Suchergebnisse

Modified halloysite nanotubes (HNTs-Cl) were synthesized by a coupling reaction with (3-chloropropyl) trimethoxysilane (CPTMS). The incorporation of chloro-silane onto HNTs surface creates HNTs-Cl, which has great chemical activity and is considered a good candidate as an active site that reacts with other active molecules in order to create new materials with great applications in chemical engineering and nanotechnology. The value of this work lies in the fact that improving the degree of grafting of chloro-silane onto the HNT's surface has been accomplished by incorporation of HNTs with CPTMS under different experimental conditions. Many parameters, such as the dispersing media, the molar ratio of HNTs/CPTMS/H2O, refluxing time, and the type of catalyst were studied. The greatest degree of grafting was accomplished by using toluene as a medium for the grafting process, with a molar ratio of HNTs/CPTMS/H2O of 1:1:3, and a refluxing time of 4 h. The addition of 7.169 mmol of triethylamine (Et3N) and 25.97 mmol of ammonium hydroxide (NH4OH) led to an increase in the degree of grafting of CPTMS onto the HNT's surface. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. ; This research was funded by Program 211 of the Government of the Russian Federation No. 02.A03.21.0006, RFBR grants 17-03-00641 and 18-29-12129 mk, the State Task from the Ministry of the Education and Science of the Russian Federation No. 4.9514.2017/8.9.

The rapid development in the field of material engineering makes it necessary to control material structure in the nanometric scale when modifying composite properties. In order to bring about the desired properties, the reinforcement phase must be dispersed properly in the matrix with the appropriate adhesion at the matrix-filler interface. To achieve that, various attempts to increase the specific surface of filler grains are made by activating the surface chemically or by covering with an intermediate, a compatibilizer. The aim of this study was to test the impact of a compatibilizer on the dispersion level of a nanofiller in the form of halloysite nanotubes (HNTs) in a low density polyethylene (LDPE) matrix. The content of halloysite nanotubes varied from 2 to 6 wt%. Compatibilizer used in this study is polyethylene grafted with maleic anhydride (PE-graft-MA). After sputtering samples with a thin layer of gold the homogenization analysis was carried out on the basis of photographs taken on a Scanning Electron Microscope (SEM), at a magnification of up to 3500 times. During the microscopic examination, the occurrence of agglomerates of halloysite nanotubes, which size reached several dozen micrometers, was observed (Figure 1). Despite the occurrence of agglomerates, the distribution of nanotubes can be described as good and even [1].We may assume that the presence of agglomerates during the halloysite nanotubes manufacturing of nanocomposites is not unusual, according to the results presented in other papers [1-3] ; EUROPEAN UNION

The aim of the present work is to investigate the e ect of halloysite nanotubes (HNT) on the mechanical properties of low-density polyethylene composites modified by maleic anhydride-grafted PE (PE-graft-MA). Polyethylene nanocomposites were prepared using an injection molding machine, Arburg Allrounder 320 C 500–170; the HNT content was varied at 0 wt %, 2 wt %, 4 wt % and 6 wt %, and the PE-graft-MA content was varied at 5 wt %. The composites were examined for their ultimate tensile stress, strain at ultimate stress, hardness, impact strength, melt flow rate, heat deflection temperature, Vicat softening temperature, crystallinity degree and phase transition temperature. It was found that the addition of halloysite nanotubes to low-density polyethylene (LDPE) led to an increased heat deflection temperature (HDT, up to 47 C) and ultimate tensile strength (up to 16.00 MPa) while the Vicat softening temperature, strain at ultimate stress, impact strength and hardness of examined specimens slightly decreased. Processing properties of the materials specified by the melt flow rate (MFR) deteriorated almost twice. The results have demonstrated that the nanoparticles can reinforce enhance LDPE at low filler content without any considerable loss of its ductility, but only when halloysite nanotubes are superbly distributed in the polyethylene matrix. ; European Union

Halloysite nanotubes are becoming interesting materials for drug delivery. The knowledge of surface interactions is important for optimizing this application. The aim of this work is to perform a computational study of the interaction between 5-aminosalicylic acid (5-ASA) drug and halloysite nanotubes for the development of modified drug delivery systems. The optimization of this nanotube and the adsorption of different conformers of the 5-ASA drug on the internal surface of halloysite in the presence and absence of water were performed using quantum mechanical calculations by using Density Functional Theory (DFT) and methods based on atomistic force fields for molecular modeling, respectively. ; Authors are thankful to Helio Anderson Duarte for providing atomic coordinates of a slice of halloysite and César Viseras for their fruitful discussions, and to the CSIC Computational Center for computation facilities. This work is funded by the Andalusian Government projects (RNM1897) and the MINECO project FIS2016-77692-C2-2P. It also supported by the Egyptian Cultural Affairs and Missions Sector (Plan 2013-2014), Ministry of Higher Education. M.E.A. is especially thankful to the Egyptian Cultural Affairs and Missions Sector, Mahmoud Mohamed El Rahmany, and Mahmoud Hassaan El-Basha (Faculty of Science, Al-Azhar University in Cairo), for their encouragements and fruitful discussions.

Halloysite nanotubes are becoming interesting materials for drug delivery. The knowledge of surface interactions is important for optimizing this application. The aim of this work is to perform a computational study of the interaction between 5-aminosalicylic acid (5-ASA) drug and halloysite nanotubes for the development of modified drug delivery systems. The optimization of this nanotube and the adsorption of different conformers of the 5-ASA drug on the internal surface of halloysite in the presence and absence of water were performed using quantum mechanical calculations by using Density Functional Theory (DFT) and methods based on atomistic force fields for molecular modeling, respectively. ; This work is funded by the Andalusian Government projects (RNM1897) and the MINECO project FIS2016-77692-C2-2P. It also supported by the Egyptian Cultural Affairs and Missions Sector (Plan 2013-2014), Ministry of Higher Education.

[EN] This work aims to study the effect of immersion in a ethanolic food simulant in mechanically recycled poly(lactic acid) (PLAR) and its nanocomposites reinforced with halloysite nanotubes (HNT). PLAR was obtained by subjecting PLA to an accelerated ageing process, which includes photochemical, thermal and hydrothermal ageing steps, followed by a final demanding washing step. PLAR was further reinforced with 4 %wt. HNT to improve the properties of the PLAR films. The materials were melt compounded by melt extrusion and processed into films by compression molding. The resulting films were exposed to food simulant D1 (50 %vol. ethanol solution) for 10 days at 40 °C. The intrinsic viscosity, crystallization behavior, thermal stability as well as the mechanical performance were analyzed before and after the contact with the food simulant. The swelling, plasticizing and hydrolyzing effect of the food simulant led to an important decrease of the intrinsic viscosity of all the samples, along with a significant increase of the crystallinity. Thermal stability was negatively affected by the decrease of the molecular weight, while the high crystallinity values resulted in materials with higher Vickers hardness values after the immersion in the food simulant. ; This work was supported by European Union's Horizon 2020 research and innovation program [grant agreement No. 860407 BIO-PLASTICS EUROPE], by MINECO-Spain [project CTM2017-88989-P] as well as Universidad Politécnica de Madrid [project UPM RP 160543006]. ; Beltrán, FR.; Arrieta, MP.; Hortal, Y.; Gaspar, G.; De La Orden, MU.; Martínez Urreaga, J. (2021). Degradation of a mechanically recycled polylactide/halloysite nanocomposite in an ethanolic food simulant. Journal of Applied Research in Technology & Engineering. 2(2):63-70. https://doi.org/10.4995/jarte.2021.15297 ; OJS ; 63 ; 70 ; 2 ; 2 ; Agüero, A., Morcillo, D.M., Quiles-Carrillo, L., Balart, R., Boronat, T., Lascano, D., & Fenollar, O. (2019). Study of the influence of the reprocessing cycles on the ...

Reinforcing thermoplastic polymers with nanotubes or nanoplatelets to form nanocomposites is a way to increase the usage of polymeric materials in engineering applications by improving their mechanical properties. The contribution presents the results of research from basic processing and mechanical properties of nanocomposites. Low-Density Polyethylene (LDPE) was used as a matrix for experiments. The material LDPE was modified by Halloysite nanotubes (HNT) with a mass share of 2, 4, 6 wt% of the matrix LDPE. Nanocomposites were filled with 5 wt% Polyethylene grafted with maleic anhydride (PE-graft-MA) as a compatibility factor. The specimens were prepared by injection molding and their selected mechanical properties were tested by static tensile test, Charpy impact test and Shore hardness test. ; European Union