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Green synthesis may be a useful approach to achieve selective cytotoxicity of silver nanoparticles on cancer cells and healthy cells. In this study, the concomitant biosynthesis of silver (Ag)/silver chloride (AgCl) nanoparticles from pineapple peel extracts and their behavior on the breast cancer cell line MCF-7 is shown. Bioreactions were monitored at different temperatures. Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), thermogravimetric analysis (TGA), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques were used to characterize nanoparticle development. The breast cancer cell line MCF-7 was used as a test model to study the cytotoxic behavior of Ag/AgCl nanoparticles and, as a counterpart, the nanoparticles were also tested on mononuclear cells. Ag/AgCl nanoparticles with spherical and triangular morphology were obtained. The size of the nanoparticles (10–70 nm) and the size distribution depended on the reaction temperature. A dose close to 20 µg/mL of Ag/AgCl nanoparticles considerably decreased the cell viability of the MCF-7 line. The best cytotoxicity effects on cancer cells were obtained with nanoparticles at 60 and 80 °C where cell viability was reduced up to 80% at a concentration of 50 µg/mL. A significant preference was observed in the cytotoxic effect of Ag/AgCl nanoparticles against cancer cells in comparison to monocytes.

Graphic abstract Graphene decorated with cooper nanostructures were prepared with and without ionic liquid (IL) using different milling times. The obtained samples were characterized by Raman, X-ray diffraction (XRD) and transmission electron microscopy (TEM), to analyze the effect of the grinding time on the copper particles adhesion to the graphene sheets. Composites of silicon with two contents of G/Cu, at two weight ratios, nanostructures were prepared and the crosslinking characteristics were analyzed by a rubber process analyzer. The thermal conductivity, electrical resistivity and antimicrobial characteristics against E. coli and S. aureus for these silicon/G/Cu composites were determined. It was found that the use of IL enhances the G/Cu nanostructures dispersion into the silicon polymer matrix with a noticeable improvement in thermal conductivity of 1.12 W/mK for a 7 wt% of G/Cu, a volume electrical resistivity of 4.1 × 1010 Ω cm with 7 wt% of G/Cu nanoparticles and antimicrobial response of 4.21 ± 0.11 to E. coli and 5.33 ± 0.11 to S. aureus with 7% of G/Cu nanoparticles. It was determined that π–π interactions between graphene and aromatic molecule of IL may be influencing the observed improvement in G/Cu dispersion and final composite performance. The novelty of this work is the use of IL to improve the G/Cu NPs dispersion into the silicon polymer matrix. This silicon/G/Cu composite could be an option to prepare medical devices for electrotherapy or face protection against COVID-19 or other silicon-based devices for medical applications.

Polypropylene composites and multi-walled carbon nanotubes (MWCNTs) modified with maleic anhydride (MA) and itaconic anhydride (IA) were prepared and their effect on the performance of nanocomposit...

The capillary infiltration of the Zn-22Al-2Cu (Zinalco) alloy into NaCl packed particles of sizes 496, 687, and 945 μm was studied using centrifugal casting. The threshold pressure for infiltration of NaCl particles with Zinalco was deduced experimentally, which increased as the diameter of the particles decreased. The work of immersion was determined from the threshold pressure with a value of 2.1. The infiltration proceeded at distinctly different rates for the three particle sizes studied. An equation to predict the threshold pressure to infiltrate Zinalco alloy into NaCl particles for given particle size and volume fraction was established. The micromechanical analysis showed that the strength of the foam depended strongly on the level of infiltration of the derived foam. As the level of infiltration increased, the stress distribution in the foams produced became homogeneously distributed in all the struts that make up the cell, which increases the strength of foam. The elastic modulus of the as-produced Zinalco foams is governed by structural parameters such as the pore size and the strut length. Thinner and shorter struts in the foam increase its ability to resist elastic deformation in the foam.

This work shows the preparation of ethylene vinyl acetate copolymer/banana starch/Cloisite 20A organoclay (EVA/starch/C20A) nanocomposites by melt processing. Wide angle X-ray diffraction (WAXD), field emission scanning electron microscopy (FE-SEM), differential scanning calorimetry and thermogravimetric analysis were used to characterize the obtained nanocomposites. Mechanical properties were also determined. In addition, the performance of the nanocomposite films under composting was preliminarily studied; it was conducted using the soil burial test method. Despite knowing that the starch is difficult to process by extrusion, nanocomposite films with high homogeneity were obtained. In this case, C20A organoclay acts as an effective surfactant to make the starch natural polymer compatible with the EVA synthetic polymer. The good compatibility between EVA, starch and C20A clay was also deduced by the formation of intercalated and intercalated-exfoliated structures determined by WAXD and FE-SEM. Physical evidence of the damage in EVA/starch/C20A nanocomposite films after the composting test was observed. It is worth noting that despite the absence of starch, the EVA/C20A nanocomposite film, used as a control, also showed surface damage. This behavior is related to the organic modifier linked to clay C20A, which contains molecules derived from fatty acids that can be used as a food source for microorganisms.

The synthesis of silver nanoparticles (AgNPs) using a Stevia rebaudiana aqueous extract and their dispersion in starch in order to obtain starch/AgNps nanocomposites are shown in this study. The AgNPs and the starch/AgNPs nanocomposites have been characterized by ultraviolet–visible spectroscopy, optical microscopy, high-resolution transmission electron microscopy, scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis. Furthermore, the interaction of starch/AgNPs nanocomposites with a MCF-7 breast cancer cell line is analyzed. AgNPs with an average size around 15–20 nm have been obtained. starch/AgNPs nanocomposite morphology changes with the content of silver (3, 5 and 8 mM), from totally separated and dispersed nanoparticles to ribbon-type morphology. The diffraction pattern of the starch/AgNPs-3 nanocomposite indicates the formation of silver chloride nanoparticles (AgClNPs). A cytotoxic behavior of starch/AgNPs-3 nanocomposite on MCF-7 cancer cells with less damage to normal cells is observed. Hence, the high dispersion of the AgNPs or AgClNPs in starch could be influencing the selective cytotoxic behavior. Thus, this study proposes the generation of biocompatible composite materials, with AgNPs immobilized on starch. These materials have selective action against breast cancer cells, where the selectivity is controlled through the AgNPs dispersion on the biopolymer.

The effect of ultrasonic (US) irradiation on solutions of low-density polyethylene (LDPE) was studied. Different irradiation times and intensities were examined. It was found that gel content increased very little as a result of US irradiation. However, this increase showed no variation with either the US irradiation time or intensity. The IR spectra of irradiated LDPE showed new absorption bands, indicating the presence of C–O groups, assumed to be the result of the US irradiation. GPC showed that the LDPE average molecular weight (Mw) decreases with an increase in either the US irradiation time or intensity. But these MWD curves, however, do not say if the “observed” modifications in Mw are due to chain scission or chain branching, which was inferred from the chain scission distribution function (CSDF) curves. From the GPC curves, it appears that chain scission is the dominant reaction at all US irradiation times and intensities. On the contrary, using the CSDF methodology, it appears that chain scission is the dominant reaction up to the intermediate irradiation times and intensities, but chain branching becomes dominant at the US higher times and intensities. On the contrary, using the proposed methodology, it appears that chain scission is the dominant reaction up to the intermediate irradiation times and power intensities, but chain branching becomes dominant at higher times and power intensities.

For the first time the combination of keratin fibers (KF), obtained from poultry feathers, with deoxyribose nucleic acid (DNA) are employed in low-density polyethylene-ethylene vinyl acetate (LDPE/EVA) blends in order to reduce the conventional hydroxide content and enhance the blend flame retardant properties. The combined effect of each filler and the use of maleated polyethylene (PEgMA) as compatibilizer on PE/EVA flame retardant properties was analyzed. DNA by its chemical structure can be considered as an intumescing agent and when it is combined with keratin the char formation is promoted and the flame retardant properties are enhanced. DNA was distributed in specific layers forming a segregated film which resulted in better PE/EVA blend flame retardant properties compared with either DNA deposited simply by compression molding on the material surface or with melt compounding in the bulk. The flame retardant behavior was compared with a reference PE/EVA sample with 55 wt% of Magnesium Hydroxide currently used for wire coatings in the wire and cable industry. The additives combination with DNA deposited as a segregated structure significantly increases the LOI up to 24.5% and reduces the heat release rate by 82% during cone calorimetry tests with very similar flame behavior as the reference sample with 55 wt% magnesium hydroxide loadings. The mechanical properties indicated that DNA has a marked increase in elongation as well as a marked reduction in torque and viscosity indicating that the combination of these additives can improve the mechanical performance, as well as facilitate the melt processing. Most important, the results indicated that the combination of these additives makes it possible to reduce the total Magnesium hydroxide filler content from 55 to 20 wt% to achieve the flame retardant requirements and with enhanced mechanical performance. Thus, this additives combination and this coating methodology provides a promising way to meet the growing demand and stringent requirements for high performance materials with high flame retardant standards using high efficient and green fire retardant coatings.

The curing reaction of the epoxy system “diglycidyl ether of bisphenol-A” (DGEBA) and the tertiary amine “2-[(2-dimethyl-amino)-ethoxy] ethanol” (DMAE), with different DMAE concentrations was studied by means of rheometric analysis using the Rubber Process Analyzer (RPA). A novel simple technique was introduced in order to allow the use of the RPA instrument in measuring the curing studies of quasi liquid reactants. It was found that the crosslinking degree; as measured by: a)- the maximum torque in the RPA analysis as well as by b)- the estimated molecular weight between crosslinks (Mc); increased with the DMAE concentration. Also, it was found that the curing reaction rate, increased with the DMAE concentration; greatly decreasing the time to gel point as well as the time to maximum torque. The degree of crosslinking, as taken from the crosslink density or by the molecular weight between crosslinks, increases roughly seven times as the tertiary amine (DMAE) concentration increases from 3 to 10 wt%. The activation energy of the crosslinking reaction was determined by plotting as an Arrhenius type equation, the log(Geltime) -vs- the inverse temperature, and it was found to be around 42.9 kJ/mol.

In this study, the combination of organomodified montmorillonite (MMT), magnesium hydroxide (MDH), graphene oxide (GO) and expandable graphite (EG) as intumescent flame retardant for Linear...

The effect of three different organomodified nanoclays (Cloisite 20A, Cloisite 30B, and Nanomer I28E) as well as the effect of a compatibilizer (PEgMA) was studied, with the purpose of developing g...

Maleic anhydride-grafted polypropylene (PP-g-MA) was reacted with aniline (NH2C6H5) to produce PP-g-NHC6H5 and used as a compatibilizer in polypropylene/carbon nanotube composites. Infrared spectroscopy (FTIR) and nuclear magnetic resonance confirmed the reaction between PP-g-MA and aniline. PP-g-NHC6H5 resulted a better compatibilizer than PP-g-MA, producing good dispersion and homogeneous distribution of the carbon nanotubes with less agglomerates, as observed by SEM analysis. Improved dispersion and distribution is assumed to be due to the π–π interactions between the –C6H5 ring in the prepared compatibilizer and the hexagonal carbon structure in the nanotubes. In addition, a higher degree of crystallinity (12%) was promoted, since it was favored by π–π interactions. This achieved higher crystallinity promoted an increase in tensile modulus, with only slight changes in tensile strength but with an adverse effect on elongation at break.

Graphene oxide (GO) derived from oxidation of natural graphite contains many active groups that can interact with a great variety of polar moieties. In this work, polypropylene (PP)/graphene oxide nanocomposites using polypropylene (PP) grafted with amine-alcohol (PPgDMAE) as compatibilizer were prepared by two different methods. Maleic anhydride grafted PP (PPgMA) was reacted with 2-[2-(dimethylamine)-ethoxy] ethanol (DMAE) in the melt for forming amine-alcohol functionalized polypropylene (PPgDMAE). Nanocomposites were prepared by two methods. In one method, PP/GO nanocomposite was prepared by direct melt mixing in an internal batch mixer using PPgDMAE as compatibilizer. In another method, a previous mixing of PPgDMAE with GO in hot Xilene was done and then, once the solvent was evaporated, it was incorporated into PP by melt-mixing. The microstructure and interface enhancement of the prepared composites were analyzed by Fourier transform infrared spectroscopy (FTIR), Raman, X-ray difraction (DRX) contact angle, scanning and transmission electron microscopy (STEM), mechanical, thermal, and electrical properties measurements. Fourier transform infrared spectroscopy (FTIR) revealed the interaction between GO and PPgDMAE. The loading of GO conducted to enhance the composite mechanical properties attributed to the strong interfacial interactions between GO and PPgDMAE. A significant improvement in mechanical thermal stability and electrical properties was observed when nanocomposites were prepared by the solution blending method compared with melt mixing method. This work suggests a potential application of GO in preparation of high performance PP composites. POLYM. COMPOS., 2016. © 2016 Society of Plastics Engineers

In this work the preparation and characterization of a multilayer film reservoir with clay/essential oil (EO) composites is described. The goal is to analyze the potential use of these reservoirs with clay/EOs composites as aroma-controlled release for various applications such as pesticide or attractant for pest control as well as antimicrobial. Two types of clays were analyzed, porous halloysite (HNT) and octadecyl modified montmorillonite (MMT) nanoclay as well as two types of essential oils, orange (OO) and thyme oil (TO). The characterization was performed by elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and gas chromatography (GC) analysis. FTIR confirmed that both clays adsorbed the EOs. The DRX and TGA results showed that MMT clay showed higher thyme oil adsorption and better interactions than with orange oil. The Clay/EO composites encapsulated in Polyethylene/tie/Polyamide/tie/Polyethylene multilayer film showed a continuous aroma release for longer periods. It was found that the Polyamide (PA) barrier layer thickness had has an effect on the liberation of the volatile compounds through the multilayer film. On the other hand, the highest cymene aroma release at 72 h was 800 μg for the MMT clay/thyme oil encapsulated in the multilayer film with lower PA layer thickness. This multilayer film encapsulated clay/EO composites could be an option to prepare aroma-controlled release systems for pest control and food packaging applications as antimicrobial or fungicidal systems.

Different mixing methods were used for the fatty acid modification of magnetite nanoparticles. The magnetite nanoparticles were dissolved in ethanol with a previously dissolved oleic or stearic acid solution. The mix was then homogenized and washed to eliminate the unreacted fatty acid. The modified nanoparticles were FTIR analysis confirmed that the modified nanoparticles presented the characteristic groups of the fatty acids. The vibrating sample magnetometer analysis (VSM) showed a very slight decrease in the magnetic properties of the magnetite, from 88.7 to 53.7 emu/g, which obviously was due to the presence of the fatty acids. TGA showed that the fatty acid modification degree of the magnetite was less than that reported elsewhere, nonetheless, during the precipitation tests in toluene; it was observed that the modification was sufficient to maintain the stability of the dispersion without affecting the magnetic properties. Additionally, TEM micrographs showed that the modified magnetite nanoparticles formed a cluster, with the fatty acids surrounding the magnetite nanoparticles. Confirming that the fatty acid layer was deposited as monolayers on the magnetite particle surface of approximately 2 nm in thickness with OA and 2.3 nm with SA. It was observed that the use of the two fatty acids produced inter-digitation among the fatty acids. Finally, nanocomposites based on liquid silicone rubber (LSR) were prepared with modified and unmodified magnetite and their rheological and magnetic behavior was studied. This fatty acid modification of magnetite particles improved the dispersion and distribution of modified particles into the silicon matrix.

A work was carried out in order to obtain a TPV based on HDPE and EPDM, studying the effect of three different peroxides. The effect of one mono- and two bifunctional peroxides was studied. In general, at equal wt% of peroxide, the bifunctional peroxides produced greater gel content, higher tensile stress, and higher elongation at break. Thereafter, the work was focused on studying the effect of this TPV, as well as a commercial TPO, on the tensile and flame retardant properties of composites based on blends of HDPE and a thermoplastic elastomer (either TPV or TPO), plus 130 phr of magnesium hydroxide (MH). The composites without the rubbery phase, but with 130 phr of MH, were highly brittle and fragile. The composites with the rubbery phase, on the other hand, (either TPO or TPV), were tougher and presented relatively much higher tensile properties. With regard to flame retardancy, the formulations containing the TPV showed better flame retardancy and passed as V-1 in the UL-94V. With respect to the cone calorimeter, those with TPO or TPV all generated a total of 80 MJ of heat energy. The compositions with TPV, however, generated this amount of heat over a larger period of time, i.e., showing less heat generated per second. In addition, the compositions with TPV presented a markedly lower pHRR, by an average of 15%. Thermogravimetric analysis (TGA) showed that the MH in the samples with a 40 wt% rubbery phase starts decomposing at 315°C. However, as the temperature increases, the MH in the TPV composite apparently decomposes at a slower rate than that in the TPO composite.

The performance of Polyethylene (PE)/Clay/Silver nanocomposites is dependent to a great extent on the properties of filler–matrix interface. To improve the interfacial properties in PE/Clay/Silver composites, different types of compatibilizers or adhesion promoters were introduced. The compatibilization provided by maleic anhydride (MA), itaconic acid (IA) and 2-[2-(dimethylamine)-ethoxy] ethanol (DMAE) functionalized PEs for forming PE-based nanocomposites was studied and compared. IA was grafted into PE by melt mixing to obtain PEgIA (compatibilizer 1), thereafter, PEgIA and PEgMA (compatibilizer 2) were reacted with DMAE also by melt mixing to obtain PEgI-DMAE (compatibilizer 3) and PEgM-DMAE (compatibilizer 4). These compatibilizers were reacted using ultrasound with a solution of AgNO3 0.04 M and ethylene glycol. Ammonium hydroxide was added in a ratio of 2:1 M with respect to silver nitrate. These silver coated compatibilizers were mixed with PE and with a quaternary ammonium modified montmorillonit...

Nanocomposites based on cyclic olefin copolymer/linear low density polyethylene blends (COC/LLDPE) with various contents of three different modified organoclays (20A, 10A, and I28E) compatibilized with polyethylene grafted maleic anhydride (PEgMA) were prepared by met mixing. The influence of content and type of organoclay and compatibilizer on nanocomposite morphology, thermal, and mechanical properties as well as on oxygen and water vapour barrier properties was determined. X-ray diffraction (XRD) and transmission microscopy (TEM) were used to investigate the clay dispersion, which showed a strong dependence on compatibilizer and type of organoclay. An exfoliated–intercalated morphology was obtained for compatibilized samples of C20A and I28E organoclays at 5 wt%. A less intercalated structure was obtained for samples with C10A. The exfoliated–intercalated structure was influenced both by the compatibilizer and the increase on the nanocomposite viscosity due to the COC incorporation as was determined by Rheological measurements. Mechanical analysis gave an evidence of increasing stiffness after nanoclay was added into COC/LLDPE blend matrix observing higher Young modulus for the compatibilized samples. A notorious decrease of Oxygen and Water vapour permeation rate was observed for COC/LLDPE blend films nanocomposites only when using C20A and I28E clays. These results can be useful in the design of sustainable flexible films for the packaging requirements of specific types of food. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

A metallurgical by product mostly constituted of Wustita (FeO) was transformed to Magnetite (Fe3O4) spheres using a flame treatment. Then magnetite spheres surface was modified by cold plasma treatment with ethylene, where a thin polyethylene film was deposited on the spheres surface. Finally, HDPE composites with modified spheres were obtained by melt mixing and its thermal conductivity was determined by MDSC. It was found that spheres surface modification helps to increase composites thermal conductivity.

The synergistic effect of organo-modified montmorillonite (Nanomer I28E and Cloisite 20A) and metal hydroxides (magnesium hydroxide MH and alumina trihydrate ATH) as flame retardants in LDPE/EVA nanocomposites compatibilized with amino alcohol grafted polyethylene (PEgDMAE) was studied. Morphological characterization of nanocomposites was carried out by means of X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). Flame-retardant properties of nanocomposites were evaluated by the UL-94 horizontal burning and cone calorimeter tests and limiting oxygen index (LOI). Thermal degradation behavior was analyzed with a Fourier transform infrared coupled with the thermogravimetric analyzer (TG-FTIR). The XRD analysis showed a displacement of the d 001 plane characteristic peak of clay to lower angles, which indicates an intercalated–exfoliated morphology. From STEM images it was observed a good dispersion of flame retardants (MH and ATH) throughout the polymer matrix which was reflected in flame-retardant properties. TG-FTIR showed a better thermal stability of nanocomposites and the gases evolved during combustion showed an important reduction. Based on thermal stability and thermal degradation results, the flame-retardant mechanism of LDPE/PEgDMAE/EVA/Clay/MH nanocomposites was proposed.

Natural rubber/organoclay/titanium dioxide nanocomposites were obtained via mechanical blending using rubber latex, organically modified montmorillonite clay (cloisite 30B) and titanium dioxide (TiO2). Glycerol was utilized as a dispersant for the inorganic components. Scanning electron microscopy analysis shows that TiO2 nanoparticles were deposited on the clay surface and that the clay–TiO2 combination was homogeneously dispersed on the natural rubber. The high aspect ratio and the polar character of the clay layers allowed interactions with individual nanoparticles of TiO2. The X-ray diffraction patterns reveal an increment of the crystalline character of the NR/C30B/TiO2 nanocomposites as a consequence of the nanoscale dispersion of the TiO2 particles. Infrared Spectroscopy spectra indicate compatibility between natural rubber and glycerol due to the formation of hydrogen bonds. A mechanism in particle–natural rubber compatibility, in which glycerol is involved, is proposed. However, nanoscale dispersion was largely dependent on the clay–TiO2 interactions. This work proposes an easy method to immobilize TiO2 nanoparticles on clay layers, which allows their dispersion in polymers. Nanocomposites obtained by this method can be used for supports of photocatalyst molecules.

In this study, the effect on the degree of organoclay exfoliation in polypropylene-ethylene (PP-EP)/Ethylene vinyl acetate (EVA)/organoclay blend system was studied while varying organoclay structural characteristics. Cloisite 6A, Cloisite 15A, Cloisite 20A, Cloisite 25A, Cloisite 30B, Cloisite 93A, and Cloisite 10A were used because they have different type of modifier. Ternary PP-EP/EVA/organoclay system was obtained with each type of clay and results were organized to analyze the effect of type of clay chemical modification (C20A, C15A, and C6A), steric effect caused by surfactant structure (C15A and C10A), length of substitute groups on the surfactant (C20 and C25A), and surfactant polarity (C30B and C93A). Samples were characterized by: wide angle X-ray diffraction, scanning transmission electron microscopy (STEM), dynamic mechanical analysis, and capillary rheometry. Results showed that clay galleries can be saturated with chemical modifier complicating the polymer chain intercalation into the clay galleries. Some clay modifier substituent groups could cause certain steric effect promoting less exfoliated platelets structures. Finally, longer chains in the modifier substituent group can promote a better intercalated–exfoliated structure. Among all the studied organoclays, best results were obtained in the ternary system when using C20A, which modifier has two hydrogenated tallows. In this case, interlayer spacing was increased more noticeable after ternary system was formed. This was corroborated with the obtained increase in viscosity and the intercalated–exfoliated structure observed by STEM. POLYM. COMPOS., 35:2241–2250, 2014. © 2014 Society of Plastics Engineers

A study on the dynamic mechanical properties of polypropylene copolymer/ethylene–vinyl acetate/organoclay (PP-EP/EVA/C20A) nanocomposites is presented. Nanocomposites were obtained by melt blending. Morphology consisting of intercalated–exfoliated clay nanolayers preferentially located within the EVA phase was observed by transmission electron microscopy (TEM) and wide angle X-ray diffraction (WAXD). Polar groups of vinyl acetate in the EVA facilitated the polymer–clay interactions. Changes in the glass transition temperature (Tg) were correlated with changes in the clay intercalation–exfoliation levels. The highly reinforced with intercalated–exfoliated clay layers EVA phase was considered as the origin of the improvement on mechanical properties of the ternary nanocomposites and is associated with the increase on viscosity, heat deflection temperature (HDT), and storage modulus.

Hydrogel silver nanocomposites have been used in applications with excellent antibacterial performance. Acrylic acid (AA)/itaconic acid (IA) hydrogels silver nanocomposites were prepared and applied as a coating on a textile substrate. Hydrogel matrices were synthesized first by the polymerization of an AA/IA aqueous (80/20 v/v) solution and mixed with 2-2-azobis(2-methylpropionamide) diclorohydrate and N,N′-methylene bisacrylamide until the hydrogel was formed. Silver nanoparticles were generated throughout the hydrogel networks with an in situ method via the incorporation of the silver ions and subsequent reduction with sodium borohydride. Cotton (C) and cotton/polyester (CP) textile fibers were then coated with these hydrogel silver nanocomposites. The influence of these nanocomposite hydrogels on the properties of the textile fiber were investigated by infrared spectroscopy (attenuated total reflectance), scanning electron microscopy, energy-dispersive X-ray spectroscopy, and antibacterial tests against Pseudomona aeruginosa and Staphylococcus aureus. The better conditions, in which no serious aggregation of the silver nanoparticles occurred, were determined. It was proven that the textiles coated with hydrogels containing nanosilver had an excellent antibacterial abilities. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2713–2721, 2013

The effect of vinyl acetat (VA) on the morphological, thermal stability, and mechanical properties of heterophasic polypropylene–(ethylene-propylene) copolymer (PP–EP)/poly(ethylene vinyl acetate) (EVA)/organoclay nanocomposites was studied. Tailored organoclay C20A was selected to enhance the exfoliation of the clay platelets. Depending on the VA content, there were two morphological organoclay populations in the systems. Both populations were directly observed by scanning transmission electron microscopy and measured by wide-angle X-ray diffraction and small-angle X-ray scattering. The content of VA in EVA originated spherical and elongated morphologies in the resultant nanocomposites. High-VA content led to a better intercalation of the organoclay platelets. Measurement of thermal properties suggested that higher VA decreases thermal stability in samples both with and without organoclay, although nanocomposites had higher thermal stability than samples without clay. The storage modulus increased both with nanoclay and VA content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The compatibilization effects provided by maleic anhydride (MA), itaconic acid (IAc), itaconic anhydride (IA), and 2-[2-(dimethylamine)-ethoxy]ethanol (DMAE) functionalized polyethylenes for forming high density polyethylene (HDPE)-based nanocomposites were studied and compared. IAc and IA were grafted into HDPE by melt mixing to obtain functionalized polyethylenes (HDPEgIAc and HDPEgIA) and amino alcohol functionalized polyethylene was prepared by reaction of commercial HDPEgMA with DMAE in the melt to form polyethylene-grafted dimethyl-amine-ethoxy-ethanol (PEgDMAE). Nanocomposites were prepared by melt processing using a twin screw extruder by blending polyethylene and these compatibilizers with a quaternary ammonium surfactant-modified montmorillonite clay (Nanomer I28E). FTIR characterization confirmed the formation of these compatibilizers and confirmed the reaction between HDPEgMA and the amino alcohol. All the compatibilized nanocomposites had better clay exfoliation compared to the uncompatibilized HDPE nanocomposites. Barrier properties, X-ray diffraction and transmission electron microscopy results showed the following order of their performance as a compatibilizer: PEgDMAE > HDPEgAI > HDPEgAcI > HDPEgMA. This behavior was attributed to the specific interactions between the anionic surface of the clay and the functionality of the compatibilizer. Samples with higher clay content showed poorer clay dispersion or intercalation which was attributed to possible clay saturation when the van der Waals attractive interactions between the clay layers become dominant when the distance between them was small enough at a certain concentration of clay. A noticeable reduction in the degree of crystallinity with the incorporation of nanoclay was observed by thermal analysis whereas the melting temperature did not change noticeably.

The compatibilization provided by itaconic acid (IA) and 2-[2-(dimethylamino)-ethoxy] ethanol (DMAE) functionalized polyethylene for forming polyethylene-based nanocomposites was studied and compared. IA was grafted into PE by melt mixing to obtain PEgIA (compatibilizer 1), thereafter, PEgIA was reacted with DMAE also by melt mixing to obtain PAgDMAE (compatibilizer 2). PE-clay nanocomposites were prepared by melt mixing polyethylene with each of the two quaternary ammonium modified montmorillonite clays (Cloisite 30B and Nanomer I28E) plus each of the two previously prepared compatibilizers (PEgIA and PEgDMAE). FTIR characterization confirmed the formation of these two compatibilizers. All the compatibilized nanocomposites had better clay exfoliation–intercalated compared to the uncompatibilized PE nanocomposites. X-ray diffraction and transmission electron microscopy results, as well as the mechanical properties attained showed that the PEgDMAE with the I28E clay produced the better exfoliated–intercalated nanocomposites. Samples with C30B clay did not show any intercalation improvement, as compared to the uncompatibilized samples, which was attributed mainly to the smaller initial intergallery spacing of this clay. Finally, it is concluded that the PEgDMAE offers an outstanding capability for preparing highly exfoliated PE clay nanocomposites.

Silver nanoparticles were deposited on the surface of the external polyamide 6 (PA6) layer of a multilayer film, by spraying and ultrasound-assisted methods. The effect of silver nanoparticles content and deposition method on the mechanical and optical properties of the multilayered films as well as the efficiency of silver ion release and their fungicidal characteristics were evaluated. Itaconic (IA) and Maleic anhydride (MA) were used as adhesion promoter agents for preventing the agglomeration of the silver nanoparticles and for improving the adhesion to the PA6 polymer surface. With IA, a homogeneous distribution of silver nanoparticles on the PA6 surface was achieved. The silver ion release and biocide effect of the multilayered films was found to be dependent on the anhydride type and on the deposition method used. The multilayer films with a layer of PA6-silver nanocomposite demonstrated good fungicidal activity, specifically against fungus Aspergillius niger. The observed results could be applied in the design of industrial films for packaging. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The combination of different types of organo-modified montmorillonite (MMT) with aluminum hydroxide (aluminum trihydrate—ATH), as a flame retard- ant system for polyethylene-ethylene vinyl acetate (LDPE/ EVA), blends were studied. Five different types of organi- cally modified montmorillonite clays, each with different modifier, were used. The structural characterization was carried out by X-ray diffraction (XRD) and scanning elec- tron microscopy in transmission mode (STEM). The me- chanical and rheological properties were also evaluated. The XRD analysis showed a clear displacement of the d001 signal, which indicates a good degree of intercalation, espe- cially for the MMT-I28 and MMT-20, from Nanocor and Southern Clay Products, respectively. The presence of ATH and the compatibilizer did not have any effect on the exfoli- ation of the studied samples. The thermal stability and flame retardant properties were evaluated by thermogravi- metric analysis (TGA), limiting oxygen index (LOI—ASTM D2863), and flammability tests (Underwriters Laboratory— UL-94). The effect of different compatibilizers on the clay dispersion and exfoliation was studied. The results indi- cated that the addition of montmorillonite makes it possible to substitute part of the ATH filler content while maintain- ing the flame retardant requirements. The thermal stability of MMT/ATH-filled LDPE/EVA blends presented a slight increase over the reference ATH-filled LDPE/EVA blend. Compositions with higher clay content (10 wt %) showed better physicochemical properties. The increased stability of the higher clay content compositions results from the greater inorganic residual formation; this material has been reported to impart better performance in flammability tests. The mechanical properties and flame retardancy remained similar to those of the reference compound. The reduced ATH content resulted in lower viscosities and densities, facilitating the processing of the polymer/ATH/clay com- pounds. Extrusion of these compounds produced a lower pressure in the extrusion head and required reduced electri- cal power consumption. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1125-1136, 2012

The compatibilization effects provided by different amine-functionalized polyethylenes (PEs) versus those provided by a maleated polyethylene (PEgMA), for forming PE-based film nanocomposites, were studied. Amine-functionalized PEs were prepared by reaction of PEgMA with two primary amines, 2-aminoethanol (EA) and 1,12-aminododecane (D12), and a tertiary amine, 2-[2-(dimethylamino)ethoxy]ethanol (DMAE), in the melt to form the corresponding PEgEA, PEgD12 and PEgDMAE. Nanocomposites were prepared by melt mixing in a twin-screw extruder PE and these three functionalized compatibilizers with a modified montmorillonite clay. The purpose of the current work was to determine the effect of the various amine-functionalized PEs on the degree of exfoliation and optical properties of PE–clay nanocomposites in order to obtain nanocomposite films for greenhouse cover applications. Fourier transform infrared analysis confirmed the formation of the amine-modified PE compatibilizers. Structural, morphological, mechanical, rheological and optical properties of film samples were used to characterize the nanocomposites. All the amine-modified PE-compatibilized nanocomposites had better clay exfoliation compared to uncompatibilized PE composites. Results showed that PEgDMAE formed highly exfoliated morphology and a favorable balance between mechanical (stiffness and ductility), optical and thermal insulating film properties even at higher clay contents. It was determined that nanocomposites with greater exfoliated structure showed better optical and thermal insulating film properties. PEgEA and PEgD12 compatibilizers did not provide a better interaction for exfoliation of the organoclay than the PEgMA material. The PEgDMAE compatibilizer led to a highly exfoliated morphology and a favorable balance between mechanical, optical and thermal insulating film properties even at higher clay contents. The PEgDMAE film nanocomposites could be used ideally for greenhouse cover applications. Copyright © 2010 Society of Chemical Industry

The compatibilization effects provided by an amine silane modified polyethylene (PEgAS) versus those by a maleated polyethylene (PEgMA), for forming PE–clay based nanocomposites, were studied. PEgAS was prepared by condensation reaction between PEgMA and g-(aminopropyl) triethoxy silane (APTS). It had the triethoxy-silane functionality on one end and was solution mixed with an organomodified clay (Cloisite 20A) to promote the reaction of the silane groups with the hydroxyl groups on the surface of the clay. The obtained masterbatches were then compounded with PE to obtain PE–clay nanocomposites by melt blending in a twin screw extruder, using different compatibilizers and clay contents. FTIR, XRD, STEM, and Instron were used to characterize the structural, morphological, and mechanical properties of the nanocomposites. Results showed that the PEgAS formed more exfoliated–intercalated morphology and better mechanical properties, especially in modulus and tensile strength as compared with PEgMA composites and neat PE. The Young modulus was 35% higher, and the tensile strength was 18% higher with PEgAS composites.

Compatibility mechanisms between EVA and PP copolymers (C-PP) blends have been studied as a function of the type of copolymer, using a heterophasic PP copolymer (PP-EP) and a random PP copolymer (PP-r-EP), with similar ethylene content. The morphology and thermal and mechanical properties of PP/EVA blends with different levels of EVA containing 28% vinyl acetate (VA) were determined. The obtained results indicated compatibility for both systems showing interactions at the amorphous interfaces; however, this interaction was higher for the PP-r-EP/EVA, which showed a single glass transition temperature and changes in the PP crystalline fraction (changes in the fusion temperature and in the diffraction patterns). The evolution of the morphology from isolated spherical domains (20% EVA) to elongated shapes (40% EVA) was related to the observed changes in thermal and mechanical properties. The impact strength and deformation properties showed significant improvement with increasing EVA content above 40% where the highest values of elongation for the PP-r-EPand of impact strength for the PP-EP were obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

The effect of processing conditions on the morphology of heterophasic PP–EP/EVA/organoclay ternary nanocomposites was examined. The nanocomposites were prepared in a co-rotating twin screw extruder with different screw configurations and incorporation methods. Three different sizes of EVA granules were used. The results obtained by X-ray scattering (WAXD) and electronic microscopy (TEM) showed an increase in d spacing value of the clay associated with the polar interactions between the vinyl acetate of EVA and the surface of the nanoclays. In addition, some chains of the non-polar copolymer PP–EP may have become intercalated into the clay galleries as a result of polymer diffusion induced by shear stress during melt mixing. An increase in surface area of EVA granules resulted in a more homogenous clay dispersion and intercalation. The morphologic changes resulted in an increase in heat distortion temperature (HDT) and flexural modulus of the ternary nanocomposites.

A study is presented on the morphological effects caused by the nanoclay organic modifier and the nanoclay concentration. This was made under previously determined compatibility conditions of heterophasic polypropylene copolymers (PP-EP)/poly(ethylene vinyl acetate) (EVA)/organoclay nanocomposites. The nanocomposites were prepared using the fluidity of the EVA phase to disperse the nanoclay platelets. Therefore, no additional compatibilizer was used to achieve the clay dispersion. Two organoclays were used with different characteristics and polarity of the substituent groups. Transmission electron microscopy and X-ray diffraction results first indicated that two hydrogenated tallow modifiers are more effective than one to enhance nanoclay exfoliation. Thermogravimetric studies indicated a low probability of thermal degradation of the nanoclay modifiers and as a consequence of their effect on the layer–layer exfoliation. Molecular simulations were made with the purpose to study additional factors affecting exfoliation. The introduction of nanoclay, within the compatibility conditions of the PP-EP/EVA system, was also studied. It was determined that the system preserved its original morphology and that the silicate layers were hosted by the EVA domains. The crystallization characteristics of the PP-EP/EVA mixtures indicated a gradual evolution of the overall crystalline structures depending on the EVA content. In the case of the ternary nanocomposites PP-EP/EVA/nanoclay, the β crystalline structure was partially formed, although it decreased with increasing nanoclay content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

The influence of organomodified nanoclay (montmorillonite) on the crystallization and melting mechanisms of isotactic polypropylene (iPP) was studied. Films of both neat polymer and clay nanocomposites were prepared after molecular weight optimization through melt extrusion. Products exhibited the tactoidlike morphology since no compatibilizers were used. The effect of introduction of nanoclay within the polymer was studied through isothermal crystallization and linear heating. The results indicated that low nanoclay concentrations induce the formation of the β-crystalline structure, its formation being inhibited with high nanoclay contents. Dynamic nonisothermal bulk crystallization experiments indicated that nanoclays act as nucleating agents of iPP. Isothermal, bulk crystallization studies indicated that the crystallization process (induction time and crystallization kinetics) is proportionally accelerated by the nanoclay presence. There was also an accelerated formation of secondary crystallization when nanoclays were present in high concentrations. POLYM. ENG. SCI., 47:1889–1897, 2007. © 2007 Society of Plastics Engineers

In this study, we present a study of polypropylene/bentonite composites where stearic acid was used as both a surface and interface modifier during the compounding of composites. The concentration of bentonite was 1.5, 2.5, 5.0, and 10 parts per hundred. The composites were characterized by impact resistance and tensile tests, rheological analysis, the dispersion state of the filler observed by optical microscopy, and interaction between bentonite and stearic acid, as analyzed by Fourier transform infrared spectroscopy. No chemical interaction was found between bentonite and stearic acid. Composites with modified bentonite and stearic acid used as interface modifiers increased the elongation at break; these samples also showed better dispersion of the filler in comparison with the other compounds. In addition, stearic acid acted as a lubricant, favoring the interaction of the polymer with the filler and decreasing the viscosity of the compounds. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42264.

A study on the thermal behavior and flammability properties of the heterophasic polypropylene–(ethylene–propylene) copolymer (PP–EP)/poly(ethylene vinyl acetate) (EVA)/montmorillonite nanocomposite is presented. Nanoclay nanocomposites were prepared using a twin screw extruder. Both the fluidity of the EVA phase and compatibility conditions between PP–EP and EVA were used in order to obtain the required nanocomposites. Therefore, no additional compatibilizer was required to achieve the clay dispersion. Products exhibited the partially exfoliated/intercalated nanoclay dispersion. Thermogravimetric analyses indicated that nanoclays retard thermal degradation depending on nanoclay concentration. The retarding process was assigned to the exfoliation and dispersion of the silicate layers which impeded heat diffusion to the macromolecules. Thermal studies, under non-isothermal crystallization, indicated the lack of influence of nanoclay on the thermal behavior. Flammability characteristics were however affected by the nanoclay layers which overall generated flame retardation both in the EVA host and in the complex nanocomposites.

Summary: Linear low-density polyethylene (LLDPE)/clay nanocomposites are obtained and studied by using a zinc-neutralized carboxylate ionomer as a compatibilizer. LLDPE-g-MA is used as a reference compatibilizer. Two different clays, natural montmorillonite (Closite Na+) and a chemically modified clay Closite 20A have been used. Nanocomposites are prepared by melt blending in a twin-screw extruder using two mixing methods: two-step mixing and one-step mixing. The relative influence of each compatibilizer is determined by wide-angle X-ray diffraction structural analysis and mechanical properties. The results are analyzed in terms of the effect of the compatibilizing agent and incorporation method in the clay dispersion, and the mechanical properties of the nanocomposites. Experimental results confirm that the film samples with ionomer show a good mechanical performance only slightly below that of the samples with maleic anhydride (MA). The two-step mixing conditions result in better dispersion and intercalation for the nanofillers than one-step mixing. The exfoliation of clay platelets leads to an improved thermal stability of the composite. The oxygen permeability of the clay nanocomposites, using ionomer as a compatibilizer, is decreased by the addition of the clay. TEM image of a PE/4 wt.-% Closite 20A nanocomposite formed using ionomer.

Mechanical properties, molecular weight, X- ray diffraction, and differential scanning calorimetry (DSC) characterization of blends of virgin high-density polyethyl- ene (HDPE) with two types of recycled material were inves- tigated. The recycled came from urban plastic waste; one kind was only washed and grounded and the other was extruded and pelletized to remove most of contaminant particles. Starting with the 30/70 virgin/grounded recycled and 50/50 virgin/pelletized recycled blends the recycled content was increased in both blends and compatibilizing agents were used to increase the blend performance. A mixture of phenolic antioxidants and phosphite costabilizers under the name of Recycloblend, ethylene vinyl acetate (EVA) copolymer, low-density polyethylene (LDPE), and linear low density polyethylene (LLDPE) were used as com- patibilizers. The effect of these additives and the recycled content on the performance of extrusion blow-molded bot- tles was determined. The results suggest that blends of virgin/grounded recycled and virgin/pelletized recycled HDPE, in general, were not significantly different among each other and both had a quite similar behavior than the virgin HDPE when compatibilizing agents were used. The addition of compatibilizing agents yielded a material with properties similar to those for the virgin HDPE, helping to reduce the effect of polymers degradation on the rheological and mechanical behavior, with Recycloblend and LLDPE being the most effective for the blends with grounded recy- cled material, and LLDPE y EVA, for the blends with pel- letized recycled. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3696 -3706, 2006