Navegando por Autor "BRITO, Paulo Roberto de Oliveira"

Agora exibindo 1 - 2 de 2

Acesso aberto (Open Access)
Perfis de polietileno reciclado carregado com fibra de açaí
(Universidade Federal do Pará, 2012-05-19) BRITO, Paulo Roberto de Oliveira; DIAS, Carmen Gilda Barroso Tavares; http://lattes.cnpq.br/2113791118142177
Were obtained porous tubular profiles, polyethylene (PE) and polyethylene/fiber açai (PE/PA) 80/20 extruded from granulated particles of high-density polyethylene packaging recycled post-consumer 600 μm, and this with fiber açaí 300 μm. For parts processing was developed a mono-screw extruder bench, with System Mechanic powered by an electric motor of ½ HP (0.37 kw) controlled by a frequency inverter with cannons, bagels, array and replaceable heating system. To allow a preview of didactic equipment operating conditions so simplified were conducted tests with paraffin in glass ranging from Cannon-if the screw rotation speeds and temperature profile, adjusting mass flow and pressure in the output. For extrusion of profiles theological tests were conducted with porous of PE and PE/FA screw, barrel being selected and aluminum matrix; bagel with step 9 mm and length diameter ratio (L/D) 22, composed of an element mixer and a floating element in the zone of flow control; angle between the axis and thread screw 17 air gap between the screw and barrel 0.15 mm; 1.3 rpm rotation; heating along the cannon 120º C; tubular array with 21 mm internal diameter and Chuck 19 mm outside diameter. PE profiles and PE/FA showed average pore diameter 0.7 and 0.6 mm; specific gravity to water at a point 28º C 0.77 and 0.73; modulus GPa 1.002 and 2.601 and maximum apparent swelling of extruded 100 and 80%.
Acesso aberto (Open Access)
Reforço superficial em alumínio fundido por nanotubos de carbono via tratamento de solubilização
(Universidade Federal do Pará, 2021-10-14) BRITO, Paulo Roberto de Oliveira; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637
Carbon nanotubes (CNTs) are noteworthy, as they reinforce the metallic matrix, due to mechanical properties, such as the ~ 1.0 TPa Young module. To improve the maintenance of the commercially pure aluminum surface, multi-walled carbon nanotubes (MWCNTs) were incorporated into the aluminum surface with heat treatment by solid solubilization, in order to improve the surface properties of aluminum. The aluminum samples were subjected to chemically attacked with the Keller reagent, for a period of 30, 60 and 120 seconds, and soon after the roughness assessment was carried out, and then they were placed in a container containing NTCs, being subjected to a 640°C for one hour. Afterwards, the morphology was evaluated in the scanning electron microscope, where an aggregate of NTCs was observed, the DRX was performed to evaluate the addition of the NTCs in the matrix, and the Raman Spectrum that evaluated the charge transfer to the matrix. Microhardness was performed to evaluate the result of the incorporation of the NTCs in the matrix. The results obtained show that the incorporation of CNTs in the aluminum matrix increases the hardness in approximately 20% of the surface, in comparison with the control sample. The process of incorporating CNTs into the aluminum matrix by solubilization is a promising, simple and inexpensive alternative to improve the durability of the aluminum surface.