The pelleting of forest and agricultural materials, mainly because many residues from both industries can be used in this process, has been an alternative in obtaining added value products to energy generation. Thus, the aim of this study was to evaluate the energy quality of the pellets produced from forest and agricultural residues as raw materials and to verify the utility of the thermogravimetric analysis (TGA) and the differential thermogravimetric analysis (DTG) in characterizing the behavior of the pellets during the combustion process. Four residues were used: (1) Pinus spp. woodchips, (2) apple pruning residues, (3) aciculated dry branches of Araucaria angustifolia and (4) A. angustifolia empty-seeds. Chemical composition of the raw materials was determined and the physical and energetic properties of the pellets were analysed. Plus, the proximate analysis of the pellets was carried out. The samples were submitted to TGA with a heating rate of 20ºC min-1 from room temperature to 1000ºC, in a N2 atmosphere. The variation of chemical composition of each residue was determinant in the characterization of each stage of the thermal degradation. Stages and events of the degradation were closely linked to the chemical and energetic nature of the samples. Use of TGA to characterize the thermal degradation of the pellets produced with different forest and agricultural residues was demonstrated as an efficient technique to quantify and qualify the events that occurred in each stage of the combustion of these biofuels.

This paper aimed to evaluate the technological properties of particleboards produced with particles of unconventional species, bamboo of the species Phyllostachys edulis, and of the genus traditionally used by the sector for the production of the particulate panels in Brazil, Pinus spp.The bamboo splints of 3 years old were collected in Frei Rogério, Santa Catarina, being transformed into particles in a mill hammer, while the particles of Pinus spp. were collected from the industrial process of MDP production in Bonet Madeiras e Papéis Ltda Company in Santa Cecília, Santa Catarina. The company used eight-year-old logs of P. taeda and P. elliottii from the thinning process, without distinction of the species. The experiment was composed of five compositions with mixing the bamboo and wood particles in different proportions ((T1)100:0%; (T2)75:25%; (T3)50:50%; (T4)25:75%; (T5)0:100%). The panels were produced nominal density of 700 kg / m³ and pressing cycle of 160ºC and 40 kgf/cm² for 8 minutes. Results reporting physical and mechanical properties of panels were evaluated through Analysis of Variance and Tukey´s Test at 95% probability. The results evidenced that bamboo particles presented potential for the production of particleboard. The most promising results were presented with the addition of 50% of bamboo in the panel composition (T3), mainly by means observed for dimensional stability, as for strength and stiffness. Values of internal bond presented significantly lower averages with the addition of more than 25% of bamboo.

Percolation threshold is an important phenomenon to be addressed when producing nanocomposites, especially because the literature suggests a depression of properties near this region. In this study, epoxy matrix nanocomposites were produced with different volume fractions of multi-walled carbon nanotubes and were characterized according to their electrical, thermal, and mechanical properties. In addition, digital image correlation (DIC) was used to measure the strain of nanocomposites and to show how it behaves in different percolation states. Electrical conductivity indicated a percolation threshold near 0.22% v/v of nanoparticles. Differential scanning calorimetry analysis showed a depression followed by an increase in glass transition temperature near the percolation threshold. Tensile strength tests presented a depression followed by an increasing near percolation threshold. DIC images showed that nanocomposites present a different behavior when near the percolation threshold, with a more distributed strain over the surface of the sample under stress and fracture toughness decreased near the percolation threshold.

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.

Potencial de utilização de resíduos do beneficiamento da erva mate (Ilex paraguariensis) na produção de painéis de partículas