Molecular access to intracrystalline tunnels of sepiolite

Ruiz‐Hitzky, Eduardo

doi:10.1039/b003197f

Cited by 298 publications

(223 citation statements)

References 29 publications

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“…improvements both below and above glass transition temperature, explained by strong interactions between the particles and PLA molecules originated from hydrogen bonding between the carbonyl groups of PLA and the hydroxyl groups belong to the structure of CLO, SEP and ZrP (see Table 1). Indeed, such interactions have been previously verified by other researchers in biopolymer nanocomposites based on similar nanoparticles rich of surface silanol groups (Si-OH) [21,39,40]. In this case, they have corroborated the possible spontaneous assembly of the biopolymer matrix and nanoparticles through hydrogen-bonding interactions, by the observed infrared perturbation of the O-H stretching vibrations assigned to the surface silanol groups.…”

Section: Dynamic-mechanical Thermal Analysis (Dmta)supporting

confidence: 62%

Properties of poly(lactic acid) nanocomposites based on montmorillonite, sepiolite and zirconium phosphonate

Fukushima¹,

Fina²,

Geobaldo³

et al. 2012

Express Polym. Lett.

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Abstract. Poly(lactic acid) (PLA) based nanocomposites based on 5 wt.% of an organically modified montmorillonite (CLO), unmodified sepiolite (SEP) and organically modified zirconium phosphonate (ZrP) were obtained by melt blending. Wide angle X-ray scattering (WAXS) and scanning electron microscopy (SEM) analysis showed a different dispersion level depending on the type and functionalisation of nanoparticles. Differenctial scanning calorimetric (DSC) analysis showed that PLA was able to crystallize on heating, and that the addition of ZrP could promote extent of PLA crystallization, whereas the presence of CLO and SEP did not significantly affect the crystallization on heating and melting behaviour of PLA matrix. Dynamic Mechanical Thermoanalysis (DMTA) results showed that addition of all nanoparticles brought considerable improvements in E! of PLA, resulting in a remarkable increase of elastic properties for PLA nanocomposites. The melt viscosity and dynamic shear moduli (G!,G") of PLA nanocomposites were also enhanced significantly by the presence of CLO and SEP, and attributed to the formation of a PLA/nanoparticle interconnected structure within the polymer matrix. The oxygen permeability of PLA did not significantly vary upon addition of SEP and ZrP nanoparticles. Only addition of CLO led to about 30% decrease compared to PLA permeability, due to the good clay dispersion and clay platelet-like morphology. The characteristic high transparency of PLA in the visible region was kept upon addition of the nanoparticles. Based on these achievements, a high potential of these PLA nanocomposites in sustainable packaging applications could be envisaged.

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Section: Dynamic-mechanical Thermal Analysis (Dmta)supporting

confidence: 62%

Properties of poly(lactic acid) nanocomposites based on montmorillonite, sepiolite and zirconium phosphonate

Fukushima¹,

Fina²,

Geobaldo³

et al. 2012

Express Polym. Lett.

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“…A sepiolita é um silicato hidratado de magnésio natural com um número significante de grupos silanol (Si-OH) presente na superfície do mineral [13] . Seu formato acilar (como agulhas) pode gerar maior molhabilidade em polímeros apolares, além de uma maior área superficial.…”

Section: -Membranas Híbridas Com Potencial Uso Em Células a Combustívunclassified

Membranas Híbridas com Potencial Uso em Células a Combustível - Parte 2: Nanocompósitos de Poli(Carbonato) Sulfonado

Gomes¹,

Machado²,

Filho³

et al. 2014

Polímeros

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Resumo: Membranas poliméricas condutoras de íons têm sido cada vez mais estudadas para o uso em células a combustível. Entretanto, as membranas poliméricas disponíveis no mercado para este fim apresentam algumas limitações de condições de trabalho. Neste estudo o poli(carbonato) modificado quimicamente para uso como membrana condutora de íons foi caracterizado e teve seu desempenho avaliado. A formação de um nanocompósito baseado em sepiolita visou ao aumento na resistência mecânica e térmica das membranas, propriedades, a princípio, prejudicadas pela sulfonação do material. As membranas foram avaliadas por FTIR, DSC, TGA, DMA, inchamento em água, transmissão de vapor de água e resistência à migração iônica. Os resultados mostraram ser possível atingir um balanço estrutura versus propriedades visando a um elevado desempenho das membranas. Palavras-chave: Membrana polimérica, nanocompósito polimérico, célula a combustível, eletrólito polimérico. Hybrid Membranes of Polymer/Clay for Fuel Cell Applications. Part 2. Sulphonated Poly(Carbonate) NanocompositesAbstract: Ion-conducting polymeric membranes have been studied for use in fuel cells. However, polymeric membranes available in the market show some disadvantages. Here we modified polycarbonate chemically for use as ion-conducting membranes, and investigated its performance. The use of the nanoclay sepiolite aimed at improving the mechanical and thermal resistance, which are negatively affected by polymer sulphonation. The membranes were evaluated using FTIR, DSC, TGA, DMA, water swelling, water vapor uptake and ionic migration resistance. The results indicated it to be possible to reach a tradeoff between structure and properties for obtaining high-performance membranes.

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“…18,24,25,28−30 Loosely bound water is relative easy to remove upon heating, while zeolitic water, coordinated water, and the surface hydroxyl groups are lost gradually as microporous minerals are heated to several hundred degrees Celsius. 18,31,32 The broad endotherms are attributed to the removal of loosely bound and zeolitic water, which makes up the majority of the heat required to remove water from the zeolites. For the HY zeolites, the endotherm peak temperature was positively correlated with the surface cation density, whereas the content of loosely bound water was negatively correlated with the surface cation density (SI Figure S1a).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Impact of Surface Chemistry on Microwave-Induced Degradation of Atrazine in Mineral Micropores

Cheng

2012

Environ. Sci. Technol.

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Surface chemistry determines the interactions of sorbate and solvent molecules with the pore wall surfaces of microporous minerals, and affects the transmission and absorption of microwave radiation for a given solvent−sorbate−sorbent system. The sorption and microwave-induced degradation of atrazine in the micropores of nine Y zeolites with different densities (0.16−2.62 site/nm 2 ) and types (Mg 2+ , Ca 2+ , H + , Na + , and NH 4 + ) of surface cations were studied. The influence of the content of cosorbed water in the mineral micropores on atrazine degradation rate was also examined. The results indicate the presence of surface cations at around 0.23 site/nm 2 on the pore wall surface was optimal for atrazine degradation, probably due to formation of insufficient number of "hot spots" with too few cations but excessive competition for microwave energy with too many hydrated cations. Atrazine degraded faster in the presence of cations with lower hydration free energies, which could be attributed to less microwave energy consumption to desorb the bounded water molecules. Reducing the content of coadsorbed water in the micropores also increased atrazine degration rate because of less competition for microwave energy from water. Such mechanistic understanding can guide the design and selection of microporous minerals in the practical application of microwaveinduced degradation.

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Molecular access to intracrystalline tunnels of sepiolite

Cited by 298 publications

References 29 publications

Properties of poly(lactic acid) nanocomposites based on montmorillonite, sepiolite and zirconium phosphonate

Properties of poly(lactic acid) nanocomposites based on montmorillonite, sepiolite and zirconium phosphonate

Membranas Híbridas com Potencial Uso em Células a Combustível - Parte 2: Nanocompósitos de Poli(Carbonato) Sulfonado

Impact of Surface Chemistry on Microwave-Induced Degradation of Atrazine in Mineral Micropores

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