utilising kenaf fibres in mat form, unidirectional E-glass fibre direct roving yarns, and unsaturated polyester resin as key constituents, pultruded kenaf/glass hybrid profiles were fabricated. The study reveals that pultruded WK/UG alternate specimens exhibit commendable fatigue properties (18,630 cycles at 60% ultimate tensile strength, UTS) and fracture energy (261.3 kJ/m2), showcasing promise for moderate load structural applications. Notably, the pultruded 3 WK/UG/3WK variant emerges as a viable contender for low-load structural tasks recorded satisfactory fatigue properties (10,730 cycles at 60% UTS) and fracture energy (167.09 kJ/m2). Fatigue failure modes indicate that the stress applied is evenly distributed. Ductile failures and delaminations during impact test can be attributed to damping and energy absorbing properties of kenaf fibres. Moreover, incorporating kenaf as a hybrid alternative demonstrates substantial reductions in cost (35.7-50%) and weight (9.6-19.1%). This research establishes a foundation for advancing sustainable and efficient structural materials and highlights the significant role of materials design in shaping the future of engineering applications.

Synergistic in-situ reinforcement of lignin and adhesive for high-performance aligned bamboo fibers composites

To replace plastics with bamboo, it is necessary to develop renewable, lightweight, high-strength, damping, and vibration-reducing bamboo structural materials that can be applied in buildings, transportation, and mechanical engineering applications. Here, a low-cost and high-efficiency top-down method was designed for processing natural bamboo into a lightweight and high-strength aligned bamboo fiber composite. This composite used oriented bamboo fibers that had their lignin and hemicellulose removed, which were used as continuous reinforcement materials, and phenolic resin was used as the adhesive, followed by hot pressing. A highly-interwoven structure was formed by the penetration of the adhesive and the combination of strong hydrogen bonds and chemical bonds formed during hot pressing. This resulted in the high performance of the composite, which exhibited a tensile strength of 421.5 MPa, a bending strength of 211.19 MPa, and an impact toughness of 26.7 J/cm2, which were respectively 2.50, 2.09, and 5.7 times higher than those of natural bamboo. Due to its low density (1.08 g/cm3) and specific tensile strength of 390 MPa g−1 cm3, it was superior to commonly used engineering structural materials such as aluminum alloy, steel, and titanium alloy. It also exhibited excellent damping and vibration reduction performance (with the first three damping ratios of 0.75 %, 0.68 %, and 1.75 %) and dimensional stability (with a 24-h water absorption thickness expansion rate of 7.75 %). Due to its excellent mechanical properties and dimensional stability under wet and hot conditions, this composite is expected to replace nonrenewable synthetic materials as a green and sustainable engineering structural material. It may find applications in drone wings, wind turbine blades, and automotive manufacturing.

Cover Image

A high‐performance and sustainable structural functional material has been developed from natural pinewood, enabled by the unique ionic bond. The obtained material shows good water resistance, thermal conductivity, thermal stability, UV resistance, corrosion resistance and antibacterial properties. This material has promising applications in waterproof enclosure structure, underfloor heating, UV resistant protective cover, and anti‐corrosion materials, etc. image

Multiscale Engineered Waste Wood Particles toward a Sustainable, Scalable, and High‐Performance Structural Material

AbstractDeveloping sustainable and lightweight structural materials is a promising strategy for reducing carbon emissions in transportation and buildings. However, producing high‐performance bulk structural materials from sustainable biomass materials while maintaining excellent mechanical strength remains a major challenge, especially for further scale‐up. Herein, a scalable and robust bottom‐up strategy is reported to fabricate bulk wooden plate (W‐plate) with a typical “brick‐and‐mortar” structure from engineered wood particles via moderate delignification and in situ LiCl/DMAc treatment followed by hot‐pressing. The W‐plate constructed by delignified wood particles and regenerated cellulose nanofibers can achieve a confluence of mechanical strengthening and toughening by the ordered lamination structure and multiscale cellulose micro/nanofiber crosslinking interactions, resulting in high flexural strength (225.17 ± 12.18 MPa) and high fracture toughness (4.01 ± 0.53 MPa m0.5) while maintaining a low density (1.34 g cm−3), superior to typical metals and ceramics. Moreover, the W‐plate exhibits advantageous thermal properties, including a low thermal expansion coefficient (<19 × 10−6 K−1) and a high storage modulus (>7.5 GPa) compared to those of petroleum‐based polymers. Coupled with abundant and renewable raw materials, all‐cellulose components, and scalable and recyclable fabrication, the W‐plate can potentially be used as a high‐performance, cost‐effective, and environmentally friendly alternative for engineering applications.

Mechanically strong, hydrostable, and biodegradable all-biobased transparent wood films with UV-blocking performance

Petroleum-based plastics are useful but they pose a great threat to the environment and human health. It is highly desirable yet challenging to develop sustainable structural materials with excellent mechanical and optical properties for plastic replacement. Here, we report a simple and efficient method to manufacture high-performance all-biobased structural materials from cellulosic wood skeleton (WS) and gelatin via oxidation and densification. Specifically, gelatin was grafted to the oxidized cellulose wood skeletons (DAWS) and then physically crosslinked via Tannic acid (TA), resulting in a significant enhancement of the material properties. Notably, only a mild pressure was applied during the drying process to form a densified TA/Gelatin/transparent wood film(TWF). The developed TA/Gelatin/TWF (thickness:100 ± 12 μm) exhibited a desirable combination of high strength (∼154.59 MPa), light transmittance (86.2 % at 600 nm), low haze (16.7 %), high water stability (wet strength: ∼130.13 MPa) and ultraviolet blocking efficacy which surpass most of the petroleum-based plastics. In addition, due to the all bio-based origins (wood and gelatin), TA/Gelatin/TWF are easily biodegradable under natural conditions, leading to less impact on the environment. These findings would hold promises for exploring high-quality all bio-based wood composites as eco-friendly alternatives to substitute plastics with wide applications, e.g. anti-counterfeiting, UV protection, and flexible electricals.

Tensile Property of Jute Fiber Sliver Reinforced Green Composite Material under Loading Speed

To assess the safety and utility of green composite materials as a sustainable structural material, this study investigated their tensile properties using unidirectional jute fiber sliver and poly (lactic acid) and poly (butylene succinate) under loading speed. The fiber volume fraction of the green composite materials was about 10%. Vacuum compression molding was used for molding. Static tensile tests of green composite materials using poly (lactic acid) and poly (butylene succinate) were conducted with 0.1–10 mm/min test speed at room temperature, yielding the following conclusions. Tensile strengths of green composite materials using poly (lactic acid) and poly (butylene succinate) increased with increased test speed. The strain rate dependence of the green composite using poly (lactic acid) became strong, but the strain rate dependence of green composite material using poly (butylene succinate) became weak. Results suggest that the matrix viscoelasticity might influence the loading speed effects on the tensile properties of these green composite materials.