Wood Flour Particles Research Articles

The Role of Coupling Agents in the Mechanical and Thermal Properties of Polypropylene/Wood Flour Composites

This work is a collaborative effort between academia and industry to promote the development of new sustainable and profitable materials for manufacturing products. Incorporating wood flour particles (WF) in polypropylene (PP) grants environmental advantages in developing products that use renewable resources to manufacture PP/WF composites using the melt intercalation process. However, the interaction between a hydrophilic strengthening phase (wood flour) with a nonpolar polymer matrix (PP) is poor, resulting in deficient mechanical performance. This investigation details the use of graft and masterbatch coupling agents to evaluate their effects on mechanical parameters. The low compatibility between the constituents favors increasing the composites’ thermal properties because the reinforcing phase acts as a nucleating agent. PP showed typical mechanical behavior, with a marked necking and a wide deformation capacity of approximately 180%. The mechanical behavior of the PP/WF composites revealed an elastic region followed by a termination after their yield point, shortening the stress–strain curves and reducing their ductility at strain values of approximately 2–4%. Graft coupling agents have better intermolecular performance with PP than masterbatch coupling agents. The modulus of elasticity of the composites increased to around 82% relative to PP. Processing methods influenced the thermal properties of the composites. The melt-blending process promoted molecular orientation, while injection molding erased the thermomechanical history of the extruded pellets. The melting temperature was similar in the composites, so there was no evidence of thermal degradation. The results showed that the coupling agents favor the crystallinity of the PP over tensile strength. SEM observations showed insufficient adhesion between the WF and PP, which promotes a reduction in stress transfer during tensile testing. The WF particles act as fillers that increase the stiffness and reduce the ductility of composites.

Study on Water Resistance of Polypropylene Based Wood-Plastic Composites Used in Building

This research was aimed at studying the preparation of polypropylene based wood plastic composite material by twin-screw extrusion. The effects of the addition of the maleic anhydride (MAH) and wood flour on WPC properties were evaluated. WPC with 4, 5, 6, 7, 8, 9, 10 wt% of MAH contents were prepared. The mechanical properties and water resistance of WPC were studied. The result showed that with the increasing of MAH, the tensile strength of WPC increases at first and then decrease, and water absorption reduced by 39%. After immersing in water for 24 h, the tensile strength of WPC decreases but the impact strength increases, and with the increasing of MAH, the reducing extent of tensile strength increases, but the improvement extent of impact strength gradually decreases. When the MAH content exceeds 8 wt%, the impact strength of dried WPC samples (dried for 24 h) can be recovered basically. WPC with 10, 20, 30, 40 wt% of wood flour contents were prepared. The result showed that with the increasing of wood flour, the tensile strength of WPC increases at first and then decreases, the impact strength decreases, and water absorption increased by 62%. When the wood flour content exceeds 10 wt%, the impact strength of dried WPC samples can only recover partially. WPC containing different wood meal sizes was prepared. The result showed that with the decreasing of wood flour particle size, the water absorption of WPC increases obviously. The impact strength of dried WPC samples is higher than that of unsoaked WPC, when the particle size of wood flour is 60 meshes. It can be seen from the SEM photos that the distance between the wood powder fibers becomes larger after 24 h of WPC soaking in water. The finer the wood flour, the easier it is to aggregate in WPC.

Superparamagnetic wood‐polypropylene nanocomposite made using magnetic wood flour with a nanoparticle‐free surface

AbstractThis study investigates the effect of removing magnetic nanoparticles from the outer surface of magnetic wood flour (MWF) particles as a filler phase on the microstructural, physical, and mechanical properties of the prepared MWF‐polypropylene nanocomposites. For producing MWF with a surface free of magnetic nanoparticles (called LFMWF), in contrast to the commonly produced MWF (called FFMWF), magnetic wood chips were first prepared and then milled. No significant changes were observed in the tensile and flexural strength of the composite specimens prepared with the LFMWF filler instead of the FFMWF. The samples containing the LFMWF filler showed lower water uptake and higher thickness swelling after 400 h of immersion. The coupling agent's effect on improving the mechanical properties of the specimens was more pronounced than its effect on the water uptake and thickness swelling of the specimens. The saturation magnetization of LFMWF was about 4.3 emu/g, while that of FFMWF was 0.94 emu/g. After melt compounding the MWFs with the polymer matrix, the saturation magnetization decreased; this decrease was about 9.9% higher for the FFMWF‐containing magnetic nanocomposites than for the LFMWF‐containing ones.

Comparative Study of the Properties of Wood Flour and Wood Pellets Manufactured from Secondary Processing Mill Residues.

The generation of secondary processing mill residues from wood processing facilities is extensive in the United States. Wood flour can be manufactured utilizing these residues and an important application of wood flour is as a filler in the wood–plastic composites (WPCs). Scientific research on wood flour production from mill residues is limited. One of the greatest costs involved in the supply chain of WPCs manufacturing is the transportation cost. Wood flour, constrained by low bulk densities, is commonly transported by truck trailers without attaining allowable weight limits. Because of this, shipping costs often exceed the material costs, consequently increasing raw material costs for WPC manufacturers and the price of finished products. A bulk density study of wood flour (190–220 kg/m3) and wood pellets (700–750 kg/m3) shows that a tractor-trailer can carry more than three times the weight of pellets compared to flour. Thus, this study focuses on exploring the utilization of mill residues from four wood species in Maine to produce raw materials for manufacturing WPCs. Two types of raw materials for the manufacture of WPCs, i.e., wood flour and wood pellets, were produced and a study of their properties was performed. At the species level, red maple 40-mesh wood flour had the highest bulk density and lowest moisture content. Spruce-fir wood flour particles were the finest (dgw of 0.18 mm). For all species, the 18–40 wood flour mesh size possessed the highest aspect ratio. Similarly, on average, wood pellets manufactured from 40-mesh particles had a lower moisture content, higher bulk density, and better durability than the pellets from unsieved wood flour. Red maple pellets had the lowest moisture content (0.12%) and the highest bulk density (738 kg/m3). The results concluded that the processing of residues into wood flour and then into pellets reduced the moisture content by 76.8% and increased the bulk density by 747%. These material property parameters are an important attempt to provide information that can facilitate the more cost-efficient transport of wood residue feedstocks over longer distances.

Investigating the effect of pressing temperature on the thermal, mechanical, and morphological properties of nanocomposites made from recycled polyethylene, nanosilica, and wood flour

This study investigated the effect of pressurized temperature on the thermal, mechanical, and morphological properties of nanocomposites made from recycled polyethylene with the weight ratio of 50%. Nanosilica was applied at 3 levels (0, 4, 8 %) and wood flour had a weight ratio of 50%. High-density polyethylene (HDPE) went through multiple procedures. It was found that by increasing the nanosilica content, the tensile and flexural strength properties, the residual ash content, and the thermal stability increased along with a reduction in the tensile and flexural modulus and impact resistance. As the temperature increased, the tensile and flexural strength and modulus and the impact resistance decreased. Scanning electron microscopy (SEM) images revealed that samples with 8% nanosilica showed different polymerization than the wood flour particles.

High density polyethylene/wood flour composite: Optimization of processing temperature, processing time and coupling agent concentration

Wood plastic composites (WPCs) consisting of high density polyethylene (HDPE) reinforced with high-loading (55 wt%) of wood flour (WF) were fabricated with melt-blending technique. In this compounding method, processing parameters such as different mixing temperatures (of 165, 180 and 195°C), mixing times (of 5, 10 and 15 minutes) and coupling agent contents (of 2 and 4 wt%) were evaluated. Prepared specimens were analyzed with tensile, Izod, shore D, DMTA, short-term creep, DSC, TGA, water absorption and water contact angle characterizations. Results revealed that mixing temperature of 180°C, mixing time of 10 minutes and coupling agent concentration of 4 wt% were found as the best processing conditions. The mentioned conditions provided enhanced dispersion of WF particles within the HDPE matrix, due to optimum viscosity of the polymer melt and effective residence time of compound in the mixer, and beside them efficient interfacial adhesion between WF and polymer matrix.

Study of the Properties of a Biodegradable Polymer Filled with Different Wood Flour Particles.

Lignocellulosic wood flour particles with three different sizes were used to reinforce Solanyl® type bioplastic in three compositions (10, 20, and 30 wt.%) and further processed by melt-extrusion and injection molding to simulate industrial conditions. The wood flour particles were morphologically and granulometric analyzed to evaluate their use as reinforcing filler. The Fuller method on wood flour particles was successfully applied and the obtained results were subsequently corroborated by the mechanical characterization. The rheological studies allowed observing how the viscosity was affected by the addition of wood flour and to recover information about the processing conditions of the biocomposites. Results suggest that all particles can be employed in extrusion processes (shear rate less than 1000 s−1). However, under injection molding conditions, biocomposites with high percentages of wood flour or excessively large particles may cause an increase in defective injected-parts due to obstruction of the gate in the mold. From a processing point of view and based on the biocomposites performance, the best combination resulted in Solanyl® type biopolymer reinforced with wood flour particles loaded up to 20 wt.% of small and medium particles size. The obtained biocomposites are of interest for injected molding parts for several industrial applications.

The role of milling time on the morphological and mechanical properties of wood flour and their polypropylene composites

Rendering unique properties by combining materials are stepping stones to innovate novel material with excellent properties. Although the combination technology has been used to obtain characteristic properties, recent new technologies develop materials with both lower density and higher strength, which are not attainable for single bulk materials. The light weight, easy availability, and biodegradability of natural fibers make them as one of the most acceptable materials for manufacturing various products. Most of the commodity plastics can be reinforced with wood flour which is one of the most abundantly available resources and can impart better properties to the composite materials. To support the industry while considering the product reliability and durability, the effect of more detailed processing factors is in demand. Thus, the present study focuses on clarifying the effects of particle size, morphology, diffraction pattern, particle size distribution of the wood flour on the final properties of the wood flour-based composites. Multiple factors like morphological, structural, interfacial interactions, and crystallinity index shows 1 h milled wood fluor to be the appropriate time to mill the wood flour particles. There is an optimal milling time, which make smaller wood flours without agglomerates, resulting in better property enhancement.

Properties of wood-plastic composites based on pvc/pla/pbat ternary blend

The objective of this work was to improve mechanical properties, thermal resistance, and biodegradability of poly(vinyl chloride) (PVC) by the addition of poly(lactic acid) (PLA), poly(butylene adipate-co-terephthalate) (PBAT), and wood flour (WF). The samples made from a mixture of PVC/PBAT exhibited the highest impact and tensile properties, while properties of the samples made from PVC/PLA had the highest flexural and thermal properties, PVC/PLA/PBAT mixed samples exhibited average mechanical properties. The addition of WF to all the blends increased impact strength, flexural properties, Young’s modulus, thermal resistance, and biodegradability of the samples in comparison to those of the neat PVC and its blends. Composite samples of PVC/PBAT/WF showed the highest impact strength, while PVC/PLA/WF composite had the highest flexural and thermal resistance. The samples manufactured from a mixture of PVC/PLA/PBAT/WF had the highest tensile strength and Young’s modulus. The overall results in this work suggested that the enhanced properties of PVC samples were strongly influenced by the compatibility between polymer blend matrix and WF particles.

Carbon foam production by biomass pyrolysis

Carbon-based foams have attracted significant attention because of their unique physical properties, such as low density, fire resistance, and low thermal conductivity. Biomass is a qualified carbon raw material used for the preparation of valuable carbon materials because it is available in high quality and huge quantity and it is an environmentally friendly renewable resource. In this work, carbon foams were developed from a wood foam precursor, by pyrolysis. The characteristics of these foams were studied in order to verify their possible use in thermal insulation. Carbon foams were produced with different wood flour particle sizes and densities. The main results indicate that the wood foam density has significant effect on the carbon foam contraction after pyrolysis and all samples presented a structure predominantly composed of carbon with higher thermal stability than the levels presented by wood foams.

Poly(lactic acid)/thermoplastic polyurethane/wood flour composites: evaluation of morphology, thermal, mechanical and biodegradation properties

This study was aimed at improving the toughness of poly(lactic acid) (PLA) without compromising its strength by developing a biodegradable composite based on PLA, Thermoplastic Polyurethane (TPU) and Wood flour (WF) particles. PLA/TPU/WF green composites with varying TPU content (0–50 wt%) were prepared on a twin screw extruder. The wood flour content was kept constant (10 wt%) for all the compositions. The addition of flexible TPU (10–50 wt% of total polymer composition) to the brittle PLA causes a significant increase in impact strength and elongation at break by ∼12.40 times and ∼3.57 times (for 50 wt% TPU content), respectively. Incorporation of WF filler brought improvement in tensile strength (∼1.47 times) and impact strength (∼871% enhancement over neat PLA) of the PLA/TPU blends with 50 wt% TPU content. Morphological analysis using SEM revealed that uniformly dispersed WF particles enhanced the interfacial interaction (H-bonding observed in FTIR spectra) between the TPU and PLA phase. Thermal analysis using DSC also shows that addition of TPU and WF depreciated the crystallinity of PLA because of enhanced interaction between the components which interferes with the crystallization of PLA. Finally, biodegradability studies (tested under soil) for 1 month demonstrated the significant degradability of PLA/TPU/WF composites in presence of WF particles. The potential applications of these bio-composites may range from automobiles, packaging to furniture industries.

Mechanical properties of wood/plastic composites formed using wood flour produced by wet ball-milling under various milling times and drying methods

The objective of this study was to investigate the mechanical properties of wood/plastic composites (WPCs) produced using wood flour (WF) prepared by wet ball-milling under various milling times (0–120 min) and drying methods (freeze- or heat drying). The drying method did not affect the particle size distribution, shape, or specific surface area of WF at milling times shorter than 40 min. At milling ≥ 40 min, freeze-dried ball-milled WF (FDWF) had smaller particle sizes and higher specific surface area than heat-dried ball-milled WF (HDWF). The highest tensile strength and modulus of rupture (MOR) were observed in WPCs made from freeze- and heat-dried WF at a milling time of 30 min. At milling time of 30 min, the amount of 100–300 µm FDWF and HDWF was 37% and 36%, respectively. The impact strength of WPCs increased, as the milling time increased. The amount of small freeze- and heat-dried WF particles increased due to an increase in the amount of 17 µm particles and specific surface area with increased milling time. Thus, impact strength of WPCs increased as particle size decreased. At milling times ≤ 60 min, there were no significant differences in mechanical properties between WPCs containing freeze- and heat-dried WF under the condition of this study.

Melt-viscosity and mechanical behaviour of polypropylene (PP)/wood flour composites: Effect of pulverization of wood flour with and without water

Abstract This study analyses the effect of pulverization of wood flour with and without water to the melt-viscosity and mechanical behaviour of polypropylene (PP)/wood flour (WF) composites. The composites were processed in an extruder and subsequent injection moulding. The effects of initial wood flour particle size, type of trees (namely cypress and European scots pine trees) as well as plate gap (200 μm and 350 μm) in pulverization were also evaluated in terms of melt-viscosity, tensile properties, Izod impact strength and fatigue behaviour of the prepared composites. PP/WF composites with pulverised wood flour with water exhibited higher melt-viscosity than that of nonpulverized and pulverized wood flour without water reinforced PP composites. Tensile strength values of composites were slightly affected by the pulverization of wood flour and the enhancement of tensile strength values were depended on the type of initial WF. From Izod impact test results of composites, it was found that the composites reinforced with pulverized wood flour with water displayed higher values of impact energy compared with the composites of pulverized WF without water. Depending on the type of initial WF particle, the positive effect of pulverization of wood flour with water to the fatigue life of the composites was also observed.

Combined effect of water uptake and temperature on wood polymer composites

ABSTRACTWood polymer composites are materials frequently used for outdoor applications, since they can operate under a large range of temperature and moisture conditions. The present work investigates the combined effect of water soaking and temperature (ranging from 10 up to 40 °C) on wood flour filled high density polyethylene. Water soaking tests have revealed that the percentage of absorbed water at the saturation plateau increases with temperature due to the induced stiffness reduction of the polymeric matrix. This hypothesis has been confirmed by scanning electron microscopy analyses, which has allowed to observe the filler–matrix interface and to measure the wood flour particle size. In addition, instrumented Charpy impact tests have shown a strong toughness reduction as a consequence of fiber–matrix debonding induced by particle swelling, which worsens with temperature. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46674.

Properties of an industrial extruded HDPE-WPC: The effect of the size distribution of wood flour particles

This work aims understanding the influence of the size distribution of wood flour particles on the physical and mechanical properties of an extruded wood plastic composite (WPC). A industrial-scaled process has been tested for both the wood flour production and the composite forming. Three size distributions of wood flour have been produced from the same batch of wood chips. The analyses of the particle size and form for the three wood flours were carried out by sieve column and by image analysis, revealing the limits of sieving in the case of particles with a high aspect ratio. The present study investigates the influence of the wood flour size distribution on the tensile and flexural behavior of WPC. The Charpy impact behavior of HDPE-WPC is also studied. In addition to the industrial process, the originality of this work lies in relating the microstructure to the mechanical performances of the extruded WPC; especially the orientation of the wood particles that differs according to the size distribution of the wood flour used. In general, mechanical performances of composites are improved by adding large particles. However, in the transverse direction to the extrusion, fine wood flour allows better performances.

Cashew tree wood flour activated with cashew nut shell liquid for the production of functionalized composites

This work is aimed at the one-step chemical modification of the surface of cashew wood flour particles using the technical grade cashew nut shell liquid (CNSL). The goal is to develop an alternative way to introduce chemically active sites on the surface of the particles, which allows the addition of new functionalities to such particles. The influence of time and temperature and catalyst on the substitution of lignocellulosic hydroxyls with cardanol/cardol urethane derivatives was evaluated by thermogravimetric analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy (FTIR), and contact angle measurements. The mechanical behavior of the modified particles in polypropylene composites was also evaluated by mechanical testing and dynamic mechanical thermal analysis. The FTIR, thermogravimetry, and contact angle results indicated changes on the particle surface, and the mechanical and thermomechanical behavior of the mercerized and modified particles in the composites was found to be similar. These results point that the CNSL approach is a viable way to chemically modify cashew wood flour particle surfaces, while maintaining their properties.

Ethylene–octene copolymer–wood flour/oil flax straw biocomposites: Effect of filler type and content on mechanical properties

The properties of biocomposites based on ethylene–octene copolymers (EOCs) were studied. The mechanical, rheological, and physical properties of the biocomposites were investigated with attention to the filler type, filler content, and grade of EOC. Three grades of EOC with different viscosities were used as the polymer matrices. Two lignocellulosic raw materials were selected as fillers: birch wood flour (WF) and oil flax straw (FS). The effect of the filler variation range (30%–70%) on the biocomposites was studied. According to microphotographs, the filler particles were quite uniformly distributed in the polymer matrix. The WF particles had ellipsoid shapes, whereas the FS particles were characterized by cylindrical shapes. The addition of fillers decreased the elongations at the copolymer's break and tensile strengths, but increased the elasticity moduli. The fillers’ hard particles increased the stiffness of the polymer chains in the biocomposites, resulting in declines in elongation at break. The biocomposites with WF had higher tensile strengths and elongations at break than those with FS because the latter were characterized by lower density values than the former. Melt viscosity analysis showed that filler content increased with melt viscosity. The FS biocomposites had higher melt viscosities than the WF biocomposites. POLYM. ENG. SCI., 57:756–763, 2017. © 2017 Society of Plastics Engineers

Preparation, structure, and property of wood flour incorporated polypropylene composites prepared by a solid‐state mechanochemical method

ABSTRACTIn this article, a solid‐state mechanochemical method based on a pan‐mill equipment was used to prepare 60 wt % loading of wood flour (WF) incorporated polypropylene (PP) wood–plastic composite (WPC) with good comprehensive performance. The particle size distribution, crystallization, microstructure, and properties of the prepared WPC were accordingly investigated. The results show that under co‐effects of the strong shear force field of pan milling and the compatibilization of PP grafted maleic anhydride (PP‐g‐MAH), the mixture of PP and WF is effectively pulverized and homogeneously mixed. Meanwhile, the WF particles are adequately activated by exposure of their characteristic functional groups, which is beneficial to the interfacial mechanochemical reaction. PP‐g‐MAH and PP prove to be in situ grafted onto WF particles surface during pan milling, thus resulting in the substantial enhancement in both the dispersion of the added WF fillers in PP matrix and the interfacial bonding. The mechanochemical effects of pan milling could also remarkably promote the heterogeneous nucleation effect of WF particles on PP crystallization and influence the dynamic mechanical behavior of composite. Compared with the unmilled and uncompatibilized composite, the milled and compatibilized WPC material possesses greatly enhanced mechanical performance and shows good application prospects. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43108.

The Influence of Dry-Milled Wood Flour on The Physical Properties of Wood Flour/Polypropylene Composites

In this study, we evaluated the influence of wood flour (particle size: <90 μm) on the physical properties of wood flour/polypropylene (PP) composites. Wood flour was obtained by dry ball-milling of forest-thinning material at a rotary speed of 250 rpm for 1, 2, 4, and 8 h. The milled wood flour was filtered using a 90 μm sieve. The water content of the wood flour was adjusted to 5, 10, or 20 wt%. Composite properties, including mechanical properties, water absorption, and thermal expansion, were evaluated at wood flour loadings of 40 wt%. When wood flour with 5 wt% water content was milled for 2 and 4 h, the resulting wood flour was granular rather than fibrous; flocculation of the fine particles was observed for milling times exceeding 4 h. This morphological change in the wood flour reduced its influence on the physical properties of the composites, although some positive influences were observed on the molding properties of the composite, such as an increase in compound fluidity. Milled wood flour with 10 wt% or 20 wt% water content was fibrous. Scanning electron microscopy observation of milled wood flour with 10 wt% water content revealed partial surface fibrillation at widths of tens to hundreds of nanometers. The addition of wood flour with nanoscale surface fibrils to PP composites positively influenced the properties of the composite, resulting in a decrease in the linear coefficient of thermal expansion in the flow direction.

Reinforcement of wood flour board containing ligno-cellulose nanofiber made from recycled wood

Wood-based materials are widely used in residential construction. These materials can be made from virgin or recycled wood, and most of the materials are fabricated with chemical adhesives. Finding replacements for such chemical adhesives poses major challenges. This study explored nanofiber technology as an alternative to these adhesives. Previous studies have shown that the three-dimensional binding effects of cellulose nanofiber (CNF) and ligno-cellulose nanofiber (LCNF), when mixed with wood flour, can significantly improve the physical and mechanical properties of wood flour board. We use the word “LCNF” as the surface nanofibrillated wood flour. Previous studies have also highlighted problems that occur during compounding and board manufacturing. In this study, a reliable method was established to mix wood flour and LCNF. The method involved a compounding machine, which facilitated board manufacturing safely. Physical and mechanical properties of the resulting wood flour boards were significantly improved with the addition of LCNF, due to close binding between LCNF and wood flour particles.