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Biological durability is an important feature for wood-plastic composites (WPC) intended for outdoor applications. One route to achieving WPC products with increased biological durability is to use wood preservative agents in the formulation of the WPC. Another option could be to use a chemically modified wood component that already exhibits increased resistance to biological degradation. There is also a need to use biobased thermoplastics made from renewable resources, which would decrease the dependency on petrochemically-produced thermoplastics in the future. The objective of this study was to examine moisture sorption properties, biological durability, and mechanical performance of injection-molded WPC samples based on acetylated or thermally modified wood components and a polylactate matrix. The biological durability was evaluated in a terrestrial microcosm (TMC) test according to ENV 807, followed by mechanical evaluation in a center point bending test. The moisture sorption properties were investigated via both water soaking and exposure in a high-humidity climate. Low or negligible mass losses were observed in the TMC test for all WPC samples. However, the mechanical evaluation after exposure in the TMC test showed 35-40% losses in both strength and stiffness for the WPC containing an unmodified wood component.

By utilizing three different grades of Polypropylene (PP) as matrix, two different kind of MAPP as coupling agent and without MAPP and Pistachio's flour, composite samples were produced. Physical and mechanical properties of wood plastic composites including: MOR, MOE, tensile strength, bending strength, impact strength, hardness, water absorption and thickness swelling (816 hours) were determined. Results indicated that the effect of different grade of polypropylene and coupling agent on water absorption, thickness swelling, hardness and impact strength variables were insignificant. Use of Polypropylene having higher Melt Flow Index (MFI) leads to increase in mechanical properties of wood plastic composite samples such as Bending and Tensile strength even if coupling agent wasn't used. Use of different kind of MAPP as coupling age in making wood plastic composites can result in better mechanical properties which based on their type have different effect.

Ayrilmis, Nadir/0000-0002-9991-4800; Akbulut, Turgay/0000-0001-9830-5643; Akbulut, Turgay/0000-0001-9830-5643 WOS: 000296862700053 Compression wood (CW) is a reaction wood formed in gymnosperms in response to various growth stresses. Many of the anatomical, chemical, physical, and mechanical properties of CW differ distinctly from those of normal wood. Because of different properties, the CW is much less desirable than normal wood. This study was conducted to investigate the suitability of CW flour obtained from black pine (Pinus nigra Arnold) in the manufacture of wood plastic composite (WPC). Polypropylene (PP) and CW flour were compounded into pellets by twin-screw extrusion, and the test specimens were prepared by injection molding. WPCs were manufactured using various weight percentages of CW flour/PP and maleic anhydride-grafted PP (MAPP). Water absorption (WA), modulus of rupture (MOR), and modulus of elasticity (MOE) values were measured. The results showed that increasing of the CW percentage in the WPC increased WA, MOR, and MOE values. Using MAPP in the mixture improved water resistance and flexural properties. CW flour of black pine can be used for the manufacturing of WPC as a reinforcing filler. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1740-1745, 2012

This study is conducted in order to measure and identify the ability of a bio-composite material to the high voltage. According to it, the developed bio-composite material is tested to ensure the maximum voltage that the material can hold. The bio-composite material which made from a mixture of Bambusa Vulgaris and a selected polymer named as High Density Polyethylene (HDPE). The Bambusa Vulgarisis going through several processes before mixed together with HDPE using wood plastic composite (WPC) technique which also consists of several stages. There are several samples of bio-composite substance are fabricated. The difference among them is the composition of the raw materials (Bambusa Vulgaris and HDPE) used. In this research, the high voltage measurement which also called as breakdown voltage measurement of the bio-composite material is examined by using appropriate experiments. All the experimental results are presented and discussed in this paper.

Date Palm Fiber (DPF) is one of the most available natural fibers in the Middle East, especially in Iran and the Persian Gulf region. This research provides a new insight into DPF, with consideration of morphological, chemical characteristics, and bulk density, as well as morphological and mechanical properties of DPF/HDPE wood plastic composite. There are three parts of date palm that are used for producing fiber, the trunk, rachis, and petiole. Results indicated that there is significant difference between trunk and petiole on fiber length but rachis has no significant differences relative to the other parts. The aspect ratios have significant differences among of three parts, with the highest and lowest values measured for the petiole and trunk, respectively. The chemical composition of various parts of the date palm tree differed significantly; with the highest amounts of cellulose and lignin content belong to rachis. Bulk density was measured for three parts of date palm, and the lowest amount was 0.082 g/cm3. The highest strengths were achieved in composites with 30 and 40% fiber content, depended on which original parts of the tree were used.

The production of wood plastic composites (WPCs) in the thermoplastic industry has gained much acceptance inrecent years and is expected to keep growing. This type of composite material has become an important family ofengineering materials due to the increasing need for sustainable, recyclable and renewable materials. This studyinvestigated the technical feasibility of insect-attacked Fir wood (Abies nordmanniana) to produce, durable WoodPlastic Composites by the Injection Molding. Despite many attempts have been done to solve the problems related towaste lignocellulosic materials, a few studies were done to utilize biological damaged-wood to produce WPCs as filler.Tensile, flexural and impact properties, thermal performance and morphology of WPCs were investigated. The use ofcoupling agent had a positive effect on the water absorption and mechanical properties. The obtained resultsdemonstrate that insect-attacked Fir wood is potentially suitable as a raw material in WPCs., Son yıllarda termoplastik sektöründe OPK üretimi büyük ölçüde kabul görmekte ve hızla gelişmektedir. Sürdürülebilir, geri dönüştürülebilir ve yenilenebilir materyallere olan ihtiyacın artması ile bu tip kompozitler mühendislik ürün ailesi içerisinde önemli bir konuma geldiği söylenebilmektedir. Bu çalışmada böcek zararı görmüş Göknar odununun enjeksiyon metodu ile Odun Plastik Kompozit (OPK) üretiminde değerlendirilmesi araştırılmıştır. Atık lignoselülozik kaynakların OPK üretiminde değerlendirilmesi üzerine literatürde birçok çalışma yapılmasına rağmen biyolojik zararlılar tarafından tahrip edilen odunlar üzerine sınırlı sayıda çalışma bulunmaktadır. Üretilen OPK’lerin çekme, eğilme ve şok özellikleri, termal performansları ve morfolojik yapıları incelenmiştir. Üretim sürecinde uyumlaştırıcı ajan kullanılması OPK’lerin su alma ve mekanik özellikler iyileştirdiği belirlenmiştir. Elde edilen sonuçlara göre böcek zararı görmüş Göknar odunun OPK üretimi için uygun olduğu belirlenmiştir.

In this study, a new composite material conception based on polypropylene (PP) and wood particles obtained from agricultural waste was investigated. Specifically, stalks and leafs of chili plants of the region of New Mexico, Texas, USA were used as a plant-based reinforcing material. For this, a design of experiments (DOE) is proposed considering different percentages of PP, wood, fire retardant, coupling agent and UV stabilizer, different mesh sizes are also considered. Samples were obtained using an extrusion molding machine. A statistical analysis is proposed to obtain the optimal percentages of the components considered in the fabrication of the samples in order to enhance the mechanical and morphologic properties of this new composite. Results show that the yield stress, breaking stress and ultimate tensile stress can be maximized with a proportion of 3 to 1 (63,75% PP and 21,25% wood fiber) of PP and wood fiber.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES Now a days, there is a worldwide tendency to value materials that, in addition to low cost, can be environmentally correct. This last condition refers to renewable, biodegradable and recyclable aspects that can be presented by the material. The production of new materials, such as wood-plastic panels (WPC, Wood Plastic Composite), with the recycling of waste is a market trend which aims at the same time achieve environmentally and ecologically correct products and reduce production costs. The aim of this study was to evaluate the possibility of producing WPC reusing polystyrene (PS) plastic cups combined with pinus wood, and test their physical and mechanical properties. The proportions of the polystyrene particles and wood particles employed were 75/25, 60/40, 50/50 and 40/60%. The performance of the panels was evaluated by determining the density, absorption and thickness swelling after 2 and 24 hours of water immersion, hardness, resistance to screws withdrawal, internal bond and bending. The addition of polystyrene tends to increase the dimensional stability of the panels, reducing water absorption and thickness swelling values. However density decreased thereof affecting other properties such as hardness, modulus of rupture (MOR) and modulus of elasticity (MOE). The tensile strength perpendicular to the board surface was higher in the panel with a higher content of (75/25%). Polystyrene reuse in the manufacture of composite wood-plastic was possible. Atualmente existe uma tendência mundial de valorizar materiais que, além de serem de baixo custo, possam ser ambientalmente corretos. Esta última condição refere-se aos aspectos renováveis, biodegradáveis e recicláveis que possam ser apresentados. A produção de novos materiais, como os painéis madeira-plástico (WPC, Wood Plastic Composite), com a reciclagem de resíduos é uma tendência do mercado que visa ao mesmo tempo obter produtos ambientalmente e ecologicamente corretos e reduzir os custos de produção. O objetivo desse trabalho foi avaliar a possibilidade de produzir compósitos madeira-plástico utilizando resina termoplástica resultante da reciclagem de copos plásticos de poliestireno (PS) com partículas de madeira de pinus, e testar suas propriedades físico-mecânicas. As proporções entre as partículas de poliestireno e partículas de madeira empregadas foram de 75/25, 60/40, 50/50 e 40/60%, respectivamente. O desempenho dos painéis foi avaliado através da determinação da densidade, absorção de água e inchamento em espessura após 2 e 24 horas de imersão em água, dureza, resistência ao arrancamento de parafusos, resistência à tração perpendicular e propriedades de flexão estática. O aumento da proporção de poliestireno tende a aumentar a estabilidade dimensional dos painéis, diminuindo os valores de absorção d’água e inchamento em espessura; porém, diminuiu sua densidade afetando outras propriedades mecânicas como a dureza, o módulo de ruptura (MOR) e o módulo de elasticidade (MOE). A tração perpendicular foi maior no painel com maior teor de PS (75/25%). Analisando os resultados de maneira geral pode-se concluir que é possível o reuso de poliestireno na confecção de compósitos de madeira-plástico, com características aceitáveis comercialmente.

Dimensional stability of wood plastic composites (WPCs) made from polypropylene and pine wood flour with and without coupling agent was investigated. The pine wood flour was prepared from wood chips which had been immersed, respectively, in boiling water for 1 h, 3 h, and 5 h or in distilled water for 1 day, 3 days, and 5 days at room temperature. It was found that thickness swelling (TS) and water absorption (WA) of the WPCs made using extracted wood were lower than those of WPCs produced with unextracted wood. The TS and WA values of WPCs decreased with extraction duration both for cold and hot water extraction. The effect of hot water extraction on the TS and WA properties of the WPCs was more pronounced than cold water extraction.

The use of lightweight construction material with high corrosion resistance and low cost plays an important role in the design and construction of marine structures such as waterfronts. One of the most common methods for strengthening the structures is composite fibre reinforced plastic (FRP) sheet that is used for member retrofitting including wood plastic composite (WPC). The WPC material is produced from wood and compressed resin, which has good mechanical properties as well as economic benefits. The main problem of WPC reinforced with FRP sheets is the debonding of the sheet from WPC surface, which leads to premature and non-economic failure in members. One of the existing methods to solve this problem is surface preparation. However, surface preparation of wood plastic composite has some additional problems, such as operational cost, environmental pollution, etc. Therefore, to avoid debonding, another method has been used, known as the grooving method at the lower parts of beams. The laboratory used 50 I-shaped specimens with the same geometrical and mechanical properties. Initially, some slots such as longitudinal, transverse and diagonal grooves were created on the surface of specimens and filled by an epoxy. All beams were armed using one or two layers of GFRP sheets embedded at the lower part and were tested under four-point flexural loading. Grooves of different shapes, various widths and depths as well as the number of reinforcement layers were determined for considering their effect on the beam's behaviour. The results expressed that the debonding of FRP sheets can be delayed by selecting the longitudinal grooves with certain width and depth, which also leads to resistance improvement.

This study investigates the feasibility of using recycled high density polyethylene (HDPE) and wood fiber from species Eucalyptus grandis (EU) to manufacture experimental composite panels. The use of maleated polyethylene as coupling agent (CA) improved the compatibility between the fiber and plastic matrix. The mechanical properties of the resultant composites were compared with polymer with and without compatibilizer. The influence of the coupling agent (CA) in the polymer matrices and composites were evaluated at different concentrations, checking the physical, mechanical and thermal properties of wood plastic composites (WPC). Results of mechanical, physical and thermal properties showed that concentration of 3% w/w CA in the polymer matrices was that which showed the best results, but in the composites properties were very similar in all formulations. Based on the findings in this work, it appears that recycled materials can be used to manufacture value-added panels without having any significant adverse influence on material properties.

The effect of virgin heterophasic PP copolymer (vPP) content on moisture absorption, as well as on thermal and mechanical properties of recycled polyethylene/ wood flour composites was investigated. The polymer matrix of recycled post-consumed plastic waste (rPE) was composed of a matrix of LDPE and a part of PP. Wood flour of Pinus radiata was used as filler at a constant loading of 45 wt.%. rPE/vPP blends and their composites were manufactured by melt blending, and then by injection molding. The morphology of the blends and composites was analyzed by means of scanning electron microscopy. The addition of vPP improved tensile and flexural moduli and flexural strength of wood plastic composites (WPC). The highest increase of these properties was observed for a WPC sample with a rPE/vPP ratio of 19. WPC made with higher virgin PP content (rPE/vPP ratio = 9 and 5.7) showed lower increase of mechanical properties compared to polymer matrix and WrPE samples. The moisture uptake of WPC made of rPE/vPP blend was higher than those of rPE, and their mechanical properties were more adversely affected by immersion in water. TGA results indicate that rPE are thermally more stable than rPE/vPP blends. The incorporation of heterophasic PP copolymer into the recycled polymer matrix of WPC delays the starting of wood flour degradation.

Wood-plastic composites (WPCs) have received increasing attention during the last decades, because of many advantages related to their use. Some of their main applications are represented by outdoor furnishing and decking; therefore, it is important to assess their behavior under Ultra Violet (UV) exposure. In this work, polypropylene/wood flour composites were prepared and their resistance to photo-oxidation investigated. The composites were prepared by extrusion and injection molding, and were subjected to mechanical and rheological tests, chemical analysis and colorimetric measurements. The results showed that the composites retained a higher fraction of the original mechanical properties after natural weathering. The study showed that for natural weathering, longer exposure time increased the degree of color change (and lightness). Weathering WPC exhibited decreased in mechanical properties when compared to no weathering WPCs respectively. From this study, relationships between chemical and color changes that occurred during exterior weathering of composites were too established. Climatic conditions directly affect the characteristics of all composites, thus indicating a significant photo-oxidation of the samples with a longer time of exposure to weathering.

This study investigated the potential use of the decayed wood in the manufacture of wood plastic composite (WPC) panel. Scots pine (Pinus sylvestris) sound wood and decayed wood (brown-rot fungi) were used as wood material. Three levels of 30%, 40%, and 50% of sound wood and decayed wood, based on the composition by weight, were mixed with the polypropylene with 3% (based on weight) maleic anhydride grafted PP (MAPP) as a coupling agent. The compound pellets were prepared from twin screw co-rotating extruder. The WPC panels were produced by hot-press molding technique. The chemical properties of sound wood and decayed wood were investigated. The flexural and tensile properties of 3 mm thick WPC panels were determined according to ASTM standards. Although the holocellulose content of the decayed wood was significantly lower than that of the sound wood, there was no great difference between the flexural and tensile properties of the WPC panels containing decayed wood or sound wood. Based on the findings obtained from the present study, it can be said that a certain amount of the decayed wood can be incorporated into the composition of WPCs containing sound wood.

International audience; The wood plastic composites studied in this work are composed of high-density polyethylene matrix and Pinus pinaster wood fibers. Despite some interesting intrinsic properties, this wood plastic composite has limited mechanical properties because of the incompatibility between the polar hydrophilic fibers and the non-polar hydrophobic matrix. In this study, the effects of maleic anhydride-modified polyethylene additive, of carbon chains grafted by acetylation and of wood fiber contents on the tensile mechanical properties of the wood plastic composite were studied. Tensile tests were carried out using digital image correlation as an intrusiveness and robust method for strain measurements. Results showed first that the addition of wood fibers made the wood plastic composite stiffer but less flexible. Acetylation improved the interfacial adhesion properties: the Young modulus was increased and a lower strain at failure was reported. The coupling agent also increased the compatibility but mainly in the case where there was no grafted chain. With regard to the carbon chains, the number of grafts improved the elastic properties while their length did not appear to have any influence. Finally, a scanning electron microscope was used to characterize the post-mortem morphology of the fracture surfaces, the results of which supported the observations obtained from the tensile mechanical properties

El objetivo del presente estudio fue observar la morfología y caracterizar las propiedades mecánicas de materiales compuestos de madera y plásticos reciclados espumados. Se mezcló polietileno de alta densidad reciclado con fibra de madera de Pinus radiata D.Don (pino radiata) de 60 mesh. Las concentraciones de fibra fueron de 15 y 25% en peso, el polímero se espumó con un agente químico ACA (azodicarbonamida) y se utilizó anhídrido maleico MAPE (Epolene E-20) como agente de acoplamiento. Los compuestos se obtuvieron usando un proceso de extrusión en un equipo doble tornillo. Los resultados demostraron que el agente acoplamiento tiene un efecto positivo sobre la adherencia del polímero reciclado y la fibra de madera. La densidad de los compuestos disminuyó con el agente espumante y las propiedades mecánicas de dureza, impacto, módulo de elasticidad en flexión y tracción fueron superiores para los compuestos no espumados. Se Se concluyó que al aumentar la concentración de fibra aumentan las propiedades mecánicas de los compuestos a excepción de la tenacidad que al incorporar el agente espumante disminuyeron ligeramente. The objective of the present study was to observe the morphology and characterize the mechanical properties of wood plastic composite foams. Recycled high density polyethylene was mixed with Pinus radiata D. Don (radiata pine) wood fiber of 60 mesh. The fiber concentrations were 15 and 25% by weight. The compounds were foamed with a chemical agent ACA (azodicabonamide) and MAPE (Epolene E-20) was used as a coupling agent. The composites were obtained by twin-screw extrusion. The results showed that the coupling agent has a positive effect on the adhesion of the recycled polymer and wood fiber. The density of the compounds decreases with blowing agent and the mechanical properties of hardness, impact, modulus of elasticity in bending and tension were higher for unfoamed composites. It was concluded that increasing the concentration of fiber increases the mechanical properties with the exception of impact resistance of the compounds and incorporating the blowing agent slightly.

Akbulut, Turgay/0000-0001-9830-5643; Ayrilmis, Nadir/0000-0002-9991-4800; Akbulut, Turgay/0000-0001-9830-5643; WOS: 000303973100009 Physical, mechanical, and fire properties of the injection-molded wood flour/polypropylene composites incorporated with different contents of boron compounds; borax/boric acid and zinc borate, and phosphate compounds; mono and diammonium phosphates were investigated. The effect of the coupling agent content, maleic anhydride-grafted polypropylene, on the properties of the composites with fire-retardant was also investigated. The composites with the zinc borate had the highest dimensional stability and strength in the bending, tensile, and izod impact, followed by the monoammonium phosphate, borax/boric acid, and diammonium phosphate treatments. The treatments produced modest improvements in fire performance as indicated by reductions in the heat release rates. Best results were achieved with the phosphate treatments. The Scanning Electron Microscope-Energy Dispersive Spectroscopy elemental mapping of the samples revealed that the outer surface of the wood fibers was coated by some crystalline deposits of the fire-retardants. (C) 2012 Elsevier Ltd. All rights reserved. Istanbul University, Istanbul, TurkeyIstanbul University [2396] This work has been supported by the Research Fund of Istanbul University, Istanbul, Turkey. Project No: 2396. Its support is gratefully acknowledged. The authors would like to thank United States Department of Agriculture, Forest Service, Forest Products Laboratory for the cone calorimetry tests.

Validerat; 20111011 (anonymous)

International audience; The tensile behavior of wood-plastic composite (WPC) with or without additive is studied using full-field strain measurements by 3D digital image correlation. It is shown that macroscopic values of the longitudinal strain are close to those measured by mechanical extensometer using standard mechanical tests. The modulus of elasticity provided by a Maxwell-Bingham model fitted to the experimental tensile curves is analyzed for several WPC formulations depending on the wood contents and the presence of additive. Color maps of the spatial strain distribution are commented. Moreover, the damage behavior and the degree of heterogeneity are analyzed thanks to the spatial standard deviation of the longitudinal strain field.

Global ecological concern has promoted an interest in renewable natural materials. One of such materials are for certain wood plastic composites (WPCs) made from wood and some type of polymer material. WPCs are often seen as green composites because the wood is a natural material from the renewable bio-resources and can be successfully recycled together with the polymer matrix. Wood fibers or wood fluor have the potential to act as a biodegradable reinforcing material or filler and they represent the good alternative for the use of glass or carbon fibers and inorganic fillers. Furthermore, wood waste (for example: sawdust) can be also used as a raw material for WPCs, which also makes them ecologically suitable. Nowadays WPCs have widespread use as window profiles, door frames, floors, decks and for some other construction applications. Such big growth in exterior applications of WPCs results in a need to study their stability. In order to predict durability of this material it is especially important to characterize the changes that occur when WPCs are exposed to different weathering conditions: UV light, rain and moisture, low and high temperatures. In this study pine wood flour filled high-density polyethylene (HDPE) composites were manufactured through extrusion. The HDPE/wood fluor ratio in composites was 70/30 while the content of UV stabilizer was from 0.25 to 1.5 phr. In order to simulate outdoor weathering conditions composites were exposed to UV light (vawelength 290 nm) in UV chamber. The samples were studied by thermogravimetric analysis (TGA). The water absorption degree for studied WPC samples was also determined. The results show relatively good resistance of WPCs to outdoor weathering conditions. The best results showed the WPC samples prepared with 0.25 phr of UV stabilizer. It can be concluded that this concentration is the optimal and ensures the most efficient stability of WPCs and delays their degradation.

In den letzen Jahren hat sich eine neue Materialgruppe, die Holz-Polymer-Werkstoffe (Wood-Plastic-Compounds), einen festen wenn auch z.Z. am Marktanteil gemessen noch kleinen Platz im Bereich hochwertiger Produkte gesichert. Durch die Kreation eines Verbundwerkstoffes aus thermoplastischer Matrix und einer CO2-neutralen, nachwachsenden Holzkomponente wurde ein Werkstoff gewonnen, welcher für den Hersteller völlig neuartige Gestaltungsmöglichkeiten eröffnet. Für die Produktion von WPC-Formteilen sind die relevanten Materialkennwerte und Verarbeitungseigenschaften bekannt, so dass dies kein Hindernis mehr darstellt. Bauteile aus WPC lassen sich mit den klassischen Techniken und Maschinen der Holzwerkstoffindustrie weiter bearbeiten. Auf Grund der Verbindung von Kunststoff- und Holzeigenschaften sind jedoch bei Entwurf und Fertigung gewisse Eigenheiten zu berücksichtigen, die aber zugleich Ansätze für neuartige Produkte in sich bergen.

The focus of this study was to examine the potential benefits of irradiating polyethylene (PE)-based wood-plastic composites (WPCs) in order to enhance the mechanical properties of the WPC. The PE-based WPCs were irradiated, post extrusion, at dose levels of 0, 50, 100, 150, 200, and 250 kGy with an electron beam (EB). The irradiated WPCs were then evaluated using a third point bending test (ASTM D4761) along with scanning electron microscopy (SEM). It was found that ultimate strength and modulus of elasticity (MOE) increased with increasing dose level. Examination of the fracture surfaces of polyethylene revealed a distinct difference in failure between irradiated and non-irradiated surfaces.

Wood Plastic Composites (WPC) is a polymeric composite with high contents of vegetal fibers. Given the porosity and the biodegradable nature of the fibers, these materials are susceptible to the microbial attack. In order to protect WPC against biological degradation, metallic nanoparticles are antimicrobial agents that have been gaining prominence. In this study, antimicrobial coatings for WPC based on poly(dimethyl siloxane) (PDMS) with silver nanoparticles (AgNPs) and zinc oxide (ZnO-NPs) were developed, using solution blow spraying (SBSp). The AgNPs were synthesized by chemical reduction of silver salts with sodium borohydride, having their nanometric particle size confirmed by ultraviolet-visible spectroscopy and a minimum inhibitory concentration against Pseudomonas aeruginosa and Staphylococcus aureus of 150 µg/mL and 250 µg/mL, respectively. The ZnO-NPs, synthesized in ethanolic medium by the microwave-assisted hydrothermal method, presented wurtzite hexagonal structure and average particle size of 229 nm, determined by dynamic light scattering (DLS). In the agar diffusion test, the ZnO-NPs showed a discrete antimicrobial activity against the two microorganisms mentioned above. The freshly prepared AgNPs colloidal suspension and the ZnO-NPs suspension in ethanolic medium containing 0.5%, 1.0%, 1.5% and 2% (m/v) were sprayed onto the PDMS partially cured surface . In the case of the PDMS/AgNPs coating, the nanoparticles were sprayed 3, 5, 8 and 10 times, with one spray per minute, in order to increase the AgNPs content adhered to the substrate. For the coating of PDMS/AgNPs, the antimicrobial action was higher according to the increase in the number of AgNPs applications. For PDMS/ZnO-NP coatings, the best antimicrobial action results were obtained for the coating containing 0.5% (m/v) of ZnO-NPs. The increase of clusters in the coatings with 1.5 and 2% of ZnO-NPs probably contributed to this result. Therefore, the coatings of PDMS/AgNPs and PDMS/ZnO-NPs have great potential of application in the protection of plastic wood composites from microbial attacks. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES A madeira plástica (Wood Plastic Composites - WPC), é um compósito de matriz polimérica, tendo altos teores de fibras vegetais. Dada a porosidade e a natureza biodegradável das fibras, esses materiais acabam sendo susceptíveis ao ataque microbiano. Assim, diante da necessidade de soluções para a proteção dos WPC contra a degradação biológica, as nanopartículas metálicas são agentes antimicrobianos que vem ganhando destaque. Neste trabalho, foram desenvolvidos e avaliados revestimentos antimicrobianos para WPC a base de poli(dimetil siloxano) (PDMS) com nanopartículas de prata (AgNPs) e de óxido de zinco (ZnO-NPs), utilizando solution blow spraying (SBSp). As AgNPs foram sintetizadas por redução química de sais de prata com borohidreto de sódio, tendo seu tamanho de partícula nanométrico comprovado por espectroscopia no ultravioleta-visível e apresentado concentração inibitória mínima frente à Pseudomonas aeruginosa e Staphylococcus aureus de 150 µg/mL e 250 µg/mL, respectivamente. As ZnO-NPs, sintetizadas em meio etanólico pelo método hidrotermal assistido por micro-ondas, apresentaram a estrutura hexagonal da wurtzita e tamanho médio de partícula de 229 nm, determinado por espalhamento dinâmico de luz (DLS). No teste de difusão em ágar, as ZnO-NPs mostraram atividade antimicrobiana discreta frente aos 2 microrganismos supracitados. A suspensão coloidal de AgNPs recém preparada e a suspensão de ZnO-NPs em meio etanólico contendo 0,5%, 1,0%, 1,5% e 2% (m/v) de nanopartículas foram aspergidas sobre a superfície parcialmente curada do PDMS. No caso do revestimento de PDMS/AgNPs, as nanopartículas foram aspergidas por 3, 5, 8 e 10 vezes, sendo de um minuto cada aspersão, de forma a aumentar o teor de AgNPs aderido ao substrato. Para o revestimento de PDMS/AgNPs, a ação antimicrobiana foi maior de acordo com o aumento do número de aplicações de AgNPs. Já para os revestimentos de PDMS/ZnO-NPs, os melhores resultados de ação antimicrobiana foram obtidos para o revestimento contendo 0,5% m/v de ZnO-NPs. O aumento dos aglomerados nos revestimentos com 1,5 e 2 % de ZnO-NPs, provavelmente, contribuiu para esse resultado. Desse modo, ficou comprovado que os revestimentos de PDMS/AgNPs e PDMS/ZnO-NPs tem grande potencial de aplicação na proteção de madeira plástica de ataques microbianos.

Surface roughness and wettability of flat-pressed wood plastic composites (WPCs) incorporated with various fire retardants (FRs) (5, 10, or 15% by weight (wt)) at 50 wt-% content of the wood flour (WF) were investigated. The most common FRs, zinc borate (ZB), magnesium hydroxide (MH), and ammonium polyphosphate (APP), were used in the experiments. The WPC panels were made from dry-blended wood flour (WF), fire retardant (FR) powder, and polypropylene (PP) powder with maleic anhydride-grafted PP (2 wt-%) formulations using a conventional flat-pressing process under laboratory conditions. The contact angle measurements were obtained by using a goniometer connected with a digital camera and computer system. Three roughness measurements, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Ry), were taken from the WPC panel surface using a fine stylus tracing technique. It was found that the surface smoothness of the WPC panels decreased with increasing content of the FR powder while the wettability increased. The control WPC panel without the FR had the smoothest surface, followed by the WPC panels containing the MH, ZB, and APP, respectively.