Papers by Keyword: Halloysite Nanotubes

Abstract: Polyphenylene sulfide (PPS) fiber is widely used in the fields of high-temperature filtration, protective clothing, electronics, automobile, and aircrafts sectors relying on its excellent heat and chemical resistance. However, PPS fiber is easily oxidized under high temperature, which vastly restricts its applications. In this study, using the copper nanoparticles loaded halloysite nanotubes (HNTs@Cu) as a nanofiller, we prepared a PPS composite fiber with improved oxidation resistance. The successful loading of copper nanoparticles into HNTs was demonstrated through TEM and elemental analysis. The crystallinity, orientation, thermal and mechanical properties of PPS nanocomposite fibers were investigated via DSC, XRD, WXRD, TGA and mechanical test. While the mechanical performance of the composite fibers was slightly decreased, the thermal stability was improved when comparing to the neat PPS fiber. The composite fiber with 1.0 wt.% loading of HNTs@Cu showed an over 100% retention rate of breaking strength after thermal oxidative aging, suggesting an improvement in oxidation resistance of PPS fiber. This work provides an effective and accessible method for improving the thermal stability and oxidation resistance of PPS fibers, which thereby helps to extend the applications of PPS fibers in high temperature environment.

Abstract: Self-healing composites are smart materials that can be fabricated through the dispersion of tubular nanofillers loaded with appropriate healing agents in a polymeric matrix. In this study, polysulfone (PSf) containing epoxy-loaded halloysite nanotubes (e-HNTs) were successfully fabricated via non-induced phase separation (NIPS) method at varying concentrations. Fourier Transform Spectroscopy (FTIR) analysis showed that epoxy (healing agent) and amine (hardener) were successfully loaded into the lumen of the HNT through the observed functional groups of the epoxy system along the HNT spectrum. The tensile strength of the loaded membranes compared to their unloaded counterpart slightly decreased due to the possible embrittlement of the unreacted epoxy. However, the membranes with epoxy-loaded HNTs garnered lower wettability on average due to the hydrophobic character of the epoxy system, which is a preferable trait for smart coatings. The self-healing capability of the membranes with 5% filler (loaded and unloaded) was investigated by scratch test and Scanning Electron Microscopy (SEM). The result revealed a high tendency of healing for the epoxy-infused nanocomposite film.

Abstract: In this study, PLA/TiO₂ and PLA/HNTs-TiO₂ nanocomposites films were fabricated via solution casting method. By testing the film density, solubility, water contact angle and water vapor permeability, the PLA nanocomposite films, the comprehensive performances of the nanocomposites were analysed. The outcomes demonstrated that maximum film density of PLA/TiO₂ and PLA/HNTs-TiO₂ nanocomposites films increased gradually with the increasing of nanofiller loadings. Moreover, the incorporation of TiO₂ and HNTs-TiO₂ significantly decreased the water vapor transmittance rate of the nanocomposite films with a slight priority to the addition of HNTs-TiO₂, the water solubility was significantly improved with the addition of both nanofillers. Furthermore, the barrier properties were developed with the addition of both TiO₂ and HNTs-TiO₂ especially after the addition of low nanofiller loadings. Overall, the performance of the PLA/HNTs-TiO₂ nanocomposite films was better than that PLA/TiO₂ film. Nevertheless, both of the PLA nanocomposite samples achieved the requests of food packaging applications.

Abstract: Polylactic acid (PLA) nanocomposite samples with different properties like mechanical, thermal, barrier and antibacterial properties are good candidates as packaging biomaterials. Unique PLA/TiO₂ and PLA/HNTs-TiO₂ nanocomposite samples were fabricated by solution casting method. The mechanical and antibacterial properties of PLA/TiO₂ and PLA/HNTs-TiO₂ samples were investigated with comparing to the pristine PLA film as a control sample. PLA nanocomposite samples with TiO₂ nanofillers showed poorer mechanical properties while PLA films with PLA/HNTs-TiO₂ showed unique developments, which tensile strength improved by 46% with the incorporation of 5 wt%. The PLA nanocomposites showed a high efficiency to both Gram positive and Gram negative bacteria, significant antibacterial effect being proved after first week elapsed time by comparing to the control sample (presenting no antibacterial effect). By considering the multifunctional characteristics of PLA/TiO₂ and PLA/HNTs-TiO₂ nanocomposites, the samples produced by solution casting can be considered a favourable alternative as environmental-friendly packaging materials.

Abstract: This study aimed to develop novel Polylactic acid/ Halloysite (PLA/ HNTs) films which showed better properties when they were used for food packaging. They also displayed better mechanical, barrier, morphological and structural properties when the researchers analysed the impact of the electron beam irradiation on the nanomaterials. They prepared PLA-based nanocomposites containing 5 % w/w of HNTs using the solution casting process. These nanocomposites were further exposed to different ebeam doses (i.e., 0, 20, 40 and 60 kGy). The researchers assessed the effect of the electron beam irradiation on the various properties of the PLA. All the composites showed a homogenous dispersion and distribution of the HNTs in this PLA matrix. Results indicated that the nanocomposites showed better barrier properties in comparison to the neat PLA. Furthermore, the ebeam irradiation could increase the glass-transition temperature and lead to the development of more crosslinks, which increased the degradation temperature and hydrophilicity of the nanocomposites. In this study, the researchers showed that the PLA/HNTs films were effective materials that could be used for the electron beam processing of the pre-packed foods. The best effect was noted for the 20 kGy dosage which was used in the study.

Abstract: Polylactic acid (PLA) has recently given a huge attention because of its mechanical properties and good physical like good biodegradability and processability, high tensile modulus and strength. In the current research, the researchers utilized sesame oil (SO) and low molecular weight polyethylene glycol (PEG) as hydrophobic and hydrophilic plasticizers, towards improvise the ductility and toughness of PLA. The researchers synthesized nanocomposites by solution casting of the neat PLA/HNTs and PLA blends with weight ratio of (0,10, 20 and 30 wt%) for PEG and (0, 5 and 10 wt%) for SO. The influence of both plasticizers on chemical, thermal and mechanical properties of the nanocomposites were investigated. Characterization of the systems was achieved by mechanical testing and thermogravimetric analysis (TGA), field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR). The FTIR analyses confirmed the existing of hydrogen bonding between PLA and both PEG and SO. significant improvement was shown by the plasticized nanocomposites in elongation at break with the adding of PEG and SO, meanwhile, the plasticized films’ strength were decreased. For the thermal analyses, all the films exhibited lower thermal stability compared to PLA/HNTs film.

Abstract: The stabilizer nature effect on the aggregative stability of the modifying concrete additives based on halloysite nanotubes in the aquatic environment is shown. The chemical composition and morphology of halloysite nanotubes and their additives, obtained by ultrasonic dispersion in the aquatic environment of the surfactant, are studied. The influence on the processes of charge stabilization on the outer and inner surface of halloysite nanotubes is determined. The dependence of nanotube sizes and specific surface area on the stabilizer type, the time of ultrasonic dispersion, and additive storage is revealed. The stabilization mechanisms of aqueous dispersions of modifying additives based on halloysite nanotubes with anion-and cation-active substances are considered. It is established that the polynaphthalenesulfonate-based modifier S-3 has got the maximum efficiency as a stabilizer of aqueous dispersions of modifying concrete additives with halloysite nanotubes.

Abstract: Polysulfone (PSf) is one of the commonly used polymeric membrane materials due to its excellent properties. One of the major concern however is that PSf membranes are mostly hydrophobic in nature. The presence of fillers like halloysite nanotubes (HNTs) into the polymer matrix can decrease this hydrophobicity and may also alter some of its important properties. This study focused on the fabrication of nanofibrous membranes by electrospinning method and characterization using SEM, UTM and contact angle goniometer to determine the effect of HNT concentration to the membrane’s surface morphology, mechanical properties and wettability. Results showed that samples subjected at the highest voltage produced finer fibers. The initial addition of HNTs also creates fiber strands with smaller diameters until beading in the fibers due to perturbation of the polymer jet caused by the increased viscosity of the solution and particle agglomeration was observed at higher concentrations. In terms of response to mechanical load, the tensile strength was higher upon HNT integration showing an effective transfer of stress to the dispersed phase despite the morphological imperfections. The contact angle results showed a decrease in hydrophobicity at the highest HNT concentration reflecting the water-loving character of the filler. The overall data gathered showed that the addition of nanoclay improved the properties of PSf matrix making them a suitable material for different filtration applications particularly in water treatment systems.

Abstract: 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. Nanocomposites were filled with 5 wt% Polyethylene grafted with maleic anhydride (PE-graft-MA) as a compatibilizer. 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.

Abstract: This paper deals with the characterization of the physico-mechanical properties of starch-grafted-polyethylene (Starch-g-PE)/unmodified Algerian halloysite nanotubes (HNT) nanocomposites prepared by melt compounding. The nanoclay was incorporated at various filler contents, i.e., 1.5, 3 and 5 wt%. Rheological and tensile properties of the nanocomposites were evaluated by different techniques and the results obtained are compared with those of virgin Starch-g-PE matrix. The study shows a decrease in melt flow index (MFI) values upon increasing the HNT content, which indicates a restriction in the polymer chains mobility due to the confinement effect of HNT. Further, a tensile strength is also improved.