Navegando por Assunto "Polymers"

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Acesso aberto (Open Access)
Confecção de discos de desbaste a partir de AI2O3 e pó de vidro
(Universidade Federal do Pará, 2009) OLIVEIRA, Rosane Felice de; DIAS, Carmen Gilda Barroso Tavares; http://lattes.cnpq.br/2113791118142177
This article describes the development of abrasive and cutting disks made of alumina and waste glass powder to apply in cutting tools. These disk mills are used to micromize rigid post-consumed thermoplastics and let its use in a lot of recycling process, as rotomolding. This cutting disk uses glass powder as a fluxing agent and poly(ethylene terephthalate) post-consumed to give a plastic behavior to the powder, making it easier to fill in the mold. The amounts of glass powder were analyzed from previous studies with different minerals, as diopside and feldspar, since the studies with waste glass powder substituting natural minerals are recent. The development of the disks occurs in two steps. The first one is the homogeneization of the compounds with the calculated amounts. Afterwards it's pressed and taken to the mufla to get the percolation of the resin and its complete degradation up to a temperature of 900oC, pre-sintering and soften the silicates. After getting these green composites, it happens the second and final step, when the disks are sintered to decrease the porosity and improve its strength, followed by a superficial finish and cutting tests.
Acesso aberto (Open Access)
Influência de aditivo polimérico no comportamento mecânico e reológico das argamassas produzidas com rejeitos industriais
(Universidade Federal do Pará, 2015-05-12) SILVA, André Luis Mileo Ferraioli; FELIPE, Augusta Maria Paulain Ferreira; http://lattes.cnpq.br/8871741271063047; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
Mortars are considered to be particulate systems in suspension with fine aggregate, binder, water and organic polymeric additive. Factors such as granulometry, cement, ash and additive contents in their composition influence mortar properties in both the fresh and hardened states. A rheological study and mechanical test were performed on mortar prepared for floors and coatings through incorporating civil construction wastes (RCC) such as fine aggregate and fly ash, a mineral waste derived from combustion in boilers at the HYDRO ALUNORTECompany. This study seeks to develop a polymeric mortar that uses CPII E-32RS Portland cement andflyashas binders and fine sand and RCC with polyvinyl acetate (PVA) as aggregates. A study was performed on the influence of cement, ash, granulometry of aggregates and use of PVA based-polymeric additives on mortar properties.The materials were submitted to physical and chemical characterization using granulometric analysis, X-ray fluorescence and FTIR. In preparing the specimens, 6 formulas with 5% cement and 3 formulas with 10% cement were used, both with different levels of ash, sand and RCC andmaintaining a constant level of Portland cement content. A comparison of the mechanical and rheological properties of formulas with and without PVA was also made.Formulas in a fresh state were submitted to rheological tests. After 28 days of curing specimens of these formulas, by then in a hardened state, were submitted to tests for mechanical resistance to compression, specific mass, apparent absorption and apparent porosity. The research demonstrated that employing a PVA-based polymeric additive improved the mechanical properties of the mortar prepared with industrial wastes, as well as guaranteeing satisfactory rheological behavior for possible applications of such mortars in civil construction.
Acesso aberto (Open Access)
Utilização de tecidos de fibras de bananeira como agente de reforço em compósitos de matriz de resina poliéster termorrígida
(Universidade Federal do Pará, 2023-08-11) BAÍA, Michele da Costa; EL BANNA, Wassim Raja; http://lattes.cnpq.br/2005046563115507; https://orcid.org/0000-0001-5085-4352
In recent decades, several studies have been observed, both nationally and internationally, which seek alternative materials to those conventionally used by industry, with emphasis on biomass residues from agricultural activities, such as vegetable fibers, in the quest to minimize the problems caused to the environment and replace products harmful to human beings. In addition to offering advantages such as atoxicity, biodegradability, low density and reduced cost, such as fibers derived from the pseudostem of the banana tree. With regard to banana trees, Brazil is one of the largest producers of its fruit at an international level, and as a result this is one of the activities that most generate waste in the country. Therefore, this research has as main objective to make composite materials with the fibers of the pseudostem of the banana tree in the form of fabrics and thermoset polyester resin, destined to the production of materials for engineering. Initially, the process of extracting and cleaning the fibers was carried out, followed by the weaving of flat-type fabrics on the nail loom, to be used as a reinforcing agent. Next, polymeric composites were molded using a manual process (hand lay up) and application of pressure at room temperature. Thus, composites were obtained: full matrix and those reinforced with glass fibers and banana tree fibers. Mechanical tests were carried out – flexion and traction –, flammability and microscopy. The polymeric composites were manufactured in the following compositions: V1 – Full matrix; V2 – with reinforcing agent with two layers of fiberglass mats; V3 – with reinforcing agent with one layer of banana fiber fabric and V4 – with reinforcing agent with two layers of banana fiber fabric. The materials of composition V3 and V4 presented tensile strength values of 29.25 MPa 51.27 MPa and bending strength of 142.45 MPa and 91.99 MPa, respectively. As for resistance to flammability, all composite materials manufactured showed values below those stipulated by the regulations and within the Brazilian standard. The analysis of the failure mechanisms present on their surfaces was performed using MEV, which can show the arrangement between matrix and reinforcing agent, as well as the presence of cracks in the matrix, fracture and rupture of fibers in the reinforcing agent, voids and pullout.