Scielo RSS <![CDATA[Polímeros]]> vol. 25 num. 4 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[Editoral]]> <![CDATA[Using glycerol produced from biodiesel as a plasticiser in extruded biodegradable films]]> AbstractThe demand for renewably sourced biodegradable materials has increased the need to produce materials that combine appropriate functional properties at competitive costs. Thermoplastic starch and polyester blends are an interesting alternative to current materials due to the low cost of starch and the functional properties and processability of the resulting blends. Producing thermoplastic starch (TPS) requires using a plasticiser at concentrations between 20 and 30%wt (in relation to starch). Glycerol is the most common plasticiser due to its high plasticising capacity and thermal stability at processing temperatures. The objective of this study was to evaluate glycerol waste from the biodiesel industry, with different degrees of purification, as plasticisers for TPS / poly (butylene adipate-co-terephthalate) (PBAT) blends. Different purities of glycerol produced films with similar mechanical, optical and barrier properties to those made with purified glycerol (99.7%). Therefore, crude glycerol is a renewable alternative plasticiser that reduces the cost of plasticisation by 6-fold. <![CDATA[Polyurethane/Poly(2-(Diethyl Amino)Ethyl Methacrylate) blend for drug delivery applications]]> AbstractA pH-sensitive blend of polyurethane (PU) and poly(2-(diethyl amino)ethyl methacrylate (PDEA) with good film-forming capacity was prepared from the corresponding aqueous dispersions. The polymer matrix was first characterized by using FTIR, DSC, water vapor transmission and water swelling capacity at different pHs. The drug release profile of films was evaluated using a vertical Franz Cell and theophylline as model drug. The water swelling degree increases from 54 to 180% when the pH of the medium is changed from 6 to 2, demonstrating the pH-responsive behavior of the film. The in-vitro release studies indicate that an anomalous transport mechanism governs the theophylline release. <![CDATA[Evaluation of chemical and mechanical resistance of virgin and recycled poly (ethylene terephthalate) and poly(methylene oxide) when applied as gravel pack in petroleum wells]]> AbstractNowadays more and more unexpected uses for common materials have been observed, especially when recycled polymers are concerned. In this work, the viability for application of virgin and recycled poly(ethylene terephthalate) (PETvir and PETrec, respectively) and also poly(methylene oxide) (PMO) as granular materials (gravel) for gravel packing in sand control systems for unconsolidated sandstone reservoirs was studied. Polymer samples were tested in conditions similar to those observed in Campos Basin sandstone formations, in Brazilian Southwest (70 °C and 24.1 MPa). Samples were individually confined in roller cells with chemicals used in formation treatment: hydrochloric acid, pentapotassic DTPA salt (chelant Trilon CK) and in a mixture of diesel, xylene and butyl glycol. Mass loss was measured and the changes in molecular mass verified by size exclusion chromatography (SEC). Physical shape and grain size distribution were verified by scanning electron microscopy (SEM) and sieving tests. The effects over the polymeric gravel pack confinement resistance and permeability were evaluated using an API permeability cell. PMO proved to have a limited use, whereas PETrec and PETvir samples were not significantly affected, suggesting the viability of applying that recycled polymer in gravel packing for sand control in petroleum wells. <![CDATA[Polyphenolic resin synthesis: optimizing plantain peel biomass as heavy metal adsorbent]]> AbstractPolyphenolic resol resins were obtained from an ethanolic extraction of green plantain peels (Musa paradisiaca) grown in Colombia. A synthesis was then performed by polycondensation in an alkaline pH solution in order to perform research on phenolic resin production with high mechanical performance. The polymers were characterized by DSC and TGA analyses and the resins showed a melting point of 94 °C and the typical properties of resol resins. Moreover, the synthesis was controlled using the infrared technique (FTIR) where different organic functional groups present in the polymers obtained are observed. The obtained resins were used as heavy metal adsorbents in which the content of those toxic agents is measured by Atomic Absorption Analysis (AA) indicating that these resins have a high retention affinity to Pb+2, Ni+2 and Cr+3 (79.01%, 98.48%, 94.14%, respectively) as determined by Freundlich isotherms. <![CDATA[Synthesis and characterization of new soluble polyamides from Acenaphtohydrazinomercaptotriazole diamine]]> AbstractA diamine Acenaphtohydrazinomercaptotriazole (AHTD) was synthesized in one step from acenaphthoqinone and 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole. The diamin was characterized by FTIR, 1HNMR, 13CNMR and melting point. Diamin was used to prepare novel polyamides. The low temperature solution polycondensation of diamin with tow aromatic and tow aliphatic diacid chlorides afforded diamin-containing polyamides with inherent viscosities of 0.38–0.47 dl/g in DMF at 25 °C. The polyamides were generally soluble in a wide range of solvents such as dimethylformamide(DMF), N-Methylpyrolidone(NMP), tetrachloroethane (TCE), dimethylsulfoxide(DMSO) and H2SO4. Thermal analysis showed that these polyamides were practically crustily and with Tg under 100 °C. <![CDATA[Natural rubber latex: determination and interpretation of flow curves]]> AbstractAs consumers become more demanding, the importance grows of guaranteeing the quality of products. The employment of reliable testing techniques that assure the origin and characteristics of the inputs used by industry is a key factor in this respect. In the rubber processing industry, the most commonly used characterization tests include determination of the total solids and dry rubber content, mechanical stability, odor, color and presence of volatile compounds, among others. For the most part, these tests are sufficient for the latex transformation industry. However, in situations where there is a need to know the behavior of latex in reaction to the mechanical forces of machines (mixers, pumps, etc.), other tests must be used. Rheological tests to determine viscoelastic data by means of plotting flow curves combined with the application of theoretical models can provide important details for characterization of different types of latex. This article presents the protocol employed by the Rheology and Image Laboratory of Rio de Janeiro State University (UERJ) for the rheological study of Brazilian latex. The samples analyzed came from the state of São Paulo. <![CDATA[Recycling assessment of multilayer flexible packaging films using design of experiments]]> AbstractThe viability of recycling post-industrial packaging waste, compounded from multilayer laminated PET-PE films, for production of polymer blends with good physico-mechanical performance is analyzed. Initially, several PET-PE model-blends were prepared from fresh polymers and were compounded with different formulations, based on design of experiments (DOE). Polymer compatibilizers based on maleic anhydride (PE-g-MA) and glycidyl methacrylate (E-GMA) have been used to promote the compatibilization reaction. The physico-mechanical properties of the model-blends were evaluated by response surface methodology (RSM). Finally, the post-industrial waste was compounded with the same concentration of compatibilizers in the previous set of model-blends. The DOE methodology showed to be a useful tool for assessing the recycling, since it helped to produce recycled materials with acceptable physico-mechanical properties. Between both compatibilizers studied, PE-g-MA showed to be the best additive for compatibilization due to the presence of a polyamide component in the waste, which undergoes a kinetically favorable compatibilization reaction. <![CDATA[Blends of ground tire rubber devulcanized by microwaves/HDPE - Part B: influence of clay addition]]> AbstractThe main objective of this work is to study the influence of clay addition on dynamically revulcanized blends of Ground Tire Rubber (GTR)/High Density Polyethylene (HDPE). GTR was previously devulcanized in a system comprised of a conventional microwave oven adapted with a motorized stirring, with a fixed microwave power and at various exposure times. The influence of clay addition on the final properties of the blends was evaluated in terms of mechanical, viscoelastic, thermal and rheological properties, with morphology being also analyzed. The results depict that the clay can modify the rheological behavior of the GTR phase, in addition to the thermal and mechanical properties of some blends. <![CDATA[Improving the thermal properties of fluoroelastomer (Viton GF-600S) using acidic surface modified carbon nanotube]]> AbstractAcid surface modified carbon nanotube (MCNT)-, Carbon nanotube (CNT)-filled fluoroelastomer (FE) and unfilled-FE were prepared (MCNT/FE, CNT/FE and FE). The compounds were subjected to thermogravimetric analysis (TGA) and heat air aging, and characterized by Energy Dispersive X-Ray (EDX). Results showed that MCNT improved the thermal properties of FE, resulting in a larger amount of FE and char remaining in the temperature range of 400-900 °C relative to unfilled FE and CNT/FE. The MCNT/FE TGA curve shifted towards higher temperatures compared to CNT/FE and FE. The same results also revealed that higher percentages of FE were undegraded or less degraded especially near MCNT in the temperature range of 400-540 °C. Energy Dispersive X-Ray (EDX) results indicated that the percentage of carbon and fluorine in the residue of TGA scans, up to 560 °C, of MCNT/FE were the same as CNT/FE, and were higher than FE. EDX results of TGA residue (run up to 900 °C) showed that most of the undegraded FE, which was not degraded at temperatures below 560 °C, was degraded from 560 °C to 900 °C in both MCNT/FE and CNT/FE, with the char in MCNT/FE being more than that in CNT/FE. EDX analysis of thermal aged specimens under air showed that, with increasing aging time, a greater percentage of C, O and F was lost from the surface of filler/FE and FE. The order of element loss after 24 hour aging time was: MCNT/FE &gt; FE &gt; CNT/FE. <![CDATA[Synthesis, characterization and thermal degradation of cross-linked polystyrene using the alkyne-functionalized esters as a cross-linker agent by click chemistry method]]> AbstractIn this study, it has been demonstrated that cross-linked polystyrene (CPS) was successfully prepared by using click chemistry. For this purpose, firstly, poly (styrene-co-4 chloromethylstyrene) with 4-chloromethylstyrene was synthesized. Secondly, alkyne-functionalized esters (dipropargyl adipate, dipropargyl succinate) were obtained using propargyl alcohol, adipoyl chloride and succinyl chloride. Azide-functionalized polystrene (PS-N3) and dipropargyl adipate (or dipropargyl succinate) were reacted in N,N-dimethylformamide for 24 h at room temperature to give CPS. The synthesized polymer and compounds were characterized by nuclear magnetic resonance (1H-NMR), gel permeation chromatography (GPC), fourier transform infrared spectroscopy (FT-IR) and thermogravimetric (TG/DTG) analysis.. The surface properties were investigated by Scanning Electron Micrography (SEM). <![CDATA[Avaliação das propriedades mecânicas e morfológicas de compósitos de PEAD com pó de <em>Pinus taeda</em> e alumina calcinada]]> ResumoNeste estudo foram desenvolvidos compósitos utilizando PEAD, pó de madeira (Pinus taeda), alumina calcinada e dois diferentes tipos de agentes compatibilizantes para avaliação das propriedades morfológicas e mecânicas dos mesmos. Para aumentar a interação entre a matriz polimérica e o pó de madeira foram utilizados 2% de polietileno graftizado com anidrido maleico em todas as formulações. Para efeito comparativo foi desenvolvida uma formulação com viniltrietoxisilano como compatibilizante para a alumina calcinada. O teor de cargas variou de 4% a 33% para os compósitos de carga única e mantiveram o percentual de 28% para os compósitos com as duas cargas. A interação entre a matriz polimérica e as cargas, proporcionada pelo agente compatibilizante anidrido maleico, foi observada nas micrografias da interface da matriz/carga. A utilização do silano não proporcionou efeito adicional nas propriedades mecânicas dos compósitos. Os compósitos isentos de alumina apresentaram maior resistência à tração, porém na resistência à flexão a presença da alumina contribuiu para o aumento desta propriedade provavelmente devido à pequena interação existente entre a interface do seu grão e a matriz polimérica.<hr/>AbstractThis work aims at the evaluation of morphological and mechanical properties of HDPE composites developed with wood flour (Pinus taeda), calcined alumina and two different types of compatibilizing agents. In order to improve the interaction between the polymer matrix and wood flour 2% maleic anhydride-grafted polyethylene was used in all formulations. For comparison a formulation with triethoxyvinylsilane as compatibilizer for the calcined alumina was developed. The filler content ranged from 4% to 33% for the single filler composite while the percentage of 28% was kept as such for the two-fillers composites. The interaction between the polymer matrix and fillers, provided by the maleic anhydride compatibilizer agent, could be observed in the micrographs of the matrix / filler interface. The silane did not improve the mechanical properties of the composite. Free alumina composites showed higher tensile strength, but concerning flexural strength the presence of alumina contributed to increased values in this property. This was probably caused by the reduced interaction between the interface of its grain and the polymer matrix. <![CDATA[Resinas poliméricas reticuladas com ação biocida: atual estado da arte]]> ResumoCopolímeros reticulados à base de divinilbenzeno vêm sendo extensivamente empregados como suportes de catalisadores e complexantes de íons metálicos, adsorventes de compostos orgânicos e fases estacionárias em separações cromatográficas. A introdução de grupos biocidas a estes materiais é relatada em patentes desde a década de 1970, contudo apenas a partir do ano 2000 estes copolímeros passaram a ser aplicados também como suportes para grupos biocidas. A presente revisão apresenta as principais combinações de suportes poliméricos e grupos biocidas estudados com o objetivo de preparar resinas biocidas reticuladas. Procura-se estabelecer relação entre as características dessas resinas e seu mecanismo de ação biocida.<hr/>AbstractCrosslinked copolymers of divinylbenzene have been extensively employed as supports for catalysts and chelating groups of metal ions, adsorbents of organic compounds and stationary phases for chromatography separations. The use of these copolymers as support for biocidal groups is reported in patents since the 1970s, but only after 2000 were these copolymers also applied as supports for biocidal groups. This paper describes the main combinations of polymeric supports and biocide groups employed in biocide polymer resins. The relationship between the characteristics of these resins and their mechanism of action is also established in this work.