Comparative study of wood flour photodegradation of two wood species submitted to artificial weathering

In this work Eucalyptus grandis and Dipteryx odorata were submitted to photodegradation by ultraviolet radiation. The effect of ultraviolet radiation irradiation on the color change and chemical composition of each wood flour were evaluated. The samples were submitted to a total of 500h of artificial weathering using condensation stages and ultraviolet radiation B irradiation cycles. The changes in wood flour color were monitored by spectrocolorimetry, while the changes in wood chemical composition were evaluated by Fourier transform infrared spectroscopy. Both species showed changes in color with increased exposure time to artificial weathering. For both wood species the variation in color change was considered very appreciable after 500h. The Eucalyptus grandis specie showed appreciable color change after 120h, while for Dipteryx odorata specie the color change is appreciable only after 240h. The Fourier transform infrared spectroscopy results showed that lignin was strongly degrades by ultraviolet radiation radiation in both species. However, Dipteryx odorata was more resistant to photodegradation than Eucalyptus grandis, probably due to lower lignin content in this wood. The results clearly indicated that for the wood species studied the rate of weathering is influenced by wood species

Influence of coupling agents on rheological, thermal expansion and morphological properties of recycled poypropylene wood flour composites

In this work, thermal expansion and morphological properties of recycled polypropylene wood flour composites were evaluated in order to verify the effect caused by the usage of a natural oil as coupling agent. The natural oil used as coupling agent was octanoic acid (C8), maleic anhydride grafted polypropylene (MAPP), widely used in industry but from non-renewable source, was also used for comparison. Composites were obtained by twin screw extrusion and injection molded. The results showed that the addition of octanoic acid and maleic anhydride grafted polypropylene reduced the coefficient of thermal expansion of the composites. The dependence of melt viscosity obeyed the Arrhenius-Eyring expression, and the activation energy values for composite viscous flow were higher than matrix. The composite morphology revels that octanoic acid promotes strong interfacial adhesion between filler and matrix, similar to that observed when maleic anhydride grafted polypropylene were used. Octanoic acid showed similar results when compared with maleic anhydride grafted polypropylene in all properties evaluated, indicating that can be used as an alternative instead of use coupling agent from non-renewable sources.    &nbsp

Assessment of the thermal behavior of lignins from softwood and hardwood species

The thermal behavior of lignins from softwood and hardwood species has been investigated using thermogravimetry and differential scanning calorimetry. Klason Lignin from Pinus taeda and Klason lignin from Eucalyptus grandis were studied. The differential scanning calorimetry results showed that both Klason lignins studied presented similar glass transition temperature. Thermogravimetric results showed that the lignin degradation occurs in three stages. The Klason lignin of Pinus taeda is more thermally stable than Eucalyptus grandis, probably because of the higher thermal stability of the guaiacyl units in softwood lignin. The degradation of both lignins initiate by a diffusion process. However when the conversion values are higher than 0,1 the lignin degradation mechanism is a complex procedure and involves the degradation of a highly condensed aromatic structure formed at the previous degradation stages

Polypropylene-based wood-plastic composites: Effect of using a coupling agent derived from a renewable resource

In this work, post-consumer polypropylene and wood flour from Pinus elliottii were used to produce wood plastic composites. The effect of polypropylene grafted with itaconic acid used as a coupling agent on mechanical properties, thermal stability and morphology of the composites was investigated and compared with the composite developed with polypropylene grafted with maleic anhydride, commonly used as coupling agent in wood plastic composites. Composites with 30 wt% of wood flour and 2 wt% of coupling agent were produced in a co-rotating twin-screw extruder and after were injection molded. The mechanical properties showed that flexural strength improved on 29% and 35% with addition of polypropylene grafted with itaconic acid and polypropylene grafted with maleic anhydride respectively, when compared with the wood plastic composites without coupling agent. On the other hand, the incorporation of polypropylene grafted with itaconic acid does not change the impact strength values significantly. Additionally, the temperature corresponding to 3 wt% of weight loss determined by thermogravimetry for composites with polypropylene grafted with itaconicacid increased by 14°C when compared with wood plastic composites without coupling agent, while addition of polypropylene grafted with maleic anhydride increased approximately 6°C the composite thermal stability. A morphological study revealed the positive effect of the polypropylene grafted with itaconic acid on the interfacial bonding of recycled polypropylene and wood flour

Effect of extractive content on the thermal stability of two wood species from Brazil

The influence of extractive content on the thermal stability and kinetic degradation of two wood species has been investigated using chemical analysis and thermogravimetry. Two wood species were studied: Pinus taeda and Eucalyptus grandis. Thermogravimetric results showed that higher extractive contents in the wood accelerate the degradation process and promote an increase in the conversion values at lower temperatures reducing the wood thermal stability. After removing the extractives from wood the thermal stability for both wood species increased. The results also demonstrated that prior information about the wood composition can be helpful to increase the range of industrial applicationsof wood

Modificação química do óleo de soja com anidrido maleico: uma alternativa sustentável para o óleo após a fritura

O óleo de soja após utilizado em processos de fritura pode causar impacto ao meio ambiente se for descartado de maneira inadequada. Este trabalho tem por objetivo modificar o óleo de soja virgem e pós-consumo com anidrido maleico. A modificação química do óleo de soja virgem e usado foi realizada a 130°C durante 1,5h a 1600 rpm com a adição de anidrido maleico ao sistema reacional. A caracterização das amostras foi realizada por espectroscopia na região do infravermelho com transformada de Fourier (FTIR), índice de saponificação e viscosidade. Na análise de FTIR foi observado o surgimento de novas bandas nos espectros dos óleos modificados, associadas aos grupos anidrido ligados às cadeias dos óleos. O índice de saponificação aumentou para os óleos maleinizados quando comparados aos óleos antes da sua modificação. Houve, também, um aumento da viscosidade do óleo modificado em relação ao virgem e em relação ao pós-consumo. Pode-se observar que, tanto o óleo de soja virgem modificado quanto o óleo de soja pós-consumo modificado apresentam potencial para serem utilizados como lubrificantes, plastificantes ou compatibilizantes em materiais poliméricos

Effect of styrene maleic anhydride on physical and mechanical properties of recycled polystyrene wood flour composites

In this work, the influence of three types of styrene maleic anhydride (SMA) oligomers on the adhesion of polystyrene wood plastic composites (WPC) was investigated. The composites were processed on a twin-screw co-rotating extruder below 200°C using 20 wt% of wood flour. The styrene maleic anhydride with different content of maleic anhydride groups, 30%, 25% and 20% (w/w) and levels of 1, 2 and 4% of coupling agents (styrene maleic anhydride 2000, styrene maleic anhydride 3000 and styrene maleic anhydride EF40) in the composite formulations were tested. Mechanical, physical and morphologic properties were evaluated. The styrene maleic anhydride improves the compatibility of hydrophilic wood flour with hydrophobic polystyrene matrix. It has been observed that the addition of styrene maleic anhydride increased the wood plastic composites mechanical properties with the incorporation of 2% wt of styrene maleic anhydride 2000. The mechanical properties showed to be dependent on content of maleic anhydride in the coupling agent. Treated and non-treated wood plastic composites showed similar density values, but the void content was reduced for treated composites. Scanning electron microscopy revel the better adhesion between polymer and matrix when coupling agent were used