Halloysite Nanotubes Nanocomposites Research Articles

Tensile modulus of polymer halloysite nanotubes nanocomposites assuming stress transferring through an imperfect interphase

In this work, Hui-Shia model is developed to reveal the efficiency of a deficient interphase on the tensile modulus of polymer halloysite nanotube (HNT) nanocomposites. “Lc” as essential HNT length providing full stress transferring is defined and effective HNT size, effective HNT concentration, and efficiency of stress transferring (Q) are expressed by “Lc”. Furthermore, the influences of all terms on the “Q” and nanocomposite’s modulus are clarified, and also the calculations of the model are linked to the tested data of some nanocomposites. Original Hui-Shia model overpredicts the moduli, but the innovative model’s predictions appropriately fit the measured data. Lc = 200 nm maximizes the sample’s modulus to 2.6 GPa, but the modulus reduces to 2.11 GPa at Lc = 700 nm. Therefore, there is a reverse relation between the sample’s modulus and “Lc”. Q = 0.5 produces the system’s modulus of 2.1 GPa, while the modulus of 2.35 GPa is achieved at Q = 1 providing a direct relation between the nanocomposite’s modulus and “Q”. Generally, narrow and big HNTs, along with a low “Lc”, enhance the “Q”, because a lower “Lc”, reveals a tougher interphase improving the stress transferring.

Synthesis of Ag nanoparticles supported on magnetic halloysite nanozyme for detection of H2O2 in milk and serum

In the present study, Ag nanoparticles modified Fe3O4 anchored on roughened halloysite nanotubes nanocomposites (Ag@Fe3O4/RHNT) with high peroxidase-like activity and good magnetism was fabricated, and accordingly, an efficient and sensitive colorimetric sensing platform was established for the detection of H2O2. Firstly, halloysite nanotubes was pre-treated and then Fe3O4 nanoparticles were uniformly deposited on the external surface of RHNTs. Finally, Ag nanoparticles were grown onto Fe3O4/RHNT by in-situ reduction method. All characterization results confirmed the successful synthesis of Ag@Fe3O4/RHNT. The resultant Ag-Fe3O4 RNHTs exhibited satisfied catalytic activity to the oxidation of TMB (4,4’-Diamino-3,3′, 5,5′-tetramethylbiphenyl) in the presence of H2O2, and the catalytic process is accompanied with the color changed from colorless to bule. Thus, a sensitive colorimetric sensor for detection of H2O2 was developed based on Ag@Fe3O4/RHNT nanocomposites. And the optimal reaction temperature and pH were determined to be 55 °C and 4, respectively. H2O2 can be detected in the range of 10–100 μM with the detection limit of 0.7 μM. In conclusion, we established an efficient colorimetric sensing system for H2O2, and applied it to detect H2O2 in milk and serum.

A modified version of conventional Halpin-Tsai model for the tensile modulus of polymer halloysite nanotube nanocomposites by filler network and nearby interphase

Conventional Halpin-Tsai model neglects the nets of filler and interphase in the composites above mechanical percolation onset. Here, Halpin-Tsai model is developed to calculate the modulus of halloysite-nanotube (HNT)-based composites by interphase/HNT nets. The novel model correlates the stiffness to the moduli and concentrations of nanofiller, HNT net and adjoining interphase net. The experimentally measured moduli of several composites and the examinations of parameters are used to examine the calculations of advanced model. All calculations correctly match to the experimental facts and the parametric examinations show the acceptable outputs. The nanocomposite's modulus of 3.27 GPa is calculated by the interphase volume fraction of 0.02. Also, HNT length of 0.5 μm obtains the modulus of 2 GPa, while the modulus of system develops to 4.3 GPa at filler length of 4 μm. The percolation onset of 0.001 maximizes the modulus to 3.9 GPa, but the stiffness reduces to 2.65 GPa in the percolation onset of 0.01. In addition, the filler net modulus of 150 GPa harvests the stiffness of 2.47 GPa, nonetheless the stiffness raises to 3.9 GPa at the net modulus of 500 GPa.

Synthesis and investigation of hyperthermia properties of Fe3O4/HNTs magnetic nanocomposite

In this study, combining magnetic nanoparticles with halloysite nanotubes (HNTs), Fe3O4/ HNTs nanocomposites were synthesized using the co-precipitation method. The synthesized nanocomposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), Thermogravimetric analysis (TGA), energy-dispersive Xray (EDX) analysis, vibrating sample magnetometer (VSM). At room temperature, the saturation magnetization (MS) showed that Fe3O4 and Fe3O4/ HNTs nanoparticles have a magnetic saturation of 73.84 emu/g and 30.63 emu/g, respectively. The maximum specific absorption rates (SARs) obtained for Fe3O4/ HNTs nanocomposites were 94 w/g at a frequency of 400 kHz and 53 w/g at a frequency of 200 kHz, respectively. The results show that Fe3O4/ HNTs nanocomposites are desirable in the application of hyperthermia to treat cancer.

Development of a model for modulus of polymer halloysite nanotube nanocomposites by the interphase zones around dispersed and networked nanotubes

Theoretical studies on the mechanical properties of halloysite nanotube (HNT)-based nanocomposites have neglected the HNT network and interphase section, despite the fact that the network and interphase have significant stiffening efficiencies. In the present study, the advanced Takayanagi equation for determining the modulus of nanocomposites is further developed by considering the interphase zones around the dispersed and networked HNTs above percolation onset. Furthermore, simple equations are provided to determine the percolation onset of HNTs and the volume portions of HNTs and interphase section in the network. The experimental values obtained for many samples and the assessments of all relevant factors validate the proposed model. The high ranges of HNT concentration, interphase depth, HNT modulus, HNT length, network modulus, interphase modulus, interphase concentration, and network fraction enhance the system modulus. However, the low levels of HNT radius, percolation onset, and matrix modulus can intensify the reinforcing effect. Notably, the moduli of the dispersed HNTs and the surrounding interphase negligibly affect the modulus of the samples. Moreover, HNTs cannot reinforce the polymer medium when the HNT volume fraction is lower than 0.01 and the interphase depth is less than 5 nm.

Microstructure and Mechanical Properties of Carboxylated Nitrile Butadiene Rubber/Epoxy/XNBR-grafted Halloysite Nanotubes Nanocomposites.

The effect of various amounts of carboxylated nitrile butadiene rubber (XNBR) functionalized halloysite nanotubes (XHNTs) on the cure characteristics, mechanical and swelling behavior of XNBR/epoxy compounds was experimentally and theoretically investigated. The morphology of the prepared XNBR/epoxy/XHNTs nanocomposites was imaged using scanning electron microscopy (SEM). The effects of various XNBR-grafted nanotubes on the damping factor of nanocomposites were evaluated by dynamic mechanical thermal analysis (DMTA). The cure behavior characterization indicated a fall in the scorch time, but a rise in the cure rate with higher loading of XHNTs into the XNBR/epoxy nanocomposites. SEM micrographs of tensile fracture surfaces were indicative of a rougher fracture surface with a uniform dispersion state of nanotubes into the polymer matrix in the XNBR/epoxy/XHNTs nanocomposites. The stress–strain behavior studies of XNBR/epoxy/XHNTs nanocomposites showed a higher tensile strength up to 40% with 7 wt % XHNTs loading. The theoretical predictions of uniaxial tensile behavior of nanocomposites using Bergström–Boyce model revealed that some of the material parameters were considerably changed with the XHNTs loading. Furthermore, the used theoretical model precisely predicted the nonlinear large strain hyperelastic behavior of nanocomposites.

UV-protective properties of poly(lactic acid) nanocomposites containing chemical treated halloysite nanotube

Abstract The aim of this study is to investigate the effects of chemical treated halloysite nanotube (HNT) on the optical and UV-protective properties of poly(lactic acid) (PLA) nanocomposites. Two strategies were used to modify the HNT, i.e., sodium dodecyl sulfate (SDS) surface modification and zinc oxide (ZnO) immobilization on HNT. The Si-O index measurement via Fourier transform infrared (FTIR) spectroscopy analysis proved that chemical interaction occurred between HNT and SDS. Transmission electron microscopy (TEM) evidenced that the ZnO nanoparticles were successfully immobilized on the HNT surface. PLA/treated HNT nanocomposites were prepared using melt compounding followed by compression molding. The PLA/HNT nanocomposites were characterized by UV-visible spectroscopy (UV-Vis). The visible-shielding ratio (VR) and UV-blocking ratio (UVR) of the PLA/HNT nanocomposite films were determined. Both PLA/SDS-treated HNT and PLA/ZnO treated HNT nanocomposites exhibited higher UV-blocking property compared to that of PLA/untreated HNT nanocomposites.

Tribological and mechanical properties of polyamide-11/halloysite nanotube nanocomposites

Abstract This article reports some morphological, tribological, and mechanical data on polyamide-11(PA11)/halloysite nanotube (HNT) nanocomposites prepared by melt-compounding. HNTs extracted from the Djebel Debbagh deposit in Algeria were incorporated into the polymer at 1, 3, and 5 wt%. For comparison, commercial HNTs were also used under the same processing conditions. Scanning electron microscopy showed that both HNTs were homogeneously dispersed in the PA11 matrix, despite the presence of few aggregates, in particular at higher filler contents. The tribological properties were significantly improved, resulting in a decrease in the friction coefficient and the wear rate characteristics due to the lubricating effect of HNTs. This is consistent with optical profilometry data, which evidenced the impact of both types of HNTs on the surface topography of the nanocomposite samples, in which the main wear process was plastic deformation. Furthermore, Young’s modulus and tensile strength were observed to increase with the filler content, but to the detriment of elongation at break and impact strength. Regarding the whole data, the raw Algerian halloysite led to interesting results in PA11 nanocomposites, thus revealing its potential in polymer engineering nanotechnology.

Surface‐modified halloysite nanotubes reinforced poly(lactic acid) for use in biodegradable coronary stents

ABSTRACTPoly(lactic acid) (PLA) was reinforced halloysite nanotubes (HNTs) in this study. To improve dispersion and interfacial adhesion of HNTs within the PLA matrix, HNTs were surface modified with 3‐aminopropyltriethoxysilane (ASP) prior to compounding with PLA. PLA/ASP‐HNTs nanocomposites were characterized by differential scanning calorimetry (DSC), Fourier transfer infrared spectroscopy (FTIR), surface wettability, thermogravimetric analysis, transmission electron microscopy (TEM), and tensile testing. The hemocompatibility and cytocompatibility of PLA and PLA composites were investigated and the in vitro degradation process of PLA/ASP‐HNTs composites was investigated for a period of 6 months by gel permeation chromatography, FTIR, weight loss measurement, DSC, and tensile testing. PLA and all PLA composites were blood compatibile and non‐cytotoxic. TEM analysis revealed that HNTs agglomeration in PLA matrix was reduced by surface treatment with ASP. ASP‐HNTs had better reinforcing effect than unmodified HNTs evidenced by tensile testing. ASP‐HNTs appeared to increase the hydrolytic degradation process as measured by weight measurement. PLA/ASP‐HNTs composites displayed 12.1% weight loss and 30.6% average molecular weight reduction while retaining 74% of Young's modulus by the 24th week of degradation. Based on this data, the reinforcement of PLA using ASP‐HNTs may prove beneficial for applications such as biodegradable stents. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46521.

Fabrication and characterization of polymer-ceramic nanocomposites containing drug loaded modified halloysite nanotubes.

Modified halloysite nanotubes (HNT-NH2 and HNT-COOH) were synthesized by a coupling reaction with 3-aminopropyltriethoxysilane and maleic anhydride from hydroxyl groups of neat halloysite nanotubes (HNTs). Successful attachment of functional groups onto HNTs was evaluated by Fourier transform infrared and thermogravimetric analysis. X ray diffraction was used to study the crystalline structure of scaffolds and the formation of intercalated structure as a result of improved dispersion and decreased agglomeration of modified nanoparticles. Neat HNT, HNT-NH2 , and HNT-COOH were subsequently introduced into polycaprolactone/Pluronic P123 (PCL/P123) electrospun substrate. Morphology, thermodynamics, mechanics, and biocompatibility of resulted electrospun nanocomposites were evaluated. Nanofibers containing modified HNTs showed excellent mechanical performance and thermal stability in comparison with those containing neat HNTs. homogeneous dispersion of the modified HNTs and strong interfacial adhesion between nanotubes and polymer matrix can be considered for mentioned improvements. Ultraviolet-visible spectrophotometer was used to study diphenhydramine hydrochloride and diclofenac sodium release from nanocomposites containing drug loaded modified and neat HNTs. Nanocomposites containing drug loaded HNT-COOH exhibited prolonged release of drug molecules in comparison with that of neat HNTs. MTT assay reveled that PCL/P123/modified HNTs nanocomposites provide a suitable platform for cell growth where PCL/P123/HNT-NH2 can facilitate cell attachment through electrostatic interactions between negatively charged phospholipids bilayer membrane of cells and positively charged HNT-NH2 embedded in PCL/P123 substrate. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1276-1287, 2018.

Nanocomposites of Polypropylene and Halloysite Nanotubes Prepared by a Novel Vane Mixer

Halloysite nanotubes (HNTs) were used to prepare polypropylene (PP) nanocomposites through a novel vane mixer. The effects of melt blend time and halloysite content on properties of composites were investigated. SEM analysis was performed to show that HNTs were well dispersed in PP matrix with the increase of mixing time. DSC showed both the degree of crystallinity and crystallization temperature increased due to the introduction of HNTs into PP, which indicating a potential nucleation effect induced by the nanotubes. TGA illustrated that the presence of HNTs had two opposite effects on the thermal behavior. A surface catalytic action of the halloysite speeded up thermal degradation of PP. However, this effect was reduced with improved HNTs dispersion. Rheological investigations revealed that rheological properties were significantly increased by the addition of low fraction of halloysite to PP. The 2 wt% HNTs nanocomposites reached maximum tensile strength because HNTs dispersed evenly in PP.

Poly(lactic acid)/halloysite nanotube nanocomposites with high impact strength and water barrier properties

Poly(lactic acid)/halloysite nanotube nanocomposites containing epoxidized natural rubber were prepared using melt compounding, followed by compression molding. The mechanical properties of the nanocomposites were determined by tensile, flexural, and Charpy impact test. The addition of 15 wt.% epoxidized natural rubber into poly(lactic acid)/halloysite nanocomposites increased the impact strength to about 340%. However, the tensile modulus, flexural modulus, tensile strength, flexural strength, and elongation at break of poly(lactic acid)/halloysite nanotube were decreased in the presence of epoxidized natural rubber. Water absorption tests were performed at three immersion temperatures (i.e. 30, 40, 50℃). The equilibrium water absorption ( Mm), diffusion coefficient ( D), and activation energy ( Ea) of water diffusion of the poly(lactic acid)/halloysite nanotube/epoxidized natural rubber nanocomposites were determined. The activation energy of poly(lactic acid)/halloysite nanotube was increased from 14.7 to 31.8 kJ/mol by the addition of epoxidized natural rubber. The percentage retention of impact strength of poly(lactic acid)/halloysite nanotube/epoxidized natural rubber nanocomposites after exposure to water absorption is higher than 80% for the one containing 5 and 10 wt.% epoxidized natural rubber loading.

Impact, Thermal, and Morphological Properties of Poly(Lactic Acid)/Poly(Methyl Methacrylate)/Halloysite Nanotube Nanocomposites

ABSTRACTPoly(lactic acid)/poly(methyl methacrylate) blends containing halloysite nanotube (2 and 5 phr) and epoxidized natural rubber (5–15 phr) were prepared by melt mixing. The impact strength of poly(lactic acid)/poly(methyl methacrylate) blend was slightly improved by the addition of halloysite nanotube. Adding epoxidized natural rubber further increased the impact strength of poly(lactic acid)/poly(methyl methacrylate)/halloysite nanotube nanocomposite. Single Tg of poly(lactic acid)/poly(methyl methacrylate) is observed and this indicates that poly(lactic acid)/poly(methyl methacrylate) blend is miscible. The addition of halloysite nanotube into poly(lactic acid)/poly(methyl methacrylate) slightly increased the Tg of the blends. The epoxidized natural rubber could encapsulate some of the halloysite nanotube and prevent the halloysite nanotube from breaking into shorter length tube during the melt shearing process.

Investigation of halloysite nanotubes with deposited silver nanoparticles by methods of optical spectroscopy

Halloysite nanotube composites covered by silver nanoparticles with the average diameters of 5 nm and 9 nm have been studied by methods of optical spectroscopy of reflectance/transmittance and Raman spectroscopy. It has been established that silver significantly increases the light absorption by nanocomposites in the range of 300 to 700 nm with a maximum near 400 nm, especially for the samples with the nanoparticle size of 9 nm, which is explained by plasmonic effects. The optical absorption increases also in the long-wavelength spectral range, which seems to be due to the localized electronic states in an alumosilicate halloysite matrix after deposition of nanoparticles. Raman spectra of nanocomposites reveal intense scattering peaks at the local phonons, whose intensities are maxima for the samples with the silver nanoparticle sizes of 9 nm, which can be caused by plasmonic enhancement of the light scattering efficiency. The results show the ability to use halloysite nanotube nanocomposites in photonics and biomedicine.

An ultrasensitive sandwich-type electrochemical immunosensor based on δ-MnO2 and palladium nanoparticles covered natural halloysite nanotubes for the detection of hepatitis B surface antigen

An ultrasensitive sandwich-type immunosensor for the detection of HBsAg based on the multifunctional natural halloysite nanotube nanocomposites (Pd/δ-MnO2/HNTs).

Preparation and Solar Light Photocatalytic Activity of N-Doped TiO2-Loaded Halloysite Nanotubes Nanocomposites

A novel method to prepare N-doped TiO2-loaded halloysite nanotubes (N-TiO2/HNTs) nanocomposites was achieved by using the chemical vapor deposition in autoclave. The N-TiO2/HNTs nanocomposites obtained by the different form of the doping N source were studied through a series of characterizations. The XRD, SEM, and TEM characterizations verified the anatase structure of TiO2 nanoparticles with the size of ca.20nm loaded on the outer surface of HNTs. The UV-vis characterization of the N-TiO2/HNTs presented a further red-shift compared to the pure N-TiO2 nanoparticles.. The XPS characterizations confirmed the N element doped into the crystal structure of TiO2 nanoparticles. The photocatalytic activities of N-TiO2/HNTs nanocomposites prepared were evaluated by degradation of phenol at room temperature under simulated solar light irradiation.

Preparation and characterization of mechanically and thermally enhanced polyimide/reactive halloysite nanotubes nanocomposites

High modulus and thermal stability of polyimide (PI)/reactive halloysite nanotubes (HNTs) nanocomposites were prepared by in situ polymerization. The pristine HNTs were firstly handled with the tetraethoxysilane (TEOS) and secondly grafted with the silane agent. The fourier transform infrared spectroscopy (FTIR) approved that TEOS was beneficial for the silane agent to modify the HNTs. Scanning electron microscopy (SEM) showed the differences of the morphology between the reactive HNTs and pristine HNTs. PI/reactive HNTs nanocomposites exhibited lower moisture absorption than pure polyimide. The reactive HNTs reduced the transmittance of the nanocomposites. Significant improvements in the thermal stability and glass transition temperature (Tg) of PI/reactive HNTs nanocomposites were achieved by addition of only a small amount of reactive HNTs. It was noteworthy that both the tensile strength and Young' modulus of PI/reactive HNTs nanocomposites were significantly enhanced. A 62.8 % increase in tensile strength and a 63.7 % increase in Young' modulus of the nanocomposites with 3 wt.% of the reactive HNTs were achieved. Finally, the preparation mechanism to obtain PI/reactive HNTs nanocomposites was proposed.

One-Step in Situ Modification of Halloysite Nanotubes: Augmentation in Polymer–Filler Interface Adhesion in Nanocomposites

Nanocomposites of chlorinated polyethylene/ethylene methacrylate copolymer (60/40 ratio) with augmented polymer–filler interface adhesion were prepared by following a facile covalent modification of halloysite nanotubes (HNTs). The covalent modification of the outer and inner lumen structures of HNTs were pursued by two different methods: in-situ ring opening polymerization of e-caprolactone and silane modification using organosilane (3-aminopropyl)triethoxysilane. Fourier transform infrared spectroscopy, X-ray diffreaction, high-resolution transmission electron microscopy, and water contact angle measurement manifests a successful organic covalent modification of the HNT surface. The synergistic mechanical properties of covalently poly(e-caprolactone)-modified HNT nanocomposites come from the ameliorated polymer–filler interface interaction that can be understood by the study of the “Pukanszky model” and dynamic mechanical analysis. The rheology study of nanocomposites help understand the polymer–filler ...

Preparation and characterization of polycarbonate nanocomposites based on surface-modified halloysite nanotubes

Halloysite nanotubes (HNTs) modified by a chemical vapor adsorption (CVA) process remarkably improve the thermal stability of polycarbonate nanocomposites. HNTs were modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPS) and n-octadecyltrimethoxysilane (OTMS) using a CVA process. Both Fourier-transform infrared spectroscopy and thermogravimetric analysis showed that the modifiers were immobilized on the HNT surfaces. Polycarbonate (PC)/HNT nanocomposites were prepared with the modified HNTs by a combination of solution mixing, precipitating and compression molding. The dispersion states of modified HNTs in PC nanocomposites were observed by optical microscopy, scanning electron microscopy and transmission electron microscopy. The storage modulus (E′) and thermal stability of the PC nanocomposites were enhanced by the modified HNTs. OTMS-modified HNT/PC nanocomposites showed higher performance than AEAPS-modified HNT/PC nanocomposites due to the stronger affinity of the hydrophobic alkyl groups of OTMS for the polymer matrix.

Towards scalable production of polyamide 12/halloysite nanocomposites via water-assisted extrusion: mechanical modeling, thermal and fire properties

In this study, polyamide 12 (PA12)/untreated halloysite nanotubes (HNTs) nanocomposites are prepared in a semi-industrial scale extruder using a non-traditional “one step” water-assisted extrusion process. A morphological study is carried out using a combination of scanning electron microscopy and transmission electron microscopy analyses to evaluate the influence of water injection and filler content on the quality of clay dispersion. The use of water injection slightly improves the nanoscale dispersion at low HNTs content (<8 wt.%), while this effect is more pronounced at higher filler loading (16 wt.%). A mechanism explaining the physico-chemical action of water during extrusion is proposed. The materials are characterized with respect to their mechanical, thermo-mechanical, thermal and fire properties. A strong correlation is found between nanostructure and physical properties; the more uniform dispersion of the clay nanotubes, the higher mechanical reinforcement, thermal stability and fire retardancy of PA12 nanocomposites. Tensile tests results are interpreted in terms of three mechanical models: the Halpin–Tsai's model for stiffness and the interfacial strength model and the Pukanszky's equation for yield strength. Linear fits of the experimental data confirm that the superior reinforcement of nanocomposites prepared using water injection results from improved clay dispersion and better interfacial adhesion between PA12 and HNTs. In view of these promising results, the proposed direct melt compounding method could be easily scaled-up towards the production of PA12–HNTs nanocomposites at an industrial scale. Copyright © 2013 John Wiley & Sons, Ltd.