Intercalation of Mg–Al layered double hydroxide by anionic surfactants: Preparation and characterization

. H O z was intercalated with lauric and stearic acid using a surfactant-assisted method. X-ray diffraction, thermal analysis and infrared spectroscopy confirmed that bilayer-intercalated compounds were formed and that the surfactant (sodium dodecyl sulfate) was not co-intercalated. These compounds shows interesting thermal behavior with two phase transformations observed at elevated temperatures. At temperatures that are significantly higher than the melting points of the corresponding free acids, the alkyl chains assume a disordered liquid-like state within the clay galleries. However, at even higher temperatures the materials become completely amorphous like true melts.

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“…A B FIGURE 8 The effect of temperature on the FT-IR spectra for (A) LDH-laurate and (B) LDHstearate.…”

Section: Figurementioning

confidence: 99%

Thermal Properties of Lauric- and Stearic Acid Intercalated Layered Double Hydroxides

Focke

Nhlapo

Moyo

et al. 2010

Molecular Crystals and Liquid Crystals

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“…In step 2, between 230°C and 370°C, the degradation of interlayered carbonate and the loss of hydroxyl groups associated to aluminum and magnesium was observed. Between 370°C and 550°C, in step 3, the total degradation of hydroxyl groups of metals happened simultaneously forming metallic oxides (Al 2 O 3 and MgO) and steam [11] .…”

Section: Characterization Of Hydrotalcitementioning

confidence: 99%

“…At 1365 cm -1 the asymmetric stretch of carbonate present between the hydrotalcite lamellae could be seen. The absorption bands located at 775 cm -1 and 637 cm -1 can be attributed to magnesium oxide and aluminum oxide [10,11] . The thermal stability of hydrotalcite was studied by TGA.…”

Section: Characterization Of Hydrotalcitementioning

confidence: 99%

Epoxidized natural rubber and hydrotalcite compounds: rheological and thermal characterization

2017

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ObstractEpoxidized natural rubber (ENR) and synthetic non-modified hydrotalcite (HT) compounds were prepared and evaluated. Natural rubber (NR) was epoxidized with 20.6% of epoxy groups from a chemical modification of the latex. A sulfur-based curing system formulation with accelerators was used. The amounts of HT in the ENR-HT compositions was varied between 0, 2, 3 and 5 phr. All compositions were evaluated as to cure parameters, rheological properties, thermal resistance and crosslink density. The results showed that the mineral filler does not have a significant influence on the cure parameters. Different methods of crosslink density determination were used (swelling at equilibrium and elastic modulus). The results turn out to be equivalent and rise as the amount of filler is increased. The best results were found for the 5 phr hydrotalcite compound (ENR-HT5).

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“…The second stage of weight loss was from 230 to 340 °C, which is ascribed to the removal of aluminum hydroxy and intercalated CO3 2− . The third stage of weight loss was from 340 to 600 °C and occurs due to the loss of dehydroxylation of the interlayer magnesium metal and CO3 2− (Costa et al 2008). For pure CNFs films, the weight loss mainly occurred in the temperature range of 50 to 400 °C, and the residue was merely about 30%.…”

Section: Resultsmentioning

confidence: 99%

Preparation and Barrier Properties of Nanocellulose / Layered Double Hydroxide Composite Film

Wang

et al. 2017

BioResources

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Cellulose nanofibrils (CNFs) were oxidized by the TEMPO oxidation system from bleached kraft eucalyptus pulp, and layered double hydroxides (LDHs) were prepared via the hydrothermal method. MgAl-CO3-LDHs/CNFs composite films with different LDH ratios were prepared via a filtering/evaporation technique that endowed the nanocomposites with barrier and strengthening properties. The MgAl-CO3-LDHs could uniformly disperse in the CNFs matrix with an improved reciprocal adhesion, and the surface result was smooth and continuous. The basic structure of the membrane did not change, but the thermodynamic properties and the water vapor barrier property improved. This composite membrane can be widely used in food, pharmaceutical, and chemical packaging industries as a gas-liquid barrier material. Keywords INTRODUCTIONCellulose nanofibrils (CNFs) film was peeled off from CNFs water suspension. This type of film exhibits environmental friendliness, high transparency, high mechanical performance, and enhanced gas barrier properties. With these multifunctional combinations, these nanocomposites have wide application prospects in the encapsulation of drugs, tissue engineering, or outdoor load-bearing applications. The transparency of the CNFs film was achieved by air-drying, which simultaneously improved the tensile strength and oxygen barrier properties. Because hydrogen bonding in cellulosic nanoparticles forms a dense percolating network, and the penetration of molecules is difficult in the crystalline domains of cellulose microfibrils, these composite films have been suggested for use as barrier films (Fukuzumi 2009;Belbekhouche et al. 2011). Due to the high hydrophilicity of nanocellulose, the fiber network of CNFs membrane material is loose, and the mechanical properties decrease when wet (Lavoine et al. 2012). To improve the barrier properties of CNFs based film materials, chemically modified CNFs were used, and lamellar substances were also added to extend the path of small molecules in the CNFs infiltration. Talc platelets (Liimatainen et al. 2013) and montmorillonite platelets (Wu et al. 2012) were used to increase gas barrier properties of the CNFs film. Compared with other typical platelet-like inorganic materials, the aspect ratio of layered double hydroxides (LDHs) nanosheets can be easily adjusted during the synthesis process. As an important nanoscale material, LDHs have a hydrophobic nature and layered structures, which make the movement of gas and water molecules become complex and difficult. LDHs improve the gas barrier properties of CNF films, as illustrated in Fig. 1 (Qian et al. 2015).LDHs were prepared via a hydrothermal method, and CNFs were prepared by TEMPO oxidation / homogenization (Saito et al. 2007). The MgAl-CO3-LDHs were PEER-REVIEWED BRIEF COMMUNICATION bioresources.com Wang et al. (2018). "Nanocellulose composite," BioResources 13(1), 1055-1064. 1056 incorporated into the CNFs via a filtering/evaporation technique, which strengthened the nanocomposites. The MgAl-CO3-LDHs dispersed uniformly int...

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Intercalation of Mg–Al layered double hydroxide by anionic surfactants: Preparation and characterization

Cited by 325 publications

References 29 publications

Thermal Properties of Lauric- and Stearic Acid Intercalated Layered Double Hydroxides

Thermal Properties of Lauric- and Stearic Acid Intercalated Layered Double Hydroxides

Epoxidized natural rubber and hydrotalcite compounds: rheological and thermal characterization

Preparation and Barrier Properties of Nanocellulose / Layered Double Hydroxide Composite Film

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