This work provides a study about the incorporation of a high density polyethylene (HDPE) matrix composite in medium density fiberboards (MDF). A composite was processed in a single screw extruder with 5% of Pinus spp fibers in a HDPE matrix and applied as reinforcing agent in MDFs, as well as pure HDPE, in 11 different variations, using 12% of urea-formaldehyde resin and nominal density of 750 kg.m−3. The composite and the pure HDPE were analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The DSC results showed that both polymeric matrix and composite presented the same melting temperature but the composite had a reduced melting enthalpy and crystallinity due to thermal history. SEM analysis showed a well distribution of fibers on the composite. The results of technological properties of MDFs were compared to commercial MDF standards. The MDF reinforced with 40% of polymeric composite reached all minimum standard requirements, being the most recommended to be used as an alternative to conventional MDF, in terms of physical and mechanical performance.
The work aimed to characterize the wood of the species Ochroma pyramidale in the longitudinal and radial direction of the tree. For the study, five six-year old trees were used. Discs were removed at different heights of the stem. The samples were obtained from each disk in different regions between the pith and bark. The preparation and the anatomical analysis of the permanent and temporary slides, chemical analyzes, and basic density measure of the stem wood were carried out according to technical standards. As a result, it was observed that the highest averages for pore diameter and fiber length were found in the region close to the bark at all heights. Regarding to the rays, it was noted that there was an interaction between the longitudinal x radial factors for most of the parameters evaluated, except for the width of the rays. For fiber lumen diameter and vessel length, the same trend line was found, the highest average observed in the region close to the pith. In the chemical analyzes, it was possible to observe that there was no significant difference in the longitudinal direction of the wood except for solubility in cold water. For basic density, there was an increase in the region closer to the pith compared to the region closer to the bark. However, in relation to the longitudinal position of the bole, the highest values were found at the base of the bole. It could be seen that the Ochroma pyramidale species has potential use for products linked to thermal and acoustic insulation, production of particleboards and pulp and paper production.
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