Organoclay Filler Research Articles

Influence of Montmorillonite Organoclay Fillers on Hygrothermal Response of Pultruded E-Glass/Vinylester Composites.

Pultruded fiber reinforced polymer composites used in civil, power, and offshore/marine applications use fillers as resin extenders and for process efficiency. Although the primary use of fillers is in the form of an extender and processing aid, the appropriate selection of filler can result in enhancing mechanical performance characteristics, durability, and multifunctionality. This is of special interest in structural and high voltage applications where the previous use of specific fillers has been at levels that are too low to provide these enhancements. This study investigates the use of montmorillonite organoclay fillers of three different particle sizes as substitutes for conventional CaCO3 fillers with the intent of enhancing mechanical performance and hygrothermal durability. The study investigates moisture uptake and kinetics and reveals that uptake is well described by a two-stage process that incorporates both a diffusion dominated initial phase and a second slower phase representing relaxation and deterioration. The incorporation of the organoclay particles substantially decreases uptake levels in comparison to the use of CaCO3 fillers while also enhancing stage I, diffusion, dominated stability, with the use of the 1.5 mm organoclay fillers showing as much as a 41.5% reduction in peak uptake as compared to the CaCO3 fillers at the same 20% loading level (by weight of resin). The mechanical performance was characterized using tension, flexure, and short beam shear tests. The organoclay fillers showed a significant improvement in each, albeit with differences due to particle size. Overall, the best performance after exposure to four different temperatures of immersion in deionized water was shown by the 4.8 mm organoclay filler-based E-glass/vinylester composite system, which was the only one to have less than a 50% deterioration over all characteristics after immersion for a year in deionized water at the highest temperature investigated (70 °C). The fillers not only enhance resistance to uptake but also increase tortuosity in the path, thereby decreasing the overall effect of uptake. The observations demonstrate that the use of the exfoliated organoclay particles with intercalation, which have been previously used in very low amounts, and which are known to be beneficial in relation to enhanced thermal stability, flame retardancy, and decreased flammability, provide enhanced mechanical characteristics, decreased moisture uptake, and increased hygrothermal durability when used at particle loading levels comparable to those of conventional fillers, suggesting that these novel systems could be considered for critical structural applications.

Effect of Carbon and Organoclay Fillers on Partial Discharge and Corrosion Properties of Polyurethane Base Composite Coated on Aluminum Alloy

Effect of Carbon and Organoclay Fillers on Partial Discharge and Corrosion Properties of Polyurethane Base Composite Coated on Aluminum Alloy

Influence of organoclay filler and dicumyl peroxide (DCP) on the properties of the low-density polyethylene (LDPE)/thermoplastic starch (TPS) blend

In this study low-density polyethylene (LDPE)/thermoplastic starch (TPS)/nanoclay (O-Mt) nanocomposites were prepared by a melt blending process using a Brabender mixer. Dicumyl peroxide (DCP) and nanoclay (O-Mt) were studied to improve interfacial adhesion and to obtain the various desired properties of the nanocomposites. The structure and properties of the materials were studied by X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and by tensile and Izod impact tests. X-ray diffraction analysis of the nanocomposites showed that the characteristic peaks of the clay were shifted to the lower angles, indicating an intercalated structure in the presence of dicumyl peroxide (DCP). The TGA curve indicated an improvement in the thermal stability of the materials with the amount of silicate and DCP. The mechanical properties of the materials were improved as a consequence of the increase in phase adhesion which gave an improvement in crystallinity confirmed by DSC. In addition, the impact strength of the modified materials was improved compared to the original materials. A modification of morphology as well as roughness was demonstrated by SEM and AFM.

Mechanical, thermal, and interfacial shear properties of polyamide/nanoclay nanocomposites

There are increasing interests in using thermoplastics to replace thermosets to laminate fabrication due to their advantages such as high toughness, shorter manufacturing cycles, and reprocessing possibilities. The aim of the current study is to select appropriate thermoplastic nanocomposites, which fit the requirements of carbon fiber (CF) composites in the automotive industry. In order to achieve the target, this research has investigated the effect of nanoclay on the mechanical, thermal, and interfacial properties with de-sized CF of polyamide (PA6) composites. PA6/clay composites were characterized by different properties, namely, bending, tensile, impact, heat distortion temperature, interfacial shear stress, and scanning electron microscope. The micromechanism of plastic deformation after bending failure of PA6-clay nanocomposites is examined with different contents of nanoclay to correlate the microstructures with the mechanical properties. The results revealed that with 3% organo-clay filler content, flexural strength and modulus improved significantly by 42% and 52%, respectively, which could be explained by scanning electron microscopy images that show rougher fracture surface with adding clay into the PA6 matrix. The increased surface roughness implies that the path of the crack tip is distorted because of the silicate nano-layer, making crack propagation more difficult. The interfacial shear strength for 1 wt% of nanoclay was about the same as the neat PA6 but decrease dramatically with increasing contents of nanoclay.

Effect of the loading of organomodified clays on the thermal and mechanical properties of a model dental resin

Experimental dental resins composed of triethyleneglycol dimethacrylate, urethane dimethacrylate, ethoxylated bisphenol-A-dimethacrylate and bisphenol A glycidyl methacrylate containing an organoclay as filler were prepared by photopolymerization. The addition of organoclay fillers results in slower polymerization rates (0.59 and 0.24 mol L-1 min-1, for the formulations without and with 15% of organoclay, respectively) and lower degrees of conversion (0.50 and 0.35 for the formulations without and with 15% of organoclay), as determined by photocalorimetry. The influence of the organoclay on the thermal and mechanical properties of the resins was evaluated using thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) techniques. The (tan δ) and E´ curves indicate the formation of more rigid materials and the damping curve data indicates more homogeneous materials. An increase of storage modulus, E’, was observed for composites with the higher organoclay filler contents. These effects are due to the higher viscosity of the systems with organoclay, resulting in a lower mobility of the radicals during the propagation step of polymerization, as well as to the scattering of the incident photopolymerizing radiation, which lowers the amount of initiation centres.

Influence of organoclay filler on the properties of polystyrene/low-density polyethylene blend

The present work deals with the study of nanocomposites based on polystyrene (PS)/low-density polyethylene (LDPE) blend and an organophilic clay (Bentone 38 (B38)). Different PS/LDPE/B38 mixtures were prepared via melt intercalation process using a two-roll mixer and a single-screw extruder. Analysis of the nanocomposites by means of X-ray diffraction showed that the characteristic peak of the clay appears only at 3% wt. content, indicating an intercalated structure of PS/LDPE/3% B38 nanocomposite. The mechanical properties of the nanocomposites reflected the effect of the addition of the filler as well as the state of interfacial adhesion between the polymer blend matrix and the filler. The incorporation of the clay into PS/LDPE blend resulted in a relative increase (particularly at 0.5% wt.) of the stress at break and microhardness owing to the interfacial interactions developed between the PS/LDPE matrix and the clay and between the two blend phases. This is in good agreement with PS/LDPE/B38 nanocomposites rheological behavior which revealed an increased maximum torque most pronounced at 0.5% clay weight. Scanning electron microscopy micrographs showed, for this same clay content, the compatibilization effect of the clay between PS and LDPE. This was also confirmed by the atomic force microscopy images and by differential scanning calorimetry analyses.

Synergistic effect of organoclay fillers based on fluorinated surfmers for preparation of polystyrene nanocomposites

ABSTRACTNovel fluorinated reactive surfactants were used for the organic modification of monmorillonite clays. These organoclays were used for the preparation of polystyrene−clay nanocomposites by in‐situ free radical polymerization. Reference systems based on hydrocarbon homologous surfmer and nonpolymerizable surfactants were also used to deduce the effect of the fluorine moiety and the polymerizable function on the morphology and thermal stability of the prepared nanocomposites. Different structural parameters of the surfactants were investigated and modulated for the clay modification including: the nature of surfactant (surfmer/classical surfactant, fluorinated, or hydrocarbonated), the length of the fluorinated chain as well as the length of the hydrocarbon spacers linking the ammonium head to the fluorine chain or the polymerizable acrylic function. Wide angle‐X‐ray scattering (WAXD), thermogravimetric analysis (TGA), and electronic microcopies (TEM and SEM) were used to establish a structure‐morphology, thermal properties relationships, and to highlight the key parameters governing the exfoliation process. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42347.

Characterisation and properties of HDPE/NR blend-layered silicate nanocomposites prepared by melt intercalation

Nanocomposites comprising high density polyethylene (HDPE) and natural rubber (NR) blend as the matrix polymer and Closite 20A as the organoclay filler were prepared using the melt intercalation technique in an internal mixer. In order to study the morphological structure of the nanocomposites obtained, X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses were carried out. The physical properties of nanocomposites were examined with dynamic mechanical analysis (DMA) and tensile tester. Test specimens were fabricated using compression moulding after the blending process. The results show that all properties analysed were strongly influenced by the composition of organoclay. The X-ray diffraction results indicated intercalation of blend into the silicate interlayer of organoclay and partially exfoliated of silicate layer in the blend. Based on the observation from transmission electron microscope, organoclay was found well dispersed within the matrix. The tensile strength of HDPE/NR blend was enhanced by the addition of low loading of this organically modified montmorillonite. The results of tensile modulus improved with increasing the content of organoclay. The DMA curves show that the incorporation of organoclay increased the storage modulus of the nanocomposites below the Tg temperature and slightly reduces the tan δ peak height.

Lignosulfonate interleaved layered double hydroxide: A novel green organoclay for bio-related polymer

New organic inorganic layered double hydroxide (LDH) organoclays are assembled through coprecipitation with lignosulfonate (LS) interleaved inorganic host structure sheets. The biopolymer is found to accommodate the interlayer space adopting a bilayer molecular arrangement resulting in a basal spacing of 2.54nm. However the crystallinity of the resulting bio-organoclay is weak, probably due to the difficulty of the inorganic sheets to be built on amorphous polymer chain, the latter inducing low structural ordering. An organoclay of composition Zn2Al/LS is subsequently used as filler in three bio-related polyesters, poly(lactic) acid (PLA), poly(butylene) succinate (PBS) and poly(butylene adipate-co-terephthalate) (PBAT). Melt polymer extrusion using 5wt.% organoclay loading yields polyester nanocomposite with a nanocomposite structure largely intercalated for both PLA and PBS (Δd (expansion)>6nm) while a non miscible structure is obtained for PBAT. The incorporation of hydrophilic Zn2Al/LS platelets decreases the water/polymer contact angle of about 10° for the LDH/LS PBAT composite only. A strong increase of the complex viscosity |η*| is observed for both nanocomposites Zn2Al/LS PLA and PBS compared to the polyester itself. This is explained on the basis of a chain extender behavior of the intercalated Zn2Al/LS platelets towards polymer chains as evidenced on the Cole Cole representation showing an increase of the real viscosity in the low-ω region. In opposition a strong decrease in |η*| is observed for PBAT, underlining a plasticizing effect of the organoclay filler. Comparatively, the thermal stability of PLA is slightly enhanced with an increase of T0.5 value while PBS and PBAT bio-nanocomposites degrade at slightly lower temperature.

Tribological Behavior of Polyamide 66-Based Binary and Ternary Nanocomposites

The tribological behavior of polyamide 66 (PA66) and its composites filled with styrene–ethylene/butylene–styrene triblock copolymers (SEBS-g-MA) and organoclay nanolayers, were comprehensively investigated. Sliding tests were performed on a block-on-ring apparatus. We observed that the addition of the single organoclay filler leads to a decrease in the wear resistance of PA66. When SEBS-g-MA copolymers and organoclay nanolayers were added simultaneously to PA66, the wear resistance of PA66 improved remarkably. The corresponding morphologies of the worn surfaces further confirm this result. Differential scanning calorimetry measurements were also performed to observe the effect of fillers on the glass transition temperature (T g). The T g of the composites increased with the addition of organoclay and decreased with the addition of the SEBS-g-MA copolymers. The dispersion states of the SEBS-g-A copolymers and organoclay nanolayers in the PA66 matrix were examined by X-ray diffraction and transmission electron microscopy. The results indicate that the organoclay platelets and the SEBS-g-MA particles were well dispersed in the PA66 matrix.

Experimental investigation and micromechanical modeling of high strain rate compressive yield stress of a melt mixing polypropylene organoclay nanocomposites

In this work, high strain rate compressive yield stress of polypropylene based organoclay nanocomposites has been studied. For this, a three-phase approach is proposed to model the yield behavior of the polymer nanocomposite. This approach is based on the micromechanical formulation of the cooperative model for the yield behavior of semi-crystalline polymers combined with the effect of nanoparticles and their distribution on yielding. In this, our proposed approach accounts for strain rate and temperature effects as well as for the extent of exfoliation of the organoclay fillers. Split Hopkinson pressure bars apparatus was used to carry out high strain rate tests at various temperatures and different strain rates. The experimental results show that the yield stress is strain rate, temperature, and organoclay concentration sensitive. It is also shown that the yield stress is significantly affected by the extent of exfoliation. Our model predictions are compared to the experimental results and a good agreement is found.

Preparation and characterization of microbial biodegradable poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)/organoclay nanocomposites

AbstractNovel biodegradable poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3HB‐co‐4HB)]/organoclay nanocomposites were prepared via solution casting. Exfoliated nanocomposite structure was confirmed by wide‐angle X‐ray diffraction (WAXD) and transmission electron microscopy (TEM) for the nanocomposites with low organoclay loadings (≤3 wt%), whereas the mixtures of exfoliated and unexfoliated organoclays were appeared in the nanocomposite with an organoclay content of 5 wt%. The organoclay fillers accelerated significantly the cold crystallization process of P(3HB‐co‐4HB) matrix. The thermal stability of the nanocomposites was in general better than that of pristine P(3HB‐co‐4HB). Considerable increase in tensile modulus was observed for the nanocomposites, especially at an organoclay content of 3 wt%. These results demonstrated that the nanocomposites improved the material properties of P(3HB‐co‐4HB). POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Investigating the Multiple Stress Creep Recovery bitumen characterisation test

Zero shear and Low shear viscosity test protocols were shown to be perfectly adequate for characterising high temperature creep behaviour of selected penetration grade bitumens but the tests were less satisfactory with respect to a proprietary SBS-modified bitumen tested in this investigation. Furthermore, Multiple Stress Creep Recovery (MSCR) tests conducted at a pre-determined temperature were argued to provide more satisfactory comparisons across a number of bitumen types compared to MSCR runs at a pre-determined target viscosity.Results show that varying the grade of unmodified bitumen did not result in a dramatic effect on the MSCR shear stress levels at failure when all testing were conducted at 70°C. Increasing the bitumen viscosity by blending in a micro-sized calcium carbonate filler or a nano-sized organo-clay filler were shown to affect the stress sensitivity but not the actual magnitude of failure stress which remained in line with the base bitumen. On the other hand, the SBS-modified bitumen had completely altered shear stress failure criterion. When considering non-polymer-modified bitumens, simple high temperature strain sweeps have also been shown to be a potentially rapid and very useful creep performance ranking tool.

Tensile and Dynamic Mechanical Behavior of Thermoplastic Natural Rubber (TPNR) Nanocomposites Treated with Ultrasonic

Melt compounding technique was employed to prepare thermoplastic natural rubber (TPNR) nanocomposite. The ultrasonic bath was used to improve the filler-matrix interfacial adhesion. TPNR nanocomposites were prepared in the ratio of (70:20:10) from polypropylene (PP), natural rubber (NR) and liquid natural rubber (LNR) as a compatibilizer, with 4% NanolinDK4. The clay layers were found to be separated further with ultrasonic treatment as compared to the sample without ultrasonic treatment as exhibited from X-ray diffraction. Young's modulus, tensile strength and elongation at break of TPNR nanocomposites increased with ultrasonic treatment, the optimum results achieved at 3h. .The results obtained from dynamic mechanical analysis (DMA) curves indicate that the addition of MWNTs led to an increase in the storage modulus E' and loss modulus E'' with maximum value is obtained at 3 hours. The glass transition temperature (Tg) also increases with Ultrasonic treatment. Ultrasonic treatment can promote the dispersion of the clay in TPNR also improve the compatibility of organoclay filler and the TPNR matrix.

The enhancement of properties of TPNR/clay nanocomposites using ultrasonic treatment

The main goal of this article was to study the effect of ultrasonic treatment time on the mechanical properties of thermoplastic natural rubber (TPNR) nanocomposites. The intercalation of TPNR enhancement into layers of clay by increasing d-spacing was found using XRD. TEM micrograph showed a combination of intercalated—exfoliated structure of the TPNR composites with organic clay. The tensile properties of nanocomposites treated with ultrasonic increased as compared with untreated nanocomposites. The optimum ultrasonic treatment time was obtained at 1 h with the addition of a coupling agent (12% PP-g-MA). DMA has shown that the storage modulus E' and loss modulus E'' of TPNR nanocomposites had improved as compared with TPNR, the optimum results with ultrasonic effect achieved at 1 and 3 h. Ultrasonic treatment can promote the dispersion of the clay in TPNR and also improve the compatibility of organoclay filler and the TPNR matrix.

Reinforcement of Dynamically Vulcanized EPDM/PP Elastomers Using Organoclay Fillers: Dynamic Properties of Rubber Vibration Isolators and Antivibration Performance

Dynamically vulcanized ethylene—propylene—diene/polypropylene (EPDM/PP) elastomers that were reinforced with various amounts of organoclay were prepared using octylphenol—formaldehyde resin and stannous chloride dehydrate as vulcanizing agents. The effects of organoclay on X-ray, mechanical properties, dynamic mechanical analysis, hysteresis, and dynamic properties were studied. X-ray analysis revealed that these organoclay-filled thermoplastic vulcanizates (TPVs) were intercalated. The organoclay improved the mechanical properties of TPVs. Dynamic mechanism analysis indicated that organoclay can increase the damping (tan δ) and storage modulus of EPDM/PP TPVs at ambient temperature. The hysteresis behavior revealed that when the organoclay content exceeded 6 phr, the antivibration performance of these TPVs increased with the organoclay content. The dynamic ratio does not vary greatly as tan δ of EPDM/PP TPVs is increased.

Organoclay Filled Natural Rubber Nanocomposites: The Effects of Filler Loading and Mixing Method

Organoclay filled natural rubber (NR) nanocomposites were prepared by the incorporation of different loadings (0—10 phr) of organoclay fillers. NR nanocomposites were prepared using two different mixing methods, namely mechanical and solution mixing methods. Results indicate that the scorch time and cure time decrease with increasing filler loading, whereas the maximum torque exhibits an increasing trend. Increasing organoclay loading also increases the tensile modulus and elongation at break, but the tensile strength reaches maximum at 4 phr of organoclay. The intercalation and exfoliation structure affects the properties of organoclay filled NR nanocomposites as shown by evidence from X-Ray Diffraction (XRD) and transmission electron microscopy studies. Organoclay filled NR nanocomposites prepared by solution mixing exhibit better properties than similar NR nanocomposites prepared by mechanical mixing.

Structure and morphology of HDPE- g-MA/organoclay nanocomposites: Effects of the preparation procedures

Nanocomposites comprising high density polyethylene (HDPE) or maleic anhydride-grafted HDPE (HDMA) as the host polymers and Cloisite ® 20A (20A) as the organoclay filler were prepared by melt-compounding, solution-blending and static annealing of polymer/clay powder mixtures. The dependence of their structure and morphology on the preparation conditions was studied by X-ray diffraction (XRD and SAXS), polarized optical microscopy (POM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was shown that intercalated nanocomposites based on HDPE or HDMA cannot be obtained by solution-blending, as long as solvent removal is made at room temperature. In fact, wide angle XRD patterns of solution blended composites are similar to those of mechanical blends of clay and polymer. However, as demonstrated by XRD and SAXS, fast intercalation or even complete delamination was obtained when the HDMA composites prepared from solution were annealed statically at temperatures higher than the polymer melting point. This implies that solution-blending causes efficient fragmentation of the clay agglomerates into thin tactoids (though unintercalated) homogeneously dispersed in the polymer matrix. This conclusion, supported by the finding that annealing mechanical blends of polymer and clay powders only leads to intercalated structures, was confirmed by TEM and SEM analyses. Morphology investigation revealed that, in contrast to melt-compounding, solution-blending followed by static annealing fails to produce significant orientation of clay platelets and polymer crystallites. However, repeated compression molding cycles were shown by XRD and SAXS to cause increasing levels of orientation of the platelets and the polymer matrix parallel to the sample flat surface.

Mechanical and Fracture Toughness Behavior of TPNR Nanocomposites

Thermoplastic natural rubber (TPNR) nanocomposites containing organophilic layered silicates were prepared by melt blending method at 180°C using internal mixer (Haake 600P). The aim of this study is to determine the influence of the organoclay filler on the mechanical and fracture properties. In this study, two mixing methods were employed to incorporate filler into matrix, namely the direct (DM) and indirect (IDM) method. The mechanical properties of TPNR nanocomposites were studied using tensile, flexural, and impact tests. The tensile and flexural tests revealed that the optimum loading of organoclay was at 4 wt% using the indirect method of mixing. Plane stress fracture toughness of thermoplastic natural rubber (TPNR) nanocomposite was determined by the essential work of fracture (EWF) concept using tensile-loaded deeply double-edge notched (DDEN-T) specimens. The EWF measurements indicated that the specific essential work of fracture (we) decreased in the presence of nanoclay. Nevertheless, these TPNR nanocomposites met the basic requirement of the EWF concept of full ligament yielding, which was marked by a load drop in the force—displacement curves of the DDEN-T specimens.

Organo clay mineral–melted polyolefin nanocomposites Effect of surfactant/CEC ratio

Abstract Clay mineral–polymer nanocomposites are prepared by dispersing solid organo clay minerals in two different melted polyolefin matrices, namely polyethylene (PE) and ethylene vinyl acetate (EVA). The organo clay minerals are prepared by adding different amounts of surfactant corresponding to the CEC of the pristine clay mineral. The characteristics of the organo clay minerals are obtained by XRD, IR spectroscopy, TGA, and swelling volume measurements. The amount of added surfactant has a direct effect on the interlayer separation and organophilicity–hydrophilicity balance of the clay mineral, evidencing a particular behavior transition about OMt1.2 The intercalation of PE is found to be dependent on the interlayer distance of the organo clay minerals while EVA intercalates in the organo clay minerals whatever the amount of surfactant (> 0.5CEC), leading to the same interlayer spacing (4 nm). The polymer intercalation is more homogeneous in clay minerals having high surfactant loading corresponding to 1.5 and 2 CEC. Cone calorimeter results of the studied nanocomposites show a PHRR reduction of 32% for PE–OMt1.5 and of 47% for EVA–OMt1. For both polymers, the best compromise between mechanical and thermal properties, is obtained for organoclay filler obtained with an amount of added surfactant in a range 1–1.5 CEC.