Presence Of Organoclay Research Articles

Rheological Characteristics of Solvent-Cast Poly(e-Caprolactone)/Organoclay Nanocomposite

As an effective way to enhance various properties of polymer, polymer/clay nanocompoiste is being adopted since it can hybrid the properties of the two components, showing superior physical and mechanical properties. In this study, poly(ε-caprolactone) (PCL) nanocomposites using an organoclay were prepared by a solution intercalation method, and their unique internal structures and rheological properties induced by the presence of organoclay at nano level were studied using WAXD and a rotational rheometer.

Melt blending of polypropylene‐blend‐ polyamide 6‐blend‐organoclay systems

AbstractThe melt blending of polypropylene‐blend‐polyamide 6‐blend‐organoclay (PP/PA6/organoclay) systems has been investigated using an internal mixer without any traditional compatibilizer. In the presence of organoclay, the melting of PA6 phase is accelerated and the dimension of the dispersed phase in the matrix is reduced. Transmission electron microscopy results reveal clay‐rich interface zones formed between the PA6 dispersed phase and the PP matrix in the PP/PA6/organoclay system. An interface blending approach has been designed to investigate the interface zones between the immiscible polymers, and the interface zones have been characterized by Fourier transform infrared and X‐ray photoelectron spectroscopy. In the presence of the organoclay, the PA6 component in interface zones is stable even after etching extraction with formic acid, suggesting a strong interaction takes place among PP, PA6 and the organoclay. Such clay‐rich interface zones act as a compatibilizer for the two immiscible polymers, resulting in a better dispersion of PA6 phase in PP matrix. Copyright © 2006 Society of Chemical Industry

Effect of Organoclay and Ethylene-Octene Copolymer Inclusion on the Morphology and Mechanical Properties of Polyamide/Polypropylene Blends

A series of compatibilized polyamide 6/polypropylene (PA6/PP) blends, of composition 70/30, 50/50, and 30/70 have been prepared in a twin screw extruder followed by injection molding. The four types of PA6/PP blends involved are the neat PA6/PP blends, PA6/PP/ethylene-octene copolymer (polyolefin elastomer, POE), PA6/PP/organoclay, and PA6/PP/POE/organoclay. Tensile, flexural, and Izod impact test are performed on these blends. The morphology of the blends is characterized by scanning electron microscopy (SEM). The mechanical properties of the blends are found to be strongly dependent on the PA6/PP blend ratio. For any blend system, with the increase in PP concentration, the strength and stiffness decreases, while the toughness increases. The incorporation of 4 wt% organoclay into PA6/PP blends significantly increases the modulus and strength but with corresponding reductions in impact strength. Conversely, the incorporation of POE increases the toughness, while the strength and stiffness decrease. However, PA6/PP blends containing both organoclay and POE elastomer are shown to have the potential to be more rigid and tougher than the neat PA6/PP itself. Blend ratio and presence of organoclay are found to influence the morphology (e.g., POE particle size and distribution) of POE toughened nanocomposites systems. A finer particle size and better distribution of POE elastomer has been observed in high PP concentration PA6/PP blends and organoclay filled PA6/PP blends.

Characteristics of polystyrene/organoclay nanocomposites prepared by in‐situ polymerization with macroazoinitiator containing poly(dimethylsiloxane) segment

AbstractPolystyrene (PS)/organoclay nanocomposites were prepared by the in situ polymerization of styrene in the presence of organoclay with macroazoinitiator (MAI), composed of repeated sequences of poly(dimethylsiloxane) (PDMS) and azo groups. The X‐ray diffraction patterns and the morphology observed with a transmission electron microscope showed that the dispersion of organoclay in polymer matrix improved as the content of the PDMS segment in the nanocomposite increased. However, negative effects on the rise of glass transition temperatures and the thermal resistance of nanocomposite, measured by differential scanning calorimetry and thermogravimetry, at a high content of the PDMS segment, suggested that organoclay lay preferentially in the PDMS domain. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2841–2847, 2006

Micro- and nano-scale deformation behavior of nylon 66-based binary and ternary nanocomposites

The primary aim of this paper is to provide an insight on the effect of the location of organoclay on the micro- and nano-scale deformation processes in melt-compounded nylon 66/organoclay/SEBS-g-MA ternary nanocomposites prepared by different blending sequences. In addition, the deformation processes of the ternary nanocomposites were compared to the binary nanocomposites (nylon 66/organoclay and nylon 66/SEBS-g-MA) and neat nylon 66. The incorporation of SEBS-g-MA particles toughened nylon 66 markedly; but the flexural modulus and strength were both reduced. Conversely, the use of organoclay increased the modulus but decreased the fracture toughness of nylon 66. Nylon 66/SEBS-g-MA/organoclay ternary nanocomposites exhibited balanced elastic stiffness and toughness. Stress-whitening studies of the fracture surfaces in terms of gray level were also performed and an attempt was made to correlate the optical reflectivity characteristics with fracture toughness. It was concluded that the capability of SEBS-g-MA particles to cavitate was decreased by the presence of organoclay in the SEBS-g-MA phase, resulting in reduced toughening efficiency. The best micro-structure for toughness and other mechanical properties is thus to maximize the amount of exfoliated organoclay in the nylon 66 matrix rather than to have it embedded in the finely dispersed SEBS-g-MA particles.

Effect of blending sequence on microstructure of ternary nanocomposites

Knowledge of the nature of molecular processes occurring during melt compounding of nanomaterials and polymers is crucial in determining the ultimate performance of polymer nanocomposites. In this paper, we demonstrate for the first time with detailed transmission electron microscopy, the parameters that affect the microstructure of polymer nanocomposites by varying the blending sequence. Nylon 66/organoclay/SEBS- g-MA ternary nanocomposites prepared by four different blending sequences exhibited distinct microstructure and mechanical properties. It was concluded that the best microstructure for toughness and other mechanical properties is to have the maximum percentage of the exfoliated organoclay in the nylon 66 matrix rather than to have it in the dispersed SEBS- g-MA phase. The presence of organoclay in the SEBS- g-MA phase reduces the latter's ability to cavitate, resulting in reduced toughening efficiency.

Effect of layered nano-organosilicate on the gel point rheology of bismaleimide/diallylbisphenol A resin

The effect of organically modified clay (organoclay) on the cross-linking of a high performance thermoset resin—diallylbisphenol A (DBA) modified bismaleimide (DBA/BMI), is studied using rheometry and FTIR spectroscopy. The validity of the Winter–Chambon criterion was examined for the cross-linking of these filled polymers. Physical gels have been formed prior to the chemical cross-linking with 3.0 and 5.0% organoclay I.30TC. The physical properties of the gel, including the loss tangent, critical relaxation exponent and the gel strength in the absence and presence of organoclay, were investigated and the results indicated that organoclay showed a great effect on the physical properties of the gel. Organoclay reduced the gel time but decreased the degree of the cross-linking slightly at the gel point, as revealed by the FTIR spectroscopy. The dispersion of organoclay also affected the gel characteristics. More elastic and stronger gel can be obtained when organoclay was better exfoliated. When another type of organoclay Cloisite 30B was used, results indicated that the nature of organoclay had a considerable effect on the cross-linking in the polymer system.

A study on phase morphology and surface properties of polyurethane/organoclay nanocomposite

In this study, polyurethane/organically modified layered silicate (organoclay) nanocomposites were prepared through in situ polymerization in the presence of organoclay. Phase morphology of the polyurethane/organoclay nanocomposite was investigated by small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM). The results suggest that the inter-domain repeat distance decreased with the introduction of organoclay. The organoclay has a more significant effect on the inter-domain repeat distance at a low hard segment content. Also with the increase of the hard segment, the inter-domain repeat distance and domain size increased markedly. The size of hard domain of the polyurethane was found to be in the range of 12–32 nm in this case, and it keeps nearly unchanged with the clay content. It is suggested by AFM phase imaging technique that the hard domain can self-organize further to form spherical aggregates. The introduction of clay into the polyurethane matrix resulted in the decrease in the size of the spherical aggregates from ∼800 nm to ∼500 nm, indicating clay has an important effect on the aggregation behavior of hard domains. The effect of clay on the surface energy was examined by means of AFM and goniometry techniques. The results obtained by two methods are consistent, i.e., with the increase of clay content, the surface energy decreased due to the effect of organic modifier.

Synthesis and characterization of nylon 1012/clay nanocomposite

AbstractA nylon 1012/clay nanocomposite was prepared by melt polycondensation polymerization of diamine and diacid in the presence of organoclay. The nylon 1012 and nanocomposite were characterized by Fourier transform IR spectroscopy with attenuated total reflection, and a shift of the SiOSi band toward a lower wavenumber was found as the result of the strong interaction of nylon 1012 with the organoclay. The X‐ray diffraction analysis and transmission electron microscopy observation showed that the clay minerals were exfoliated. Clay platelets increased the crystallization rate but decreased the crystallinity. Differential scanning calorimetry and dynamic mechanical thermal analysis measurements showed that the glass‐transition temperature of the nylon 1012/clay nanocomposite decreased to some degree as compared to nylon 1012 because of the combined effect of confinement and the reduction of the physical crosslink density. The mechanical properties of the nanocomposite such as the tensile strength and tensile modulus are higher than those of nylon 1012, and the water absorption is reduced because of the improvement in the barrier property of the nanocomposite. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2403–2410, 2002

The Hydraulic Conductivity and Adsorptivity of Organoclay in a Sand-Bentonite Barrier to Hydrophobic Organic Chemicals

This study investigates the hydraulic conductivity and adsorptivity of simulated clay barrier material containing organoclay, for the purpose of discovering whether the inclusion of organoclay in a clay barrier can effectively immobilize hydrophobic organic chemicals. The surface of a commercial Na-bentonite was modified by replacing the original inorganic cations with hexadecyltrimethylammonium, a cationic surfactant. Batch adsorption tests using dilute concentrations of the hydrophobic organic chemicals — pentachlorophenol, naphthalene and toluene — were performed on the bentonite samples and the resulting organoclay. Hydraulic conductivity tests using permeants containing dilute concentrations of pentachlorophenol, naphthalene and toluene were performed on the bentonite samples with and without organoclay. The batch adsorption tests showed that the organoclay adsorbed hydrophobic organic chemicals from 10 to 40 times more effectively than did untreated bentonite. The hydraulic conductivity tests indicated that the presence of organoclay in a clay barrier material significantly increased the hydraulic conductivity whether or not hydrophobic organic chemicals were present in the permeant. Naphthalene or toluene in the permeant increased the hydraulic conductivity of the bentonite samples containing organoclay, while pentachlorophenol in the permeant had no apparent effect on the hydraulic conductivity.