Estevão Freire

Characterization of hybrid composites produced with mats made using different methods

This work is focused on the development and evaluation of manufacturing methods to produce short fibers hybrid mats. Different methods were developed, including: aqueous and fluidized bed. Composites were molded to help evaluating the produced mats. The analysis showed that composites manufactured by the fluidized bed method presented the best mechanical properties.

Use of Sawdust in Polyethylene Composites

In this study, composites were made with wood sawdust residues and a polyolefin. Experiments were carried out in order to analyze different parameters for processing the composites. The parameters analyzed were the sawdust/polymer ratio and the type of coupling agent. The sawdust and the polymer were mixed in a single extruder in order to produce profiles. The results showed that the composites made of HDPE and sawdust had good mechanical properties, suitable for industrial applications. These results, together with the availability of the residues in the northeast of Rio Grande do Sul state, (Brazil), makes these composites a good alternative for the use of residues.

Modelagem de misturas na fabricação de compósitos polímero-fibra, utilizando polietileno e serragem de Pinus sp.

In this work, the effect of different compositions of virgin and recycled high density polyethylene/ Pinus sp. on physical-mechanical properties of sheets made by compression molding was studied. The compositions were blended in a thermokinetic mixer (Draiss) and compression molded at 150 o C. ASTM samples for tensile, flexural, impact and hardness tests were taken from the sheets. The density of the sheets were determined. The statistical model used was a centroid simplex with seven compositions and three repetitions. Results showed that tensile and flexural strength as well as hardness and density followed a linear model, while impact strength is explained by a quadratic model. Physical-mechanical properties of compositions using virgin and recycled HDPE did not show significative changes, except for impact strength, when virgin HDPE showed higher numerical results.

Development of adhesive compositions using powder coating residues

The industry of powder coatings, for base polyester/epoxy, produces about 300 kg.day−1 of residue in a production of 6,000 kg.day−1 (5% residue). Powder coatings with equal or lower to 10 μm of granulometer are considerate residues. The use of these residues in the formulation of adhesives is studied in the present work. Portions of residue with 0.1 a 0.5 g.mL−1 were tested with 7 solvents and 5 kinds of elastomers. Two solvents compatible with the residue and three elastomers, so, three mixtures were obtained: A, B and C; then, 15 g of a petroleum derivated was additioned. The mass of mixtures was homogenized in a mechanic stirrer for 15 minutes. The preliminary tests have demonstrated that the adhesives A, B and C had effective adherence in carpet on cement slab and HDF® (High Density Fiber). The formulations of A, B and C show superior to other 8 tested specially in: fast drying, migration of adhesive upon the surface (carpet) and adherence to the slab. According to the rules ASTM D2094 and D2095 the results of tension test are compared to commercial adhesives, resulting that adhesive C had an efficiency similar to a commercial adhesive for the same utilization.