Wasted polystyrene (PS) plastic cups were used in the synthesis of sodium poly(styrenesulfonate) (NaPSS). The produced polyelectrolyte was water-soluble. The viscosimetric molecular weight was 126,146 g molThe sulfonation of the polymer was estimated through FTIR spectroscopy and chemical analysis of the number of sulfonic groups. The presence of bands at 1326 and 1188 cm Ϫ1 in the infrared spectra was characteristic for sulfonic groups. The polymer was obtained with 60.3% of sulfonation. An aqueous solution of NaPSS was used as an admixture in concrete of portland cement. The results showed that the slump increasing of the concrete was up to 300% with 0.3% content of NaPSS per weight of cement. It was possible to reduce the water content of the concrete in 13.2% using NaPSS solution as an admixture. The compressive strength gain was 23.9% after 28 days of curing. The results indicated that NaPSS, produced from waste PS cups, can be satisfactorily used either as a plasticizer or as an admixture for water reduction in concrete.

Methylcellulose was produced from the fibers of Mangifera indica L. Ubá mango seeds. MCD and MCI methylcellulose samples were made by heterogeneous methylation, using dimethyl sulfate and iodomethane as alkylating agents, respectively. The materials produced were characterized for their thermal properties (DSC and TGA), crystallinity (XRD) and Degree of Substitution (DS) in the chemical route. The cellulose derivatives were employed as mortar additive in order to improve mortar workability and adhesion to the substrate. These properties were evaluated by means of the consistency index (CI) and bond tensile strength (TS) tests. The methylcellulose (MCD and MCI) samples had CI increased by 27.75 and 71.54% and TS increased by 23.33 and 29.78%, respectively, in comparison to the reference sample. Therefore, the polymers can be used to produce adhesive mortars.

The cross section variation, mechanical properties and moisture absorption of vegetable sisal fibres compressed at temperatures of 120, 160 and 200 °C were determined and compared with values obtained in non-compressed fibres. The thermo-mechanical treatment carried out resulted in a relevant increasing of fibre stiffness (elastic modulus) and decreasing of fibre moisture absorption.

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RESUMOEstudou-se neste trabalho as propriedades de concretos com adição de fibras vegetais (sisal e rami) e de polipropileno para uso em paredes estruturais. Realizou-se uma comparação do desempenho do concreto com a adição de fibras vegetais e de fibra de polipropileno, a fim de se verificar a possível substituição. Foram avaliadas a retração por secagem restringida, pelo ensaio do anel, além das propriedades mecânicas (resistência à compressão, tração por compressão diametral e módulo de elasticidade) e físicas (massa específica, índice de vazios, absorção por imersão e por capilaridade). Os teores utilizados foram de 0,25 % e 0,5 % para as fibras vegetais e para a fibra de polipropileno o teor de 0,25 %. Em relação à retração restringida foi observado que a adição de 0,25 % de fibras não resultou em incremento do desempenho comparado ao concreto sem adição de fibras. Porém a adição de 0,5 % de fibras vegetais demonstrou resultados satisfatórios, sendo superiores ao concreto de referência. Foi constatado que as propriedades mecânicas dos concretos com adição de fibras, em geral inferiores ao concreto de referência, não sofreram grandes alterações, exceto para o concreto com o maior teor de rami, que não apresentou dispersão adequada das fibras. O concreto com 0,25 % de rami apresentou a maior absorção e índice de vazios, dentre todos os concretos estudados. Em relação à absorção por capilaridade, os concretos com adição das fibras vegetais demonstraram melhor desempenho, ou seja, redução da absorção por capilaridade. Concluiu-se que é plausível a substituição da fibra de polipropileno pelas fibras vegetais, principalmente de sisal. Palavras-chave:Propriedades do concreto; fibra de polipropileno; fibra de rami; fibra de sisal; retração por secagem restringida. ABSTRACTThe properties with addition of vegetal fibers (sisal and ramie) and of polypropylene for use in structural walls was studied in this research. An evaluation of the performance of the concrete with an addition of vegetable fibers and of polypropylene fiber was carried out, to verify the possible displacement. Were evaluated, the shrinkage under restrained conditions by ring test, as well the mechanical properties (compressive strength, splitting tension and static modulus of elasticity) and physical properties (specific mass, voids, immersion and capillary absorption). The contents used were 0.25 % and 0.5 % for the vegetable fibers and for the polypropylene fiber or 0.25 % content. In relation to the shrinkage under restrained conditions, it was observed that the addition of 0.25 % of fibers did not result in an increase in performance compared to concrete without fiber addition, but the addition of 0.5 % of vegetal fibers showed satisfactory results, being superior to the reference concrete. The mechanical properties of the concrete with fiber addition, generally lower than the reference concrete, did not undergo major changes, except for concrete with the highest ramie content, which did not present adequate fibers dispersion. The concrete with ...

Flaxseed gum (FG)-based films were developed with the addition of glycerol as a plasticizer and glutaraldehyde as a crosslinking agent. HCl was added to improve crosslinking and decrease the hydrophilicity of the matrix. Different cellulose nanocrystal (CN) amounts were used as reinforcements in the optimum FG formulation. The crosslinking process at pH 3.5 led to a lower solubility of FG in water (from 100% to 53%) and an increase in thermal stability (from 160 ºC to 209 ºC). FTIR analysis confirmed a reduction in the-OH band due to crosslinking between the hydroxyl groups of FG. A diffuse diffraction pattern was observed for all FG films. The addition of 4% w/w of CN contributed to reduction of water solubility (from 53% to 20.8%) and absorption (from 21.9% to 6.8%). Finally, an improvement was observed in the tensile mechanical properties in the nanocomposites, showing satisfactory results for the proposed formulations, mainly with 8% w/w of CN added to the matrix. Overall, this study demonstrated that FG/CN nanocomposites are promising materials to be use as a sustainable biopolymer for application as bioplastics.

Neste trabalho foi investigado o uso do Poliestireno sulfonado (PSSNa), produzido a partir de copos plásticos descartáveis de Poliestireno (PS), como aditivo em argamassas e concretos de cimento Portland CPV32. A avaliação do PSSNa como aditivo foi baseada em ensaios de fluidez e resistência mecânica à compressão de corpos de prova. Foi observado, em argamassas com relação água/cimento (a/c) de 0,48, um aumento na fluidez com o aumento das porcentagens de PSSNa (0,25 a 1,00%). A adsorção do PSSNa sobre as partículas de cimento melhora a dispersão dos componentes da argamassa, aumentando a resistência mecânica à compressão dos corpos de prova após a cura. A aplicação do PSSNa em concreto apresentou o mesmo efeito. O abatimento do concreto sem PSSNa foi de 50 mm, atingindo cerca de 200 mm com o uso do polieletrólito. Devido à elevada plasticização observada é possível empregar o PSSNa como aditivo redutor de água. Foi produzido um concreto com o mesmo abatimento da referência sem aditivo reduzindo-se a quantidade de água em 20,8%. O ganho de resistência mecânica à compressão obtido foi de 21,5 e 26,3 %, respectivamente aos 7 e 28 dias de cura. Estes resultados mostraram que soluções de PSSNa podem atuar eficientemente como aditivo superplastificante ou redutor de água em argamassas e concretos.

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