Layered Double Hydroxide Loading Research Articles

Effect of graphene oxide/layered double hydroxide modified by 7‐octenyltrimethoxysilane on the mechanical and gas barrier properties of fluoroelastomers

AbstractLayered double hydroxide/graphene oxide (GLDH) composites (SGLDH) modified by 7‐octenyltrimethoxysilane (7‐OTOS) were prepared by co‐precipitation method. The structure and morphology of SGLDH were characterized using x‐ray diffraction, Fourier‐transform infrared spectroscopy (FTIR), x‐ray photoelectron spectroscopy, scanning electron microscopy (SEM), high‐resolution transmission electron microscopy, energy‐dispersive x‐ray spectroscopy, and thermogravimetric analysis. According to the obtained results, 7‐OTOS was successfully grafted onto graphene oxide (GO) and layered double hydroxide (LDH) surfaces. 7‐OTOS was grafted on both GO and LDH surfaces, which is why the amount of LDH loaded on the SGLDH surface was significantly increased compared with that on the GLDH composite. The filler‐matrix interfacial interactions of the SGLDH‐filled fluoroelastomer composites were characterized using contact angle analysis, dynamic mechanical analysis, RPA analysis, FTIR, SEM, and cross‐linking density tests. It was indicated that the interfacial interactions between the SGLDH and matrix were significantly improved, and the SGLDH was well dispersed in the fluoroelastomer composites. In addition, the gas barrier properties and mechanical properties of the fluoroelastomer composites were tested. The carbon dioxide permeability coefficients of the fluoroelastomer composites filled with 10‐phr SGLDH increased by about 32.1% and 20.3%, and the tensile strengths increased by about 47.6% and 27.7%, respectively, compared with those of the fluoroelastomer composites filled with 10‐phr LDH and GLDH.Highlights SLDH nanocomposites are based on silyl ether linkages to increase LDH loading. Elastomer nanocomposites exhibited interfacial cross‐linking mechanism. Interfacial interactions were exhibited between FKM and SGLDH. FKM/SGLDH exhibited enhanced gas barrier properties (+32%) compared to FKM. FKM/SGLDH exhibited enhanced mechanical properties (+47%) compared to FKM.

Enhancing sorption of layered double hydroxide-based magnetic biochar for arsenic and cadmium through optimized preparation protocols

The impact of multiple preparation protocols on properties and performance of modified biochar remains unclear. This study prepared layered double hydroxide (LDH)-based magnetic biochars (LMBCs) with different LDH loading rates (LLR), pyrolysis temperatures, and biomass sources to explore their performance-characterization relationships toward As(III) and Cd(II). Higher LLR and pyrolysis temperature enhanced LMBCs᾿ adsorption capacities by increasing specific surface area (SSA) and metal/O-containing groups. Hence, LMBC produced at 2:1 LLR (LDH: magnetic biochar) and 800 ℃ pyrolysis exhibited maximum adsorption over 2 times that of LMBC with 0.5:1 LLR and 400 ℃ pyrolysis. Bamboo-sourced LMBC demonstrated superior adsorption than sewage sludge and garlic-sourced LMBCs due to its increased SSA, enabling a higher loading of nano-LDH. Adsorption of As(III) and Cd(II) onto LMBCs was governed by metal-mineral and metal-containing group through co-precipitation and complexation. This study provides a reference for adjusting the preparation protocols to improve sorption performance of modified biochar toward multiple heavy metals.

Engineering g-C3N4 with CuAl-layered double hydroxide in 2D/2D heterostructures for visible-light water splitting

CuAl layered double hydroxide (LDH) and polymeric carbon nitride (g-C3N4, GCNN) were assembled to construct a set of novel 2D/2D CuAl-LDH/GCNN heterostructures. These materials were tested towards H2 and O2 generation from water splitting using visible-light irradiation. Compared to pristine materials, the heterostructures displayed strongly enhanced visible-light H2 evolution, dependent on the LDH content, which acts as a cocatalyst, replacing the benchmark Pt. The optimal LDH loading was achieved for 0.2CuAl-LDH/GCNN that exhibited an increased number of active sites and showed a trade-off between charge separation efficiency and light shading, resulting in a 32-fold increase in the amount of evolved H2 compared with GCNN. In addition, the 0.2CuAl-LDH/GCNN heterostructure generated 1.5 times more O2 than GCNN. The higher photocatalytic performance was due to efficient charge carriers’ separation at the heterojunction interface via an S-scheme (corroborated by work function, steady-state and time-resolved photoluminescence studies), enhanced utilisation of longer-wavelength photons (>460 nm) and higher surface area available for the catalytic reactions.

Nanocomposite Membranes for PEM-FCs: Effect of LDH Introduction on the Physic-Chemical Performance of Various Polymer Matrices.

This is a comparative study to clarify the effect of the introduction of layered double hydroxide (LDH) into various polymer matrices. One perfluorosulfonic acid polymer, i.e., Nafion, and two polyaromatic polymers such as sulfonated polyether ether ketone (sPEEK) and sulfonated polysulfone (sPSU), were used for the preparation of nanocomposite membranes at 3 wt.% of LDH loading. Thereafter, the PEMs were characterized by X-ray diffraction (XRD) and dynamic mechanical analysis (DMA) for their microstructural and thermomechanical features, whereas water dynamics and proton conductivity were investigated by nuclear magnetic resonance (PFG and T1) and EIS spectroscopies, respectively. Depending on the hosting matrix, the LDHs can simply provide additional hydrophilic sites or act as physical crosslinkers. In the latter case, an impressive enhancement of both dimensional stability and electrochemical performance was observed. While pristine sPSU exhibited the lowest proton conductivity, the sPSU/LDH nanocomposite was able to compete with Nafion, yielding a conductivity of 122 mS cm-1 at 120 °C and 90% RH with an activation energy of only 8.7 kJ mol-1. The outcome must be ascribed to the mutual and beneficial interaction of the LDH nanoplatelets with the functional groups of sPSU, therefore the choice of the appropriate filler is pivotal for the preparation of highly-performing composites.

Royal Jelly Nanoparticle Alleviates Experimental Model of Breast Cancer Through Suppressing Regulatory T Cells and Upregulating TH1 Cells.

Royal jelly, a natural product from bees' hypopharyngeal glands, is commonly used in biomedicine due to its antioxidant and anti-tumor activities. The aim of this study was to compare royal jelly in free form and loaded in layered double hydroxide (LDH) nanoparticle for the treatment of breast cancer with a focus on Th1 and T regulatory parameters in an animal model. Nanoparticles were produced using the coprecipitation method and characterized using DLS, FTIR, and SEM techniques. Forty female BALB/c mice were inoculated with 7.5 x 105 4T1 cells and treated with royal jelly in free and nanoparticle form. Clinical signs and tumor volume were assessed weekly. The effect of royal jelly products on the serum level of IFN-γ and TGF-β was measured by ELISA. In addition, the mRNA expression of these cytokines and Th1 and regulatory T cells' transcription factors (T-bet and FoxP3) was assessed by real-time PCR in the splenocytes of tumor-bearing mice. The physicochemical analysis of nanoparticles confirmed the synthesis of LDH nanoparticles and loading of royal jelly into the LDH structures (RJ-LDH). Animal studies showed that royal jelly and RJ-LDH significantly reduced the size of tumor in BALB/c mice. Additionally, treatment with RJ-LDH significantly inhibited TGF-β and increased IFN-γ production. The data also revealed that RJ-LDH inhibited the differentiation of regulatory T cells, while promoting Th1 cell differentiation via regulating their master transcription factors. These results indicated that royal jelly and RJ-LDH could inhibit breast cancer progression by in-hibiting regulatory T cells and expansion of Th1 cell. Furthermore, the current study demonstrated the therapeutic efficacy of royal jelly is enhanced by LDH nanoparticles; hence, RJ-LDH is significantly more efficient than Free-RJ in the treatment of breast cancer.

2D/2D Co-Al layered double hydroxide/TiO2 heterostructures for photoreduction of Cr (VI)

Co-Al layered double hydroxide (LDH)/TiO2heterostructures were synthesized using TiO2 nanobelts by a solvothermal method. X-ray diffraction analysis and morphology observation indicate that layered Co-Al LDH was grown on TiO2nanobelts consisted of anatase and TiO2(B). The phase composition of TiO2nanobelt samples depended on the calcined temperature. The phase composition of TiO2 affected the adsorption ability of composite samples. The pseudo-second-order kinetics model fits for the Cr(VI) ions adsorption kinetics of LDH/TiO2 composite samples. In the case of dark condition, the Cr(VI) removal using composite sample (LT4) was about 45%.In contrast, the Cr(VI) removal of the sample reached up to 100% within 10 min under full solar spectrum irradiation. The excellent performance of the sample can be ascribed to the formation of CoAl-LDH/TiO2 heterostructures consisted of one-dimensional TiO2 nanostructure with mixed anatase and TiO2(B) phases and optimized LDH loading. This heterostructure revealed relatively high stability. The interface of two phases effectively hinders the recombination of photo-generated carriers. In addition, the presence of uniformly distributed CoAl-LDH improved the conductivity and light absorption of the composite sample.

Novel fluoride rechargeable dental composites containing MgAl and CaAl layered double hydroxide (LDH)

ObjectiveThis study aims to incorporate 2:1 MgAl and 2:1 CaAl layered double hydroxides (LDHs) in experimental dental-composites to render them fluoride rechargeable. The effect of LDH on fluoride absorption and release, and their physico-mechanical properties are investigated. Methods2:1 CaAl and 2:1 MgAl LDH-composite discs prepared with 0, 10 and 30wt% LDH were charged with fluoride (48h) and transferred to deionized water (DW)/artificial saliva (AS). Fluoride release/re-release was measured every 24h (ion-selective electrodes) with DW/AS replaced daily, and samples re-charged (5min) with fluoride every 2 days. Five absorption-release cycles were conducted over 10 days. CaAl and MgAl LDH rod-shaped specimens (dry and hydrated; 0, 10 and 30wt%) were studied for flexural strength and modulus. CaAl and MgAl LDH-composite discs (0, 10, 30 and 45wt% LDH) were prepared to study water uptake (over 7 weeks), water desorption (3 weeks), diffusion coefficients, solubility and cation release (ICP-OES). ResultsCaAl LDH and MgAl LDH-composites significantly increased the amount of fluoride released in both media (P<0.05). In AS, the mean release after every recharge was greater for MgAl LDH-composites compared to CaAl LDH-composites (P<0.05). After every recharge, the fluoride release was greater than the previous release cycle (P<0.05) for all LDH-composites. Physico-mechanical properties of the LDH-composites demonstrated similar values to those reported in literature. The solubility and cation release showed a linear increase with LDH loading. SignificanceLDH-composites repeatedly absorbed/released fluoride and maintained desired physico-mechanical properties. A sustained low-level fluoride release with LDH-composites could lead to a potential breakthrough in preventing early stage carious-lesions.

Effect of polarization switching on piezoelectric and dielectric performance of electrospun nanofabrics of poly(vinylidene fluoride)/Ca–Al LDH nanocomposite

ABSTRACTAt present, highly flexible, durable, and lightweight piezoelectric nanogenerators with high‐power density and energy conversion efficiency are of great interest. The present study reports a new synthetic route for Ca–Al layered double hydroxide (LDH) nanosheets and incorporation of these two‐dimensional nanosheets as filler material into poly(vinylidene fluoride) (PVDF) to produce composite nanofabrics by electrospinning. The polymorphism, crystallinity, and the interaction between PVDF and LDH were studied by Fourier transform infrared spectroscopy, X‐ray diffraction, and differential scanning calorimetry techniques. The synergetic effect of PVDF–LDH interaction and in situ stretching due to electrospinning facilitates the nucleation of electroactive β phase up to 82.79%, which makes it a suitable material for piezoelectric‐based nanogenerators. The piezoelectric performance of PVDF/Ca–Al LDH composite nanofabrics was demonstrated by hand slapping and frequency‐dependent mechanical vibration mode, which delivered a maximum open circuit output voltage of 4.1 and 5.72 V, respectively. Moreover, the composite nanofabrics exhibited a high dielectric constant and low dielectric loss due to superior interfacial polarization at low‐frequency region with LDH loading, promising its potential applications in electronic devices. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48697.

Development of Copper-Aluminum Layered Double Hydroxide in Thin Film Nanocomposite Nanofiltration Membrane for Water Purification Process.

This study aims to fabricate a thin film composite (TFC) membrane, modified with copper-aluminium layered double hydroxide (LDH) nanofillers via interfacial polymerization technique for nanofiltration (NF) processes. It was found that Cu-Al LDH nanofillers possessed layered structured materials with typical hexagonal plate-like shape and positive surface charge. The study revealed that TFN membrane exhibits a relatively smooth surface and a less nodular structure compared to pristine TFC membrane. The contact angle of TFN progressively decreased from 54.1° to 37.25°, indicating enhancement in surface hydrophilicity. Moreover, the incorporation of LDH nanofillers resulted in a less negative membrane as compared to the pristine TFC membrane. The best NF performance was achieved by TFN2 membrane with 0.1° of Cu-Al LDH loading and a water flux of 7.01 Lm-2h-1.bar. The addition of Cu-Al LDH resulted in excellent single salt rejections of Na2SO4 (96.8%), MgCl2 (95.6%), MgSO4 (95.4%), and NaCl (60.8%). The improvement in anti-fouling properties of resultant TFN membranes can be observed from the increments of pure water flux recovery and normalized water flux by 14% and 25% respectively. The findings indicated that Cu-Al LDH is a promising material in tailoring membrane surface properties and fouling resistance. The modification of the LDH-filled TFN membrane shows another alternative to fabricating a high-performance composite membrane, especially for water softening and partial desalination process.

Incorporation of layered double hydroxide nanofillers in polyamide nanofiltration membrane for high performance of salts rejections

Abstract In this work, thin film composite (TFC) membrane embedded with self-synthesized layered double hydroxide (LDH) nanofillers was prepared via interfacial polymerization technique for nanofiltration (NF) process. Prior to filtration experiments, the morphologies and physicochemical properties of the prepared LDH nanofillers and TFC membranes were characterized using TEM, XRD, FESEM, FTIR, AFM, zeta potential analyzer and contact angle goniometer. The results revealed that the self-synthesized LDH nanofillers possessed layered structured materials with typical hexagonal plate-like shape. Meanwhile, it was found that the membrane contact angle decreased remarkably from 53° to 33.96° upon addition of 0.1 wt% LDH nanofillers in the active polyamide layer. TFN membrane of 0.1 wt% LDH loading possessed the highest water flux of 54.62 Lm−2 h−1 at 7 bar. The highest rejections of Na2SO4 (97.3%), MgSO4 (95.5%), MgCl2 (95.2%) and NaCl (63.7%) were also achieved by the TFN embedded with 0.1 wt% LDH in polyamide layer. In addition to the excellent water flux and rejection, incorporation of LDH also enhanced the fouling resistance, proven by the improvement of pure water flux recovery by 52% after BSA filtration. The findings indicated the potential of the newly developed TFN membrane incorporated with LDH nanofillers for efficient NF membrane in water softening and pre-desalination process.

Synthesis and properties of polypropylene/layered double hydroxide nanocomposites with different LDHs particle sizes

ABSTRACTIn order to investigate whether the particle sizes of inorganic additives in polymer have an influence on the flame‐retardant and other properties of the polymer, five types of Mg3Al–CO3 layered double hydroxide (LDHs) with particle diameters of 80–100, 200–350, 500–550, 550–600, and 700–900 nm were synthesized using a hydrothermal method. The obtained Mg3Al–CO3 LDHs were treated using the aqueous miscible organic solvent treatment method to give highly dispersed platelets in Polypropylene (PP). The thermal stability, flame retardancy, and mechanical properties of the PP/AMO–LDH nanocomposites were investigated systematically. The results showed that the thermal stability and flame retardancy of PP could be improved after incorporating AMO–LDHs. The temperature at 50% weight loss (T0.5) of PP/LDH (700–900 nm) nanocomposites with a LDH loading of 15 wt % was increased by 57 °C. When the LDHs loading was 40 wt %, the peak heat release rate (PHRR) of the PP/LDH nanocomposites with small LDHs particle sizes (&lt;350 nm) was decreased by ca. 58%. The limiting oxygen index was increased by 5% for PP/LDH (80–100 nm) nanocomposites. The response surface regression results also indicated that both LDH particle size and loading have influence on PHRR, heat release capacity, tensile strength, and elongation at break. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46204.

Rheological Behavior of Polystyrene (PS)/Co-Al Layered Double Hydroxide (LDH) Blend Solution obtained Through Solvent Blending Route: Influence of LDH Loading and Temperature

This investigation deals with the preparation of organically modified Co-Al layered double hydroxide (LDH) and influence of its loading and temperature on the rheological behavior of polystyrene (PS)/Co-Al LDH blends prepared via solvent blending method (SBM). Firstly, Co-Al LDH was synthesized by co-precipitation technique. Thereafter, PS blends with various LDHs content (3, 5 and 7 wt.% with respect to pure PS) were synthesized by SBM. The structural properties of the modified Co-Al LDH were characterized by XRD and FTIR analysis. The d-spacing value of modified LDH was found to be 2.8 nm by XRD analysis. The existence of sulfate groups in the modified LDH was affirmed by FTIR analysis. Rheological studies were done for the prepared samples in the shear rate array of 0.1-100 s-1 at various temperatures (20, 30 and 40 °C). It was observed that the rheology of PS solution is influenced by increasing Co-Al LDH loading, shear rate and temperature. All PS/Co-Al LDH blends showed an increment in their shear viscosity than pure PS. Also, the rheological data were fitted with different models, namely, Power law, Casson, Cross, Sisko, Herschel-Bulkley and Carreau models, to explain the rheological behavior. The results clearly indicated that Herschel-Buckley model displays good fit at lower temperature (20 °C), whereas Cross model offers best fit at higher temperatures (30 and 40 °C) for both pure PS and PS solution with various concentration of Co-Al LDH.

Size Effect of Layered Double Hydroxide Platelets on the Crystallization Behavior of Isotactic Polypropylene.

Layered double hydroxide (LDH) platelets with nanosized and microsized level were synthesized and used as fillers in an isotactic polypropylene (PP) matrix. The nucleation and crystallization behavior of PP/LDH composites (denoted as 1-PPLx and 2-PPLx for composites containing nanosized and microsized LDH, respectively; x represents the mass percentage of LDH) was investigated by differential scanning calorimetry and polarized optical microscopy techniques. It is found that the crystallization temperature of PP/LDH composites is largely enhanced and the half crystallization time is reduced remarkably relative to pure PP, especially for 2-PPLx composite. The 2-PPLx composite exhibits stronger heterogeneous nucleating ability and faster crystallization rate than 1-PPLx samples with the same LDH loading. In addition, the crystallized PP/LDH composites possess significantly enhanced thermal stability, gas barrier, and flame-retardant properties relative to neat PP, which would show a broad application prospect in engineering plastics and packing industry.

Enhanced mechanical and thermal properties of polystyrene nanocomposites prepared using organo-functionalized Ni Al layered double hydroxide via melt intercalation technique

Abstract The article reports upon the preparation and characterization of organo-functionalized Ni Al layered double hydroxide (LDH)-polystyrene (PS) nanocomposites. Initially, pristine Ni Al LDH was synthesized via the co-precipitation technique and was subsequently treated using sodium dodecyl sulfate to obtain organo-functionalized Ni Al LDH (ONi Al LDH). PS nanocomposites were fabricated by melt intercalation using a twin screw extruder in presence of ONi Al LDH nanofiller (1, 3, 5, and 7 wt.%). The PS nanocomposites were characterized for their structural, thermal and mechanical properties. The dispersion and morphology of the obtained PS nanocomposites were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Mechanical and thermal properties of the PS nanocomposites as a function of LDH content were examined by tensile tests, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The XRD and TEM results revealed the formation of an exfoliated structure of the PS nanocomposite with 1 wt.% ONi Al LDH loading. The maximum improvements of the mechanical and thermal properties of the nanocomposites with ONi Al LDH loading over pristine PS included tensile strength = 34.5% (1 wt.%), thermal decomposition temperatures (T15%) = 27.4 °C (7 wt.%), and glass transition temperature (Tg) = 4.3 °C (7 wt.%). The PS nanocomposites possessed higher mechanical strength and thermal degradation resistance compared to the pristine PS. The activation energy (Ea) and reaction mechanism with respect to thermal degradation of the pristine PS and its nanocomposites were evaluated by the Coats-Redfern and Criado model, respectively.

Processing and characterization of polystyrene nanocomposites based on CoAl layered double hydroxide

Abstract The present work deals with the development of polystyrene (PS) nanocomposites through solvent blending technique with diverse contents of modified Co Al layered double hydroxide (LDH). The prepared PS as well as PS/Co Al LDH (1–7 wt.%) nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), rheological analysis, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The XRD results suggested the formation of exfoliated structure, while TEM images clearly indicated the intercalated morphology of PS nanocomposites at higher loading. The presence of various functional groups in the Co Al LDH and PS/Co Al LDH nanocomposites was verified by FTIR analysis. TGA data confirmed that the thermal stability of PS composites was enhanced significantly as compared to pristine PS. While considering 15% weight loss as a reference point, it was found that the thermal degradation (T d ) temperature increased up to 28.5 °C for PS nanocomposites prepared with 7 wt.% Co Al LDH loading over pristine PS. All the nanocomposite samples displayed superior glass transition temperature (T g ), in which PS nanocomposites containing 7 wt.% LDH showed about 5.5 °C higher T g over pristine PS. In addition, the kinetics for thermal degradation of the composites was studied using Coats-Redfern method. The Criado method was ultimately used to evaluate the decomposition reaction mechanism of the nanocomposites. The complex viscosity and rheological muduli of nanocomposites were found to be higher than that of pristine PS when the frequency increased from 0.01 to 100 s −1 .

Interaction between Poly(vinyl alcohol) and Layered Double Hydroxide (LDH) Particles with Different Topological Shape and Their Application in Electrospinning

To explore the influence of filler topological shape on the rheological behavior of poly(vinyl alcohol) (PVA) aqueous solution, three kinds (nanosized layered crystals, microsized layered crystals, and nanoscrolls) of layered double hydroxides (LDHs) were synthesized. Except for nanosized layered crystals, both LDH microsized layered crystals and nanoscrolls filled system showed distinct “N” shape viscosity curves with increasing LDH loadings. Notably, the one-dimensional LDH nanoscrolls could increase or decrease the viscosity of PVA solution by only changing the loadings. With combined theoretical calculation with dynamic mechanical analyses, the adsorbed state of PVA chains on surface of the three LDH particles was proposed, in which PVA chains exhibited various adsorbed states due to different interactions between PVA chains and LDH particles with disparate topological shape. Taking the advantage of remarkable rheological modulation and adsorption capacity, LDH nanoscrolls were introduced into PVA aqu...

Preparation and characterization of hydrophilic and antifouling poly(ether sulfone) ultrafiltration membranes modified with Zn–Al layered double hydroxides

ABSTRACTZn–Al layered double hydroxide (LDH)‐entrapped poly(ether sulfone) (PES) ultrafiltration membranes with four different weight percentages, 0.5, 1.0, 2.0, and 3.0%, were prepared by a phase‐inversion method. Characterization by scanning electron microscopy, atomic force microscopy and contact angle (CA), equilibrium water content, porosity, average pore size, mechanical strength, and ζ potential measurement were used to evaluate the morphological structure and physical and chemical properties of membranes. Static protein adsorption, filtration, and rejection experiments were conducted to study the antifouling properties, water permeability, and removal ability of the modified membranes. The results show that significant change occurred in the membrane morphology and that better hydrophilicity, water permeability, and antifouling ability were also achieved for the PES/LDH membranes when a proper amount of LDH was used. For example, the CA value decreased from 66.60 to 50.21°, and the pure water flux increased from 80.21 to 119.10 L m−2 h−1 bar−1 when the LDH loading was increased from 0 to 2.0 wt %. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43988.

Analysis of dynamic oscillatory rheological properties of PP/EVA/organo-modified LDH ternary hybrids based on generalized Newtonian fluid and generalized linear viscoelastic approaches

A comprehensive investigation was performed on single-step melt processed polypropylene (PP)/(ethylene vinyl acetate copolymer (EVA)/organo-modified layered double hydroxide (LDH) counterpart ternary hybrids to explore the effect of LDH loading on small-amplitude oscillatory shear (SAOS) rheological properties and to correlate the properties with microstructure. The rheological results were analyzed in detail from qualitative and quantitative perspectives. Using qualitative interoperation of storage modulus and complex viscosity alteration against LDH loading, and also quantitative analysis by viscosity models based on both the generalized Newtonian fluid (GNF) and generalized linear viscoelastic (GLVE) approaches, detailed predictions were carried out on the microstructure of samples and also partitioning of the organo-modified LDH particles and their intercalation and exfoliation extent within hybrids. By comparing the elasticity and relaxation spectrum of PP-rich/LDH with those of EVA-rich/LDH hybrids, it was predicted that organo-modified LDH platelets, in the case of PP-rich samples, have been located at the interface or within the EVA dispersed particles, while in the case of EVA-rich samples, they mainly localized within the matrix. In addition, the crossover frequency and slope of G′ and G″ curve at terminal region were correlated with the extent of intercalated and exfoliated structures of filler. The validity of these predictions on microstructure of the developed hybrids was confirmed visually using transmission electron microscope (TEM) micrographs.

Heterocoagulated clay-derived adsorbents for phosphate decontamination from aqueous solution

A series of nanocomposite adsorbents were prepared by heterocoagulation of negatively charged delaminated montmorillonite (Mt) and positively charged synthetic layered double hydroxide (LDH) colloids with different LDH loading amounts. The mineralogy and physicochemical properties of the resulting nanocomposites were characterized. Their potential applications for phosphate (P) removal from aqueous solution, as a function of P concentration (2.5–200 mg/L), contact time (1 min–48 h) and pH (3–10), were evaluated by using batch adsorption modes. It was found that the adsorption data could be well described by both Freundlich and Langmuir isotherm models. The maximum adsorption capacity of three different LDH heterocoagulated montmorillonites (LDH-Mts) for P removal was found to increase with LDH loadings, reaching 12.6, 16.2 and 23.3 mg/g respectively; Adsorption kinetic data revealed that 90% of adsorption onto LDH-Mts was completed within 1 h (h) and the adsorption process could be well described by the pseudo-second-order model. These results demonstrated that heterocoagulation of Mt and LDH could preserve the adsorption capacity of LDH for P and enhance the stability of both clay minerals, and LDH-Mts could be effectively used as a potential promising filtration medium for P removal.

Effect of organically modified Ni–Al layered double hydroxide loading on the thermal and morphological properties of l-methionine containing poly(amide-imide) nanocomposites

This work deals with the synthesis of an organically modified Ni–Al layered double hydroxide (LDH) and the effect of the LDH loading on the thermal and morphological behavior of poly(amide-imide)/Ni–Al LDH nanocomposites.