Polymer Nanocomposites for Hydrogen Storage

Hydrogen is considered to be a clean, economical and safe renewable energy source that would be ideal to replace fossil fuels, because it is light, highly abundant and its oxidation product (water) is environmentally benign. However, hydrogen is easy to burn (the chemical energy per mass of hydrogen is at least three times larger than that of other chemical fuels), which has the risk of fire and explosion. The problems of transportation and storage restrict the application of hydrogen energy, which has become a key factor in the development and utilization of hydrogen energy. This gas adsorbs at solid surfaces depending on the applied pressure and temperature. For storage purposes in mobile applications, the adsorption of hydrogen has been studied mainly on carbon species, but light and reasonably cheap materials of high surface area should prove to be attractive as well. Porous material is a very promising hydrogen storage material, which stores the gas in the form of molecules at low temperatures and compresses hydrogen into the holes effectively. The purpose of this work was to develop a hybrid porous materials consisting of sulfonated polyetherimide matrix with aluminum nanoparticles and faujasite type zeolite. Dilute solutions were first prepared under stirring at room temperature and the solutions were dried under vacuum. The hybrids were analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and hydrogen sorption measurements. The addition of aluminum decreased the glass transition temperature of the hybrids when compared to the sulfonated polymer and the TEM images showed that simply physically mixture occurred between polymer and metallic nanoparticles. Hydrogen sorption tests showed an increase in the amount of hydrogen in the presence of zeolite.CNPq (Brazilian Counsel of Technological and Scientific Development)FAPESP (Sao Paulo Research Foundation)Univ Fed Sao Carlos, Dept Mat Engn, Sao Carlos, SP, BrazilUniv Fed Pelotas, Ctr Technol Dev, Pelotas, RS, BrazilUniv Fed Sao Paulo, Inst Sci & Technol, Sao Jose Dos Campos, SP, BrazilUniv Fed Sao Paulo, Inst Sci & Technol, Sao Jose Dos Campos, SP, BrazilCNPq: 159187/2014-1FAPESP: 2013/23586-0Web of Scienc

Caracterização estrutural de nanocompósitos de blendas HDPE/LLDPE e OMMT obtidos por diferentes sequências de mistura Structural characterization of HDPE/LLDPE and OMMT blend-based nanocomposites obtained by different blending sequences

Nanocompósitos de blendas de polietileno de alta densidade (HDPE) com polietileno linear de baixa densidade (LLDPE) e OMMT (montmorilonita organofílica) foram preparados em um reômetro de torque, utilizando-se como sistema compatibilizante uma mistura de HDPE-g-MA e LLDPE-g-MA, ambos com 1% de anidrido maleico. O efeito de cinco sequências de mistura na formação da microestrutura dos nanocompósitos foi estudado. A caracterização estrutural foi realizada por análises de difração de raio X de alto ângulo (WAXD), microscopia eletrônica de transmissão (MET) e comportamento reológico em regime permanente de deformação. Os resultados mostraram que a formação da microestrutura depende da ordem de mistura dos componentes e a utilização de mistura de dois agentes compatibilizantes miscíveis com os constituintes da matriz auxiliou na distribuição da polaridade, facilitando a dispersão das nanoargilas por toda a matriz. Dentre as sequências estudadas, as que a nanoargila foi primeiramente misturada com componentes de menor viscosidade e cristalinidade (LLDPE e/ou LLDPE-g-MA) apresentaram melhor dispersão e distribuição da nanoargila na blenda polimérica.<br>High density polyethylene/linear low density polyethylene (HDPE/LLDPE) blend-based nanocomposites were prepared in a torque rheometer, using a mixture of HDPE-g-MA and LLDPE-g-MA both containing 1% of maleic anhydride as compatibilizer system. The effect from five blending sequences on the microstructure of the nanocomposites was investigated. The structural characterization was performed through wide angle X-ray diffraction (WAXD), transmission electron microscopy (TEM) and rheological properties. The results showed that the formation of morphology is dependent on the sequence of nanocomposite preparation and that the use of a mixture of two compatibilizer agents, miscible with both components of the blend matrix, facilitated the dispersion of the nanoclay throughout the matrix. The blending sequence where the nanoclay was first mixed with components of lower viscosity and crystallinity (LLDPE and/or LLDPE-g-MA) yielded better distribution and dispersion of nanoclay in the polymer blend

Preparation of Maleic Anhydride Grafted Poly(trimethylene terephthalate) (PTT-<i>g</i>-MA) by Reactive Extrusion Processing

Maleic anhydride (MA) grafted with poly(trimethylene terephthalate) (PTT)&#8212;abbreviated as PTT-g-MA&#8212;can be used as a compatibilizing agent to improve the compatibility and dispersion of nanofillers and a dispersed polymer phase into PTT matrix. This work suggests the preparation of PTT-g-MA using a mixture of PTT, MA, and benzoyl peroxide (BPO) by a reactive extrusion process. PTT-g-MA was characterized to confirm the grafting reaction of maleic anhydride on PTT chains by Fourier transform infrared (FTIR) spectroscopy. Thermal properties (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)) and rheological analysis (parallel plates rheology) were used to prove the changes that occurred after the graphitization reaction. The reactive processing route allowed the production of the compatibilizing agent (PTT-g-MA) with good thermal properties and with lower viscosity compared to neat PTT, and this could be an alternative for the compatibilization of polymer blends, as example for PTT/ABS (acrylonitrile butadiene styrene) blends and nanocomposites based on PTT matrix

Nanocompósitos de blendas HDPE/LLDPE e OMMT - parte I: avaliação das propriedades termo-mecânicas e da resistência ao intemperismo

Nanocompósitos de blendas de polietileno de alta densidade (HDPE) com polietileno linear de baixa densidade (LLDPE) e OMMT (montmorilonita organofílica) foram preparados sob fusão em extrusora de dupla-rosca, utilizando HDPE-g-MA como agente compatibilizante. A caracterização estrutural foi realizada por análises de difração de raios X em alto ângulo (WAXD), microscopia eletrônica de transmissão (MET). Os resultados indicam que a adição do agente compatibilizante favoreceu a formação da microestrutura predominantemente intercalada. Estudos dinâmico-mecânicos mostraram que a adição do agente compatibilizante aumentou as interações entre a carga e a matriz poliolefínica. As diferentes condições de intemperismo as quais os materiais foram submetidos influenciaram no comportamento mecânico dos nanocompósitos de blenda HDPE/LLDPE. Os tratamentos realizados em estufa com circulação forçada de ar e em água proporcionaram o alívio de tensões residuais presentes no sistema, enquanto que o tratamento realizado em câmara de envelhecimento acelerado levou à formação de grupos carbonílicos, de pequena massa molar, que diminuíram o grau de cristalinidade e o módulo elástico dos nanocompósitos

Characterization of nanocomposites for hydrogen storage

The use of hydrogen as an energy carrier suitable to replace gasoline and other fossil fuels has been widely discussed as a way to sustainably fuel our civilization. However, hydrogen storage is a major harrier in the establishment of infrastructure for hydrogen technology. The incorporation of nanoparticles to the polymer matrix may be an alternative to obtain materials with promising properties for hydrogen storage. in this work, polyetherimide-based Nanocomposites were prepared using carbon nanotubes doped with sodium alanate (NaAlH4) as tiller. The sodium alanate content was fixed at 30 wt% and were studied three carbon nanotubes concentrations: 5, 10 and 20 wt%. The nanocomposites were characterized by differential scanning calorimetry (DSC), thennogravimetric analysis (TGA) and Hydrogen sorption measurements.FAPESP (Sao Paulo Research Foundation)Univ Fed Pelotas, Ctr Technol Dev, Pelotas, RS, BrazilUniv Fed Sao Carlos, Dept Mat Engn, Sao Carlos, SP, BrazilUniv Fed Sao Paulo, Inst Sci & Technol, Sao Jose Dos Campos, SP, BrazilUniv Fed Sao Paulo, Inst Sci & Technol, Sao Jose Dos Campos, SP, BrazilWeb of Scienc

Nanocompósitos de blendas HDPE/LLDPE e OMMT - Parte II: avaliação das propriedades térmica, óticas e de transporte a gases

Nanocompósitos de blendas de polietileno de alta densidade (HDPE) com polietileno linear de baixa densidade (LLDPE) e OMMT (montmorilonita organofílica) foram preparados sob fusão em extrusora de dupla-rosca, utilizando HDPE-g-MA como agente compatibilizante. Os nanocompósitos foram caracterizados através das propriedades térmicas, óticas e de transporte de gases. A blenda HDPE/LLDPE e os nanocompósitos das blendas HDPE/LLDPE como esperado comportam-se como barreira ao vapor de água e são permeáveis ao CO2 e O2. A adição de nanoargila modificou o grau de cristalinidade da matriz polimérica dos nanocompósitos e a diminuição do coeficiente de permeabilidade foi atribuída ao aumento do grau de cristalinidade e do aumento ao caminho difusional para as moléculas do gás passarem pelo filme polimérico. O caminho difusional mais longo devido ao aumento da tortuosidade está relacionado a uma boa dispersão da carga inorgânica, boa molhabilidade desta pela matriz e forte interações na interface. Modelos teóricos de permeabilidade propostos por Nielsen e Bharadwaj foram utilizados para estimar a razão de aspecto da nanoargila nos nanocompósitos e forneceram resultados que se correlacionam bem com as morfologias observadas por microscopia eletrônica de transmissão

Analysis of the Degradation During Melt Processing of PLA/Biosilicate^® Composites

Poly (lactic acid) (PLA)/bioactive composites are emerging as new biomaterials since it is possible to combine stiffness, mechanical resistance, and bioactive character of the bioglasses with conformability and bioabsorption of the PLA. In this study, PLA/Biosilicate&#174; composites were prepared using a melt-processing route. The processability and properties were evaluated aiming to produce composites with bioactive properties. Two different PLA (PLA 2003D and PLA 4043D) were tested with the addition of 1 wt. % of Biosilicate&#174;. Both materials presented a huge reduction in melt viscosity after internal mixer processing. The degradation effects of the addition of Biosilicate&#174; in the PLAs matrices were evaluated using zeta potential tests that showed a very high liberation of ions, which catalyzes PLA thermo-oxidative reactions. To understand the extension of degradation effects during the processing, the composites were characterized using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and rheological tests. GPC results showed that PLA with the lowest residual acid content (RAC), PLA 2003D, presented higher thermal stability, higher molecular weight, and viscosity baseline compared to PLA 4043D. The composites showed a significant decrease in molecular weight for both PLA with the addition of Biosilicate&#174;. TGA results showed that Biosilicate&#174; might have reduced the activation energy to initiate thermodegradation reactions in PLAs and it occasioned a reduction in the Tonset by almost 40 &#176;C. The DSC results showed that severe matrix degradation and the presence of bioglass did not significantly affect glass transition temperature (Tg), melting temperature (Tm) and crystallinity of PLAs, but it influenced cold crystallization peak (Tcc). In this way, the type of PLA used influences the processability of this material, which can make the production of filaments of this material for 3D printing unfeasible

Engineering 3D printed bioactive composite scaffolds based on the combination of aliphatic polyester and calcium phosphates for bone tissue regeneration

In this study, polylactic acid (PLA) filled with hydroxyapatite (HA) or beta-tricalcium phosphate (TCP) in 5 wt% and 10 wt% of concentration were produced employing twin-screw extrusion followed by fused filament fabrication in two different architectures, varying the orientation of fibers of adjacent layers. The extruded 3D filaments presented suitable rheological and thermal properties to manufacture of 3D scaffolds envisaging bone tissue engineering. The produced scaffolds exhibited a high level of printing accuracy related to the 3D model; confirmed by micro-CT and electron microscopy analysis. The developed architectures presented mechanical properties compatible with human bone replacement. The addition of HA and TCP made the filaments bioactive, and the deposition of new calcium phosphates was observed upon 7 days of incubation in simulated body fluid, exemplifying a microenvironment suitable for cell attachment and proliferation. After 7 days of cell culture, the constructs with a higher percentage of HA and TCP demonstrated a significantly superior amount of DNA when compared to neat PLA, indicating that higher concentrations of HA and TCP could guide a good cellular response and increasing cell cytocompatibility. Differentiation tests were performed, and the biocomposites of PLA/HA and PLA/TCP exhibited earlier markers of cell differentiation as confirmed by alkaline phosphatase and alizarin red assays. The 3D printed composite scaffolds, manufactured with bioactive materials and adequate porous size, supported cell attachment, proliferation, and differentiation ,which together with their scalability, promise a high potential for bone tissue engineering applications.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001 and for the European Regional Development Fund (EFDR), under the scope of the INTERREG España-Portugal (POCTEP) project 0302_CVMAR_I_1_P. The authors would like to thanks the FAPESP (Process Number 2018/13625-2, 2017/11366-7 and 2017/09609-9), Catarina F. Marques thanks Fundação para a Ciência e a Tecnologia (FCT) for the contract CEECIND/04687/2017 and Emanuel M. Fernandes thanks to Structured Projects for the contract NORTE-01-0145-FEDER-000021. The authors would like to thank Professor Luiz Henrique Capparelli Mattoso, Dr. Paulo Renato Orlandi Lasso and Empresa Brasileira de Pesquisa Agropecuária (Embrapa) for Micro-CT analysis. The authors would like to thank Professor Silvia H. Bettini and Dra. Talita R. Rigolin for GPC analysis (FAPESP Process Number 2011/21313-1