Estudo morfológico da blenda polimérica poli(metacrilato de metila)/poli(tereftalato de etileno) reciclado (PMMA/PET)

Among the options for plastics modification more convenient, both from a technical-scientific and economic, is the development of polymer blends by processing in the molten state. This work was divide into two stages, with the aim to study the phase morphology of binary blend PMMA / PET blend and this compatibilized by the addition of the poly(methyl methacrylate-co-glycidyl methacrylate-co-ethyl acrylate) copolymer (MMA-GMA-EA). In the first stage is analyzed the morphology of the blend at a preliminary stage where we used the bottle-grade PET in a Haake torque rheometer and the effect of compatibilizer in this blend was evaluated. In the second stage the blend was processed using the recycled PET in a single screw extruder and subsequently injection molding in the shape of specimens for mechanical tests. In both stages we used a transmission electron microscopy (TEM) to observe the morphologies of the samples and an image analyzer to characterize them. In the second stage, as well as analysis by TEM, tensile test, scanning electron microscopy (SEM) and atomic force microscopy (AFM) was performed to correlate the morphology with the mechanical properties. The samples used in morphological analyzes were sliced by cryo-ultramicrotomy technique for the analysis by TEM and the analysis by SEM and AFM, we used the flat face of the block after cut cryogenic. It was found that the size of the dispersed phase decreased with the addition of MMA-GMA-EA in blends prepared in a Haake. In the tensile test, the values of maximum tensile strength and modulus of elasticity is maintained in a range between the value of pure PMMA the pure PET, while the elongation at break was influenced by the composition by weight of the PMMA mixture. The coupling agent corroborated the results presented in the blend PMMA / PETrec / MMA-GMA-EA (80/15/5 %w/w), obtained by TEM, AFM and SEM. It was concluded that the techniques used had a good morphologic correlation, and can be confirmed for final analysis of the morphological characteristics of the blends PMMA / PET

Efeito da adição do poli(etileno acrilato de metila) (ema) e da fibra de linter de algodão nas propriedades do poli(tereftalato de etileno) reciclado (petrec)

The development of new materials to fill the demand of technological advances is a challenge for many researchers around the world. Strategies such as making blends and composites are promising alternatives to produce materials with different properties from those found in conventional polymers. The objective of this study is to evaluate the effect of adding the copolymer poly(ethylene methyl acrylate) (EMA) and cotton linter fibers (LB) on the properties of recycled poly(ethylene terephthalate) (PETrec) by the development of PETrec/EMA blend and PETrec/EMA/LB blend composite. In order to improve the properties of these materials were added as compatibilizers: Ethylene - methyl acrylate - glycidyl methacrylate terpolymer (EMA-GMA) and maleic anhydride grafted polyethylene (PE-g-MA). The samples were produced using a single screw extruder and then injection molded. The obtained materials were characterized by thermogravimetry (TG), melt flow index (MFI) mensurements, torque rheometry, pycnometry to determinate the density, tensile testing and scanning electron microscopy (SEM). The rheological results showed that the addition of the EMA copolymer increased the viscosity of the blend and LB reduces the viscosity of the blend composite. SEM analysis of the binary blend showed poor interfacial adhesion between the PETrec matrix and the EMA dispersed phase, as well as the blend composite of PETrec/EMA/LB also observed low adhesion with the LB fiber. The tensile tests showed that the increase of EMA percentage decreased the tensile strength and the Young s modulus, also lower EMA percentage samples had increased the elongation at break. The blend composite showed an increase in the tensile strength and in the Young`s modulus, and a decrease in the elongation at break. The blend formulations with lower EMA percentages showed better mechanical properties that agree with the particle size analysis which showed that these formulations presented a smaller diameter of the dispersed phase. The blend composite mechanical tests showed that this material is stronger and stiffer than the blend PETrec/EMA, whose properties have been reduced due to the presence of EMA rubbery phase. The use of EMA-GMA was effective in reducing the particle size of the EMA dispersed phase in the PETrec/EMA blend and PE-g-MA showed evidences of reaction with LB and physical mixture with the EMA

Aplicação de nanopartículas de quitosana com potencial de adjuvante na produção de soro contra o venneno do escorpião Tityus serrulatus

In Brazil, several species of scorpions are known to cause accidents which can lead to death, which are mainly belonging to the genus Tityus. The scorpion Tityus serrulatus is the main responsible for more severe cases. Anti-scorpion serums are routinely produced by various institutions, despite their effectiveness, quality and action depends on how quickly treatment is started. Studies have been developed in the search for appropriate technologies to encapsulate and release recombinant or natives proteins capable of inducing antibody production. In this context, chitosan copolymer which can be obtained from the partial deacetylation of chitin or in some microorganisms and it is biocompatible and biodegradable has been widely used for this purpose. This study aimed to search for a system release from chitosan nanoparticles for peptide / protein of the venom of the scorpion T. serrulatus, able to provide a new model of immunization in animals, in order to obtain a potential novel polyclonal serum, anti-venom T. serrulatus. The chitosan nanoparticles were prepared by ionic gelation with polyanion tripolyphosphate (TPP). After standardizing the concentrations of TPP and chitosan was evaluated the efficiency of incorporation of bovine serum albumin (BSA) and scorpion venom, showed particle size compatible with the intended purpose. The particles showed adequate size around 200nm. The crosslinking was confirmed by absorption spectroscopy in the infrared. After verified the high encapsulation efficiency (EE) for acid bicinconínico method (BCA) protein assay and the particle size distribution, the success of the technique was proven and the potential for in vivo application of nanoparticles. The experimental animals were vaccinated and the antibodies measured by ELISA

Micropartículas de poli (ácido láctico)/ poloxámero obtids por spray drying para liberação modificada de metotrexatro

New drug delivery systems have been used to increase chemotherapy efficacy due the possible drug resistance of cancer cells. Poly (lactic acid) (PLA) microparticles are able to reduce toxicity and prolong methotrexate (MTX) release. In addition, the use of PLA/poloxamer polymer blends can improve drug release due to changes in the interaction of particles with biological surfaces. The aim of this study was developing spray dried biodegradable MTX-loaded microparticles and evaluate PLA interactions with different kinds of Pluronic® (PLUF127 and PLUF68) in order to modulate drug release. The variables included different drug:polymer (1:10, 1:4.5, 1:3) and polymer:copolymer ratios (25:75, 50:50, 75:25). The precision and accuracy of spray drying method was confirmed assessing drug loading into particles (75.0- 101.3%). The MTX/PLA microparticles showed spherical shape with an apparently smooth surface, which was dependent on the PLU ratio used into blends particles. XRD and thermal analysis demonstrated that the drug was homogeneously dispersed into polymer matrix, whereas the miscibility among components was dependent on the used polymer:copolymer ratio. No new drug- polymer bond was identified by FTIR analysis. The in vitro performance of MTX-loaded PLA microparticles demonstrated an extended-release profile fitted using Korsmeyer- Peppas kinetic model. The PLU accelerated drug release rate possible due PLU leached in the matrix. Nevertheless, drug release studies carried out in cell culture demonstrated the ability of PLU modulating drug release from blend microparticles. This effect was confirmed by cytotoxicity observed according to the amount of drug released as a function of time. Thus, studied PLU was able to improve the performance of spray dried MTX-loaded PLA microparticles, which can be successfully used as carries for modulated drug delivery with potential in vivo application

Caracterização de poliacrilamida parcialmente hidrolisada em regime concentrado

A partially hydrolyzed polyacrylamide (HPAM) is a copolymer composed of acrylamide and sodium acrylate. Due to its wide range of applications there are different methods for its quantification and characterization in solution systems. Evaluation of C* is important to describe the transition from dilute to semi-dilute, behavior, when the solution will have its characteristic viscosity at concentrations above C*. This dissertation describes the determination of the critical concentration of overlap C* by potentiometry of partially hydrolyzed polyacrylamide - HPAM under acidic conditions. Based on the law of mass action and the proper treatment of the constant of aggregate formation, polymer molecular weight, degree of polymerization and hydrolysis were calculated. The inflection point was determined by the intersection of the resulting equation and mathematical development, statistically satisfy the experimental points relating the number of moles of monomers (n), equilibrium constant of formation of the entanglements (K*), pH, C* and acidity constant of the polymer (Ka). The viscometric parameters of C* showed a percentage difference compared to potentiometers. The results for the determination of C*, and degree of copolymerization molar mass proved to be a simple alternative for the characterization of polymers with protonated monomers and water soluble

Hidróxidos duplos lamelares de magnésio e alumínio modificados com carbonato e p123 para adsorção de dióxido de carbono

Muitos mecanismos provocados pela ação humana vêm gerando um aumento na queima de combustíveis fósseis e processos químicos (produtos orgânicos, carvão, madeira, óleo diesel, gasolina e outros derivados de petróleo) e, consequentemente, há um aumento na emissão de CO2 na atmosfera. Uma das alternativas para a captura desse poluente é o processo de adsorção, o qual pode ajudar na redução do CO2. As hidrotalcitas ou hidróxidos duplos lamelares (HDL s) estão dentre esses materiais estudados, já que apresentam alta estabilidade e uma boa porosidade, tornando-se assim um promissor adsorvente de gases poluentes. Os HDL s formam um grupo de argilas do tipo aniônico que consiste em camadas positivamente carregadas de óxido de metal (ou hidróxido de metal) com intercamadas de ânions. Foi constatado que ânions que possuem duas cargas negativas, estabilizam muito mais que ânions monovalentes, sendo o carbonato o mais estável dos ânions divalentes. Neste trabalho, foi proposta uma modificação na síntese direta através da co-precipitação a pH constante utilizando sais de cátions divalentes (Mg2+) e trivalentes (Al3+) reportados na literatura. Durante a síntese dos HDL s retirou-se o carbonato, bem como, utilizou-se um copolímero como um template para o alargamento das lamelas. As amostras foram caracterizadas utilizando as técnicas de DRX, TG/DTG, FTIR, MEV/EDX, MET e adsorção e dessorção de N2. Os dados obtidos indicam que a estrutura, mesmo após a modificação, apresentou resultados condizentes com os encontrados na literatura. Dentre as várias aplicações dos HDL s foi realizado o estudo da adsorção do CO2. A capacidade de adsorção do material foi testada de acordo com o tempo de contato entre o adsorvente e o adsorbato, sendo esperado que os materiais tratados com template apresentassem um maior desempenho

Síntese, caracterizaçao e propriedades catalicas da peneira molecular nanoestruturada modificada com lantanio

The nanostructured molecular sieve SBA-15 was synthesized by the hydrothermal method, and modified with lanthanum with Si/La molar ratios of 25, 50, 75 and 100. The materials were evaluated as catalysts for the cracking of n-hexane model reaction. Type SBA- 15 and LaSBA-15 mesoporous materials were synthesized using tetraetilortosilicato as a source of silica, hydrochloric acid, heptahydrate lanthanum chloride and distilled water. Pluronic P123 triblock. polymer was used as structure template. The syntheses were carried out by 72 hours. The obtained SBA-15 samples were previously analyzed by thermogravimetry, in order to check the conditions of calcination for removal of organic template. Then, the calcined materials were characterized by X-ray diffraction, infrared spectroscopy, adsorption and desorption of nitrogen, scanning electron microscopy and X-ray microanalysis by dispersive energy. The acidity of the samples was determined using adsorption of n-bulinamina and desorption followed by thermogravimetry. It was found that the hydrothermal synthesis method was suitable for the synthesis of the SBA-15 mesoporous materials, with an excellent degree of hexagonal ordering. The reactions of catalytic cracking of n-hexane were carried out using a fixed bed continuous flow microreactor, coupled on-line to a gas chromatograph. From the catalytic evaluation, it was observed that the mesoporous materials containing lanthanum showed different results for the reaction of cracking of nhexane compared to the unmodified mesoporous material SBA-15. As a result of cracking was obtained as main products hydrocarbons in the range of C1 to C5. The catalyst that showed better properties in relation to the acidity and catalytic activity was LaSBA-15 with the ratio Si/La = 50

Reciclagem química de Polietileno utilizando Sílica Mesoporosa tipo SBA-15 avalizada por Termogravimetriae Espectrometria de Massas

The chemical recycling of polyolefins has been the focus of increasing attention owing potential application as a fuel and as source chemicals. The use of plastic waste contributes to the solution of pollution problems.The use of catalysts can enhance the thermal degradation of synthetic polymers, which may be avaliated by Themogravimetry (TG) and mass spectrometry (MS) combined techniques. This work aims to propose alternatives to the chemistry recycling of low-density polyethylene (LDPE) on mesoporous silica type SBA-15 and AlSBA-15.The mesoporous materials type SBA-15 and AlSBA-15 were synthesized through the hydrothermal method starting from TEOS, pseudobohemite, cloridric acid HCl and water. As structure template was used Pluronic P123. The syntheses were accomplished during the period of three days. The best calcination conditions for removal of the organic template (P123) were optimized by thermal analysis (TG/DTG) and through analyses of Xray diffraction (XRD), infrared spectroscopy (FT-IR), nitrogen adsorption and scanning electron microscopy (SEM) was verified that as much the hydrothermal synthesis method as the calcination by TG were promising for the production of mesoporous materials with high degree of hexagonal ordination. The general analysis of the method of Analog Scan was performed at 10oC/min to 500 oC to avoid deterioration of capillary with very high temperatures. Thus, with the results, we observed signs mass/charge more evident and, using the MID method, was obtained curve of evolution of these signals. The addition of catalysis produced a decrease in temperature of polymer degradation proportional to the acidity of the catalyst. The results showed that the mesoporous materials contributed to the formation of compounds of lower molecular weight and higher value in the process of catalytic degradation of LDPE, representing an alternative to chemical recycling of solid waste

Avaliação das propriedades físico-químicas de sistemas a base de carboximetilcelulose e poli (N-isopropilacrilamida) em soluções aquosas para aplicação na indústria do petróleo

Sustainable development is a major challenge in the oil industry and has aroused growing interest in research to obtain materials from renewable sources. Carboxymethylcellulose (CMC) is a polysaccharide derived from cellulose and becomes attractive because it is water-soluble, renewable, biodegradable and inexpensive, as well as may be chemically modified to gain new properties. Among the derivatives of carboxymethylcellulose, systems have been developed to induce stimuli-responsive properties and extend the applicability of multiple-responsive materials. Although these new materials have been the subject of study, understanding of their physicochemical properties, such as viscosity, solubility and particle size as a function of pH and temperature, is still very limited. This study describes systems of physical blends and copolymers based on carboxymethylcellulose and poly (N-isopropylacrylamide) (PNIPAM), with different feed percentage compositions of the reaction (25CMC, 50CMC e 75CMC), in aqueous solution. The chemical structure of the polymers was investigated by infrared and CHN elementary analysis. The physical blends were analyzed by rheology and the copolymers by UV-visible spectroscopy, small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and zeta potential. CMC and copolymer were assessed as scale inhibitors of calcium carbonate (CaCO3) using dynamic tube blocking tests and chemical compatibility tests, as well as scanning electron microscopy (SEM). Thermothickening behavior was observed for the 50 % CMC_50 % PNIPAM and 25 % CMC_75 % PNIPAM physical blends in aqueous solution at concentrations of 6 and 2 g/L, respectively, depending on polymer concentration and composition. For the copolymers, the increase in temperature and amount of PNIPAM favored polymer-polymer interactions through hydrophobic groups, resulting in increased turbidity of polymer solutions. Particle size decreased with the rise in copolymer PNIPAM content as a function of pH (3-12), at 25 °C. Larger amounts of CMC result in a stronger effect of pH on particle size, indicating pH-responsive behavior. Thus, 25CMC was not affected by the change in pH, exhibiting similar behavior to PNIPAM. In addition, the presence of acidic or basic additives influenced particle size, which was smaller in the presence of the additives than in distilled water. The results of zeta potential also showed greater variation for polymers in distilled water than in the presence of acids and bases. The lower critical solution temperature (LCST) of PNIPAM determined by DLS corroborated the value obtained by UV-visible spectroscopy. SAXS data for PNIPAM and 50CMC indicated phase transition when the temperature increased from 32 to 34 °C. A reduction in or absence of electrostatic properties was observed as a function of increased PNIPAM in copolymer composition. Assessment of samples as scale inhibitors showed that CMC performed better than the copolymers. This was attributed to the higher charge density present in CMC. The SEM micrographs confirmed morphological changes in the CaCO3 crystals, demonstrating the scale inhibiting potential of these polymers

Síntese, caracterização e estudo da associação em meio aquoso de copolímeros responsivos de carboximetilcelulose-g-Jeffamine®

This thesis presents the synthesis, characterization and study of the associative behaviour in aqueous media of new responsive graft copolymers, based on carboxymethylcellulose as the water-soluble backbone and Jeffamine® M-2070 e Jeffamine® M-600 (commercial polyetheramines) as the thermoresponsive grafts with high cloud point temperatures in water. The synthesis was performed on aqueous medium, by using 1-ethyl-3- (3-(dimethylamino)-propyl)carbodiimide hydrochloride and N-hydroxysuccinimide as activators of the reaction between carboxylategroupsfrom carboxymethylcellulose and amino groups from polyetheramines. The grafting reaction was confirmed by infrared spectroscopy and the grafting percentage by 1H NMR. The molar mass of the polyetheramines was determined by 1H NMR, whereas the molar mass of CMC and graft copolymers was determined by static light scattering. The salt effect on the association behaviour of the copolymers was evaluated in different aqueous media (Milli-Q water, 0.5M NaCl, 0.5M K2CO3 and synthetic sea water), at different temperatures, through UV-vis, rheology and dynamic light scattering. None of the copolymers solutions, at 5 g/L, turned turbid in Milli-Q water when heated from 25 to 95 °C, probably because of the increase in hydrophibicity promoted by CMC backbone. However, they became turbid in the presence of salts, due to the salting out effect, where the lowest cloud point was observed in 0.5M K2CO3, which was attributed to the highest ionic strength in water, combined to the ability of CO3 2- to decrease polymer-solvents interactions. The hydrodynamic radius and apparent viscosity of the copolymers in aqueous medium changed as a function of salts dissolved in the medium, temperature and copolymer composition. Thermothickening behaviour was observed in 0.5M K2CO3 when the temperature was raised from 25 to 60°C. This performance can be attributed to intermolecular associations as a physical network, since the temperature is above the cloud point of the copolymers in this solvent.

Estudo morfológico da blenda polimérica poli(metacrilato de metila)/poli(tereftalato de etileno) reciclado (PMMA/PET)

Among the options for plastics modification more convenient, both from a technical-scientific and economic, is the development of polymer blends by processing in the molten state. This work was divide into two stages, with the aim to study the phase morphology of binary blend PMMA / PET blend and this compatibilized by the addition of the poly(methyl methacrylate-co-glycidyl methacrylate-co-ethyl acrylate) copolymer (MMA-GMA-EA). In the first stage is analyzed the morphology of the blend at a preliminary stage where we used the bottle-grade PET in a Haake torque rheometer and the effect of compatibilizer in this blend was evaluated. In the second stage the blend was processed using the recycled PET in a single screw extruder and subsequently injection molding in the shape of specimens for mechanical tests. In both stages we used a transmission electron microscopy (TEM) to observe the morphologies of the samples and an image analyzer to characterize them. In the second stage, as well as analysis by TEM, tensile test, scanning electron microscopy (SEM) and atomic force microscopy (AFM) was performed to correlate the morphology with the mechanical properties. The samples used in morphological analyzes were sliced by cryo-ultramicrotomy technique for the analysis by TEM and the analysis by SEM and AFM, we used the flat face of the block after cut cryogenic. It was found that the size of the dispersed phase decreased with the addition of MMA-GMA-EA in blends prepared in a Haake. In the tensile test, the values of maximum tensile strength and modulus of elasticity is maintained in a range between the value of pure PMMA the pure PET, while the elongation at break was influenced by the composition by weight of the PMMA mixture. The coupling agent corroborated the results presented in the blend PMMA / PETrec / MMA-GMA-EA (80/15/5 %w/w), obtained by TEM, AFM and SEM. It was concluded that the techniques used had a good morphologic correlation, and can be confirmed for final analysis of the morphological characteristics of the blends PMMA / PET

Efeito da adição do poli(etileno acrilato de metila) (ema) e da fibra de linter de algodão nas propriedades do poli(tereftalato de etileno) reciclado (petrec)

The development of new materials to fill the demand of technological advances is a challenge for many researchers around the world. Strategies such as making blends and composites are promising alternatives to produce materials with different properties from those found in conventional polymers. The objective of this study is to evaluate the effect of adding the copolymer poly(ethylene methyl acrylate) (EMA) and cotton linter fibers (LB) on the properties of recycled poly(ethylene terephthalate) (PETrec) by the development of PETrec/EMA blend and PETrec/EMA/LB blend composite. In order to improve the properties of these materials were added as compatibilizers: Ethylene - methyl acrylate - glycidyl methacrylate terpolymer (EMA-GMA) and maleic anhydride grafted polyethylene (PE-g-MA). The samples were produced using a single screw extruder and then injection molded. The obtained materials were characterized by thermogravimetry (TG), melt flow index (MFI) mensurements, torque rheometry, pycnometry to determinate the density, tensile testing and scanning electron microscopy (SEM). The rheological results showed that the addition of the EMA copolymer increased the viscosity of the blend and LB reduces the viscosity of the blend composite. SEM analysis of the binary blend showed poor interfacial adhesion between the PETrec matrix and the EMA dispersed phase, as well as the blend composite of PETrec/EMA/LB also observed low adhesion with the LB fiber. The tensile tests showed that the increase of EMA percentage decreased the tensile strength and the Young s modulus, also lower EMA percentage samples had increased the elongation at break. The blend composite showed an increase in the tensile strength and in the Young`s modulus, and a decrease in the elongation at break. The blend formulations with lower EMA percentages showed better mechanical properties that agree with the particle size analysis which showed that these formulations presented a smaller diameter of the dispersed phase. The blend composite mechanical tests showed that this material is stronger and stiffer than the blend PETrec/EMA, whose properties have been reduced due to the presence of EMA rubbery phase. The use of EMA-GMA was effective in reducing the particle size of the EMA dispersed phase in the PETrec/EMA blend and PE-g-MA showed evidences of reaction with LB and physical mixture with the EMA