Modified Nano Clay Research Articles

Identification of nano clay in composite polymers

Industrialized food production is in urgent search for alternative packaging materials, which can serve the requirements of a globalized world in terms of longer product shelf lives, reduced freight weight to decrease transport costs, and better barrier functionality to preserve its freshness. Polymer materials containing organically modified nano clay particles as additives are one example for a new generation of packaging materials with specific barrier functionality to actually hit the market. Clay types used for these applications are aluminosilicates, which belong to the mineral group of phyllosilicates. These consist of nano‐scaled thin platelets, which are organically modified with quaternary ammonium compounds acting as spacers between the different clay layers, thereby increasing the hydrophobicity of the mineral additive. A variety of different organically modified clays are already available, and the use as additive for food packaging materials is one important application. To ensure valid risk assessments of emerging nano composite polymers used in the food packaging industry, exact analytical characterization of the organically modified clay within the polymer matrix is of paramount importance. Time‐of‐flight SIMS in combination with multivariate statistical analysis was used to differentiate modified clay reference materials from another. Time‐of‐flight SIMS spectra of a reference polymer plate, which contained one specific nano clay composite, were acquired. For each modified clay additive, a set of characteristic diagnostic ions could be identified, which then was used to successfully assign unknown clay additives to the corresponding reference material. Thus, the described methodology could be used to define and characterize nano clay within polymer matrices. Copyright © 2014 John Wiley & Sons, Ltd.

Effect of Nanoclay Surface Modifier Chemical Reactivity on Morphology and Rheological Properties of PP/PA6 Blend Nanocomposite

Abstract An attempt was made to explore the role of nanoclay surface modifier chemical reactivity on the morphology and the rheological properties of a polypropylene/polyamide6 (PP/PA6 75/25) nanocomposite blend. The Na-MMT surface was modified with two types of cations; a) diamine cation (D-Clay), and b) a combination of diamine and quaternary alkylammonium cations (A-Clay) via cation exchange reaction. The nanocomposites samples compatibilized with PP-g-MA were prepared by melt compounding in an internal mixer. The XRD patterns indicated the intercalated/exfoliated microstructure for both nanocomposite samples. The SEM results showed a significant decreases in the PA6 droplet size, from 3.2 μm of the simple blend to the 0.4 μm in the D-Clay containing sample. Moreover, in the sample containing A-Clay the average droplet size was found to be 1 μm. The D-Clay containing sample showed the rheological properties similar to a simple blend in high frequencies with a nonterminal behavior in low frequencies storage modulus. This was explained by locating of D-Clay layers in the interphase and hence, significantly reducing the effective interfacial tension, α/R. In contrast, the sample containing A-Clay showed an increased complex viscosity and storage modulus within a range of frequencies, which was attributed to presence of a large amount of A-Clay layers in the PP matrix. These types of nanoclay partitioning were explained by the possibility of chemical reaction between amine group of nanoclay surface modifier and maleic group of PP-g-MA compatibilizer or in-situ formed block copolymer. Consequently, the D-Clay layers bounded with PP-g-MA is preferentially located in the interphase, while, the non reactive nanoclay layers (containing alkylammonium cations) is dispersed in the PP matrix by assistance of PP-g-MA. These findings were also evidenced by TEM micrograph of both nanocomposite samples.

Effect of Nanoclay and Precipitated Calcium Carbonate on Mechanical Properties of Asphalt Concrete

Modified bituminous materials can bring real benefits to highway maintenance/construction, in terms of better and longer lasting roads, and savings in total road life castings. This paper present the effect of there novel modifier as Precipitated Calcium Carbonate (PCC) and Nanoclay on engineering properties of asphalt concrete. Various empirical and fundamental tests such as Marshall test, indirect tensile strength, resilient modulus, dynamic creep and diametric fatigue have been investigated in this research. These tests have been conducted at different temperature and various lording forms. The results show that nanoclay modifier can improve cohesive and strength of the mix by increase in marshal stability, indirect tensile, resilient modulus but has non proper response in fatigue behaviour. Precipitated Calcium Carbonate can improve fatigue response of the mix but has not salient effect on marshal stability and indirect strength.

A Nano Quasi-Solid Electrolyte With Modified Nano-Clay Applied to Dye-Sensitized Solar Cells

The gel electrolytes for dye-sensitized solar cells (DSSCs) have been reported recently. Such electrolytes have their own liquid electrolyte properties and a quasi-solid electrolyte morphology. In this paper, nano-clay was chosen as gelator and mixed with liquid electrolytes to form clay type nanocomposite gel. This gel electrolyte consists of liquid electrolytes and surface modified nano-clay. The surface modifier makes nano-clay disperse well in liquid electrolytes. Nano-clay mixed with electrolyte will increase its viscosity and it is believed to be helpful in fabricating flexible DSSC. In general, an increase in viscosity will decrease ionic mobility and decrease photovoltaic conversion efficiency. The ionic conductivity was determined by the viscosity of the nano-clay gel with different surface modifiers. The ionic transfer rate of the nano-clay gel electrolyte is controlled by the diffusion and exchange reaction. The clay type gel electrolyte has higher ionic conductivity. Finally, the electrochemistry properties and the DSSC performances for the nano-clay type gel electrolyte have been discussed in this paper.

Preparation of tailor-made polystyrene nanocomposite with mixed clay-anchored and free chains via atom transfer radical polymerization

Tailor-made polystyrene nanocomposite with mixed free and clay-attached polystyrene chains was synthesized using atom transfer radical polymerization. Vinylbenzyl trimethylammonium chloride having a double bond, which could be incorporated into polystyrene chains by a grafting through process, was used as a nanoclay modifier. Conversion and molecular weight evaluation was carried out using gas chromatography and gel permeation chromatography, respectively. The thermogravimetric analysis results confirmed the elevated thermal stability of the nanocomposites in comparison with the neat polystyrene sample. Additionally, the Tg increases by clay loading was confirmed by differential scanning calorimetry (DSC). The difference in the degradation temperature of CBr bond in attached and free polystyrene chains was well revealed in DSC thermograms. Finally, a lower clay loading resulted in an exfoliated structure as proved by X-ray diffraction and transmission electron microscopy results. © 2010 American Institute of Chemical Engineers AIChE J, 2011

Mechanical Behavior of Nanoclay Modified Asphalt Mixtures

Abstract Polymeric nanocomposites are among the most exciting and promising classes of materials discovered recently. A number of physical properties are successfully enhanced when a polymer is modified with small amount of nanoclay on condition that the clay is dispersed at nanoscopic level. In this research, comparative rheological tests on binders and mechanical tests on asphalt mixtures containing unmodified and nanoclay modified bitumen, were carried out. Two types of nanoclay were used: Nanofill-15 and Cloisite-15A. Rheological tests on binder were penetration, softening point, ductility, and aging effect. Mechanical tests on asphalt mixture were Marshall stability, indirect tensile strength, resilient modulus, diametric fatigue, and dynamic creep tests. Test results show that nanoclay can improve properties such as stability, resilient modulus, and indirect tensile strength and result in superior performance compared to that of unmodified bitumen under dynamic creep. Nanoclays do not seem to have beneficial effect on fatigue behavior in low temperature. Optimum binder content and void in total mixture increase by adding nanoclay to bitumen.

Nanoclay Modified Water-Blown Polyurethane Foams Derived from Bifunctional Soybean Oil-Based Polyol

In this brief communication, we report on the modification of polyurethane (PU) foams based on bifunctional soy bean oil-based polyol by nanoclay. Presence of clay at small loading has been observed to make the foam system more rigid. Modification has been analyzed by measurements on density and compressive strength. In addition, differential scanning calorimetry and thermogravimetric analysis have been used to explain changes in properties of the foams. Scanning electron microscopy have been used to verify the foam rigidity in presence of nanoclay. We conclude that nanoclays are capable of strengthening PU foams derived from bifunctional soy polyol.

Wheat-Gluten-Based Natural Polymer Nanoparticle Composites

A series of wheat-gluten-based nanocomposites were produced by dispersing Cloisite-30B nanoclay particles into plasticized wheat gluten systems under thermal processing conditions. The exfoliation of the nanoparticles as confirmed by wide-angle X-ray diffraction and transmission electron microscopy has resulted in significant enhancement of the mechanical properties for both deamidated proteins and vital gluten systems under 50% relative humidity (RH). Such strength improvement was also pronounced for wheat gluten (WG) systems under a high humidity condition (RH = 85%). A similar level of further strength enhancement was obtained for the WG systems that had been strengthened by blending with poly(vinyl alcohol) (PVA) and cross-linking with glyoxal. Although the nanoclay modifier, a quaternary ammonium, caused an additional plasticization to the materials, the interactions between the gluten matrix and the nanoparticles were predominant in all of these nanocomposites. A solid-state NMR study indicated that the polymer matrix in all of these nanocomposites displayed a wide distribution of chain mobilities at a molecular level (less than 1 nm). The interactions between the nanoparticles and the natural polymer matrix resulted in motional restriction for all components in the mobile phases including lipid, plasticizers, and plasticized components, although no significant influence from the nanoparticles was obtained in the mobility of the rigid phases (unplasticized components). On a scale of 20-30 nm, the deamidated protein systems tended to be homogeneous. The small domain size of the matrix resulted in modifications of the spin-lattice relaxation of these systems via spin diffusion. The residual starch seemed to remain in a relatively larger domain size in WG systems. The nanoparticles could enhance the miscibility between the starch and the other components in the WG nanocomposite, but such miscibility enhancement did not occur in the WG/PVA blend and the cross-linked system. These polymer matrixes were still heterogeneous on a scale of 20-30 nm.

Nanoclay and Modified Nanoclay as Sorbents for Anionic, Cationic and Nonionic Dyes

The nanoclay, montmorillonite, and some modified nanoclays were used as sorbents for nonionic, anionic and cationic dyes. From the sorption differences among the different dye and clay structures, both chemical and morphological, the sorption forces that played important roles were identified. The nanoclay could easily have a sorption capacity of more than 600 mg sorbate per gram of sorbent at a liquor-to-sorbent ratio of 100 to 1. Furthermore, it could have a sorption of 90% at an initial dye concentration of 6 g/L, or 60% based on the weight of the sorbent, indicating an extremely high dye affinity. This study showed that with certain modifications the nanoclay, montmorillonite, could easily become an excellent sorbent for anionic, cationic and nonionic dyes.