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Polímeros, Volume: 29, Número: 4, Publicado: 2019
  • Effects of polyether siloxane surfactant on the hydrophilic capacity of polypropylene films Original Article

    Antunes, Lucas Fiamenghi; Simon, Douglas Alexandre; Fiorio, Rudinei; Francisquetti, Edson

    Resumo em Inglês:

    Abstract To evaluate the hydrophilic capacity, polypropylene and surfactant (polyether siloxane) samples were extruded in the proportions of 0.0, 0.5, 1.0 and 3.0 (wt%) and films were obtained in a heated press. The samples were submitted to measurements of contact angle, surface tension, melt flow index and surface roughness. The results indicated that increasing surfactant content promoted better wettability and consequently higher hydrophilicity. Using water, the increase in the surfactant content reduced the contact angle (92.58° to 68.10°) and increased the surface tension (26.7 to 56.9 mN.m-1). However, with ethylene glycol, increasing the surfactant content promoted a small variation on the contact angle (59.14° to 65.10°) and on the surface tension (5.5 to 5.0 mN.m-1). The surfactant promoted a slight change in the melt flow index but not affected the roughness of the samples.
  • Investigation of TPP-Chitosomes particles structure and stability as encapsulating agent of cholecalciferol Original Article

    Iida, Aline Sayuri Lima; Luz, Karina Novais; Barros-Alexandrino, Taís Téo; Fávaro-Trindade, Carmen Sílvia; Pinho, Samantha Cristina de; Assis, Odílio Benedito Garrido; Martelli-Tosi, Milena

    Resumo em Inglês:

    Abstract Tripolyphosphate (TPP)-chitosomes were produced aiming at the encapsulation and conservation of vitamin D3. This hybrid system is made of liposomes, vesicles consisting of phospholipid bilayers, surrounded by chitosan wall ionic-crosslinked with TPP. Chitosan concentrations (2 and 4 mg mL-1) were tested and the vitamin stability in aqueous dispersions monitored for 49 days. The results confim that D3 remained stable throughout the analyzed period (49 days), whereas the non-encapsulated vitamin totally degrades after the second week of storage. The particle diameters ranged from 0.1 to 5 μm with good colloidal stability (+22 to +48 mV), and encapsulation efficiency of 97%. Thermal stability was also improved when using the TPP-chitosomes. The protection performed was attributed to the stable interactions conferred by the phospholipids crosslinking with the chitosan amino groups and a formation of a net of hydrogen bonds established amongst the hydroxyl groups of the interacting compounds as revealed by infrared spectroscopy.
  • Application of metric entropy to determine properties of structural materials Original Article

    Garbacz, Grzegorz; Kyzioł, Lesław

    Resumo em Inglês:

    Abstract Composite materials have nowadays become a group of construction materials whose application in mechanical structure designing has been constantly increasing. There is therefore a real demand for an objective opinion on the mechanical properties of composites. According to the authors, determining those properties based on the recommended methods included in current standards requires objectivization. The difficulty is that those methods are usually based on the geometrical shape of stress curves in the strain function. The study proposes an new method of testing the mechanical properties of composites through analyzing the internal dynamics of measurement data based on uniaxial stretching tests. A tool in such an analysis is determining the Kolmogorov-Sinai metric entropy values of measurement data. Nine samples of composite materials having various compositions have been tested. In selecting these materials, the focus has been on the possibility of introducing composite recyclates as their structural components.
  • Stabilization of gelatin and carboxymethylcellulose water-in-water emulsion by addition of whey protein Original Article

    Laranjo, Mayara Rocha; Costa, Bernardo de Sá; Garcia-Rojas, Edwin Elard

    Resumo em Inglês:

    Abstract Due to their aqueous nature and biocompatibility, water/water emulsions are particularly advantageous in the production of low calorie functional food and bioactive carrier microparticles. The aim of this study was to investigate the stability of water/water emulsions formed by gelatin and carboxymethycelullose through the Pickering effect, by addition of whey protein particles. The effect of phase composition and pH on emulsion stability over 3 days of storage was studied and the emulsion properties were characterized. Finally, the effect of the addition of different concentrations of whey protein particles on the emulsion stability was investigated. The added protein particles contributed to reduce the rate of phase separation and higher protein concentration showed this effect more clearly. The time of complete phase separation increased 12 h after addition of 15% (w/w) protein. Emulsions at pH 5.5 with protein particles, however, showed lower stability than those at pH 7.5 without particles.
  • Kraft lignin and polyethylene terephthalate blends: effect on thermal and mechanical properties Original Article

    Lazzari, Lívia; Domingos, Eloilson; Silva, Letícia; Kuznetsov, Alexei; Romão, Wanderson; Araujo, Joyce

    Resumo em Inglês:

    Abstract In this work, bottle-grade poly(ethylene terephthalate) (PETR), kraft lignin (KL), and chemically modified lignin (ML) were used to form blends to improve the mechanical and thermal properties of pure PET. The PET/KL and PETR/ML blends were produced with 0.5, 1, 3, and 5 wt.% of lignin via melt extrusion and injection molding. The produced blends and PETR were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TGA), differential scanning calorimetry (DSC) and mechanical properties testing. The FTIR measurements confirmed the chemical modifications of the ML samples, while the TGA results showed KL to be thermally more stable than ML. The glass transition temperature of PETR changed as a function of the amount of lignin, as revealed by the DSC measurements. The PET/KL blends demonstrated their potential for use as an engineering material due to their improved thermal and mechanical properties compared to those of PETR.
  • Design of chitosan-alginate core-shell nanoparticules loaded with anacardic acid and cardol for drug delivery Original Article

    Paiva Filho, João Campos; Morais, Selene Maia de; Nogueira Sobrinho, Antonio Carlos; Cavalcante, Gessica Soares; Silva, Nilvan Alves da; Abreu, Flávia Oliveira Monteiro da Silva

    Resumo em Inglês:

    Abstract Anacardic Acid (AA) and Cardol (CD) are the main constituents of the cashew nut shell liquid, which presented several biological activities. In this study, a 23 factorial experimental design was employed in order to evaluate the influence of the reaction conditions in the nanoencapsulation of AA and CD using Chitosan (CH), Alginate (ALG) and Arabic Gum matrices. The nanoparticles (NPs) with higher stability and encapsulation efficiency were those with ALG as an outer coating and with lower content of surfactant. The NPs presented nanometric size with 90% of the distribution ranging from 70 to 250 nm. The in vitro kinetics revealed that CH-ALG/AA and CH-ALG/CD NPs followed zero-order kinetics model, showing a significantly slow release rate, with values of 33% and 63%, respectively, after 240h. Particularly, CH-ALG/CD NPs presented higher inhibitory capacity for all strains of dermatophytes due to their release rate, with promising results for antimicrobial control.
  • Synthesis of immobilized biocatalysts for wastewater decontamination Original Article

    Silva, Thâmara Machado e; Borges, Leonardo Luiz; Souza, Eli Regina Barboza e; Caramori, Samantha Salomão

    Resumo em Inglês:

    Abstract The use of biodegradable polymers arouses biotechnological interest. This use allows applications in health and environment. Here is present the characterization and a proposition for the use of cashew (Anacardium othonianum Rizz.) polysaccharide including peroxidase immobilization for wastewater bioremediation. From the cashew gum exudate, the polysaccharide was extracted by precipitation in ethanol at 4 °C. This material is able to immobilize Horseradish peroxidase by physical adsorption and via sodium periodate with 75% and 93% of efficiency, respectively. These systems have a storage and operational stability, and removed phenolic compounds above 50% in industrial effluent samples. The bioassays in the presence of Artemia salina and Allium cepa root not only revealed no toxicity to this polysaccharide, but also presented the ability to reduce the toxicity of the industrial effluent by 50%. Immobilized cashew polysaccharide complexes are potential alternatives for waste treatment and decontaminant agents for water treatment applications. The polysaccharide is a low-cost natural matrix for environmental-technological applications.
  • Evaluation of antimicrobial action of silver composite microspheres based on styrene-divinylbenzene copolymer Original Article

    Mandu, Maria Aparecida Larrubia Granado Moreira Rodrigues; Costa, Luciana da Cunha; Tiosso, Rodrigo Bernardes; Grasso, Rômulo Pires; Calderari, Mônica Regina da Costa Marques

    Resumo em Inglês:

    Abstract This article reports the evaluation of the antimicrobial activity of a silver composite based on sulfonic resin. The antimicrobial action of the composite was evaluated against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus through plate, batch and colunm experiments. In batch studies, the efficiency of the composite was evaluated as a function of composite mass, bacterial concentration and contact time. We also developed a method to evaluate the antimicrobial activity of this composite using column tests. The antimicrobial activity of the composite was similar against the three bacteria in halo inhibition and batch experiments. The antibacterial activity was 100% against all bacteria above 0.20 g of composite and for all concentrations of bacteria studied. Column studies showed that the composite (1 g) had 100% action against 48 cm3 of S. aureus and 55 cm3 of E. coli and P. aeruginosa suspensions (105 cells mL-1, 50 cm3 min-1).
  • Design of a polymeric composite material femoral stem for hip joint implant Original Article

    Costa, Romeu Rony Cavalcante da; Almeida, Fellipe Roberto Biagi de; Silva, Amanda Albertin Xavier da; Domiciano, Sandra Mara; Vieira, André Ferreira Costa

    Resumo em Inglês:

    Abstract Hip joint prosthesis are structural components that still have some challenging problems such as the interaction of physical and biological properties between the stem and the human femur. Composite materials allow to obtain high strength structures with a large variety of modulus of elasticity and favorable characteristics in the context of orthopedic implants. Therefore, the objective of this work was the development of a prosthesis model with biopolymeric matrix, namely the polyurethane (PU) derived from castor oil, reinforced with fiberglass. The implants were made of pure PU, PU with fiberglass, and PU with glass fiber and calcium carbonate. The reinforcement was constructed in the form of a core to be inserted into the hip prosthesis. The core and stem prototypes were produced using three-dimensional printing techniques, and subsequently used in the manufacture of flexible silicone molds. The results showed good mechanical potentialities of this material for orthopedics applications.
  • Positron annihilation spectroscopy of chain-end-functionalized polystyrenes with definite numbers of benzyl alcohol and perfluorooctyl groups Original Article

    Mahmoud, Kamal Reyad; El-Shehawy, Ashraf; Atta, Hoda

    Resumo em Inglês:

    Abstract A series of well-defined chain-end-functionalized polystyrenes with a definite number of benzyl alcohol and perfluorooctyl groups [PS(BnOH)n & PS(BnORf)n, respectively] linearly aligned in a double line at the chain-ends were prepared and investigated using XRD, SEM, PALS and DBAR spectroscopy. XRD studies showed that PS(BnOH)n are crystalline and the degree of crystallinity increases with increasing the number of benzyl alcohol functionalities, while XRD pattern of PS(BnORf)n revealed that incorporating perfluorooctyl groups resulting in some fractions of polystyrene chains that were intercalated or broken between the interlayer spacing. PALS measurements yielded three lifetime components and the formation probabilities as well as lifetime of ortho-positronium in polymer series were found to be dependent on the chain-end polymer structure. DBAR measurements suggested that only one type of defect is present in the polymer samples.
  • Mechanical characterization of HDPE reinforced with cellulose from rice husk biomass Original Article

    Bosenbecker, Mariane Weirich; Cholant, Gabriel Monteiro; Silva, Gabriela Escobar Hochmuller da; Paniz, Oscar Giordani; Carreño, Neftali Lenin Villarreal; Marini, Juliano; Oliveira, Amanda Dantas de

    Resumo em Inglês:

    Abstract High-density polyethylene (HDPE) reinforced with cellulose from rice husk (RH) were prepared and studied. The RH biomass was submitted to acid extraction and bleaching process and then analyzed for its cellulose extraction efficiency by X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR). After that, the RH cellulose (RHC) was incorpored to the HDPE matrix by melt blending with different filler contents (5, 10 and 15 wt%), and then characterized in terms of mechanical properties and morphology. The RHC incorporation in the HDPE matrix resulted in an increase in elastic modulus regardless the filler content added; also, the impact resistance was maintained for RHC contents up to 10%. The morphological analysis of the composites showed that the cellulose was well dispersed in the matrix, which contributed to the improvement of the final rigidity of these materials, indicating the feasibility of incorporating this residue in the production of HDPE composites.
  • Acoustic approach of weldability for nanocomposite (nanosilica/PA6) welded by ultrasonic welding Original Article

    Ribeiro, Anderson; Casanova, Jaime; Brandi, Sérgio Duarte; Pinheiro, Diego de Moura

    Resumo em Inglês:

    Abstract Polymer matrix nanocomposites (NMP) have attracted a great interest mainly in the automotive, aerospace and medical industries since they have good mechanical properties, dimensional, thermal and chemical stability, as well as interesting electrical conductivity and cost reduction in the manufacturing process. However, welding of this class of materials presents serious challenges such as improving weldability of the joint and understanding the mechanisms responsible for coalescence. The objective of this work was to evaluate the coalescence of an NMP joint (comprising a PA6 matrix and with nanosilica of different percentages of silicon) using ultrasonic welding, as well as to perform an acoustic approach of the energy dissipation during the welding process. It is concluded that the NMP samples tend to show better coalescence as the percentage of nanosilica increases, up to a certain limit. On the other hand, the higher the content of nanoparticle the smaller the energy absorption.
  • Synthesis and performance of AM/SSS/THDAB as clay hydration dispersion inhibitor Original Article

    Du, Wei-Chao; Wang, Xiang-Yun; Liu, Man; Bi, Tai-Fei; Song, Shun-Xi; Zhang, Jie; Chen, Gang

    Resumo em Inglês:

    Abstract In this paper, a novel zwitterionic copolymer AM/SSS/THDAB clay hydration dispersion inhibitor was synthesized by copolymerization of tris hydroxyethyl diallyl ammonium bromide (THDAB), sodium p-styrene sulfonate (SSS) and acrylamide (AM) initiated in an aqueous solution. The copolymer was characterized by FT-IR, GPC, TGA-DSC and SEM. Results demonstrated that molecular weight of AM/SSS/THDAB was 43674 g/mol and its temperature resistance ability was up to 225 °C. Evaluation experiments showed that AM/SSS/THDAB has an excellent clay hydration inhibitive performance. Methods including particle size analysis and SEM were utilized to study its dispersion inhibition mechanism by using sodium montmorillonite (Na-MMT). Results indicated that the micro-structure of Na-MMT has been successfully changed by AM/SSS/THDAB. In a word, the superior inhibition property makes the novel clay hydration dispersion inhibitor promised in water-based drilling fluids.
  • Evaluation of commercial arrowroot starch/CMC film for buccal drug delivery of glipizide Original Article

    Gayathri, Dhanasekaran; Jayakumari, Lakshmanan Saraswathy

    Resumo em Inglês:

    Abstract In the present work, commercial arrowroot starch (AR starch) has been successfully used as a base material with sodium salt of carboxy methyl cellulose (CMC) for buccal drug delivery system. Different ratio of CMC and AR starch has been prepared with constant ratio of drug. In our study, glipizide has been used as the drug for controlled drug delivery through buccal mucosa. Films were cast by solution casting method with glycerol as plasticizer. All the films were characterized for thickness, swelling index, moisture content, relative pH, drug content uniformity, compatibility of polymer and drug, surface morphology of films, muco adhesive property and in-vitro drug release study. Formulation F3 shows a residence time of 140 minutes with good mucoadhesive property, compatibility within polymers, drug content uniformity of 100 ± 6.0% and a controlled drug release among all the ratios.
  • Effect of nanoclay addition and chemical treatment on static and dynamic mechanical analysis of jute fibre composites Original Article

    Arulmurugan, Seetharaman; Venkateshwaran, Narayanan

    Resumo em Inglês:

    Abstract In this article, the influence of alkali treatment and addition of montmorillonite nanoclay as filler on mechanical and visco-elastic behaviour of jute fibre polymer composite were investigated. The composites are fabricated using 5wt% of nanoclay, untreated and chemically treated jute fibre of various percentage by handlayup method. The static mechanical properties like tensile, flexural, impact and inter laminar shear strength are studied as per respective ASTM standard. The dynamic mechanical analysis was carried out to evaluate storage modulus and damping factor of the prepared composite. The composition and structure of the functional groups of modified fibres were examined by Fourier transform infrared spectroscopy. The results showed that the interaction of filler addition and NaOH+KMnO4 treatment of fibres have significantly improved the tensile, flexural and impact properties to 47.12, 201.13, 172.61MPa respectively. Dynamic mechanical analysis results revealed that the incorporation of filler increases the storage modulus and glass transition temperature. The incorporation of 5wt% clay and 25wt% jute fiber increase the glass transition temperature of the composite material from 109 to 115 °C.
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