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Polímeros, Volume: 27, Número: 4, Publicado: 2017
  • Polímeros has a new President of the Council Board and two newly appointed Associate Editors Editorial

    Canevarolo, Sebastião V.
  • Nanostructured magnetic alginate composites for biomedical applications Original Article

    Bedê, Pedro Marins; Silva, Marcelo Henrique Prado da; Figueiredo, André Ben-Hur da Silva; Finotelli, Priscilla Vanessa

    Resumo em Inglês:

    Abstract This is a study of the preparation and characterization of polymeric-magnetic nanoparticles. The nanoparticles used were magnetite (Fe3O4) and the chosen polymers were alginate and chitosan. Two types of samples were prepared: uncoated magnetic nanoparticles and magnetic nanoparticles encapsulated in polymeric matrix. The samples were analyzed by XRD, light scattering techniques, TEM, and magnetic SQUID. The XRD patterns identified magnetite (Fe3O4) as the only crystalline phase. TEM analyses showed particle sizes between 10 and 20nm for magnetite, and 15 and 30nm for the encapsulated magnetite. The values of magnetization ranged from 75 to 100emu/g for magnetite nanoparticles, and 8 to 12emu/g for coated with chitosan, at different temperatures of 20K and 300K. The saturation of both samples was in the range of 49 to 50KOe. Variations of results between the two kinds of samples were attributed to the encapsulation of magnetic nanoparticles by the polymers.
  • Green polyurethane synthesis by emulsion technique: a magnetic composite for oil spill removal Original Article

    Costa, Raphael Maria Dias da; Hungerbühler, Gabriela; Saraiva, Thiago; De Jong, Gabriel; Moraes, Rafael Silva; Furtado, Evandro Gonçalves; Silva, Fabrício Machado; Oliveira, Geiza Esperandio de; Ferreira, Luciana Spinelli; Souza, Fernando Gomes de

    Resumo em Inglês:

    Abstract After the consolidation of the Brazilian biodiesel industry, issues related to the final destination of the glycerin, the by-product from the biodiesel industrial process, drawing the attention of several researchers. There are several uses to this byproduct. Among them, the obtaining of polymers, such as polyurethane (PU), are very encouraged since the glycerin ca be used, as well as the castor oil, in the replacement of petrochemical polyols. The aim of this work was to propose a new route for the obtainment of a petroleum sorbent based on polyurethane resin from glycerin and castor oil, through the emulsion technique. In addition, maghemite (γ-Fe2O3) was mixed to the polymer matrix, producing a magnetic composite, able to make easier the oil cleanup process. The products synthesized were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, simultaneous Thermogravimetry (TGA) and Differential scanning calorimetry (DSC), Optical microscopy, Scanning electron microscopy (SEM). In addition, magnetic force and oil removal capability tests were also performed. The magnetic material was used to remove oil from water, exhibited a good oil removal capability. In a typical test, 1g of the composite containing 5wt% of maghemite was able to remove 10g of oil from water.
  • Thermal degradation of polymer systems having liquid crystalline oligoester segment Original Article

    Matroniani, Renato; Wang, Shu Hui

    Resumo em Inglês:

    Abstract Block copolymers and blends comprised by liquid crystalline oligoester and polystyrene were prepared and their thermal stability were characterized by thermogravimetric analysis (TGA). The samples have shown three main decomposition temperatures due to (1) lost of flexible chain and decomposition of mesogenic segment, (2) decomposition of polystyrene and (3) final decomposition of oligoester rigid segment. Both copolymers and polymer blends presented lower thermal stability compared to polystyrene and oligoester. The residual mass after heating at 600 °C in copolymers and polymer blends were lower than those found in the oligoesters. A degradative process of aromatic segments of oligoester induced by decomposition of polystyrene is suggested.
  • New technologies from the bioworld: selection of biopolymer-producing microalgae Original Article

    Martins, Roberta Guimarães; Gonçalves, Igor Severo; Morais, Michele Greque de; Costa, Jorge Alberto Vieira

    Resumo em Inglês:

    Abstract Microalgae are studied because of their biotechnological potential. The growth of microalgae aims at obtaining natural compounds. Due to the large amount of accumulated polymer waste, one of the solutions is the use of biodegradable polymers. The objective of this work was to select biopolymer-producing microalgae and to study the cell growth phase in which maximum production occurs. Microalgae Cyanobium sp., Nostoc ellipsosporum, Spirulina sp. LEB 18 and Synechococcus nidulans were studied. The growth was carried out in closed 2 L photobioreactors kept in a chamber thermostated at 30 °C with an illuminance of 41.6 μmolphotons.m-2.s-1 and a 12 h light/dark photoperiod. The biopolymers were extracted at times of 5, 10, 15, 20 and 25 d. The microalgae that had the highest yields were Nostoc ellipsosporum and Spirulina sp. LEB 18 with crude biopolymer efficiency of 19.27 and 20.62% in 10 and 15 d, respectively, at the maximum cell growth phase.
  • Microalgae biopeptides applied in nanofibers for the development of active packaging Original Article

    Gonçalves, Carolina Ferrer; Schmatz, Daiane Angelica; Uebel, Lívia da Silva; Kuntzler, Suelen Goettems; Costa, Jorge Alberto Vieira; Zimmer, Karine Rigon; Morais, Michele Greque de

    Resumo em Inglês:

    Abstract This study was conducted to develop PCL nanofibers with the incorporation of microalgae biopeptides and to evaluate the stability of chicken meat cuts during storage. PCL and PCL/biopeptides nanofibers were formed by electrospinning method, and the diameters obtained were 404 and 438 nm, respectively. The tensile strength, elongation, melting temperature and thermal stability of biopeptide-added PCL nanofibers were 0.245 MPa, 64%, 56.8 °C and 318 °C, respectively. PCL/biopeptide nanofibers showed a reducing power of 0.182, inhibition of 22.6% and 12.4% for DPPH and ABTS radicals, respectively. Chicken meat cuts covered by the PCL/biopeptide nanofibers showed 0.98 mgMDA∙kg-1 and 25.8 mgN∙100g-1 for TBARS and N-BVT analysis, respectively. Thus, the PCL/biopeptide nanofibers provided greater stability to the product and control of oxidative processes ensuring the product quality maintenance during the 12 d of storage.
  • Modification of thermal and rheological behavior of asphalt binder by the addition of an ethylene-methyl acrylate-glycidyl methacrylate terpolymer and polyphosphoric acid Original Article

    Pereira, Gerson da Silva; Morales, Ana Rita

    Resumo em Inglês:

    Abstract This study evaluated the modification effects of adding ethylene-methyl acrylate-glycidyl methacrylate terpolymer (EMGMA) in the presence of polyphosphoric acid (PPA) to an asphalt binder graded as 50/70 (0.1mm) in the Brazilian penetration grade specification (AC 50/70). The EMGMA terpolymer has been presented as a new alternative to modify asphalt binders properties, as scientific literature is scarce on its usage in this context and also on the role of PPA when used in combination with reactive polymers. The characteristics of the modified binder were analyzed by standard and rheological testing, including Multiple Stress Creep Recovery test (MSCR) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The MSCR test showed that the modified binder presented lower values of non-recoverable compliances (Jnr) and a higher percent recovery, when compared to the conventional binder. This behavior indicates that addition of EMGMA and PPA in asphalt binders could enhance the resistance to rutting of asphalt mixtures. The statistical evaluation showed that EMGMA had greater influence on the studied properties of Jnr (0.1kPa), MSCR recovery, softening point and elastic recovery at 25°C and that the PPA had also significant influence on these properties. FTIR analysis showed that chemical reactions occurred between the asphalt binder and EMGMA, forming a three-dimensional polymeric network, which promotes improved characteristics.
  • Dynamic mechanical analysis and crystalline analysis of hemp fiber reinforced cellulose filled epoxy composite Original Article

    Palanivel, Anand; Veerabathiran, Anbumalar; Duruvasalu, Rajesh; Iyyanar, Saranraj; Velumayil, Ramesh

    Resumo em Inglês:

    Abstract The Dynamic mechanical behavior of chemically treated and untreated hemp fiber reinforced composites was investigated. The morphology of the composites was studied to understand the interaction between the filler and polymer. A series of dynamic mechanical tests were performed by varying the fiber loading and test frequencies over a range of testing temperatures. It was found that the storage modulus (E’) recorded above the glass transition temperature (Tg) decrease with increasing temperature. The loss modulus (E”) and damping peaks (Tan δ) values were found to be reduced with increasing matrix loading and temperature. Morphological changes and crystallinity of Composites were investigated using scanning electron microscope (SEM) and XRD techniques. The composites with Alkali and Benzoyl treated fibers has attributed enhanced DMA Results. In case of XRD studies, the composites with treated fibers with higher filler content show enhanced crystallinity.
  • Production of biodegradable starch nanocomposites using cellulose nanocrystals extracted from coconut fibers Original Article

    Cerqueira, Jamile Costa; Penha, Josenai da Silva; Oliveira, Roseane Santos; Guarieiro, Lilian Lefol Nani; Melo, Pollyana da Silva; Viana, Josiane Dantas; Machado, Bruna Aparecida Souza

    Resumo em Inglês:

    Abstract Different polymeric matrices have been investigated for use in the development of biodegradable films. The incorporation of cellulose nanocrystals in such films has particularly attracted attention because of the potential for achieving improved properties of starch nanocomposites. In the present study, cellulose nanocrystals were extracted from coconut fibers and incorporated in cassava and potato starch films at different concentrations. The properties of the different nanobiocomposite films were comparatively evaluated, including their barrier and mechanical properties. All the films, regardless of the nanocrystal concentration, were found to exhibit low solubility in water, with increased moisture content particularly observed in the films with higher nanocrystal concentrations. The potato starch film with the lowest nanocrystal concentration was found to exhibit the best mechanical properties. The observations of this study indicated that the source of the starch and the nanocrystal concentration determined the properties of the nanobiocomposite films.
  • Layer-by-Layer technique employed to construct multitask interfaces in polymer composites Original Article

    Vitorino, Luísa Sá; Oréfice, Rodrigo Lambert

    Resumo em Inglês:

    Abstract The properties of glass fiber-reinforced polymer composites are closely related to the fiber-matrix interface. Interfacial treatments to improve mechanical properties are usually limited to enhance interfacial adhesion. In this work, Layer-by-Layer (LbL) technique was introduced to build a novel interface in polymer composites. Different numbers of bilayers of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate) with carbon nanotubes were deposited through LbL on the surface of woven glass fibers (GFs). Polypropylene composites containing the modified GFs were prepared by compression molding. Thermogravimetric analysis, scanning electron microscopy and Raman spectroscopy proved that multilayers of polymers with carbon nanotubes could be deposited on GFs surface. Mechanical tests on composites with modified GFs revealed an increase in Flexural Modulus and toughness. The overall results attested that the LbL technique can be used to design interfaces with different compositions to perform diverse tasks, such as to improve the stiffness of composites and to encapsulate active nanocomponents.
  • Influence of tribological test on the global conversion of natural composites Original Article

    Correa, Carlos Eduardo; Zuluaga, Robin; Castro, Cristina; Betancourt, Santiago; Vázquez, Analía; Gañán, Piedad

    Resumo em Inglês:

    Abstract The vinyl ester resins and natural composites have emerged as a suitable alternative in tribological application due to mechanical behavior, which relates to the conversion of the double bonds. During tribological test the permanent contact between polymeric sample and counterpart can increase the temperature affecting the crosslinking of the samples. These variations have direct implications in the curing rate and the global conversion. In this work, the FTIR evaluation is used to evaluate possible changes on the global conversion of vinyl ester and their composites reinforced with Musaceae fiber bundles and cured using two hardeners, after a specific tribological test. Increments around 15% on global conversion of styrene double bonds were observed for neat matrix and composites using both hardeners, suggesting that during tribology test some alterations on resin structure takes place. These results open alternatives to manipulate the curing conditions in order to control the tribological behavior.
  • Effect of concentrations of plasticizers on the sol-gel properties developed from alkoxides precursors Original Article

    Kunst, Sandra Raquel; Longhi, Marielen; Beltrami, Lilian Vanessa Rossa; Zini, Lucas Pandolphi; Boniatti, Rosiana; Cardoso, Henrique Ribeiro Piaggio; Vega, Maria Rita Ortega; Malfatti, Célia de Fraga

    Resumo em Inglês:

    Abstract Coatings developed through sol-gel method is presented as an interesting replacement to chromium coating. Sol-gel method present advantages as high purity and excellent distribution of the components. The objective of this work is to synthesize and characterize a film obtained by sol-gel route. The film was prepared with 3-(trimethoxysilylpropyl) methacrylate (TMSPMA), tetraethoxysilane (TEOS) and cerium nitrate, using water and ethanol as solvents. Polyethyleneglycol (PEG) plasticizer was added at four different concentrations. The sol was characterized by techniques of viscosity, thermogravimetric analysis (TGA), X-ray diffraction (XRD) nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FT-IR). The results showed that tetrafunctional alkoxides condensation was retarded by the plasticizer, forming a compact film. The film with 20 g.L-1 of PEG showed the best electrochemical behavior.
  • Evaluation of Out-of-Autoclave (OOA) epoxy system Original Article

    Guilherme, Fernanda; Cassu, Silvana Navarro; Diniz, Milton Faria; Leal, Tanila Penteado de Faria Gonzales; Sanches, Natália Beck; Dutra, Rita de Cássia Lazzarini

    Resumo em Inglês:

    Abstract Epoxy resins (EP) usually cure in autoclave to minimize resin voids and to achieve the desired resin/fiber ratio. Cure parameters such as temperature, vacuum and pressure levels are controlled and monitored. Aiming time and cost optimization, new out-of-autoclave (OOA) cure processes have been developed lately. This study evaluated the cure cycle and the effect of non-programmed interruptions in an OOA process. Fourier Transform Infrared spectroscopy (FT-IR) results show similarities between the resin used and diglycidyl ether of bisphenol A (DGEBA) and also that the curing system is composed of cyan and sulfur hardeners, codified in industry, as Components of #2511 Resin System. The cure cycle and its interruptions were simulated by dynamic-mechanical analysis (DMA). The samples obtained were evaluated by FT-IR and differential scanning calorimetry (DSC), whose results show that the degree of cure varying between 0.8 to 0.85 was achieved at 120 °C.
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