Surface Of Wood Flour Research Articles

Recycled PLA – Wood flour based biocomposites: Effect of wood flour surface modification, PLA recycling, and maleation

• The recycling of PLA, after one-process, had substantial effect on the overall crystallinity. • The addition of wood, even in small inclusions (2.5 wt%), had substantially improved the PLA crystallinity. • Modification of wood fiber with DDSA had pronounced effects on the WPC’s water absorption properties. • Substitution of pristine wood to DDSA-modified wood has no effect on mechanical properties. • Synergistic effects of maleated-PLA and DDSA-modified wood further enhanced WPCs water-resistant properties. This study investigated the effects of simulated recycling of PLA and Maleated PLA using thermo-mechanical processes on its structure and physico-chemical properties and combined with pristine and modified wood flour (WF) for biocomposites. The WF modification entails a base catalyzed reaction of dodecenylsuccinic anhydride to effectively reduce its polarity and enhance the system’s compatibility. Recycling of PLA had a profound effect on PLA’s crystallinity and modulus. The addition of WF had significantly affected PLA’s crystallinity and moduli of the fabricated biocomposites. The modified samples had superior water repellent and dimensional stability capabilities of the wood-plastic composites.

Synthesis and characterization of wood flour modified by graphene oxide for reinforcement applications

Abstract The performance of thermoplastic polyurethane (TPU) reinforced with natural fibers can be tailored through a suitable choice of the fibers nature or the type of surface treatment applied to them. The present work deals with the improvement of the interfacial properties of natural fibers, namely wood flour (WF) by the introduction of graphene oxide (GO), which may easily disperse on the WF surface to provide hybrid fibers (WF-GO). The latter were then used as reinforcement of a TPU matrix at different ratios of 1, 3 and 5 wt%. The different samples were characterized by FTIR and RAMAN spectroscopies, XRD, SEM and TGA to confirm the structure, morphology and the thermal stability of the prepared hybrid fibers as well as their composites (TPU/WF-GO). SEM micrographs revealed that the surface treatment applied to WF, the distribution of GO sheets on the fiber interface, and the dispersion of (WF-GO) on the polymer matrix were successfully carried out. The thermal stability of the TPU-base composites increased with the increase of WF-GO content from 325 °C for the pure TPU matrix to 343 °C for the composite reinforced by 5% of (WF-GO). In addition, the results confirmed that the incorporation of GO into WF led to a significant improvement in the mechanical properties of the TPU-based composites, with an improvement in strength from 10.9 MPa to 19 MPa.

Recycled Pla – Wood Flour Based Biocomposites: Effect of Wood Flour Surface Modification, Pla Recycling, and Maleation

Recycled Pla – Wood Flour Based Biocomposites: Effect of Wood Flour Surface Modification, Pla Recycling, and Maleation

Plasma Treatment and TEOS Modification on Wood Flour Applied to Composite of Polyvinyl Chloride/Wood Flour

In this work, the effects of wood flour and tetraethyl orthosilicate (TEOS) content on the fusion time, fusion torque, fusion temperature, and fusion energy of polyvinyl chloride/wood flour (PVC/WF) composites were studied. Plasma-assisted surface treatment of WF before modifying with TEOS to form the silica nanoparticles on the surface of wood flour plays a role as a reinforcement of the phase interaction. This modification was confirmed by X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM) techniques. Moreover, BET data showed that specific surface area and volume of plasma treated WF and TEOS modified WF (WS) were considerably improved in comparison with original WF. By increasing WF, a remarkable increase in time, temperature, and energy of mixing process led to the enhancement of fusion torque. In the case of composite using WS, the increase of TEOS content resulted in shorter fusion time, whereas the other fusion characteristics of composites increased. The investigation of mechanical and rheological properties such as Young’s modulus and dynamic storage modulus G′ showed the stiffness of the PVC/WF composites has been significantly improved with increasing wood flour and modifier contents. The research showed an application of nanoparticles in the industrial production of polymer composite materials.

Fabrication of Green Superhydrophobic/Superoleophilic Wood Flour for Efficient Oil Separation from Water

The removal of oil from waste water is gaining increasing attention. In this study, a novel synthesis method of green superhydrophobic/superoleophilic wood flour is proposed using the deposition of nano–zinc oxide (nZnO) aggregated on the fiber surface and the subsequent hydrophobic modification of octadecanoic acid. The as-prepared wood flour displayed great superhydrophobicity and synchronous superoleophilicity properties with the water contact angle (WCA) of 156° and oil contact angle (OCA) of 0° for diesel oil. Furthermore, the as-prepared wood flour possessed an excellent stability, probably due to the strong adhesion of nZnO, which aggregates to the fiber surface of wood flour with the action of glutinous polystyrene. The maximum adsorption capacity of as-prepared wood flour was 20.81 g/g for engine oil, which showed that the as-prepared wood flour is a potential candidate as an efficient oil adsorbent in the field of water-oil separation. Moreover, it has good chemical steadiness and environmental durability. Taken together, all the information acquired from this research could be valuable in evaluating the potential of as-prepared wood flour as a competitive and sustainable oil-water separation material.

Novel amino glycerin decorated ammonium polyphosphate for the highly-efficient intumescent flame retardance of wood flour/polypropylene composite via simultaneous interfacial and bulk charring

Wood flour (WF) filled polymer composites are widely used in our daily life. Unfortunately, a wick effect of WF during burning seriously deteriorates the flame retardancy of wood-plastic composites. Traditional flame retardants cannot efficiently restrict the wick effect of WF due to their random distribution. In this work, amino glycerin decorated ammonium polyphosphate (APD-APP) was well designed and prepared through an ion exchange reaction to tailor the dispersion of flame retardant in WF-filled polymer composites. When the APD-APP was incorporated into the WF/polypropylene composite (WPC), it showed significantly different distribution compared to that of APP and mainly accumulated at the surface of WF, and then resulted in the formation of core-shell WF@APD-APP. More importantly, the flame retardancy of WPC/APD-APP is remarkably superior to that of WPC/APP. In vertical burning test, 25.0 wt% of APD-APP upgraded the UL-94 rating and limiting oxygen index (LOI) of WPC from no rating and 19.0% to the corresponding V-0 rating and 29.0%. Moreover, the melt dripping of WPC was completely eliminated by APD-APP. In the combustion test, the peak of heat release rate and total smoke production for WPC were respectively decreased by 70.0% and 76.6% in the presence of 30.0 wt% of APD-APP. In addition, mechanical properties of WPC/APD-APP are also superior to that of WPC/APP. The mechanism for the excellent flame retardancy of WPC/APD-APP revealed that the formed core-shell WF@APD-APP affected a residual network through the intergrowth charring of APD-APP and WF during thermally decomposing, and then the wick effect of WF was significantly weakened. Finally, the flame retardancy of WPC/APD-APP was enhanced through typical intumescent flame-retarding action via simultaneous interfacial and bulk charring.

Mechanical and Physical Properties of Wood–Plastic Composites Containing Cellulose Nanofibers Added to Wood Flour

Abstract Recently, the usage of wood–plastic composite (WPC) products has increased, mainly for exterior decking. The shape of fillers is one of the important factors deciding the mechanical and physical properties of WPCs. Surface-fibrillated wood flour (WF) improves the mechanical properties of WPCs, although it requires a lot of energy and time to produce the fibrous structure during the pulverization process. Therefore, the adsorptive interaction between cellulose nanofiber (CNF) and WF by hydrogen bonding was investigated. We considered that CNF could form the fibrous structures on the WF surface by mixing CNF and WF. Also, it is thought that the addition of CNF could increase mechanical and physical properties of WPC because CNF has better physical and mechanical properties than most other fibers. The objective of this study was to produce WF-CNF fillers and to evaluate the mechanical and physical properties of WPCs containing WF-CNF fillers. WF-CNF fillers could be produced by freeze-drying after mixing WF, CNF, and water. The fibrous structures on the WF surface were observed through scanning electron microscope images of WF-CNF filler containing 3 weight percent CNF. A WPC with WF-CNF filler containing 22 percent (by weight) WF and 3 percent (by weight) CNF showed improved mechanical properties compared with WPCs without CNF. The water absorption of WPCs containing CNF was found to decrease with increasing CNF content.

Monofunctional compatibilizer with long alkyl end for fabrication of superior tensile wood flour‐polyolefin composites

ABSTRACTA novel monofunctional compatibilizer (OID) was prepared and used as compatibilizer for fabrication of wood‐plastic composites. OID was successfully synthesized by esterification reaction of isophorone diisocyanate and octadecanol as confirmed by Fourier transform‐infrared spectra. After OID modification, the hydrophobicity of wood flour surface was enhanced as indicated by the increase of surface water contact angle. By using OID as compatibilizer, an obvious enhancement of the interfacial adhesion between wood flour and polyolefin was observed by scanning electron microscopy. As a result, the tensile properties of the obtained polypropylene/wood flour composites and polyethylene/wood flour composites were significantly enhanced. Besides, the processability of polyolefin/wood flour composites was also improved by adding OID. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44429.

Development and optimization of renewable vinyl plastisol/wood flour composites exposed to ultraviolet radiation

The application of vegetable oils as novel plasticizers for poly(vinyl chloride) (PVC) is currently in the spotlight of the polymer industry due to their ingrained sustainability. In this study, novel vinyl plastisol/wood flour composites based on epoxidized linseed oil (ELO) were evaluated. For this, PVC was first plasticized by 70 parts by weight of ELO per hundred parts of resin (phr) to form a vinyl plastisol. Wood flour, obtained by dry grinding from reed (Phragmite communis), was then incorporated at five different loadings (10, 15, 20, 25, and 30wt.‐%) and three particle sizes (100, 250, and 500μm). The effect of ultraviolet (UV) radiation was explored to activate the surface of wood flour to increase its interfacial adhesion with the vinyl plastisol. Stereomicroscopy and scanning electron microscopy (SEM) were used to examine the composites fracture and determine the dispersion of wood flour in the vinyl matrix. As per the surface appearance and mechanical results, optimal materials were observed for vinyl plastisol composites at high contents of wood flour with the largest particles that were previously exposed to UV for 4min. Resultant renewable vinyl plastisol composites show a great deal of potential as designed materials for wood replacement in building applications.

Thermal stability of organo‐montmorillonite‐modified wood flour/poly(lactic acid) composites

In this research, wood flour (WF) was modified using sodium–montmorillonite (Na‐MMT) at four different concentrations (0.5, 1.0, 2.0, and 4.0 wt%, respectively) and didecyl dimethyl ammonium chloride (DDAC) in a two‐step process to form organo‐montmorillonite (OMMT) inside the WF or attached to the WF surface. The thus‐modified WF was then mixed with poly(lactic acid) (PLA) to produce WF/PLA composites. The thermal stability of these composites with respect to their resistance against both thermal deformation and thermal decomposition was characterized by stress relaxation, differential scanning calorimetry (DSC), and thermogravimetric (TG) analysis. Besides, the activation energies for thermal decomposition of the composites were calculated. The results showed the following: (1) The modification of WF by OMMT improved the resistance against thermal deformation of the composites at appropriate OMMT loadings (lower than 1 wt% in this study). However, after introducing excessive OMMT, the enhancements in thermal stability diminished. Composite containing WF modified by 0.5 wt% of OMMT showed the optimal thermal deformation stability in this study, reflected in the highest values of thermal properties such as the glass transition temperature, melting temperature, crystallization temperature, and slowest stress relaxation rate. (2) OMMT showed a negative effect on the resistance against thermal decomposition. Namely, OMMT accelerated the thermal decomposition of the composites, probably by the easier degradation of the organic surfactant used for the WF modification. However, this behavior might be favorable for achieving fire retardancy. POLYM. COMPOS., 37:1971–1977, 2016. © 2015 Society of Plastics Engineers

Effect of woody biomass surface free energy on the mechanical properties and interface of wood/polypropylene composites

The aim of this study is to investigate the effect of surface free energy of wood flour (WF) and silanized WF on the mechanical properties and interface of wood/polypropylene (PP) composites. The contact angles of three probe liquids against unmodified and modified spruce WF were tested by capillary rise method based on the Washburn equation. Then the surface free energy and its corresponding dispersion and polar components were calculated according to the method developed by Owens–Wendt–Kaelble. The tensile strength and flexural strength of the wood/PP composite samples made with unmodified and modified WF were tested and the flexural fracture surfaces were analyzed by scanning electron microscopy (SEM). The results showed that the surface free energy of WF increased from 26.0 to 36.1 mJ/m2, which was higher than that of PP (29.4 mJ/m2), and its corresponding polar component decreased from 13.1 to 4.4 mJ/m2, and the dispersion component increased from 12.9 to 31.7 mJ/m2 after the modification with 4 wt.% vinyltriethoxy silane, which makes it possible for spreading of PP on the surface of WF, the tensile strength and flexural strength of wood/PP composites made with modified WF were obviously improved. In addition, the improved compatibility between WF and PP was well confirmed by SEM.

Novel DCPD-modified polyester containing epoxy groups: thermal, viscoelastic, and mechanical properties of their wood flour filled copolymers

In this article, the synthesis of novel DCPD-modified polyesters containing epoxy groups and their possible utilization as polar matrices for wood flour filled copolymers have been studied. The novel DCPD-modified polyester containing epoxy groups was prepared during three-step process. First, the addition reaction of maleic acid to DCPD norbonenyl double bond has been performed. Then, the polyesterification of acidic ester of DCPD, cyclohex-4-ene dicarboxylic anhydride, and ethylene glycol (ethane-1,2-diol, EG) or neopentyl glycol (2,2-dimethyl-1,3-propanediol, NP) in the presence of catalyst was carried out using melt condensation technique. Finally, the oxidation process of prepared DCPD-modified polyesters led to obtain DCPD-modified polyesters containing epoxy groups. The structural characterization of prepared DCPD-modified polyesters containing epoxy functionality has been carried out using FTIR and HNMR spectroscopic methods. The thermal, viscoelastic, and mechanical properties of their unfilled and wood flour filled copolymers have been studied by DSC, DMA, TGA analyses, three-point bending test, and Brinell’s hardness. The performed investigations indicated that novel DCPD-modified polyesters containing epoxy groups can be successfully applied as polar matrices for preparation wood flour filled copolymers due to their “compatibility” with hydrophilic wood flour surface which resulted with stronger interactions between wood and polymer surface and thus producing copolymers which were characterized by improved thermo-mechanical properties compared to unfilled copolymers.

Interface Reaction and Molecule Recognition Among Wood Flour, Amino Silane Coupling Agent and POE-g-MAH Compatibilizer

The interface reaction and molecule recognition among wood flour, amino silane coupling agent and maleic anhydride grafted polyolefin compatibilizer were studied by fourier transform infrared analyzer (FTIR), scanning electron microscope with an energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray photoelectron spectra (XPS). According to molecule recognition principles, γ-APS in the wood flour surface was identified by SEM-EDS. A new state of N1 s at 401.33 eV appears in XPS as γ-APS and maleic anhydride grafted polyolefin compatibilizer are introduced simultaneously, which shows the occurrence of reaction between γ-APS and maleic anhydride-grafted polyolefin compatibilizer, and amino is formed.

Effect of Fibrillation on the Performance of Wood-Plastic Composites with High Filler Content

Even though fibrous wood filler is known to be effective for improving mechanical and water-resistant properties of wood plastic composite (WPC), it has not been commercially adopted because of its high cost and less handling ability. In the present study, with an expectation of similar positive effect of fibrous wood filler, we carried out a fibrillation of a surface of practical wood flour in pre-mixed compound, containing wood flour, polypropylene, and compatibilizer, for producing WPC with high filler content by means of wet disk-milling. Scanning electron micrography revealed a micro-fibrillation on the surface of wood flour in the ground pre-mixed compound. The size of the surface micro-fiber could be controlled by disk-milling conditions. The formation of the micro-fibrous structure affected the melt viscosity of the compounds and improved mechanical properties of molded samples. The positive effect of the surface micro-fiber formation can be attributed to an interaction among the micro-fibers such as hydrogen bonding and entanglement. The observed reinforcement effect by the surface fibrillation was essentially identical to that of wood fiber although fibrillation was attained just in the surface of wood flour.

Studies of surface-modified wood flour/polypropylene composites

Wood flour (WF)/polypropylene (PP) composites have been made by extrusion and hot press compression molding. The composite water uptake and flexural properties were investigated. The composite fracture surfaces were studied by SEM. WF esterified with octanoyl chloride was used in WF/PP composites to improve the composites’ water resistance. Maleated polypropylene (MAPP) was also studied and compared with esterification by acid chlorides. Esterification by octanoyl chloride reduced the composite water uptake. However, the C8 chain is still not long enough to form effective entanglements with the PP matrix. So, despite enhancements in hydrophobic interactions, flexural strengths and flexural moduli decreased. MAPP (MW = 47000) polymer chains can entangle with the matrix polypropylene molecules. Therefore, when MAPP’s maleic anhydride functions esterify WF surface hydroxyls, improved water resistance and composite flexural properties were achieved. The modifier chain length is of critical importance and more important than the surface density of hydrophobic groups for improving WF–PP interfacial adhesion and composite mechanical performance.

Thermal and dynamic mechanical behavior of poly(vinyl chloride)/wood flour composites

AbstractThermal and dynamic mechanical behaviors of wood plastic composites made of poly vinyl chloride (PVC) and surface treated, untreated wood flour were characterized by using differential scanning calorimetry and dynamic mechanical analysis. Glass transition temperature (Tg) of PVC was slightly increased by the addition of wood flour and by wood flour surface treatments. Heat capacity differences (ΔCp) of composites before and after glass transition were markedly reduced. PVC/wood composites exhibited smaller tan δ peaks than PVC alone, suggesting that less energy was dissipated for coordinated movements and disentanglements of PVC polymer chains in the composites. The rubbery plateaus of storage modulus (E′) curves almost disappeared for PVC/wood composites in contrast to a well defined plateau range for pure PVC. It is proposed that wood flour particles act as “physical crosslinking points” or “pinning centers” inside the PVC matrix, resulting in the absence of the rubbery plateau and high E′ above Tg. The mobility of PVC chain segments were further retarded by the presence of surface modified wood flour. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Surface modification of wood flour and its effect on the properties of PP/wood composites

The surface of wood flour used as reinforcement in PP/wood composites was successfully modified by benzylation in NaOH solution of 20 wt% concentration at 105 °C. The time of the reaction was changed between 5 and 360 min in several steps. The progress of modification was followed by the measurement of weight increase and by diffuse reflectance infrared spectroscopy (DRIFT). The structure of the wood was characterized by X-ray diffraction (XRD) and its surface tension was determined by inverse gas chromatography (IGC). PP composites containing 20 wt% filler were prepared from a PP block copolymer and the modified wood flour. The mechanical behavior of the composites was characterized by tensile testing. The majority of the active hydroxyl groups at the surface were replaced by benzyl groups in about 2 h under the conditions used. Further increase in reaction time did not influence the properties of the filler. Both the structure of the wood flour and its surface tension changed as an effect of modification. The reduction of surface tension led to significant changes in all interactions between the wood flour and other substances resulting in a considerable decrease of water absorption, which is the major benefit of this modification. All measured mechanical properties of the composites decreased slightly with increasing degree of modification. A detailed analysis of the results proved that the dominating micromechanical deformation process of these PP/wood composites is debonding, which is further facilitated by the decrease in the surface tension of the filler. Chemical modification of wood flour slightly improved processability and the surface appearance of the composites prepared with them and considerably decreased the water absorption of these latter.

Wood flour: A new filler for the rubber processing industry. II. Cure characteristics and mechanical properties of NBR compounds filled with corona‐treated wood flour

AbstractCorona‐treated wood flour was evaluated as a filler for NBR (nitrile butadiene rubber) compounds by studying its influence on their cure characteristics and mechanical properties. The different operating conditions of the corona treatment, such as voltage and duration, which led to different degrees of surface etching, were observed by means of electron microscopy. Accumulation of different oxygen‐containing groups on the wood flour particles' surface was confirmed by means of ESCA. Wood flour–filled materials were thus obtained with varying final properties. The cure characteristics, mechanical parameters, and water adsorption of the composites were estimated to determine an optimum level of the wood flour surface modification. The corona treatment of the wood flour renders it into a semiactive filler. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 883–889, 2004

Thermal and dynamic mechanical characterization of polypropylene‐woodflour composites

AbstractThe performance of wood particle/polypropylene (PP) composites with modified compatibilities was compared. Woodflour modification was performed by esterification with maleic anhydride (MAN) and a non‐commercial maleic anhydride‐polypropylene copolymer (PPMAN) was selected as compatibilizing agent. The thermogravimetric analysis indicates that the onset of thermal degradation of treated woodflour occurs at lower temperature than that of the untreated one, and the same behavior was found in the corresponding composites. Differential scanning calorimetry indicated that both woodflours acted as nucleating agents for PP, while only treated woodflour induced PP crystallization in β‐phase in the composites. X‐ray diffractometry demonstrated that the crystallization in β‐phase was a shear‐induced phenomenon favored by the chemical modification of the woodflour surface. Dynamic mechanical studies suggested that composite properties decreased at concentrations higher than 40 wt% of woodflour and that the overall performance of MAN‐treated woodflour composites was lower than that of the composites where a compatibilizing agent was added.