RESUMO A produção de blendas de PLA/ PBAT tem por objetivo superar as desvantagens que cada polímero possui individualmente, como fragilidade, limitações de processabilidade e custo. Neste estudo, investigamos a miscibilidade e as propriedades de filmes biodegradáveis de PLA - Poli (ácido lático), PBAT- Poli (butileno adipato-co-tereftalato) e de suas blendas com proporções de 95/5, 70/30, 30/70 e 5/95 de PLA/PBAT, respectivamente, produzidos pelo método de evaporação de solvente. As blendas produzidas foram caracterizadas pelas técnicas de espectroscopia Raman, calorimetria exploratória diferencial (DSC), termogravimetria (TGA), microscopia eletrônica de varredura (MEV), viscosimetria de soluções diluídas e ensaio mecânico de tração. A análise dos espectros Raman, temperatura de transição vítrea (Tg), e TGA indicaram imiscibilidade dos polímeros em todas as composições estudadas. As análises mecânicas apontaram para diminuição da rigidez das blendas com a adição do PBAT. Os valores dos parâmetros de interação obtido pela análise de viscosimetria de soluções diluídas, sugerem miscibilidade parcial da blenda contendo 5% de PBAT. O estudo da miscibilidade e das propriedades das blendas de PLA/PBAT obtidas por evaporação de solvente possibilitarão a produção de novos materiais por diferentes técnicas visando novas aplicação para este material.

ABSTRACT The production of PLA / PBAT blends aims to overcome the disadvantages that each polymer had individually, such as fragility, processability and cost limitations. In this study, we investigated the miscibility and properties of biodegradable films of PLA - Poli (lactic acid), PBAT-Poli (butylene adipate-co-terephthalate) and their blends with proportions of 95/5, 70/30, 30/70 and 5/95 PLA / PBAT, respectively, produced by the casting method. The blends produced were characterized by the techniques of Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TGA), scanning electron microscopy (SEM), diluted solutions viscosimetry and mechanical tensile testing. The Raman spectra, glass transitions temperature (Tg), and TGA analysis indicated that the polymers are immiscible in the compositions studied. Mechanical analyzes point to a decrease in the stiffness of the blend with the addition of PBAT. The interaction parameters, obtained by viscosimetry analysis of diluted solutions, suggest partial miscibility of the blend with 5% of PBAT. The study of the miscibility and properties of the PLA / PBAT blends obtained by solvent evaporation will enable the production of new materials by different techniques aiming at new applications for this material.

In this study raw and processed silkworm (Bombyx mori) cocoons were investigated using confocal Raman spectroscopy in conjunction with differential scanning calorimetry (DSC) in order to examine the effect of temperature on the molecular conformation of silk fiber structures. Using DSC, a broad endothermic curve was observed at moderate temperatures, shedding light on the vaporization of both raw and processed cocoons, a phenomenon that could also indicate a strong interaction between silk fibroin and water molecules. Over the temperature range set for this study, Raman spectra of raw and processed cocoons were compared at different excitation radiations after drying both kinds of cocoon in an oven at 80 and 125 ºC for 60 minutes. By correlating the intensity ratios of the deconvoluted Raman bands using the broad bands characteristic of amide I and III, it was possible to evaluate the conformational changes in both materials. At excitation radiation of 532 nm, the deconvoluted Raman spectra for the amide III band indicated that, for both samples, there was a reduction in β-sheet conformation compared to α-helix conformation, and this structural disruption was driven by increased temperature. At radiation of 785 nm, the bands attributed to amino acid residues in the side chains increased in intensity, and by deconvoluting the amide I band, increased temperature was found to induce a transition from β-sheets to β-turns in both materials.

Devido às inúmeras aplicações do aço carbono na indústria, torna-se necessária a utilização de tratamento de superfície para controle e prevenção da corrosão deste metal. Um dos sistemas utilizados como pré-tratamento do aço carbono para posterior pintura é a fosfatização à base de zinco, a qual permite melhorar a ancoragem da tinta sobre o substrato metálico. No entanto, este tratamento gera para a indústria um passivo ambiental relacionado ao lodo e ao íon metálico alergênico e poluente utilizado no processo, neste caso o Ni2+. O objetivo deste trabalho é desenvolver e caracterizar um tratamento alternativo ao fosfato de zinco para o aço carbono 1008, utilizando-se um fosfato orgânico. O método utilizado foi o de imersão do substrato metálico em uma solução aquosa de uma molécula orgânica à temperatura ambiente. Os corpos de prova do aço carbono foram avaliados utilizando-se microscopia óptica e eletrônica de varredura, espectroscopia Raman, ensaios eletroquímicos de polarização potenciodinâmica anódica e espectroscopia de impedância eletroquímica em meios ácido e neutro, além dos ensaios em Salt Spray. Os resultados eletroquímicos e de corrosão acelerada mostraram que o filme de fosfato orgânico minimiza a corrosão no aço carbono, podendo ser utilizado em substituição ao tradicional fosfato de zinco.

Due to the numerous applications of carbon steel in industry, the use of surface treatment to control and prevent the corrosion of this metal becomes necessary. One of the systems used as pre-treatment of carbon steel for subsequent painting is zinc phosphating, which allows to improve adhesion of ink onto the metal substrate. However, this treatment causes an environmental liability to industry, related to the silt and allergenic, pollutant metal ion used in the process, in this case Ni2+. The objective of this work is to develop and characterize a treatment alternative to zinc phosphate for the 1008 carbon steel, using an organic phosphate. The method used was that of immersing the metal substrate in an aqueous of an organic molecule at room temperature. Specimens of carbon steel were evaluated using optical microscopy and scanning electron microscopy, Raman spectroscopy, electrochemical tests of anodic polarization and electrochemical impedance spectroscopy in acidic and neutral medium, besides the Salt Spray tests. The electrochemical and fast corrosion results showed that the accelerated organic phosphate film minimizes the corrosion of the carbon steel, and it can be used instead of the traditional zinc phosphate.

We studied the adsorption of glyphosate (GPS) onto soil mineral particles, using FT-IR and Mössbauer spectroscopy. From IR measurements for samples collected under native vegetation of a forest reserve, bands at 1632 and 1407 cm-1 could be attributed to the interaction between the carboxylic group of GPS and structural Al3+ and Fe3+ on the surface of mineral particles; bands at 1075 and 1000 cm-1 were observed only for cultivated soil. Mössbauer spectra for these soils were definitely fitted using a broad central doublet in addition to the magnetic component. This multiple quadrupolar component may be attributed to all non-magnetic Fe3+ contributions, including that of the GPS/Fe3+ complex.

The main goal of this paper was to study the degradation of synthetic dyes using photoelectrocatalytic properties of particulate films of TiO2 supported on plates of titanium and stimulated by UV-Vis radiation. The dyes decolorizations were measured using spectrophotometric methods to verify which the conditions on Ti/TiO2 electrode was the best for the photoelectrodegradation of them. The results showed that decolorization rates were higher than 90% during a period of 270 min. FT-IR spectroscopy showed that intermediate substances were formed after the decolorization and N=N group/aromatic structures were preserved independently of the specific structure of the dyes.

No presente trabalho foi mostrado que a adsorção de glifosato (GPS) depende da área superficial (argilas) e da quantidade de argilas e da CTC (solos). A matéria orgânica (MO) tem um papel secundário na adsorção do GPS sobre solos. A adsorção de GPS sobre os solos de Londrina e Florai e argilas (montimorilonita, caulinita) diminui com o aumento do pH e manteve-se constante para a bentonita e o solo de Tibagi. Para os solos estudados, a adsorção competitiva entre GPS e fosfato mostrou que o deslocamento do GPS pelo fosfato depende da quantidade de argilas, CTC e pH. O GPS não foi facilmente desorvido das argilas pelo fosfato. Os espectros IV-FT dos solos e argilas mostraram que o solo de Londrina e a caulinita são muito semelhantes. Portanto, isto poderia explicar os resultados de adsorção do GPS e da adsorção competitiva entre o GPS e o fosfato apresentarem resultados semelhantes.

This work showed that the adsorption of glyphosate (GPS) depends on surface area for clays and amount of clays and CEC for soils. Organic matter (OM) had a secondary role in the adsorption of GPS on soils. The adsorption of GPS on soils from Londrina and Floraí counties and clays (montmorillonite, kaolinite) decreased when pH increased, however, for bentonite clay and soil from Tibagi county was kept constant. For the soils, the competitive adsorption between GPS and phosphate showed that displace of GPS by phosphate was related to the amount of clays, CEC and pH. GPS was not easily displaced by phosphate on the clays. The FT-IR spectra of the soils and clays showed that soil from Londrina resembled kaolinite. Thus, this could explain the results of adsorption of GPS and the competitive adsorption between GPS and phosphate.

Glyphosate, an enzyme inhibitor herbicide, has been widely used around the world in agriculture. Dr. John Franz from Monsanto Corporation (USA) discovered glyphosate in 1970. It has been showed that glyphosate is strongly adsorbed by inorganic soil components especially aluminium and iron oxides, and the phosphate group is involved in this interaction. The inactivation of glyphosate in soils can last for days or even months depending on soil characteristics. The addition of phosphate from fertilizers can displace glyphosate from the soils and this could be the cause of decreased productivity of some crops.

The structural characterization of molecules used in the sterilization of blood for transfusions, such as crystal violet (CV), is relevant for understanding the action of these prophylactic drugs. The characterization is feasible by surface enhanced resonance Raman spectroscopy (SERRS) of CV in solution or on surfaces. The limit of detection of CV by SERRS, in the presence of colloidal particles, using 514.5 nm as excitation radiation, was found to be around 1 ppb. The characterization of CV was also made by SERS, by using different active-particles-containing substrates, proving the versatility of this technique for the study of such structures. The results suggest that the controlled production of highly efficient SERS-active substrates may allow qualitative and quantitative analysis, with high sensitivity, with potential applications in medical and environmental fields.

Guanidina é uma substância importante para os seres vivos atuais assim como para a química prebiótica. No presente trabalho foi estudada a reação entre as espécies amônio e tiocianato em estado sólido com diferentes substâncias (areia de rio, caulin, metais de transição e sais da água do mar) e temperaturas (80, 120 e 150 ºC). As recuperações de tiocianato ou amônio nas amostras com areia de rio ou caulin a 150 ºC foram estatisticamente diferentes (p<0,05) das recuperações de tiocianato e amônio nas amostras sem aquelas substâncias. A decomposição do tiocianato de amônio nas amostras com areia de rio ou caulin a 150 ºC foi de 40%. Caulin mostrou ser mais efetivo na síntese de guanidina do que areia de rio, visto que a concentração de guanidina sempre foi maior nas amostras com caulin do que nas amostras com areia de rio. A decomposição do tiocianato de amônio nas amostras com metais de transição mais areia de rio a 120 ºC foi de 30%. Sais da água do mar ou metais de transição mais tiocianato de amônio mais areia de rio (120 ºC) aumentaram a concentração de tiouréia (água do mar: 538%, metais de transição: 357%) ou guanidina (água do mar: 393%, metais de transição: 806%) quando os resultados foram comparados com amostras sem estas substâncias. Comparando os resultados obtidos com as amostras de tiocianato de amônio (120 ºC) mais sais da água do mar ou metais de transição com a amostra de tiocianato de amônio observamos que houve um aumento na produção de tiouréia (168%) e guanidina (268%) respectivamente. Os rendimentos obtidos para a síntese de guanidina mostrados neste trabalho são melhores do que os mostrados por outros autores. Experimentos mostraram que Fe (III) está envolvido na formação do composto amarelo obtido da reação entre amônio e tiocianato e espectros Raman mostraram que este composto pode ser o enxofre.

Guanidine is an important substance for modern living beings as well as for the prebiotic chemistry. We studied the reaction between ammonium and thiocyanate species in solid state with different substances (river sand, kaolin, transition metals, salts of seawater) and temperatures (80, 120 and 150 ºC). The recoveries of thiocyanate and ammonium in the samples with river sand or kaolin at 150 ºC were statistically different (p<0.05) from the recoveries of thiocyanate and ammonium in the sample without them. The decomposition of ammonium thiocyanate in the samples river sand or kaolin at 150 ºC was about 40%. Kaolin showed to have more effect on the synthesis guanidine than river sand, because, the concentrations of guanidine in the samples with kaolin were always bigger than in the samples with river sand. The decomposition of ammonium thiocyanate in the samples with transition metals plus river sand at 120 ºC was about 30%. The salts of seawater or transition metals plus ammonium thiocyanate plus river sand (120 ºC) showed to increase the concentration of thiourea (seawater: 538%; transition metals: 357%) or guanidine (seawater: 393%, transition metals: 806%) when they were compared to the samples without them. When the results obtained with sample of ammonium thiocyanate were compared to the samples of ammonium thiocyanate (at 120 ºC) plus salts of seawater or transition metals also an increased on the production of thiourea (168%) and guanidine (268%) was obtained, respectively. The yield for the synthesis of guanidine showed in this paper is better than that obtained by other authors. Experiments showed that iron (III) is involving in the formation of the yellow compound and Raman spectra showed this compound could be sulphur.

The atrazine photoelectrochemical degradation has been examined in solutions containing TiO2 on immobilized films under a variety of experimental conditions. It was possible to observe that the supporting electrolyte nature affects the intensity of the photocurrent, being an indicative of the adsorption process. The disappearance of the organic molecule follows approximately a pseudo-first order kinetic. As mineralization product, NH4+ and NO3- ion have been identified. These results indicated that the formation of NH4+ ion can be associated to the effect of atrazine adsorption, due to need of potential adaptation together with a variation in the supporting electrolyte concentration.