Compósitos de polietileno de baixa densidade contendo Hidróxidos duplos e hidroxissais lamelares organofílicos e organofóbicos

Orientador: Prof. Dr. Fernando WypychDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia de Materiais - PIPE. Defesa: Curitiba, 14/06/2013Bibliografia: fls. 121-124Área de concentraçao: Engenharia e ciência de materiaisResumo: Nesse trabalho foram sintetizados hidróxidos duplos lamelares (HDLs) e hidroxissais lamelares (HSLs), os quais foram utilizados como agentes de carga em uma matriz de polietileno de baixa densidade (PEBD). Os HDLs e HSLs foram preparados pelo método de co-precipitação e os ânions intercalados foram o cloreto e o nitrato (cargas organofóbicas) e os ânions dodecilsulfato (DDS) e dodecilbenzenosulfonato (DBS) (cargas organofÍlicas). Os compósitos poliméricos foram processados via fusão com o auxílio de uma microextrusora e injetados na forma de corpos de prova segundo norma ASTM 638. Os compostos lamelares e os compósitos foram caracterizados por diversas técnicas instrumentais e as propriedades mecânicas investigadas. Os resultados dos difratogramas de raios X comprovaram o sucesso na síntese das cargas, as quais apresentaram boa cristalinidade. Esses resultados foram também confirmados pelas medidas de espectroscopia vibracional na região do infravermelho, com transformada de Fourier. Após incorporação na fase polimérica, principalmente os HDLs e HSLs organofílicos, alteraram as propriedades mecânicas do PEBD. Os resultados de difração de raios X sugerem que os HSLs organofílicos foram esfoliados na matriz polimérica, enquanto que os organofóbicos foram somente delaminados. Nos compósitos, as temperaturas de fusão e cristalização se mantiveram praticamente constantes, com pequenas variações pontuais nos índices de cristalinidade. As micrografias obtidas por microscopia eletrônica de varredura mostraram que os HSLs e HDLs apresentaram boas dispersões na matriz polimérica, especialmente os organofílicos.Abstract: In the present work, layered double hydroxides (LDH) and layered hydroxide salts (LHS) were synthesized and used as fillers into a low density polyethylene (LDPE). The LDHs and LHSs were prepared by the co-precipitation method and the intercalated anions were chloride and nitrate (organophobic fillers), dodecylsulfate (DDS) and dodecylbenzenesulfonate (DBS) (organophilic fillers). The polymeric composites were processed by fusion, with the aim of a microextruder and injected in the form of essay samples following the ASTM 638 norm. The layered compounds and the composites were characterized by several instrumental techniques and the mechanical properties investigated. The X-ray diffraction patterns proved the fillers synthesis success, which were of good crystallinity. These results were also confirmed by the Fourier transform infrared spectroscopic measurements. After incorporation in the polymeric matrix, especially the organophilic LDHs and LHSs have changed the mechanical properties of LDPE. The X ray diffractions results suggest that the organophilic fillers were exfoliated into the polymeric matrix while the organophobic were only delaminated. In the composites, the melting temperatures were maintained almost constant, with small and punctual variations of the crystallinity indexes. The scanning electronic microscopic images have shown that LDHs and LHSs presented good dispersions in the polymeric matric, especially the organophilic ones

Compósitos de polietileno de baixa densidade contendo hidróxidos duplos lamelares coloridos, intercalados com surfactantes aniônicos

Orientador : Prof. Dr. Fernando WypychTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Química. Defesa: Curitiba, 28/07/2017Inclui referências : f. 147-161Resumo: Na presente tese hidróxidos duplos lamelares (HDLs) contendo diversos M2+foram preparados por diversos métodos para a obtenção de um composto lamelar puro e bem cristalino, os quais foram usados como aditivos em matriz polimérica. Na primeira etapa de estudo, os HDLs foram hidrofobizados com a intercalação dos ânions orgânicos dodecilsulfato, laurato, palmitato e estearato. Esses compostos lamelares hidrofóbicos foram caracterizados por diversas técnicas instrumentais, as quais comprovaram a formação de HDLs com boa cristalinidade e empilhamento basal contendo os ânions orgânicos intercalados. Depois de caracterizados, os HDLs verdes (contendo Ni/Al) e rosa (contendo Co/Al) foram utilizados como aditivo funcionais em polietileno de baixa densidade (PEBD) livre de aditivos, em percentagens de 0,2; 0,5; 2,0; 5,0 e 7,0 % (m/m). Amostras com teores de cargas entre 0,2 a 5,0 % apresentaram, em geral, a manutenção do módulo de Young e a resistência à tração, tendendo à redução com a adição de 7% de carga. Os compósitos apresentavam boa homogeneidade de cor e dispersão do aditivo no polímero. A maioria dos nanocompósitos apresentou alongamentos similares, embora o compósito contendo HDL de Ni/Al intercalado com estearato tenha se destacado, com aumento de alongamento de 300%. Os resultados de microscopia eletrônicos de varredura e difração de raios X dos nanocompósitos de PEBD indicaram que com baixo teor de aditivo, os cristais dos HDLs foram delaminados/esfoliados na matriz polimérica. Todas as amostras dos compósitos contendo HDL de Co/Al mostraram a formação de um domínio cristalino de alta temperatura no PEBD, induzido pelo aditivo. As propriedades reológicas indicaram em geral a redução do módulo de cisalhamento devido à incompatibilidade entre algumas regiões de HDL e PEBD, promovendo a separação de fases. No entanto, a interação dos HDLs de Ni/Al com a superfície polimérica indicou alta afinidade do HDL com PEBD em comparação com o aditivo contendo HDL de Co/Al, formando redes permanentes. Na segunda etapa de estudo, HDLs de Ni/Al, Co/Al e Zn/Al hidrofílicos e hidrofóbicos foram utilizados como aditivos (2 e 4%) na matriz de PEBD modificado com anidrido maleico. Em geral, os resultados mostraram que as aditivos hidrofóbicos estavam bem dispersas na matriz polimérica, as entalpias de fusão e cristalização foram reduzidas com a adição do aditivo hidrofóbico, indicando boa interação entre a carga e a matriz polimérica, reduzindo o índice de cristalinidade o polímero. Os compósitos, também apresentaram redução da inflamabilidade, conforme indicado pela calorimetria de combustão de microescala. Palavras-Chaves: hidróxidos duplos lamelares, compósitos coloridos, polietileno de baixa densidade, propriedades mecânicas, reologia.Abstract: In the present thesis, layered double hydroxides (LDH) containing several M2+ were prepared by several methods to obtain a pure crystalline layer compound, which were used as additives in polymer matrix. In the first stage of study, LDHs were hydrophobized with the intercalation of organic anions dodecylsulfate, laurate, palmitate and stearate. These hydrophobic layer compounds were characterized by several instrumental techniques, which proved the formation of LDHs with good crystallinity and basal stacking containing organic anionsintercalated. After characterization, green (containing Ni/Al) and pink (containing Co/Al) LDHswere used as functional additive in low density polyethylene (LDPE) free of additives, in percentages of 0.2; 0.5; 2.0; 5.0 and 7.0% (w/w). Samples with filler contents between 0.2 and 5.0% showed, in general, the maintenance of the Young's modulus and the tensile strength, tending to the reduction with the addition of 7% of filler. The composites had good color homogeneity and dispersion of the additive in the polymer. Most of the nanocomposites presented similar stretches, although the composite containing Ni/Al LDH intercalated with stearate was highlighted, with a 300% elongation increase. The X-ray scanning and diffraction electron microscopy results of LDPE nanocomposites indicated that with low additive content, the LDH crystals were delaminated/exfoliated in the polymer matrix. All samples of composites containing Co/Al LDH showed the formation of a high temperature crystalline domain in LDPE, induced by the additive. The rheological properties indicated in general the reduction of the shear modulus due to the incompatibility between some regions of LDH and LDPE, promoting the separation of phases. However, the interaction of Ni/Al LDHs with polymer surface indicated high affinity of LDH with LDPE compared to the additive containing Co/Al LDH, forming permanent networks. In the second stage of study, hydrophilic and hydrophobic Ni/Al, Co/Al and Zn/Al LDHs were used as additives (2 and 4%) in maleic anhydride modified LDPE matrix. In general, the results showed that the hydrophobic additives were well dispersed in the polymer matrix; the enthalpies of melting and crystallization were reduced with the addition of the hydrophobic additive, indicating good interaction between the filler and the polymer matrix, reducing the polymer crystallinity index. The composites also showed reduced flammability, as indicated by the micro scale combustion calorimetric. Keywords: Layered double hydroxides, colored composites, low density polyethylene, mechanical properties, rheology

Mechanochemical Synthesis of Expanded Vermiculite with Urea for Filler into Alginate/Collagen Spherical Capsules: A Urea Slow-release System

The annual growth of the world population increasingly provokes the search for highly productive agriculture, with an effective and economical application of fertilizers capable of supplying the necessary nutrients to the plants. In this context, the development of technologies to control these fertilizers in the environment is relevant. This study presents a potential slow-release fertilizer created from the intercalation of urea in the expanded vermiculite (EV) and encapsulated in a sphere constituted of alginate/collagen. The intercalation tests were performed by the mechanochemical process between EV and urea, and the intercalated materials were characterized by XRD, TGA/DSC, and FTIR. The results showed that urea was intercalated at all studied ratios, but the sample containing 20% of urea (EVU20%) did not present peaks from the starting reagents. Thus, the sample EVU20% was chosen for the encapsulation process and release test. Urea concentration released was determined by colorimetric analysis, and the test revealed that the spheres produced with EVU20% encapsulated into an alginate/collagen matrix were able to release the urea up to 210 hours. Therefore, this system has the potential to be a new fertilizer of slow-release to be applied in agriculture, promoting the gradual release of urea for plant development. DOI: http://dx.doi.org/10.17807/orbital.v13i2.148

Low-Density Polyethylene Nanocomposite Containing Zn/Ti Layered Double Hydroxide

The presented work shows the synthesis and characterization of Zn/Ti layered double hydroxide (LDH) intercalated with carbonate and dodecyl sulfate ions following its application as a functional filler in LDPE in order to improve the thermal properties and resistance degradation in UV-Vis radiation. X-ray diffractogram patterns of Zn/Ti LDH-CO3 and Zn/Ti LDH-DDS present basal spacing value in the order of 6.81 Å and 38.09 Å, respectively, indicating success in layered compound synthesis. LDPE nanocomposite containing hydrophobic and hydrophilic LDH presented a very well dispersed nanocomposite, as demonstrated in XRD and DSC results. The addition of only 1 % of LDH as filler into LDPE causes an increase of 5.43 oC in the thermal property. Zn/Ti LDH-DDS absorbs more light compared to the Zn/Ti LDH-CO3 due to the enhanced interlayer distance in the presence of DDS in the basal space of LDH, which further the intercalation process of polymer chains within the interlayer regions of LDH

Synthesis of Periclase Phase (MgO) from Colloidal Cassava Starch Suspension, Dual Application: Cr(III) Removal and Pigment Reuse

peer reviewedThis study aimed to synthesize magnesium oxide (MgO) using a colloidal starch method for two primary purposes: the removal of chromium (III) ions from synthetic wastewater and the subsequent use of the chromium-containing material as synthetic inorganic pigments (SIPs) in commercial paints. The synthesis used to obtain the oxide (St-MgO) is a promising method for using plants, such as cassava, as green fuels due to their abundance, low cost, and non-toxicity. With this, the oxide showed greater porosity and alkalinity, compared to commercial magnesium oxide (Cm-MgO). The MgO samples were subjected to structural characterization using XRD and FTIR, surface area and pore volume study by B.E.T. and SEM, and chemical composition by ICP-OES and thermogravimetric analysis (TGA). The crystalline periclase phase was identified for both samples, but the brucite phase was shown to be a secondary phase for the commercial sample. After the removal of chromium ions, the brucite crystalline phase became the majority phase for the samples, regardless of the concentration of ions removed. The pigments were characterized by color measurements and discussed in terms of colorimetric parameters using the CIELab method and electron spectroscopy (VIS-NIR). This study also evaluated the colorimetric stability of green pigments in aggressive environments (acidic and alkaline) over a 240 h exposure period, demonstrating minimal color difference. This study aims to develop materials for the decontamination of wastewater containing chromium and its reuse as a synthetic inorganic pigment, using an innovative and sustainable synthesis method

Nanocompósitos de poli(álcool vinílico) contendo materiais híbridos mimetizando o pigmento Azul Maya

Resumo De forma a mimetizar o pigmento Azul Maya, dois corantes azo (alaranjado de metila - AM e vermelho congo - VC) foram inseridos na estrutura porosa da paligorsquita. Os materiais híbridos foram caracterizados por difração de raios X, espectroscopia de energia dispersiva, microscopia eletrônica de varredura, espectroscopia na região do ultravioleta-visível e análise superficial (área superficial por BET, tamanho e volume de poros por BJH). Após dispersar os materiais híbridos no poli(álcool vinílico), filmes coloridos e transparentes foram obtidos por casting úmido. Após acondicionamento em uma dessecador por uma semana a uma umidade controlada de 43 ± 2% os filmes foram avaliados em relação as suas propriedades mecânicas. De modo geral, o material PVA-PGS/AM teve um aumento no módulo de Young, tensão de ruptura e redução do alongamento enquanto que a paligorsquita bruta e PVA-PGS/VC apresentaram um comportamento oposto

Rheological properties of low-density polyethylene filled with hydrophobic Co(Ni)-Al layered double hydroxides

Abstract Cobalt/aluminum and nickel/aluminum layered double hydroxide (LDH - M+2:Al molar ratio of 3:1) were intercalated with dodecylsulphate (DDS), laurate (LAU), stearate (STE) and palmitate (PAL) and used as filler in low-density polyethylene (LDPE) in percentages between 0.2 and 7.0wt%. After injection molding, the samples were submitted to morphological characterization by scanning electron microscopy (SEM), analysis of thermal behavior by differential scanning calorimetry (DSC) and investigation of rheological properties. All Co/Al-LDPE samples showed the formation of a high temperature polymer crystal domain, induced by the LDH filler. The rheological properties indicated in general a reduction of shear modulus due to incompatibility between some regions of LDH and LDPE, which promoted phase separation. However, interaction with the LDH surface indicated higher affinity of the Ni/Al-LDH for the LDPE compared to Co/Al-LDH, forming permanent networks

Nanocompósitos poliméricos de polietileno de alta densidade contendo hidróxidos duplos lamelares intercalados com ânions derivados de corantes azo

O presente trabalho descreve a síntese e caracterização de hidróxidos duplos lamelares (HDL) de Zn/Al na razão molar 2:1, os quais foram intercalados com íons cloreto hidratados e ânions derivados dos corantes azo alaranjado de metila (AM) e alaranjado II (AII). Após caracterização, os materiais foram utilizados como cargas em polietileno de alta densidade (PEAD) e nanocompósitos foram preparados por extrusão e injeção, seguindo a norma ASTM D638-10. Os teores de cargas variaram de 0,1 até 2% (incluindo-se os sais de sódio dos corantes) e os nanocompósitos homogêneos foram avaliados em relação as suas propriedades estruturais, térmicas e mecânicas. De modo geral, após a adição das cargas existe somente uma pequena influência na temperatura de fusão e cristalização do PEAD. Para os HDLs contendo o pigmento intercalado com o ânion do corante AM e sais de sódio de ambos os corantes, as propriedades mecânicas apresentaram leve aumento do módulo e tensão de ruptura e diminuição do alongamento em relação ao polímero puro e um comportamento inverso foi observado para o ânion AII, além do HDL contendo ânions cloreto hidratados

New Alternative to Produce Colored Polymer Nanocomposites: Organophilic Ni/Al and Co/Al Layered Double Hydroxide as Fillers into Low-Density Polyethylene

<div><p>Green (Ni2+/Al+3) and pink (Co2+/Al+3) layered double hydroxides (LDH) (molar ratio of 3:1) were intercalated with several organic anions and used as functional colored fillers into low density polyethylene (LDPE) by melt mixing in amounts of 0.2 to 7 wt.%. Scanning electron microscopic (SEM) results of LDPE nanocomposites indicated that with low percentage of filler, all the LDH samples showed efficient delamination/exfoliation in the polymer matrix. Fillers added to LDPE with concentrations of 0.2, 0.5, 2 and 5% presented, in general, maintenance of Young's modulus and tensile strength, tending to the reduction with a loading of 7%. Most of the nanocomposites presented similar elongations, although NiUS stood out, with an elongation increase of 300%. Differential scanning calorimetry (DSC) indicated the effect of the Co/Al-LDH in inducing the formation of LDPE crystalline domains, especially at higher temperature than neat LDPE.</p></div