Cloisite 20A Research Articles

On the possibility of using waste disposable gloves as recycled fibers in sustainable 3D concrete printing using different additives

Due to the Covid-19 pandemic, using large amounts of personal protective equipment (PPE) throughout the world has extensively increased in recent years. The lack of a practical method to dispose of these recycled materials is one of the main concerns of researchers. Hence, comprehensive experimental tests were conducted in the present study to investigate the feasibility of using disposable gloves in mortars to achieve a sustainable mixture. Accordingly, latex and vinyl gloves as recycled fibers were considered in the experimental program to improve the sustainability of 3D printing concrete. As using these recycled materials causes some deficiencies for printing layers, different mineral and chemical admixtures were used in the present study, including graphene oxide nanomaterials, polyvinyl alcohol, Cloisite 15A nanoclay, and micro silica fume. Also, the hybrid use of latex, vinyl, and polypropylene (PP) fiber was considered to improve the printability of concrete mixtures containing waste fibers. Moreover, the effect of internal reinforcement was also considered by using plain steel wire mesh to increase the composite behavior of printed layers in this simplified experimental program. Results indicate that the synergic influence of recycled fibers and admixtures meaningfully enhanced the 3D printing properties of mortar so that about 20%, 80%, 50%, and more than 100% improvements were obtained for workability, direct tensile strength, flexural strength, and buildability index respectively. However, an average percentage − 28.3% reduction was recorded for the concrete compressive strength. Sustainability analysis also showed that using waste disposable gloves considerably reduced CO2 emissions.

Effects of nanoclay cloisite 20A and alkali treatments on structure-property relationships of bagasse/recycled polypropylene nanocomposites

This study was aimed at evaluating the individual and combined effects of organically modified nanoclay cloisite 20A and alkali treatments on the valorization of totally waste-based bagasse fiber/recycled polypropylene nanocomposites. FTIR spectra indicated the reduction of bagasse fibers’ hydroxyl moieties due to hemicellulose removal resulting from alkali treatment. There were also trace diminutions in C-O peak intensities due to the degradation of little amounts of lignin. X-ray Scattering revealed the intercalation of nanoclay in the polymer matrix. The improved interaction of fiber-polymer interfaces brought about by alkali treatment was also confirmed by scanning electron microscopy. The physical properties of the nanocomposites were improved due to the barrier properties of nanoclay against water ingress. The flexural strength and modulus of elasticity increased by both individual and combined treatments; however, the impact strength decreased by the individual treatments. Thermogravimetric analysis demonstrated that the temperatures of first and second stages of composites’ thermal degradation increased due to the treatments via the formation of a carbonized char layer thermally insulating the deeper composite layers. Differential scanning calorimetry showed some slight increases in the melting temperature, melting enthalpy, crystallisation temperature, crystallisation enthalpy, and crystallinity index of the treated composite formulations due to the nucleating effect of nanofillers. The overall results confirmed that the combination of nanoclay cloisite 20A and NaOH treatments could significantly improve the overall properties of the studied composites. This was due to some interesting synergistic effects of the given treatments on the nanocomposites converting the bagasse/recycled PP composites to high performance materials of choice.

Effects of types and concentrations of modified Cloisite Clays on properties of chitosan nanocomposites for food packaging

AbstractBiodegradable chitosan has excellent film‐forming properties compared to other biodegradables but also some limitations, such as poor water barrier and low mechanical strength. Thus, in this research, the effects of various types (Cloisite Ca, 15A, 20A, and 30B) and concentrations (0.5, 1, 2.5, and 5 wt%) of Cloisite on barrier, mechanical, structural and thermal properties on chitosan films were investigated. Cloisite was revealed to significantly lower the lightness (L*) depending on the type and concentration of Cloisite. The films containing Cloisite significantly improved oxygen barrier properties by 34.5%–73.6% compared to control, particularly Cloisite 30B. Cloisite 20A and Ca were found to significantly improve the water barrier by up to 84.61%, and Cloisite 20A and 30 B the tensile properties by up to 30%. The chitosan with less Cloisite content exhibited better smoothness and elongation. The dispersed Cloisite clays improved the thermal stability and enhanced the barrier and tensile properties of the chitosan with the increased Cloisite loading.

Dispersion and morphology analysis of PMMA/organoclay nanocomposites using the Ripley functions and determination of effective elastic properties

This paper deals with the microstructure of PMMA/organoclay nanocomposites and their effective elastic properties by the means of micro-mechanical modeling and numerical homogenization. PMMA matrix was reinforced by two types of organoclay (Cloisite 20A and Cloisite 30B) at both weight fraction from 1wt% to 5wt%. The microstructure characterization was based on the TEM images from which, Ripley functions K(r) and ImageJ software were used for organoclays dispersion and morphology analyses, respectively. Microstructures parameters such as elastic properties, volume fraction, random dispersion, platelet and prism inclusion types and aspect ratios were considered to 3D RVEs generation using Digimat-FE software. From the 3D RVEs, the numerical models were obtained and the effective elastic properties were determined by using Digimat-FE Solver. Thus, the variation of the computed properties has been investigated and illustrated. The Young’s moduli (E) of each aspect ratio were compared to experimental data. From the results, the nanocomposite rigidity depends not only on the organoclays volume fraction in PMMA matrix but also on the dispersion state and the considered aspect ratio. The inclusion type would therefore not have an important impact on the effective elastic properties. Considering the same volume fraction and dispersion state of the organoclays, the best elastic effective properties were obtained for the smallest aspect ratio.

Shear amplification of orientation in Nylon 11/clay nanocomposites during melt casting and resulting electrical properties

AbstractIn this study, the effect of organically modified clay on the orientation enhancement in Nylon 11 in melt casting was investigated. Nylon 11 was mixed with 1 and 3 wt% Cloisite 20A using twin screw extrusion and they were cast into films with varying take‐up speeds. The addition of clay in Nylon 11 helped increase orientation levels substantially in melt cast films, both as a function of clay concentration as well as take‐up speeds. This was primarily due to shear amplification effect caused by the movement of adjacent clay nanoparticles due to the shear flow gradient within the die. At low clay concentrations, the sub‐Tm stretchability, and electrical breakdown strength improve as the presence of clay reduces inter/intrachain hydrogen bonding. At higher clay concentrations, both orientation and electrical breakdown levels decrease. The latter is primarily caused by increased percolation path of charge carriers. Nevertheless, clay nanoplatelets were very effective in their role as melt processing aids, as they enhance orientation levels of Nylon 11 thin films by shear amplification effect where they increase local chain orientation of chains trapped between clay platelets while their orientation relaxation is suppressed.

Effects of organoclay on colorless and transparent polyimide nanocomposites: thermomechanical properties, morphology, and optical transparency.

Although aromatic polyimide (PI) exhibits excellent mechanical performance and thermal stability, its dark color limits applicability in optical displays. Therefore, it is desirable to manufacture colorless, transparent PI (CPI) nanocomposite films that retain excellent physical properties. In this study, a solution intercalation method was used to disperse organoclay (Cloisite 25A; CS25A) in poly(amic acid), which was prepared using 4,4'-oxydiphthalic dianhydride and 3,4'-oxydianiline as monomers. This dispersion was then subjected to thermal imidization to synthesize CPI hybrid films. The influence of the CS25A content (0-1.00 wt%) on the thermomechanical properties, optical transmittance, and morphology of the prepared films was investigated. The hybrid film with a CS25A content of 0.50 wt% exhibited the best thermomechanical properties. However, upon further increasing the organoclay content to 1.00 wt%, the physical properties deteriorated. At 0.50 wt% CS25A, some agglomeration occurred but most of the clay was well dispersed as nano-sized particles, as revealed by transmission electron microscopy. In contrast, when the CS25A content exceeded a critical content, most of the clay was agglomerated and the physical properties were reduced. All the obtained CPI hybrid films were colorless and transparent, regardless of the organoclay content.

In vitro anti-prostate adenocarcinoma and lung cancer studies of phenoxyaniline-block-poly(methyl methacrylate) based nanocomposites via controlled radical polymerization.

A phenoxyaniline-based macroinitiator is utilized for the first time in order to produce phenoxyaniline-block-poly(methyl methacrylate) composites through single electron transfer-living radical polymerization (SET-LRP) under mild conditions. A different weight percentage of Cloisite 93A is added into the polymer mixtures in order to increase their biochemical properties. The prepared block copolymer nanocomposites are characterized using ATR-IR, UV-vis-spectroscopy, XRD, Raman, TGA, DSC, a particle size analyzer, contact angle measurements and SEM in order to characterize their structural, thermal, surface and morphological properties. Further, the developed polymeric nanocomposites are successfully applied in two different cancer cell lines (prostate adenocarcinoma and lung cancer), which show excellent anticancer properties. Also, acridine orange/ethidium bromide (AO/EtBr) dual staining is performed, which causes drastic cell death by apoptosis in both A549 and PC-3 cell lines, which indicated that the prepared polymeric nanocomposites effectively inhibit the cell proliferation and induce the apoptosis in both the cancer cells. Here nanoclay is used for cancer treatment because of its complete water solubility, which essentially causes the formation of a cationic complex between the clay and drug through electrostatic interactions. Hence, the exchange of ions between the clay and other ions in the biological environment leads to inhibition of the proliferation of prostate adenocarcinoma and lung cancer cells in the system.

Mechanical, Thermal Stability and Water Absorption Properties of Recycled Thermoplastic Blend Nanocomposites: Comparison of Nanoclay and Carbon Nanotube

This present paper investigates the influenceof clay (Cloisite 10A) and multiwalled carbon nanotubes (MWCNT) loading for the tensile, flexural, thermal stability and water absorption properties of recycled thermoplastic blend made from recycled high-density polyethylene (rHDPE)and recycled polyethylene terephthalate (rPET). The nanocomposites were prepared via extrusion blending technique by using extruder and compressed using hot and cold press molding machine. The findings showed that the sample with 1 phr of Cloisite 10A and 4 phr of MWCNT showedthe optimumof tensile strength at 13.9 MPa and 14.5 MPa as compared to other loadings. The flexural strength exhibited inconsistent trend with the increasing of Cloisite 10A and MWCNT content. The addition of Cloisite 10A and MWCNT-reinforced nanocomposite showed better thermal stability than pure polymer blend. As the increment of Cloisite 10A and MWCNT loading, the percentages of water uptake increased but the values were still lower than the neat thermoplastic blend.

Fabrication of Nylon 6-Montmorillonite Clay Nanocomposites with Enhanced Structural and Mechanical Properties by Solution Compounding.

Melt compounding has been favored by researchers for producing nylon 6/montmorillonite clay nanocomposites. It was reported that high compatibility between the clay and the nylon6 matrix is essential for producing exfoliated and well-dispersed clay particles within the nylon6 matrix. Though solution compounding represents an alternative preparation method, reported research for its use for the preparation of nylon 6/montmorillonite clay is limited. In the present work, solution compounding was used to prepare nylon6/montmorillonite clays and was found to produce exfoliated nylon 6/montmorillonite nanocomposites, for both organically modified clays with known compatibility with nylon 6 (Cloisite 30B) and clays with low/no compatibility with nylon 6 (Cloisite 15A and Na+-MMT), though to a lower extent. Additionally, solution compounding was found to produce the more stable α crystal structure for both blank nylon6 and nylon6/montmorillonite clays. The process was found to enhance the matrix crystallinity of blank nylon6 samples from 36 to 58%. The resulting composites were found to possess comparable mechanical properties to similar composites produced by melt blending.

Progressive Intercalation and Exfoliation of Clay in Polyaniline–Montmorillonite Clay Nanocomposites and Implication to Nanocomposite Impedance

Conducting polymers, such as polyaniline (PANi) and polypyrrole (PPy), and their nanocomposites, are desired in a wide range of applications, including supercapacitors, lithium ion battery, chemical sensors, biosensors, barrier thin films, and coatings, because of their interesting electrical and electrochemical properties. It is well known that the properties of polymer nanocomposites depend on their chemical structure, as well as their microstructure, yet scientists and engineers have not fully understood how to properly control the structure of polymer nanocomposites. In this study, it is shown that the structure of polyaniline–montmorillonite clay nanocomposites (PACN) can be controlled by varying the ammonium persulfate (APS, oxidant) concentration. The structure of polyaniline and Cloisite 20A clay are, therefore, profoundly affected during the synthesis of PACN nanocomposites. The thickness of polyaniline crystal decreased with increasing oxidant concentration. Fourier transform infrared spectroscopy (FTIR) was used to determine the oxidation state of PANi. The structure of the nanocomposites was studied by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), wide-angle X-ray diffraction (WAXD), wide-angle X-ray scattering (WAXS), and small-angle X-ray scattering (SAXS). Electrochemical impedance spectroscopy (EIS) analysis of polyimide nanocomposite coatings containing PACN with varying levels of intercalation and exfoliation indicate that the coating impedance decreased with exposure time for some coating systems. It is shown that polyimide–PACN nanocomposite coating containing highly intercalated clay was more durable and maintained constant impedance after 20 weeks of exposure in a corrosive medium.

Essential oils as natural root‐repellent herbicides for drip irrigation systems

AbstractThe increasing use of synthetic herbicides in agriculture creates severe ecological and environmental threats. Several essential oils (EOs) (Thymol, Carvacrol, Cinnamaldehyde, and Eugenol) were investigated as natural herbicides, and their potential use as a substitute for synthetic and toxic chemicals for preventing roots intrusion in subsurface drip irrigation systems. To overcome their high volatility and to increase their thermal stability during processing, multiphase hybrid blends based on polymer/nanoclays (NCs) were prepared, enabling control of the EOs migration rate from the final active film. Germination experiments on mash bean seeds in open and closed systems have been conducted to evaluate the EOs efficacy as germination inhibitors. The amount of EO remaining in the films, after processing and for varying timepoints, was determined by UV–Vis spectroscopy through extraction. From these two experiment's results, we identified Thymol as the most effective herbicide. The effects of polymers/Thymol affinity and organoclay polarity were investigated to achieve a slow‐release effect. Linear low‐density polyethylene/polyamide 6 system showed better efficiency compared to the linear low‐density polyethylene in retaining Thymol during processing due to the thermodynamic affinity of the polyamide 6 phase with Thymol. NCs have been found to be nuclear foci during the first thermal process to obtain smaller highly surface voids allowing better absorption of the Thymol during the second thermal processing. NC Cloisite 15A showed better dispersion in the polymer matrix and improved chemical affinity between the nanocomposite and the Thymol. As a result, Thymol's desorption was delayed and a controlled release was obtained. Eventually, it was concluded that Thymol could be a natural and environmentally friendly alternative to the synthetic herbicides and use as root‐repellent agent.

Correlating mechanical properties of polyurethane-organoclay nanocomposite coatings with processing

In this study, mechanical properties were computed for polyurethane (PU)/ Cloisite20A (C20A) coatings. These coatings material were synthesized by three processing methods at variable clay weight percentages (0–3 wt%). Dispersion of C20A platelets in pre-polymer suspension were assessed by the transmission electron microscopy (TEM). In order to scrutinize the conformational changes in the functional groups at the molecular level, deconvolution of Fourier transform infrared spectroscopy – attenuated total reflectance (FTIR-ATR) spectrum was employed. An enhancement in elongation at break with the reduction in stiffness for the nanocomposites was quantified from dynamic tensile testing. For instance, 3 wt% C20A PU nanocomposites processed by sonication and subsequent homogenization showed a decrease of Young's modulus by 53% but exhibits an increase in both elongation at break and toughness by 97% and 93% respectively. The amount of shear force exerted during the processing protocols played a crucial role w.r.t dispersion of C20A. Even at low wt% (1–2) nanocomposite samples exhibit better mechanical properties in simultaneous processing using sonication and homogenization. To quantify the relationship between theoretical and experimental observations, three conventional mathematical models have been applied. Deviations in model behavior was observed, due to the high sensitivity of the nanocomposites to processing schemes, even with same chemical formulations.

Effects of Cloisite 20A Dispersion on the Structure and Properties of LDPE/Modified Clay/Coupling Agent Ternary Nanocomposites

Effects of Cloisite 20A Dispersion on the Structure and Properties of LDPE/Modified Clay/Coupling Agent Ternary Nanocomposites

Prolonged repellent activity of Ruta graveolens essential oil adsorbed on different mineral matrices against Sitophilus zeamais (L.) (Coleoptera: Curculionidae)

Plant-derived essential oils (EOs) have been considered as promising alternatives to conventional insecticides. But because of their high biodegradability and rapid volatilization, EOs are not persistent. To overcome this drawback of short protection time, EOs can be adsorbed onto protective mineral matrices to enhance efficiency by slowing down volatilization. This work was aimed at assessing the potential effectiveness of Ruta graveolens L. (Rutaceae) essential oil (RGEO)-adsorbed zeolite (ZEO) and cloisite 20A (C20A) mineral bio-composites in prolonging the odor-driven repellent efficacy of RGEO towards Sitophilus zeamais (L.) (Coleoptera: Curculionidae). Chemical profile of RGEO was identified using GC and GC-MS. Produced bio-composites were physiochemically characterized by FTIR, SEM-EDS, and TGA. The compounds, 2-undecanone (44.7%) and 2-nonanone (30.3%) were the major constituents of RGEO. Repellent action of bio-composites accounting for 50–100% was persisted for 90 d towards S. zeamais adults, whereas the RGEO used without the adsorbents recorded 0% and 44% of repellent potency within 24 h at the lowest and highest concentrations respectively. Given the volatility of RGEO, IR analyses demonstrated successful adsorption and 90-d long persistence of RGEO on both mineral matrices. Micro-/nanostructural architecture of bio-composites ranged from hierarchically porous for ZEO to intercalated platelets for C20A. EDS imaging confirmed the homogenous dispersion of constituent elements of RGEO on both mineral matrices. Bio-composites indicated improved thermal stability in the presence of air flow relative to the neat mineral matrices. Repellent potency of the bio-composites was arranged in the sequence, RGEO-ZEO < RGEO-C20A throughout the 90 d of experimental period. Findings further suggested that formulations based on EOs adsorbed on solid minerals represent a promising strategy in overcoming EOs’ limitations through retaining enough volatility while maintaining their slow release, thereby prolonging the repulsive effect of EOs for use in stored-product protection.

Melt Intercalation in Montmorillonite/Polystyrene Nanocomposites

AbstractAtactic polystyrene (PS) was used to study the effect of flow field (shear and/or elongational) on the intercalation of polymer/clay nanocomposites (PNC). Three grades of (PS), with different molecular weights, were compounded with an ammonium-modified montmorillonite (Cloisite 10A) in a twin-screw extruder (TSE). The compounds were subsequently fed to a single screw extruder, fitted with one of three specially designed torpedo-attachments. The attachments were designed to provide combinations of different levels of shear and elongational deformations. The resins, TSE compounds, and final PNC’s were characterized for the degree of intercalation, degradation, rheological behavior, and mechanical properties. The data showed that the thermal decomposition of the quaternary ammonium intercalant caused severe damage to both PNC components: a collapse of the organoclay interlayer spacing, and the thermo-oxidative degradation of PS. In spite of these detrimental effects, the attachment employing combined elongational and shear flow resulted in generally larger gallery spacing and more improvement of the mechanical properties than the other two attachments.

Effect of Cloisite 15A on the mechanical properties of an abaca-based composite

Abstract The combined effect of resin containing nanoclay along with natural fibers elevates the mechanical properties. In addition, the dispersion of nanoclay at the fiber-matrix interface would create strong physical interaction between the two. The significant enhancement in mechanical properties is achieved for the composite containing 30 wt.% abaca fiber content and 2 wt.% nanoclay, which is treated by 8 vol.% NaOH concentration. The enhancement in the mechanical properties can be attributed to the wettability of fiber by the matrix, homogeneous distribution of fibers and nanoclay in the matrix phase and physical interaction between reinforcement and matrix. Increase in the addition of abaca fiber and nanoclay beyond the above mentioned content leads to drop in the mechanical properties. This can be due to many nanoclay agglomerates are not broken down to nano scale during preparation, it may also be the reason for drop in the mechanical properties.

Mechanical responses of epoxy/cloisite nanocomposites

Polymeric nanocomposites based on nanoclay are extensively utilized in various structural applications. In this work, the effect of organically modified nanoclay (cloisite 20A) on the chain confinement, mechanics, structure, and thermal properties of epoxy resin cured with diamino diphenyl sulphone (DDS) was analysed. The viscoelastic properties were analysed by dynamic mechanical analysis (DMA). The stiffness parameter and the peak parameters from loss modulus and tan δ indicate effective adhesion of nanoclay with the polymer matrix. The filler-matrix confinement has created a constrained zone around the polymer-matrix interface resulting in the immobilization of polymer chains near the fillers. The chain confinement was determined from tan δ curve. The heterogeneity of the cloisite 20A/epoxy nanocomposites was analysed by Cole-Cole plots. Fine dispersion of cloisite 20A was achieved by intercalation of nanoclay as observed by transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. Finally, the thermal properties of the nanocomposites were analysed by thermogravimetric analysis (TGA).

Development and characterization of green polyethylene/clay/antimicrobial additive nanocomposites

In this work, nanocomposites were developed and evaluated using high-density bio polyethylene (BPEAD)/Cloisite 20A (3 and 6%)/commercial antimicrobial additive (0,5 and 1%) containing 1% of zinc pyrithione dispersed in vinyl acetate (EVA). The samples were prepared in a single screw extruder using the melt intercalation technique and then by flat extrusion to obtain the films. X-ray diffraction (XRD) showed an increase in basal spacing and exfoliation of the structure of some films. The Fourier Transform Infrared Spectroscopy (FTIR) analysis illustrated the main functional groups for BHDPE and EVA. Thermal analysis indicated that BHDPE degradation did not change with organoclay addition, but crystallinity increased. The mechanical properties showed an increase in the elastic modulus and a decrease in maximum tensile strength. This work contributes to the development and improvement of the natural properties of BHDPE in order to enlarge its applications.

Investigation into mechanical properties of EPDM/SBR-nanoclay nanocomposites

Rubber composites (poly-ethylene propylene diene monomer rubber (EPDM) / poly-styrene butadiene rubber (SBR)-nanoclay) reinforced with 2.5 parts per hundred rubber (phr), 5 phr, 7.5 phr, and 10 phr nanoclay (Cloisite 15A) were synthesised on a two-roll mill with a vulcanizing agent (sulphur) and evaluated. Cure characteristics revealed that nanoclay not only speeds up the cross linking process but also causes a considerable increase in torques, indicating that the cross linking density of the synthesized composites increases when nanoclay is present. Furthermore, the inclusion of nanoclay increased the mechanical characteristics and it is explained in this work.

Preparation and characterization of novel glycidyl methacrylate/clay nanocomposites

The impact of the type and amounts of nanofiller on the features of the glycidyl methacrylate-co-ethylene glycol dimethacrylate (GMA-co-EGDMA)/organomodified montmorillonite (OMt) nanocomposites that were prepared by in situ radical suspension polymerization, was examined. Cloisite 30B and Cloisite 25A were used in this study as nanofillers, in amounts of 2 and 10 wt.%. The structure, morphology, thermal stability and porosity of the initial GMA-co-EGDMA copolymer and their nanocomposites were examined by ATR-FTIR analysis, wide angle X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), thermogravimetric analysis (TG) and mercury porosimetry. It has been established that both clay nanofillers were successfully incorporated into the structure of the initial copolymer, simultaneously on their surface and also on cross-sectional area. Prepared samples with 2 wt.% have predominantly exfoliated, while samples with 10 wt.% have some tactoids-aggregates structure of the OMt layers. Thermogravimetric analysis revealed that after ~ 30 % of degradation, all nanocomposites become more thermal stable than the initial copolymer. The obtained results indicate that porosity parameters can be easily modified with the addition of clay nanofillers and thus prepared nanocomposites adjusted to specific purposes.