RESUMO Neste estudo, teve como obejtivo usar o bio-óleo como alternativa ao fenol à base de petróleo na produção de resina de fenol-formaldeído (PF) utilizada na fabricação de compensado exterior. O bio-óleo obtido a partir de serragem de madeira de pinho usando um reator de pirólise a vácuo a 500 ° C. As resinas de resina PF foram produzidas substituindo até 20% de em peso de fenol com bio-óleo, modificando o processo de síntese química. A análise FT-IR foi realizada para caracterizar os grupos funcionais orgânicos do bio-óleo pelas resinas PF. Em comparação com as resinas de PF comerciais e feitas em laboratório, as resinas de PF modificadas com bio-óleo apresentaram pesos moleculares médios maiores, índices de polidispersão mais altos e tempos de gel mais curtos. Seis diferentes tipos de painéis de compensado foram produzidos a partir das resinas PF experimentais que eram resina PF comercial, resina PF feita em laboratório e resinas PF modificadas com óleo biológico com conteúdo de 5, 10, 15 ou 20% em peso, respectivamente. As amostras de compensado produzidas com a resina PF modificada com bio-óleo até 20% em peso apresentaram maior força de cisalhamento de tração (condição úmida), módulo de ruptura e módulo de elasticidade em flexão em comparação com as resinas PF comerciais e feitas em laboratório.

ABSTRACT In this study, it was aimed to use of bio-oil as an alternative to petroleum-based phenol in the production of phenol-formaldehyde (PF) resin used for making exterior plywood.Bio-oil obtained from pine wood sawdust using a vacuum pyrolysis reactor at 500 °C. The PF resol resins were produced by substituting up to 20 wt% of phenol with bio-oil by modifying the chemical synthesis process. FT-IRanalysis was performed to characterizethe organic functional groups in the bio-oil modified PF resins. In comparison to the commercial and lab-made PF resins, the bio-oil modified PF resins were found to have larger average molecular weights, higher polydispersity indices, and shorter gel times. Six different types of plywood panels were produced from the experimental PF resins which were commercial PF resin, lab-made PF resin, and PF resins modified with bio oil of 5, 10, 15 or 20 wt% contents, respectively. Plywood specimens produced with the PF resin modified with bio-oil up to 20 wt% had better tensile shear strength (wet condition), modulus of rupture, and modulus of elasticity in bending as compared to the commercial and lab-made PF resins.

ABSTRACT Water resistance, mechanical properties, and limiting oxygen index (LOI) of wood plastic composites (WPCs) and neat polypropylene filled with different amounts (3, 6, and 9% by weight) of dolomite powder and wood flour (15 and 30 by weight) were investigated. Wood flour, dolomite powder, polypropylene, and wax were dry-mixed in a high-intensity mixer to produce a homogeneous blend. This blend was then compounded in a laboratory-scale single screw extruder. Test specimens were produced by injection moulding process from the pellets dried to moisture content of 1%. The thickness swelling and water absorption of the dolomite polypropylene composites (DPCs) and WPCs slightly increased with increasing dolomite powder content but the differences were not significant. The flexural modulus and tensile modulus of the WPCs and DPCs increased with increasing dolomite powder content while the flexural strength and tensile strength slightly decreased. The LOI of the WPCs and DPCs increased with increasing dolomite powder content, which extended the times to ignition of WPC and polypropylene. Based on the findings obtained from the present study, it can be said that 6 wt% dolomite powder is the optimum amount in the manufacture of WPC and DPC.

This study evaluated the individual and interaction effects of inner bark flour (IBF), outer bark flour (OBF), wood flour (WF), and blending of IBF, OBF, and WF content of poplar tree on the morphology and mechanical properties of wood-plastic composites (WPCs). The IBF, OBF, and WF with 2 wt% maleic anhydride-grafted polypropylene (MAPP) and polypropylene were compounded into the pellets using a counter-rotating twin-screw extruder. Test specimens were prepared by injection molding machine. The results indicated that the WF alone significantly (P<0.05) increased the flexural strength, flexural modulus, and tensile strength. The composites made with IBF/WF exhibited higher tensile modulus compared to those made with WF alone and IBF/OBF alone. Moreover, the results showed that the IBF/OBF alone increased the notched impact strength compared to all of reinforced composites. The neat polypropylene had higher notched impact strength than the other reinforced composites (P<0.05).

Effect of zeolite content on the physical, mechanical and thermal properties of wood plastic composites was investigated in this study. To meet this objective, pine wood flour (0, 10, 20, 30, 40, 50 wt%) with compatibilizing agent, zeolite (0, 10, 20, 30, 40, 50 wt%), and polypropylene were compounded in a twin screw co-rotating extruder. The mass ratio of the wood flour to polypropylene was 50/50 (w/w) in all compounds. Test specimens were produced using injection molding machine from the pellets. Physical and mechanical, and thermal (Thermogravimetry Analysis/Differential Scanning Calorimetry) properties of the wood plastic composites were determined. The water absorption and thickness swelling properties of wood plastic composites improved with increasing zeolite content. The flexural and tensile properties of the wood plastic composites decreased with increasing zeolite content. All the wood plastic composites provided the values of flexural strength (58,4-72,9 MPa) and flexural modulus (2718-5024 MPa) that were well over the requirement by the standard specified in ASTM D 6662. The mass loss rates values of wood plastic composites increased with increasing zeolite contents. The Differential Scanning Calorimetry analysis showed that the melt crystallization enthalpies and degree of crystallization of wood plastic composites decreased with increasing zeolite content. The decrease in the Tc and Xc indicated that zeolite was the poor nucleating agent for the wood plastic composites.

The effect of montmorillonite (MMT) loading (0, 2.5, and 5 wt%) and almond shell flour (ASF) content (30, 35, and 40 wt%) on the decay resistance, hardness, water resistance of injection molded polypropylene (PP) composites was investigated. The amount of maleic anhydride grafted polypropylene was kept constant at 2% for all formulations. White-rot (Trametes versicolor) fungal treatment was applied to the produced composites for 14 weeks according to BS 838:1961 with the Petri dishes method. The weight loss of the composites decreased with increasing MMT content. The highest hardness (66 Shore D) was noted in the undecayed control composites (40ASF60PP0MMT) while the lowest hardness (61.3 Shore D) was recorded in the decayed control composites (30ASF70PP0MMT). The water absorption of the undecayed and decayed composites decreased with increasing amount montmorillonite at 30-40 wt% content of the ASF loading level. The water absorption of the decayed composites was higher than that of the undecayed composites but their thickness swelling was lower. Based on the findings obtained from the present study, a 35/5/65/2 formulation of the ASF/MMT/PP/MAPP can be used in outdoor applications requiring a high dimensional stability.

The effect of wood-derived charcoal flour on the water resistance and mechanical properties of wood plastic composite (WPC) panels was investigated. The hot press molded WPC panels were produced from polypropylene (37 wt%) with maleic anhydride-grafted polypropylene (MAPP, 3 wt%) and different mixtures of wood flour and charcoal flour. The amount of charcoal flour was gradually increased up to 60 wt%. The thickness swelling and water absorption of WPC panels considerably decreased with increasing charcoal flour content. The internal bond strength and bending properties of the WPC panels significantly improved with increasing charcoal flour content. This was mainly attributed to the high amount of pores and gaps in the charcoal flour. Melted polypropylene could get into the pores and gaps during the hot press molding, which lead to a better interfacial adhesion between polymer matrix and wood filler. The results showed that the charcoal flour could be partially substituted for the wood flour in the production of WPC panels having higher dimensional stability and internal bond strength.

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.

This study investigated the combined effect of adhesive type and content on the dimensional stability and mechanical properties of three-layer particleboards made from a mixture of wood particles (face layer: 30 wt %) and rice husk particles (core layer: 70 wt %). Two types of thermosetting adhesives, liquid urea-formaldehyde (UF) and phenol-formaldehyde (PF), and thermoplastic adhesive (low density polyethylene: LDPE) powder were used as binder in the experiments. Thickness swelling and water absorption of the particleboards significantly decreased with increasing content of the LDPE powder. The incorporation of LDPE powder into the core layer of particleboard greatly improved the internal bond strength.