Wood Plastic Composites Research Articles

An energy storage composite using cellulose grafted polyethylene glycol as solid–solid phase change material

AbstractPhase‐change material (PCM) has great thermal energy ability, which has been used as building material for energy conservation. While the most widely used solid–liquid PCM usually appeared leakage during the phase change transition. In order to overcome the leakage of solid–liquid PCM and prepare a viable building energy‐saving materials for indoor temperature regulation, thermal energy storage composites were prepared by utilizing cellulose grafted PEG as phase change material (PCM) and high‐density polyethylene (HDPE) as the substrate. The liquid leakage of PEG was solved after graft to fabricate solid–solid PCM. HDPE is beneficial for solving the leakage and improving the mechanical property by its secondary encapsulation. The synthesized Cellulose‐PEG was characterized by scanning electron microscopy (SEM), X‐ray diffractometer (XRD), and differential scanning calorimetry (DSC). Thermal and mechanical characteristics of the composite were explored. The outcomes revealed that: (1) PEG was successfully grafted to the surface of cellulose and Cellulose‐PEG showed solid–solid phase change behavior. (2) Both the melting‐cooling temperatures and the thermal stability of solid–solid wood plastic composite (SSWPC) had the potential as thermal energy storage material for temperature regulating. (3) The addition of Cellulose‐PEG adversely affected moisture resistance, flexural property, and impact strength due to the weak interface bonding. The physical and mechanical degradation was tolerable for applying situation where mechanical performance is less crucial.Highlights Cellulose‐PEG showed solid–solid phase change behavior without liquid leakage. High‐density polyethylene (HDPE) was used as the matrix to realize the second encapsulation of PCM. Cellulose‐PEG negatively influenced the physical and mechanical property of HDPE. Solid–solid wood plastic composite presented great thermal storage capacity for indoor temperature regulating.

Effect of Coupling Treatment on Interfacial Bonding Properties of Wood Veneer/Wood Flour–Polyvinyl Chloride Composites with Sandwich Structure

Wood–plastic composites (WPCs) have received growing attention due to their good water resistance, environmental friendliness, and recyclability. For the application of WPCs in interior decoration and other high–value fields, it is necessary to preserve these characteristics whilst enhancing their mechanical properties and surface aesthetics. In this study, we used a sandwich structure and four interface modifiers to prepare wood veneer/wood flour–polyvinyl chloride composites (WWPVCs). The results revealed that the WWPVCs treated with a silane coupling agent exhibited superior interfacial bonding and mechanical properties compared to those obtained using other interface modifiers. The interfacial bonding strength of the treated sample reached 1.22 MPa, which was 122% higher than that of the untreated sample. In addition, the wood failure ratio of the optimal sample reached 80%. Furthermore, the dipping–peeling length was found to be shorter than those achieved using other interface modifiers after tests at 63 and 100 °C, indicating that the material treated using the silane coupling agent exhibits an excellent resistance to moisture and heat. Notably, silane coupling agents are easily prepared as solvent–based modifiers, and they do not release harmful gases (e.g., formaldehyde), thereby rendering them highly effective in the preparation of environmentally friendly WPC products.

Utilization of Torrefied and Non-Torrefied Short Rotation Willow in Wood-Plastic Composites.

The torrefaction process is widely used in the energy field, but the characteristics of the torrefied wood also have positive effects on the production of wood plastic composites. In this study, short-rotation shrub willow was torrefied at 225 and 300 °C and incorporated into polypropylene composites filled with changing levels of weight percent (wt%) of non-torrefied and torrefied (5, 15, 25, and 40 wt%) wood. Nine different formulations were extruded for mechanical, thermal, and water absorption properties. The tensile properties of composites were not affected by any level of torrefaction, while higher flexure properties were in favor of lower wt% of torrefied wood. The slowest rate of thermal degradation was confirmed for the highest wt% of torrefied wood with a torrefaction temperature of 300 °C. In contrast, the presence of torrefied wood in composites did not show a difference in crystallization or melting temperatures. The most noticeable contribution of torrefaction temperature and wt% was found for water-absorbing properties, where the higher torrefaction temperature and largest wt% of torrefied wood in the composite resulted in decreased water uptake.

Effect of Zeolite Mineral on the Formulation of a Wood-plastic Composite

The present work studies the positive or negative effect of zeolite mineral on the tensile and flexural mechanical behavior of a wood-plastic composite. Eight different blends were developed, the components used were wood flour (WF), polypropylene (PP), zeolite (Z) and maleic anhydride modified polypropylene (MAPP) as coupling agent. The eight blends were made using a counter-rotating twin-screw extruder, while the specimens were produced on a plastic injection molding machine with a 60ton clamping capacity. The standards used to determine the tensile and flexural mechanical properties were ASTM 638 and ASTM 790, respectively. Ten repetitions of each mixture were carried out. In addition, a reference (100% polypropylene) was used to compare the results obtained to determine whether the effect of using the zeolite mineral generated positive or negative results in the compounds obtained. Both studies showed that as the proportion of zeolite increases in the blend, the tensile and flexural properties are affected. However, the mixture (M7) with proportions in its components of, 34.375% WF, 55.875% PP, 6.75 % Z and 3% MAPP, showed an increase in the tensile and flexural mechanical properties, indicating a strong relationship between the components that integrate the wood-plastic composite (WPC), mainly between wood and mineral.

Optimizing the water absorption behaviour and natural weathering resistance of compatibilized ironwood-based recycled polypropylene composites

This study focused on the optimization of material resistance of wood-plastic composite (WPC) made using recycled polypropylene and industrial ironwood residues toward water and natural weathering exposure. The Taguchi method was employed to optimize the WPC composition and manufacturing process parameters based on the L9 orthogonal array experimental design. The WPC specimens were prepared using two-step of extrusion compounding and compression moulding. As input process parameters, ironwood content, coupling agent content, moulding temperature, and pressure holding time have been taken into consideration. The results were then optimized to get the maximum tensile properties of strength and modulus of elasticity as well as minimum water-weight gain and discolouration area after exposure to water immersion and natural weathering. The grey relational analysis (GRA) was carried out to identify the most significant factors and optimal levels that work synergistically to produce enhanced results. For optimizing the performance after water uptake, the ironwood content and moulding temperature are the most significant parameters with percentage contributions of 48.71% and 43.16%, respectively. Meanwhile, the multi-objective optimization technique of GRA obtains that ironwood content is the most significant factor for optimizing the mechanical and physical performance of the WPC after exposure to natural weathering with a percentage contribution of about 71%. Considering the good resistance of the material toward environmental exposure, this study opens up a pathway to effectively utilize ironwood and recycled polymer waste as a sustainable composite material in outdoor applications.

Determination of Mechanical Properties of Fruit Shell Powders Reinforced Wood Plastic Composite (WPC) Materials and Case Study for I-Type Snap-Fit Model

High quality material production has been among the work of many researchers in recent years. These materials, which are obtained mostly by the production of composite materials, enable the production of lighter, more durable and less costly products. Increasing environmental pollution in recent years, protection of natural resources and ensuring recycling have increased the importance of wood plastic composite material production. In this study, wood plastic composite material was obtained by using ABS (Acrylonitrile butadiene styrene) plastic material and six different fruit shell powders (walnut, pistachio, peanut, almond, hazelnut and apricot shell). The mechanical properties of the obtained composite material were determined and its effect on the I type snap-fits was analyzed in ANSYS software. When the resulting composite material's mechanical properties were tested, it was found that the density and tensile strength decreased while the Vicat softening point value and melt flow rate increased. In the analysis performed using the ANSYS software, it was found that the composite I type snap-fit design of the same size can resist 12.6% N less force when the material is subjected to its maximum values when it achieves the elongation at break value.

Processing and Properties of Wood-Plastic Composite Containing Alkali-Treated Birch Wood Shavings and Bioadditive Obtained by Biorefinery of Birch Bark

In the last two decades, there has been increased interest in research focused on developing innovative polymer composite materials for food packaging, obtained by compounding polymers with organic fillers, intended for the manufacture of food storage containers. Woodplastic composites (WPCs), due to high content of lignocellulosic filler, are consideredbiocomposites and can be used for the fabrication of such types of containers. Their formulations include, along with the matrix and the filler, functional additives. One of the most important considerations while developing a food packaging material is to choose eco-friendly additives. The suberinic acids (SAs), extracted from birch outer bark by hydrolysis in KOH water solution, were examined as lubricants in the formulation of recycled polypropylene/polylactic acid (rPP/PLA) composite filled with the alkali-treated milled birch shaving microparticles and proceeded by extrusion and injection molding. The incorporation of Sas in a birch wood-rPP/PLA composite was performed by treaing the wood microparticles with the SAs water suspension at the defined concentration. Their presence at the optimal content in the composite improved its processing by reducing the extruder rotor torque and injection pressure, which increased the mechanical properties and decreased the wettability of the composite.

Use of Post-Consumer Plastics in the Production of Wood-Plastic Composites for Building Components: A Systematic Review

This systematic review study adopted the PRISMA methodology to investigate recent research on wood-plastic composites (WPC) utilizing post-consumer plastics in the construction industry. Initially, 3111 articles were selected from academic databases using keywords such as “wood and plastic composites”, “WPC”, “polymer”, “recycled”, “waste”, “construction”, and “sustainability.” After stringent exclusion criteria, 15 relevant studies on plastic waste composites were identified. These studies often employ post-consumer plastics like polypropylene and high-density polyethylene, along with plant-based fillers, aiming to enhance mechanical properties and reduce reliance on virgin materials. Analysis of these studies revealed that the optimal plastic composition in the composites ranged from 40% to 45% wood and from 50% to 60% plastic, with the extrusion process being the most employed for shaping. Specific factors, such as the use of compatibilizers and the particle size of raw materials, were identified as significant influencers on composite strength. These materials exhibited high thermal stability, rendering them suitable for construction applications exposed to high temperatures. The diversity of plastic waste explored in the studies underscores the potential to tailor thermal properties to specific application demands. These composites facilitate closed-loop plastic recycling, enabling their reintegration into the production chain and offering opportunities for lightweight, durable, and high-performance products in the construction industry. However, beyond the factors examined in the studies, a meticulous assessment of the fire resistance, weather resistance, ultraviolet resistance, moisture absorption, dimensional stability, degradation, long-term durability, impact strength, recyclability, and cost-effectiveness of the material is crucial. Thoughtful consideration of these factors is essential to achieving a comprehensive understanding of the potential and limitations of recycled plastic composites in promoting energy efficiency and sustainability in the construction industry.

ZnO Treatment on Mechanical Behavior of Polyethylene/Yellow Birch Fiber Composites When Exposed to Fungal Wood Rot.

Wood plastic composite (WPC) usage and demand have increased because of its interesting chemical and mechanical properties compared to other plastic materials. However, there is a possibility of structural and mechanical changes to the material when exposed to the external environment; most research on wood plastic is performed on the material with elevated fiber content (40-70%). Therefore, more research needs to be performed regarding these issues, especially when the fiber content of the WPC is low. In this study, composite materials composed of high-density polyethylene (HDPE) reinforced with yellow birch fibers (20 and 30%) were made by injection molding. The fibers were treated with dissolved zinc oxide (ZnO) powder in sodium oxide (NaOH) solution, and the fabricated material was exposed to fungal rot. ZnO treatment in this case is different from most studies because ZnO nanoparticles are usually employed. The main reason was to obtain better fixation of ZnO on the fibers. The mechanical properties of the composites were assessed by the tensile and Izod impact tests. The impact energies of the samples fabricated with ZnO-treated fibers and exposed to Gloephyllum trabeum and Trametes versicolor decreased, when compared to samples fabricated with ZnO-nontreated fibers. The mechanical properties of the samples composed of ZnO-treated fibers and exposed to rot decreased, which were reported by a decreased Young's modulus and impact energies. The usage of ZnO treatment prevented mycelium proliferation, which was nonexistent on the samples. It has been noted that the decrease in mechanical properties of the treated samples was because of the action of NaOH used to dissolve the ZnO powder.

STUDY ON PREPARATION AND PROPERTIES OF ANTI-ULTRAVIOLET AGING WOOD-PLASTIC COMPOSITES

The degradable wood-plastic composites (WPC) were prepared by compression molding in this study. Polylactic acid (PLA), poly (butylene adipate-co-terephthalate) (PBAT) and salix powder were used as the main raw materials and nano-titanium dioxide (nano-TiO2) was used as anti-ultraviolet filler. The results show that when the addition amount of nano-TIO2was 2%, the static bending strength and elastic modulus of WPC reach 41.88 MPa and 3730MPa, respectively, which can meet the commercial application of WPC in building formwork. At this time, the composite material has a better effect of absorbing and reflecting ultraviolet light. The static bending strength, elastic modulus, tensilestrength and impact strength of WPC were reduced by 68.3%, 61.5%, 51.9% and 57.4%, respectively. The mass loss rate and water absorption were 6.1% and 22.6%, respectively, that shows its good degradation performance. This study provides a low-cost and simple method for the design of anti-UV aging, high-performance and degradable WPC, which has broad application prospects inpackaging, construction and other fields.

Mechanical Properties Variation in Wood-Plastic Composites with a Mixed Wood Fiber Size.

In this study, the influence of fiber particle size on the mechanical properties of a wood--plastic composite (WPC) was investigated using a combination of experimental measurements and numerical modeling. Four different sizes of wood fibers (10-20 mesh, 20-40 mesh, 40-80 mesh, and 80-120 mesh) were used to reinforce high-density polyethylene (HDPE), either separately or in combination. The different sizes of fibers produced varying properties in the resulting composites. The smallest fiber size (80-120 mesh) resulted in the lowest flexural and tensile properties, but the highest impact strength (15.79 kJ/m2) compared to the other three sizes (12.18-14.29 kJ/m2). Using a blend of fiber sizes resulted in improved mechanical properties. Composites containing a mix of 20-40 mesh and 40-80 mesh fibers exhibited the best flexural (strength 74.16 MPa, modulus 5.35 GPa) and tensile performance (strength 48.27 MPa, modulus 4.30 GPa), while composites containing a mix of all four fiber sizes had the highest impact-resistant strength (16.08 kJ/m2). Several models, including the Rule of Mixtures (ROM), the Inverse Rule of Mixtures (IROM), and the Hirsch models, were used to predict the performance of WPCs. The ROM model was found to be the most accurate in describing the mechanical properties of WPCs reinforced with multi-size wood fibers, based on the sum squared error (SSE) analysis.

Comparison of Wood-Based Biocomposites with Polylactic Acid (PLA) Density Profiles by Desaturation and X-ray Spectrum Methods.

Wood-plastic composites (WPCs) represent composite materials that employ shredded wood combined with a thermoplastic substance, such as polylactic acid (PLA), to establish structural cohesion within the product profile. This amalgamation of materials results in a robust structure designed to fulfill specialized roles under the influence of pressure and temperature. Given the nature of the constituent materials, the resultant product can be classified as a biocomposite. The creation of such biocomposites entails a rigorous process necessitating the fine-tuning of specific parameters and suitable technologies. The foundational materials employed in this process must be both natural and biodegradable. However, it is noteworthy that natural components like fibers exhibit anisotropic behavior, wherein their mechanical attributes are contingent on the direction of the applied force. Consequently, predicting their performance during biocomposite production proves challenging. The principal objective of this study was to conduct a comparative analysis of wood-based composites incorporating PLA thermoplastic binding agents. The intention was to discern variations in density profiles arising from distinct measurement methodologies. Two measurement methods were used for the measurement: X-ray and spectrum desaturation. Additionally, the study sought to investigate the impact of introducing PLA additives at 25% and 50% concentrations on the fabrication of WPC from wood chips. The properties of these composites were assessed by considering the inherent traits of the composite materials.

Chemical Degradation of Waste PET and Its Application in Wood Reinforcement and Modification.

In recent years, with the increasing scarcity of fossil resources and the worsening environmental pollution, the effective utilization of wood and plastic waste has become a critical issue. In this paper, propylene glycol (PG) was used as an alcoholysis agent to degrade waste poly(ethylene terephthalate) (PET), and unsaturated polyester (UPR) was synthesized by the polycondensation reaction. The Chinese fir was modified by chemical impregnation to obtain a new type of waste PET-based wood-plastic composites. It exhibits a compressive strength of about 107 MPa and a water absorption of less than 20%. These results highlight the outstanding modification effect on fir, demonstrating excellent mechanical properties and corrosion resistance. This study presents a green and efficient method for the preparation of wood-plastic composites and the recycling of waste PET, providing promising solutions for sustainable resource utilization and environmental protection.

Rheological Properties of Wood Plastic Composites Based on Polypropylene and Birch Plywood Residues - Sanding Dust

This article summarizes the investigation results of the rheological and thermal stability properties of industrially prepared wood plastic composites based on virgin polypropylene (PP) and birch plywood production waste product, plywood sanding dust (PSD). Wood plastic composites (WPCs) PP+40 wt.% PSD contain different modifiers, such as functional lubricant Struktol TWP, antioxidant 1010, thermal stabilizer 168, ultraviolet (UV) stabilizer 770, and pigment concentrate based on low density polyethylene (LDPE). According to these studies, it was concluded that rheological properties studied by the capillary rheometry method depend on WPC composition and the parameters of rheological measurements. On the contrary, melt flow index (MFI) values did not change so much and fluctuated in the range of 1.52–1.66 g/10 min. The presence of thermal and antioxidant stabilizers promoted an increase in the thermal stability of WPCs, as determined by the thermal gravimetric analysis (TGA) method. The characteristics of fluidity curves indicated the character of typical pseudo-plastic liquids, in which viscosity not only depends on temperature, shear stress, and shear deformation rate but also decreases with an increase in shear deformation rate. That also confirmed the values of the fluidity index (n), which for pseudo-plastic polymer melts are always smaller than 1.

Constructing a rigid-flexible grid structure for simultaneously strengthening and toughening bamboo flour/plastic composites through the introduction of continuous carbon fabric meshes via multi-layer co-extrusion

The defects of low strength, brittle fracture, and creep deformation of traditional wood–plastic composites (WPCs) significantly limit their applications as high-value-added products. This study aimed to develop advanced WPCs with high strength, toughness, and creep resistance via a structural design. A continuous rigid-flexible grid structure, sandwiched by carbon fabric mesh prepreg (CFMP) and casting film (MSF) with high toughness, was introduced into bamboo flour/high-density polyethylene composites (BPCs) via a multi-layer co-extrusion technology. The sandwiched grid structure was in-situ cured in the near-surface layers of BPCs to form a multi-layer composite (BPC-CFMP-F) during co-extrusion. The tensile strength, flexible strength, and impact strength of BPC-CFMP-F were 68.4 MPa, 89.0 MPa, and 22.5 kJ m−2, which are 138.3%, 96.4%, and 87.6% higher than those of BPCs, respectively, and the thermal expansion and 1000-hr creep strain of BPC-CFMP-F decreased by 45.8% and 61.7%, respectively. The simultaneous strengthening and toughening of BPCs were attributable to the rigid-flexible grid structure and the strong interfacial bonding between CFMP and BPCs and the surface- and core-layer BPCs through the grid of CFMP. Owing to these unique features, BPC-CFMP-F is a promising advanced composite with high strength, toughness, excellent creep resistance, and thermal stability for high value-added applications.

Wood plastic composites (WPC) waste based triboelectric nanogenerator for mechanical energy harvesting and self-powered applications

The utilization of waste materials for energy production and storage is gaining significant attention due to its numerous advantages, including waste material reuse and the reduction of environmental pollution. A promising technology in this field is triboelectric nanogenerators (TENG), which have proven to be a simple and cost-effective method for harnessing ambient mechanical energy using waste materials. This report focused on applying waste wood-plastic composite (WPC) collected from the house construction sites to fabricate TENG for energy harvesting. The fabricated TENG device exhibited an output voltage and current of approximately 31 V and 30 µA, respectively, with a power density of 107.5 mW/m2. Moreover, the device successfully powered around 80 LEDs and portable electronic devices. By repurposing waste materials like WPC and utilizing TENG technology, this approach showcases the potential for efficient and sustainable energy generation.

Compatibility studies of in-house prepared sustainable wood-plastic composites with commercial composites

In the present research, sustainable wood-plastic composites (WPCs) were produced utilizing recycled expanded polystyrene (EPS) and biomass like sawdust and rice husk. A compatibility analysis was conducted to compare the physico-mechanical properties of the WPCs prepared in-house with those of commercial WPCs and a commercial plywood material. The experiments were carried out following standard procedures and under identical conditions. The results indicated that the WPCs produced in-house demonstrated superior physico-mechanical properties compared to the commercial WPCs, depending on the polymer content mixed. The study also revealed the increase in tensile strength was approximately 2.3 to 3.1 times which was higher than that of the commercial composites, and the in-house WPCs also exhibited better tensile modulus. The flexural strength of the in-house composites increased by approximately four times, and the compression strength increased by about four to eight times when compared to the commercial composites. The estimated hardness and impact strength values of the in-house WPCs were relatively like those of the commercial materials. However, the in-house composites exhibited significantly lower water absorption capacity compared to the commercial composites and plywood. In conclusion, the in-house produced WPCs demonstrated excellent physico-mechanical properties compared to commercial composites, while their properties were comparable to commercial plywood in most cases. These findings suggest that the in-house prepared WPCs can be utilized in various applications.

Enhancement of sustainable wood-plastic composite properties in presence of bio-based additive

In the study, sustainable wood-plastic composites (WPCs) were prepared using recycled expanded polystyrene (EPS) and rice husk biomass. The bio-based material that is coconut coir was used as an additive in the study. The EPS quantity was kept constant at 50 wt%, and the number of bio-based materials varied. In the study, the coconut coir loading was used in the range of 0–5 wt%. The effect of coir on the physico-mechanical properties such as tensile strength, tensile modulus, flexural strength, compression strength, hardness and water absorption of the in-house prepared composites was studied. From the results, it is observed that the mechanical properties of the composites increased in presence of coir; and also its loading of up to 3 wt%. Around 52% increase in tensile strength, 83% increase in tensile modulus, 54% increase in flexural strength, 39% increase in compression strength and 21% increase in hardness of the composites is observed with the increase of coir content from 0 to 3 wt%. However, the composite properties have deteriorated with the increase of coir loading beyond 3 wt%. The water absorption values continuously decreased with the increase in coir content but the decrease in water absorption is insignificant.

EFFECTS OF VEGETATION AND PCM IN REDUCING URBAN HEAT ISLAND

Globally, fast-tracked urbanization has led to diversified environmental challenges since the time of the industrial revolution. Among the challenges faced, Urban Heat Island (UHI) is caused by the replacement of natural materials with man-made ones such as concrete, asphalt, and increased anthropogenic heat production, among other factors. This study is on understanding the reasons behind UHI, its effects, and finding out proper strategies for mitigation in the context of Bangladesh. Among many ways, proper interior and exterior vegetation, sufficient wind flow, and appropriate building materials are chosen to be the proper methods to reduce UHI effects in Bangladesh. CFD analysis has been carried out to understand the effect of vegetation, wind flow, and different material to mitigate UHI. An estimation of the effect of temperature reduction in energy efficiency is also done. It is observed that a significant amount of energy can be saved by reducing the cooling load if these suggestions are followed. The study shows that the temperature is decreased up to 3°C with the increasing vegetation on exterior walls and rooftop. By using Wood Plastic Composite (WPC) on the rooftop as a phase change material, temperature is decreased around 4°C. By using all conditions (rooftop, sidewall, interior vegetation & PCM on rooftop) together temperature could be mitigated around 5°C.

Improvement of weathering and thermal resistance of wood-plastic composites with iron oxide nanoparticles

This study comprehensively investigated the effect of iron-oxide nanoparticles (NPs) on weathering durability and thermal resistance of wood-plastic composites (WPCs). The hydrophobic nature of NPs improved the dimensional stability of WPCs. The small size of NPs deposits the voids in the matrix, which helps to increase the mechanical properties, even after weathering test. The decrease of modulus of rupture (MOR) reached up to 16% for control samples, while it was 2% for IO40-1. Despite the intensive weathering conditions, NPs cover the surface of materials like a UV shield, improving WPCs' UV resistance. Moreover, the increase in the wood and NPs content limited the UV degradation, which resulted in lower color changes. The attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) analysis also proved that there were nearly no changes in the characteristic bands of polymer (2916 and 2846 cm−1) and wood (1512 cm−1). The microscopic investigation, however, revealed the deterioration on the surface of WPCs after weathering exposure. Even though UV degradation is inevitable, iron oxide NPs significantly preserved the WPCs surface. However, there were also crack formations, which were also inhibited. On the other hand, NPs decelerated the thermal degradation by acting as a heat barrier. Thermogravimetric analysis (TGA) analysis revealed an increase in the degradation temperature. Limit oxygen index (LOI) values also increased up to 27.6%, which demonstrated an improvement against flammability.