Organo-modified Nanoclay Research Articles

Barrier properties of polyhydroxybutyrate/ethyl cellulose-blend-coated paper through the incorporation of organo-modified nanoclay as a coating component

A sodium bentonite product (nanoclay) was added to a polyhydroxybutyrate/ ethyl cellulose (PHB/EC) blend coating agent, and the impact of the nanoclay content on the properties of the coated paper was investigated. The organically treated nanoclay exhibited enhanced compatibility with the PHB/EC blend, ensuring uniform dispersion within the coating layer and improving the barrier properties of the coated paper. The mechanical properties of the PHB/EC blend-coated paper with nanoclay demonstrated ductile behavior, reducing the tensile strength and increasing the elongation. However, at higher nanoclay loadings, specifically up to 25%, aggregation among nanoclay particles occurred. This hindered the enhancement of barrier properties, thereby decreasing the degree of elongation. Incorporating nanoclay as a filler in the PHB/EC blend at suitable levels showed potential for further enhancing the barrier properties and ensuring economic feasibility in the production of packaging paper.

Addition of Organo-Modified Nanoclay for Tuning the Microstructure, Thermal Stability, and Biodegradability of Poly(lactic acid)/Polycarbonate Immiscible Blends

Addition of Organo-Modified Nanoclay for Tuning the Microstructure, Thermal Stability, and Biodegradability of Poly(lactic acid)/Polycarbonate Immiscible Blends

Effect of re-modified nanoclays on the extent of transesterification in poly (ethylene terephthalate)/poly (ethylene 2,6-naphthalenedicarboxylate) blend nanocomposites

In the present work, the extent of transesterification reaction was investigated in the poly (ethylene terephthalate) /poly (ethylene 2,6-naphthalenedicarboxylate) (PET/PEN) (90/10 and 75/25 w/w) blends filled with three nanofillers, i.e., an organo-modified nanoclay (NC), a transition metal ion re-modified NC (TMI-NC), and a [3-(glycidyloxy)propyl]trimethoxysilane re-modified NC (GPTMS-NC). FTIR test confirmed the successful re-modification of NC. The results of the wide-angle X-ray scattering (WAXS) test revealed that the PET/PEN (75/25 w/w) blend containing 3 phr TMI-NC indicated the best intercalation. Also, the proton nuclear magnetic resonance (1 H NMR) demonstrated that the extent of transesterification was decreased by incorporating the nanofillers into the PET/PEN blend. The 75/25 blend containing 3 phr GPTMS-NC showed the highest decrement. In addition, thermogravimetric analysis (TGA) revealed that the 75/25 blend containing 3 phr TMI-NC showed the best thermal stability.

Structure-Property Relationships in Bionanocomposites for Pipe Extrusion Applications.

In this work, bionanocomposites based on different biodegradable polymers and two types of nanofillers, namely a nanosized calcium carbonate and an organomodified nanoclay, were produced through melt extrusion, with the aim to evaluate the possible applications of these materials as a potential alternative to traditional fossil fuel-derived polyolefins, for the production of irrigation pipes. The rheological behavior of the formulated systems was thoroughly evaluated by exploiting different flow regimes, and the obtained results indicated a remarkable effect of the introduced nanofillers on the low-frequency rheological response, especially in nanoclay-based bionanocomposites. Conversely, the shear viscosity at a high shear rate was almost unaffected by the presence of both types of nanofillers, as well as the rheological response under nonisothermal elongational flow. In addition, the analysis of the mechanical properties of the formulated materials indicated that the embedded nanofillers increased the elastic modulus when compared to the unfilled counterparts, notwithstanding a slight decrease of the material ductility. Finally, the processing behavior of unfilled biopolymers and bionanocomposites was evaluated, allowing for selecting the most suitable material and thus fulfilling the processability requirements for pipe extrusion applications.

Subcritical gas‐assisted processing of ethylene vinyl alcohol + nanoclay composites

AbstractEthylene vinyl alcohol (EVOH) was melt compounded with an organomodified nanoclay (NC) at a loading level of 5% by weight in a twin‐screw extruder using a subcritical gas‐assisted process (SGAP). Carbon dioxide and nitrogen were used as blowing agents to induce foaming inside of the barrel of the extruder and as the melt exits the die. Samples processed with SGAP demonstrated better dispersion of NC vs the traditional extrusion process due to the additional stresses that bubble expansion provides during foaming. The dispersion was assessed by dynamic rheology, wide‐angle X‐ray diffraction, scanning electron microscopy, and microcomputed tomography. Additionally, it was found that the inert gasses used in SGAP prevented some of the thermo‐oxidative degradation EVOH experienced during processing, as evidenced by thermogravimetric analysis and Fourier transform infrared spectroscopy.

Evaluation of thermal and mechanical properties of crumb/natural rubber nanocomposites

Although crumb rubber or waste tires are not classified as hazardous waste, they can cause environmental pollution if disposed incorrectly or irresponsibly. Waste tires can be put to many beneficial uses from one side and to protect the environment via limitting its accumulation when reaching their end of life from the other side. Shredded tires can be added to rubbers to be used in making school playgrounds, equine bedding and football pitches. This may result in the reduction of the mechanical properties of the composites which can be kept by the use of higher levels of other fillers in addition to crumb and hence keeping and even more enhancing these mechanical properties. The crumb rubber was added to natural rubber in the ratio of 10:100 by weight with the partial removal of the carbon black, from 60 to 20 phr, by montmorillonite (organo-modified nanoclay). The modified nanoclay was added in different loadings; 0, 2.5, 5, 7.5, and 10 phr to the rubber mix formulations. Results of morphological analysis revealed the good miscibility and homogeneity between crumb and Natural rubber in one hand and all other ingredients in the other hand.The mechanical, thermal measurements the role of OMMT in enhancing the mechanical and thermal properties of the crumb/NR nanocomposites. The addition of crumb rubber reduces the hazardous working environments for personnel, lower the production cost by making a good use of waste tires and presents a green solution for getting rid of an environmental problem.

Study of the microhardness and erosive wear behavior of organo-modified nanoclay filled glass-epoxy composites and optimization

This research concentrates on examination and optimization of microhardness and erosion resistance of epoxy-glass-nanoclay composites (EGCN’s). The parameters considered were the weight content of Cloisite 15A (A), the volume of glass fiber (B), and the direction of glass fibers (C). Hand lay-up technique was used to make the composites and tested for microhardness and erosive wear as per ASTM standards. The L9 orthogonal array was utilized to design the microhardness tests and erosive wear test, and it was noted that the composite with high clay content, low fiber volume, and 45° orientation had shown low erosion rate (Er) even though its hardness was lesser than the optimized value. At the optimum composition corresponding to the lowest Er, further erosion studies were conducted with the L18 orthogonal array for optimizing machine testing parameters. Scanning electron microscopy (SEM) was used to explain the effect of each parameter on the output. This research gives a thought regarding the consolidated effect of A, B, and C on the erosion resistance of the EGCN’s and the effect of testing parameters.

Effect of nanoclay on mechanical and thermal properties of triblock SBS (styrene–butadiene–styrene) and its binary blend nanocomposites: comparison between polyethylene and polystyrene

ABSTRACTIn this study, the effect of organo-modified nanoclay (OMMT) on the mechanical and thermal properties of SBS and its blend with low-density polyethylene (LDPE) and polystyrene was investigated. The effect of nanoclay content in the presence of LDPE or PS on the final properties of SBS was studied by tensile tester, dynamic mechanical thermal analysis (DMTA), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Addition of nanoclay affected the mechanical and rheological properties. From X-ray and DMTA results, it was found that due to more affinity between the nanoparticles and the SBS/PE blend, the 2 theta characteristic peak of nanoclay shifted to lower angles. SEM studies showed better dispersion and lower inter-particle distance of nanoparticles in SBS/PE composites in comparison with SBS/PS and SBS composites, confirming the XRD and DMTA results. It can be concluded that nanoclay acts as a compatibilizer in the SBS/LLDPE blend. TGA studies showed higher stability of SBS/PS composites compared to SBS and SBS/PE ones.

DISPERSION OF NANOCLAY IN 1,4-POLYBUTADIENE

ABSTRACT Two approaches to obtaining better dispersion of organo-modified nanoclay in high-molecular weight polybutadiene were assessed: (1) chemical modification of the polymer to increase its affinity for the silicate layers and (2) increasing the stretching component of the flow field used to mix the materials. As expected, the degree of dispersion, that is, the extent of intercalation of the polymer into the clay galleries and amount of exfoliation of the clay layers, increased with closer matching of the respective solubility parameters of the components. The efficiency of mechanical mixing was greater for flow fields dominated by stretching (extensional flow); less mix energy had to be expended to achieve a given level of reinforcement. However, without sufficient affinity of the polymer for the clay, complete exfoliation could not be obtained solely by mixing. Nevertheless, incomplete dispersion of the nanoclay still yields more than 40-fold increases in viscosity with 5% clay.

Effect of Organo-Modified Nanoclay on the Mechanical Properties of Sugar Palm Fiber-reinforced Polyester Composites

The aim of this study was to investigate the effect of nanoclay on the mechanical properties of sugar palm fiber-reinforced polyester composites. Organo-modified nanoclay (OMMT) was dispersed in unsaturated polyester resin at various weight contents from 1% to 5% using a mechanical stirrer. Naturally woven sugar palm fibers were reinforced in the nanoclay-modified resin, which were then hot compressed to form the composites. The effect of the OMMT weight content on the tensile, flexural, and impact properties of the composites were analyzed. The addition of OMMT resulted in a noticeable improvement in all of the investigated properties, until a certain weight percentage. The tensile properties showed the best improvements at a 2% nanoclay content. However, the 4% nanoclay content resulted in the best enhancements to the flexural and impact properties.

Organo Modified Nanoclay/Sawdust Mixtures for Hydrocarbon Removal from Water

Organo modified nanoclay (OMNC) and OMNC/sawdust mixture were prepared and applied for hydrocarbon removal from water. Montmorillonite and sawdust were used as raw materials while cetyl trimethyl ammonium bromide (CTAB) used as surfactant. The removed oils were gasoline, diesel and lubricating oil. The sawdust contents in the mixture were 0, 5, 10, 15, 20, 30, 40 and 50 wt.-%. The obtained OMNC and OMNC/sawdust mixture were investigated for their oil removal characteristics by foster swelling test, adsorption capacity, hydrocarbon-water separation test and remaining hydrocarbon determination. The results revealed that the OMNC adsorbed gasoline and diesel 3 times more than its weight and about 2 times for lub.oil and the adsorption increased with increasing surfactant loading. For the mixtures containing 5, 10, 15 and 20% sawdust, improvement in adsorption capacity and coagulation efficiency were detected as compared with those of OMNC alone. The sawdust in the mixtures was functioned as a fibrous framework for combination of coagulated oil and OMNC. This facilitated the floating as well as aggregate formation and subsequently removing of hydrocarbon aggregates. On the other hand, when the sawdust content exceeded 20%, deterioration in adsorption capacity and coagulation efficiency of hydrocarbon was obtained. The total hydrocarbon removal percentage was reached as high as 97.32% and the purified water was totally free from hydrocarbon.

Short-Term Pulmonary Toxicity Assessment of Pre- and Post-incinerated Organomodified Nanoclay in Mice.

Organomodified nanoclays (ONCs) are increasingly used as filler materials to improve nanocomposite strength, wettability, flammability, and durability. However, pulmonary risks associated with exposure along their chemical lifecycle are unknown. This study's objective was to compare pre- and post-incinerated forms of uncoated and organomodified nanoclays for potential pulmonary inflammation, toxicity, and systemic blood response. Mice were exposed via aspiration to low (30 μg) and high (300 μg) doses of preincinerated uncoated montmorillonite nanoclay (CloisNa), ONC (Clois30B), their respective incinerated forms (I-CloisNa and I-Clois30B), and crystalline silica (CS). Lung and blood tissues were collected at days 1, 7, and 28 to compare toxicity and inflammation indices. Well-dispersed CloisNa caused a robust inflammatory response characterized by neutrophils, macrophages, and particle-laden granulomas. Alternatively, Clois30B, I-Clois30B, and CS high-dose exposures elicited a low grade, persistent inflammatory response. High-dose Clois30B exposure exhibited moderate increases in lung damage markers and a delayed macrophage recruitment cytokine signature peaking at day 7 followed by a fibrotic tissue signature at day 28, similar to CloisNa. I-CloisNa exhibited acute, transient inflammation with quick recovery. Conversely, high-dose I-Clois30B caused a weak initial inflammatory signal but showed comparable pro-inflammatory signaling to CS at day 28. The data demonstrate that ONC pulmonary toxicity and inflammatory potential relies on coating presence and incineration status in that coated and incinerated nanoclay exhibited less inflammation and granuloma formation than pristine montmorillonite. High doses of both pre- and post-incinerated ONC, with different surface morphologies, may harbor potential pulmonary health hazards over long-term occupational exposures.

Thermally stable low‐density polyethylene/polyhydroxybutyrate pairs: Synergy between organomodified nanoclay and LDPE‐g‐MAH

ABSTRACTNanocomposites of low‐density polyethylene/polyhydroxybutyrate (LDPE/PHB) containing organomodified montmorillonite (OMMT) and/or LDPE grafted maleic anhydride (LDPE‐g‐MAH) were prepared with a wide range of composition ratios using a vertical co‐rotating twin‐screw microCompounder. To infer the effect of OMMT and LDPE‐g‐MAH on the thermal stability of prepared nanocomposites, all samples were characterized by thermogravimetric analysis while changing clay and compatibilizer contents. Accordingly, two commonly used kinetic models (Coats–Redfern and Horowitz–Metzger) were employed to correlate the thermal stability of the samples with kinetic parameters, including activation energy and pre‐exponential factor. Furthermore, morphological features of LDPE/PHB in the presence or absence of OMMT and LDPE‐g‐MAH were studied using scanning electron microscopy, transmission electron microscopy, and wide‐angle X‐ray diffraction analysis. It was found that for a specific OMMT composition ratio (1 wt %), the thermal stability is enhanced due to an exfoliated structure. However, for samples containing more organoclay (>=3 wt %), the thermal stability was reduced showing the competition between the barrier effect of organoclay platelets and the catalyzing effect of ammonium salts. Moreover, when using LDPE‐g‐MAH as compatibilizer, it acted as a good coupling agent in all compositions in LDPE major phase systems in contrast to PHB major phase samples. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45922.

Vermiculite/poly(lactic acid) composites: Effect of nature of vermiculite on hydrolytic degradation in alkaline medium

Unmodified and different organomodified vermiculites were used for the preparation of poly(l-lactide) (PLLA) composites via melt mixing. The effect of the clay mineral surface modification, the type of organic modifier of the vermiculite and sample thickness on the degradation of PLLA in alkaline medium at 37°C was studied. The degradation was evaluated by analyzing mass loss, pH, molecular weights, and morphological changes. Alkaline hydrolysis of PLLA was accelerated by the presence of clay mineral and the degradation rate was very much dependent on type of clay mineral and state of dispersion. Morphological changes suggested that the erosion mechanism of polymer matrix occurred at the film surfaces and started at the interface of polymer and clay minerals. The results presented here show that the hydrolytic degradation of PLLA can be controlled through the preparation of nanocomposites introducing the appropriate organomodified nanoclay mineral.

Combined influence of organo-modified Indian bentonite nanoclay and fire retardants on thermal and fire behavior of vinylester

This article reports synergetic effect of naturally available Indian bentonite nanoclay and fire retardants on the thermal and fire retardation behavior of vinylester. Indian bentonite nanoclay organically modified with hexadecyltrimethylammonium bromide by cation exchange capacity method, along with aluminum trihydroxide and magnesium hydroxide were dispersed in vinylester and tested. Addition of 30% aluminum trihydroxide and 4 wt% Indian bentonite increased the glass transition temperature of vinylester by 24.4%; decreased thermal degradation by 47%, vertical burning rate by 54% and horizontal burning rate by 72%; and increased limiting oxygen index by 56.6% and microhardness by 49.6%.

Investigation on influence of nanoclay addition on rheological performance of asphalt binder

Organo-modified nanoclay has got considerable attention in recent years to improve the performance of asphalt binders. However, various aspects such as rutting performance using Multiple Stress Creep Recovery (MSCR) test, fatigue performance using Linear Amplitude Sweep (LAS) test and ageing resistivity potential using advanced rheological parameter are still unexplored for better rheological characterisation. The present study deals with rutting, ageing resistivity potential and fatigue performance of asphalt binder (AC-10) modified with organo-modified nanoclay (CL-30B). Different percentages (0, 2, 4 and 6% by weight of binder) of CL-30B were mixed with AC-10 using a high-shear mixer. Different rheological studies, such as Brookfield viscosity, Superpave performance grading, time–temperature sweep, MSCR and LAS tests, were conducted on CL-30B-modified asphalt binders. Effects of CL-30B on performance were observed to be predominant in intermediate to high-temperature range as obtained from the master curve. The ageing resistivity of asphalt binder increased with the addition of CL-30B. The Superpave rutting parameter (G*/Sinδ) increased and non-recoverable creep compliance (Jnr) estimated from MSCR decreased with inclusion of CL-30B, indicating a better rutting performance of asphalt binders. The number of cycles to fatigue estimated from the LAS test showed improvement in fatigue performance of asphalt binder with addition of CL-30B. The high-temperature performance grade of CL-30B-modified binder was found to be higher compared to virgin binder. The relationship between Jnr and G*/Sinδ, and recovery (R) and storage modulus (G′) parameters are presented in this paper. In addition, ranking of asphalt binder based on various parameters (i.e. G*/Sinδ, AI, Jnr, R, Nf) is discussed in this paper.

Studying the effect of organo-modified nanoclay loading on the thermal stability, flame retardant, anti-corrosive and mechanical properties of polyurethane nanocomposite for surface coating

Abstract Clay polyurethane nanocomposite (CPN) coating films were fabricated by uniformly dispersing nanoclay, organically modified with 25–30 wt.% octadecylamine in varying concentrations up to 5 wt.%, in a commercial two component, glossy, acrylic aliphatic polyurethane using ultrasonication. Organo-modified nanoclay was characterized by X-ray diffraction (XRD). The dispersion of the nanoclay into the matrix was investigated by scanning electron microscopy (SEM). CPN coating films were characterized by thermogravimetric analysis (TGA), and flame retardant, corrosion resistance and mechanical properties were also investigated. The XRD measurement indicated that, the organo-modified nanoclay particles were mainly constituted of montmorillonite with traces of quartz and calcite also found to be present. The SEM analysis showed that the nanoclay layers were dispersed and intercalated into the polyurethane coating. Thermogravimetric analysis showed that incorporating 5 wt.% organo-nanoclay into polyurethane considerably enhanced the thermal stability and increased the char residue to 14.11 wt.% relative to 4.58 for the sample without organo-nanoclay (blank polyurethane). The limiting oxygen index (LOI) test revealed that incorporation of organo-nanoclay led to a further increase in LOI values, which indicate an improvement in flame retardancy properties. The corrosion resistance also improved and this improvement increases with increase nanoclay wt.%. The mechanical resistance measurements demonstrated that the gloss of the CPN coating films slightly decreased, although hardness, adhesion and impact resistance of the CPN coating films improved with the incorporation of the organo-nanoclay.

Effect of Organo-Modified Nanoclay on the Thermal and Bulk Structural Properties of Poly(3-hydroxybutyrate)-Epoxidized Natural Rubber Blends: Formation of Multi-Components Biobased Nanohybrids.

Multi-component nanohybrids comprising of organo-modified montmorillonite (MMT) and immiscible biopolymer blends of poly(3-hydroxybutyrate) (PHB) and epoxidized natural rubber (ENR-50) were prepared by solvent casting technique. The one and three dimensional morphology of PHB/ENR-50/MMT systems were studied using Polarizing Optical Microscopy (POM) and Scanning Electron Microscopy (SEM). Differential scanning calorimetry (DSC) technique was used to evaluate the thermal properties of the nanohybrids. The melting temperature (Tm) and enthalpy of melting (ΔHm) of PHB decrease with respect to the increase in ENR-50 as well as MMT content. The non-isothermal decomposition of the nanohybrids was studied using thermogravimetric (TG-DTG) analysis. FTIR-ATR spectra supported ring opening of the epoxide group via reaction with carboxyl group of PHB and amines of organic modifier. The reaction mechanism towards the formation of the nanohybrids is proposed.

Moisture diffusion through nanoclay/vinylester processed using twin‐screw extrusion

This research concerns moisture absorption through nanoclay/vinylester composites in artificial seawater medium and the resulting properties of degradation. Cloisite 15A, an organomodified nanoclay, and Cloisite Na, a naturally occurring nanoclay, were studied to examine the influence of organomodification on the moisture ingress behavior of the nanocomposites processed by using ultrasonication and twin‐screw extrusion. Although X‐ray diffraction and transmission electron microscopy analysis revealed exfoliation of Cloisite 15A in vinylester, Cloisite Na was only intercalated. Moisture diffusivity decreased by 72% due to the addition of 5 wt% of Cloisite 15A to vinylester. However, the same increased in the case of the addition of Cloisite Na, suggesting a positive influence of the organomodification on the moisture barrier properties. Although Fick's Law of Diffusion showed deviation from the experimental data in the nonlinear region of moisture absorption as a function of duration of exposure, the Langmuir Model was in better agreement with the experimental data in the entire range. (Cloisite 15A)/vinylester showed lower levels of microhardness deterioration due to moisture absorption than that of (Cloisite Na)/vinylester. J. VINYL ADDIT. TECHNOL., 20:152–159, 2014. © 2014 Society of Plastics Engineers

Influence of the epoxidation degree of a polystyrene–polybutadiene–polystyrene (SBS) triblock copolymer on the compatibilization with an organomodified nanoclay

In this work, the addition of organophilic-modified montmorillonite into polystyrene–polybutadiene–polystyrene (SBS) triblock copolymers was investigated with and without the use of epoxidized SBS as a compatibilization agent. The nanocomposites were prepared by melting mixture at 60 rpm and 130 °C. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), tensile tests, and dynamic-mechanical analysis (DMA). XRD and TEM showed the formation of an intercalated dispersion of clay platelets oriented on the SBS surface. The AFM showed the typical lamellar microstructure of the styrene and butadiene phases of SBS. The estimation of the average distance between the styrene lamellae by AFM analysis showed that the platelets are anchored between the phases, and this structural feature caused an increase in elastic modulus. DMA analysis showed that the T g of butadiene decreased in the nanocomposites. The decrease of the T g and the increase in the elastic modulus are correlated to mechanisms at the micro- and the macro-scales, respectively. The decrease in the T g indicates flexibilization at the interface, whereas the intercalation of the platelets restricted the interphase macroscale deformation.