Nanoclay Cloisite Research Articles

Influence of the Organoclay Content on the Structure, Morphology, and Surface Related Properties of Novel Poly(dimethylsiloxane)-Based Polyurethane/Organoclay Nanocomposites

Novel poly(dimethylsiloxane)-based polyurethane nanocomposites (TPU-NCs) were synthesized using in situ polymerization with the nanoclay Cloisite 30B. Differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical thermal analysis showed that TPU-NCs with an organoclay content of ≤5 wt % exhibited increased thermal stability, storage modulus, and hard-segment melt temperatures but decreased degrees of crystallinity. TPU-NCs displayed increased surface hydrophilicity and enhanced surface free energy with increasing organoclay content. Small- and wide-angle X-ray scattering confirmed intercalated formations of organoclays in the nanocomposites. Individual clay particles on the surfaces of TPUs with lower organoclay loadings (1 or 3 wt %) or organoclay agglomerates in TPUs with higher amounts of organoclay (≥5 wt %) were detectable using scanning electron microscopy. The relatively smooth and homogeneous character of pure TPU and the distinctly heterogeneous and rough surfaces of TPU-N...

Optimizing cure cycle of nanoclay-reinforced unsaturated polyester resins considering various curing kinetic models

In this research, a method has been presented for optimizing cure cycle of neat unsaturated polyester resin and polyester resin containing 3 wt% nanoclay Cloisite® 10 A (UP/10 A) and nanoclay Cloisite® 30B (UP/30B) in thin components. We refer to this optimization method as the directed grid search method. To model cure behaviour of unsaturated polyester resin, four different kinetic models were considered, including advanced iso-conversional method, Kamal method, Kamal method with Chern diffusion factor, and Kamal method with Sbirrazzuoli diffusion factor. The comparison of our proposed optimized cure cycles indicates that addition of nanoclay to the resin causes the cure cycle duration and also the maximum temperature during the cure to decrease. In addition, by adding nanoclay to the resin, the optimal cure cycle is transformed from a five-stage cure cycle to a four-stage one. Our investigations indicate that optimal cure cycles for the UP/10 A and UP/30B systems do not significantly differ. This is because the pre-exponential factor can influence the optimal cure cycle as much as the activation energy. Our results show that the optimal cure cycle obtained from the Kamal model is much shorter than the optimal cure cycle obtained from the advanced iso-conversional method, while the optimal cure cycle obtained from the Kamal model with Chern diffusion factor is very similar to the cure cycle resulting from the advanced iso-conversional method.

Effects of nanoclay and nanocomposites on bitumen rheological properties

Nanoclays have been successfully introduced into the asphalt, either separated or in the form of polymer/bitumen blends, improving mechanical and rheological properties. In this paper, the organoclay montmorillonite (OMMT) was prepared to be used as an additive for bitumen and for a polymer modified bitumen. A nanoclay Cloisite® 20Å (CLO), was also investigated for comparison purposes. A bitumen was modified with 4% nanoclays (OMMT and CLO), with 4% SBS, and with 4% SBS/nanoclay. All modified bitumens (MB) exhibited higher G∗ and lower δ, indicating an improvement in the stiffness and in the elasticity. SBS/Nanoclay MB presented similar rheological behavior compared to SBS MB which may result in cost savings. The addition of SBS and SBS/OMMT resulted in increase in PG grade and decrease in non-recoverable creep compliance (Jnr) indicating a better rut resistant compared to pure bitumen.

Anticorrosive epoxy/clay nanocomposite coatings: rheological and protective properties

The preparation of epoxy/clay nanocomposites (NCs) and their insertion into coatings are of great importance since the NCs could enhance the protective performances. In this study, epoxy NCs with 1–10 wt% of nanoclay Cloisite 30B (C30B) were prepared by the sonication-assisted solution method. The rheological measurements of epoxy/C30B suspensions revealed non-Newtonian, shear-thinning behavior of the uncured NCs, with an increase in the viscosity, yield stress, and shear modules with increasing organoclay content, while the dispersion effectiveness of C30B decreased. A significant enhancement of the rheological parameters was observed at the second percolation threshold (4.1 vol%) due to the formation of a continuous network of 45-layer-thick tactoids. Although NCs with 1–3 wt% C30B exhibited slightly reduced mechanical and adhesion properties compared with the cured reference epoxy resin, the epoxy primer and topcoat based on NC with 1 wt% C30B generally displayed improved impact resistance and maintained flexibility, pendulum hardness, and good adhesion properties. Two-layer coating systems, i.e., NC-based primers and topcoats, had higher corrosion stability in a salt spray chamber compared to the unmodified system.

Mechanical and Thermal Properties and Morphology of Thermoplastic Polyurethane (TPU)/Clay Composites

In this study, thermoplastic polyurethane (TPU) composites were prepared with different nanoclay contents (1, 3 and 10 wt%). The nanoclay Cloisite ®30B (C30B) was dispersed in the TPU matrix by melt processing using a twin-screw extruder. The synthesis method of TPU involved the two-step bulk polymerization of polyesterpolyol and 4,4’ diphenylmethanediisocyanate with butane-1,4-diol as the chain extender. The dispersion of the nanoclay particles and its effect on the mechanical and thermal properties of the composites was investigated. The characterization of TPU/nanoclay composites was carried out by means of scanning electron microscopy, energy dispersion microanalysis and X ray diffraction. The mechanical characterization was performed through determination of the tensile strength. The TPU 3 wt% composite showed the best improvement with increases in stress and tensile at break (28% and 35%, respectively), compared to the neat TPU (sample without nanoclay). The differential scanning calorimetry and thermogravimetry analyses for composites indicated that the nanoclay did not affect significantly the glass transition, melt, and degradation temperatures of the polymeric matrix, but reduces the molecular mobility. http://dx.doi.org/10.18226/23185279.v3iss2p50

Sulfonated poly(2,5-benzimidazole) (ABPBI)/ MMT/ ionic liquids composite membranes for high temperature PEM applications

The effect of nanoclay cloisite Na+ on the mechanical and conductive properties of ionic liquids (ILs) doped sulfonated ABPBI (SABPBI) composite membranes for high temperature proton electrolyte membrane (PEM) applications were investigated in this report. The composite SABPBI membranes with well-dispersed cloisite Na+ showed great improvement in mechanical properties with the increase of over 90% in ultimate tensile strength and 40% in Young's modulus, respectively, compared with those of pristine ABPBI membrane. The ILs absorption was also increased due to the incorporation of well-dispersed cloisite Na+, resulting in significant increase in the ionic conductivities of SABPBI membranes at the temperatures above 100 °C. The highest conductivities were 4.0 × 10−2 S/cm at 220 °C for [HMIM]Cl doped 3 wt% SABPBI composite membranes (doping level 1.32), and 9.6 × 10−3 S/cm × 10−3 S/cm at 220 °C for [TMG][BF4] doped SABPBI composite membranes (doping level 1.37), respectively.

Silver ion beam irradiation effects on poly(lactide-co-glycolide) (PLGA)/clay nanocomposites

Swift heavy ions induced modification of thin films of blends of poly(lactide-co-glycolide) (PLGA) (50:50) with organically modified nanoclay (Cloisite® 30B) has been studied, using optical, structural and surface morphological analysis. Presence of nanoclay is found to enhance the properties of this degradable copolymer by reducing the rate of degradation even at high irradiation fluence. Optical and structural analysis of the polymer nanocomposites suggests that both the cross-linking and chain scission phenomenon are caused by swift heavy ion irradiation. XRD measurements show intercalation of PLGA in the clay galleries. Surface morphology of a nanocomposite indicates significant changes after irradiation at various fluences.

Effects of nanoclay and short nylon fiber on morphology and mechanical properties of nanocomposites based on NR/SBR

Natural rubber and styrene butadiene rubber (NR/SBR) reinforced with both short nylon fibers and nanoclay (Cloisite 15A) nanocomposites were prepared in an internal and a two roll-mill mixer by a three-step mixing process. The effects of fiber loading and different loading of nanoclay (1, 3 and 5 wt. %) were studied on the microstructure and mechanical properties of the nanocomposites. The adhesion between the fiber and the matrix was improved by the addition of a dry bonding system consisting of resorcinol, hexamethylene tetramine and hydrated silica (HRH). This silicate clay layers was used in place of hydrated silica in a HRH bonding system for SBR/NR-short nylon fiber composite. Nanoclay was also used as a reinforcing filler in the matrix-short fiber hybrid composite. The cure and scorch times of the composites decreased while cure rate increased when the short fiber and nanoclay were added. The mechanical properties of the composites showed improvement in both longitudinal and transverse directions with increasing short fiber and nanoclay content. The structure of the nanocomposites was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM). X-ray diffraction results of nanocomposites indicated that the interlayer distance of silicate layers increased. The mechanical properties of nanocomposites (tensile, hardness and tear strength) are examined and the outcome of these results is discussed in this paper.

Preparation and characterization of poly(vinylidene fluoride)/nanoclay nanocomposite flat sheet membranes for abrasion resistance

Membranes with more resilience to abrasive wear are highly desired in water treatment, especially for seawater desalination. Nanocomposite poly(vinylidene fluoride) (PVDF)/nanoclay membranes were prepared by phase inversion and then tested for abrasion resistance. Their material properties were characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), tensile testing, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Nanoclay Cloisite® 15A was utilised as the inorganic nanoparticle incorporated into PVDF. FTIR results showed a shifting of the PVDF crystalline phase from α to β thus indicating that the nanoclay altered the PVDF host material's structure and mechanical properties in terms of stiffness and toughness. Water permeation test showed that nanoclay at low concentration tended to reduce water flux. All nanocomposite membranes, with between 1 wt% and 5 wt% initial nanoclay loading, were more abrasion resistant than the control PVDF membrane. However, the 1 wt% exhibited superior resistance, lasting two times longer than the reference PVDF membrane under the same abrasive condition. The 1 wt% nanoclay membrane appeared less abraded by SEM observation, while also having the greatest tensile strength improvement (from 4.5 MPa to 4.9 MPa). This membrane also had the smallest agglomerated nanoclay particle size and highest toughness compared to the higher nanoclay content membranes. Nanoclays are therefore useful for improving abrasion resistance of PVDF membranes, but optimal loadings are essential to avoid losing essential mechanical properties.

Tribological Analysis of the Nano-modified Industrial Polymer

The aim of this paper is research of positive influence of the commercially available nano-additive on tribological properties of the essential polymer for the industry. The nano-filler amount was chosen equal to commonly needed for amending of other paramount properties of the polymer. The tribological behavior of polymer nanocomposite was investigated during the rubbing against low alloyed steel in oilless contact. The composites consist of Ultramid which was modified by 1, 3 and 5wt.% of nanoclay Cloisite. Samples were tested on T-05 block-on-ring tribometer and observed with SEM and Laser Confocal Microscope LEXT OLS 3000. There were observed a positive and pronounced effect of nano-additive on temperature regulation in contact zone, investigated and analyzed other aspects of tribological behavior of a polymer/steel contact joints.

Development of low density polyethylene nanocomposites films for packaging

Requirements for adequate permeability of polymeric materials to gases and vapors, good barrier and mechanical properties of polymers have boosted interest in developing new strategies to improve these properties. Research and development in polymeric materials coupled with appropriate filler, matrix-filler interaction and new formulation strategies to develop composites have potential applications in various types of packaging (agricultural produce, dried food, frozen food etc.). In this study, LDPE composites containing various types of fillers (zeolite TMAZ 7, nanoclay Cloisite 20A and precipitated calcium carbonate, CaCO3) were prepared using extrusion/injection molding. The microstructural and morphological changes as well as mechanical features of samples were characterized by scanning electronic microscopy and by tensile tests. The thermal degradation of LDPE composites was studied using thermogravimetric analysis. Barrier properties (permeability, the diffusion and the solubility constant) in modified LDPE samples were determined. It is found that used minor clay concentration is already very effective for achievement of good morphology. In the presence of nanoparticles, at lower content, the value of oxygen permeability of LDPE decreases. Also, the results have revealed that the samples containing fillers have increased thermal stability in comparison to pure LDPE.

Preparation and Properties of Low Density Polyethylene Film Modified by Zeolite and Nanoclay

PE-LD samples containing two types of filler in concentrations of 2–10 wt.% (zeolite TMAZ 7 and nanoclay Cloisite 20A). The microstructural and morphological changes as well as mechanical features of samples were characterized by scanning electronic microscopy (SEM) and by tensile tests. The thermal degradation of PE-LD composites were achieved using thermogravimetric analysis (TGA). The permeability, the diffusion and the solubility constants of the gases in modified PE-LD films were calculated and the gas separation (N2/O2; O2/CO2) ability was determined. In the presence of nanoparticles, at lower content, the value of oxygen permeability of PE-LD decreases.

Glass/epoxy composites and aluminium alloy joint using Kevlar® intermediate layer and nanoclay-reinforced epoxy adhesive

Adhesive lap joint between glass fibre/epoxy composites and aluminium alloy (2014 T4) was prepared by an in situ moulding process using a matched die mould. The surface of aluminium alloy was treated with chromic acid before adhesive bonding. Lap shear strength and fatigue life were evaluated in tensile mode and tension–compression mode (at 40% of lap shear load of adhesive joint), respectively. Knurling on the surface of aluminium alloy improved the lap shear strength of the adhesive joint but did not influence the fatigue life of the same. Lap shear strength and fatigue life of adhesive joint made with neat epoxy adhesive and reinforcement of an intermediate layer of Kevlar® between glass/epoxy composite and aluminium alloy were observed to be 0.44 kg/mm2 and 3.6 × 105 cycles, respectively. In another case, lap shear strength and fatigue life of similar type of adhesive joint made from nanoclay (Cloisite 30B)-reinforced epoxy adhesive and without reinforcement of an intermediate layer of Kevlar® were observed to be 0.38 kg/mm2 and 2.3 × 105 cycles, respectively. Whereas, lap shear strength and fatigue life of adhesive joint made from nanoclay-reinforced epoxy adhesive along with the reinforcement of an intermediate layer of Kevlar® were 0.48 kg/mm2 and 3.9 × 105 cycles, respectively. Therefore, adhesive joint made from nanoclay-reinforced epoxy adhesive along with the reinforcement of an intermediate layer of Kevlar® was the best.

Nanocomposites Based on NR/SBR: Effects of Nanoclay and Short Nylon Fibers on the Cure Characteristics and Thermal Properties

Natural rubber and styrene butadiene rubber (NR / SBR) reinforced with both short nylon fibers and nanoclay (Cloisite 15A) nanocomposites were prepared in an internal and a two roll-mill mixer by a three-step mixing process. The effects of fiber loading and different loading of nanoclay (1 wt%, 3 wt%, 5 wt%) were studied on the Cure Characteristics and Thermal Properties of the nanocomposites. The adhesion between the fiber and the rubber was enhanced by the addition of a dry bonding system consisting of resorcinol, hexamethylene tetramine and hydrated silica (HRH). This nanoclay was used in place of hydrated silica in a HRH bonding system for SBR/NR–short nylon fiber composite. Nanoclay was also used as a reinforcing filler in the matrix–short fiber hybrid composite. The curing characteristics of the composites have been studied by using cure rheometer. Samples were vulcanized at 150°C using a hot press after determination of the curing characteristics. The cure and scorch time of the composites decreased while minimum, maximum torque, and cure rate increased when short fiber and nanoclay content were increased. The values of storage modulus above the glass transition temperature of NR/SBR/organoclay nanocomposites increased remarkably with increasing the content of organoclay and fiber loading. The height of the tan δmax has decreased and glass transition temperature (Tg) has increased with increasing nanoclay and loading fiber. These results were consistent with the dynamic mechanical thermal analysis (DMTA) data as well as macroscale mechanical properties tested on the samples. The thermogravimetry analysis (TGA) shows that a small amount of organoclay greatly improved the thermal stability, which was attributed to the good barrier properties of the dispersed organoclay layers.

Impact response of sandwich composites with nano-enhanced epoxy resin

Present work intends to study the improvement of impact performance on sandwich composites by the addition of nanoclays. For this purpose, nanoclays Cloisite 30B were previously subjected to a silane treatment in order to improve their dispersion and interface adhesion. Different incident impact energy levels were used and, for both sandwiches, the maximum load, displacement or elastic recuperation shows to be very dependent of the impact energy. Mathematical relationships are proposed to estimate the maximum impact force and displacement, based on the total impact energy and impact bending stiffness. Finally, sandwiches enhanced by nanoclays presented higher maximum impact loads, lower displacements, the best performance in terms of elastic recuperation and maximum residual flexural strength.

Nanocompounds: Better Formulations for Recycled Polyethylene

AbstractSummary: To improve the properties of recycled PE for pipe applications, additions of nanoclay and adhesion promoter were done. The presence of the nanoclay Cloisite 93A and the polyethylene grafted with maleic anhydride in the compounds have promoted the thermal properties. The possible exfoliation/intercalation of the PE in the nanoclay layers increases the barrier properties and reduced permeation to oxidation agents. The melt flow index, the glass transition temperature and the initial decomposition temperature (TG) have decreased. The XRD analysis has presented increase of interplanar distance in the nanoclay layers. The FTIR analysis has showed a decrease in the oxidation peaks intensity. These results are indicators of nanocomposite/microcomposite formation.

Impact response of Kevlar composites with nanoclay enhanced epoxy matrix

Kevlar fibres have been widely used as impact-resistant reinforcement in composite materials. However, there are very few works about the effects of nanoclays on the impact strength of Kevlar/epoxy laminates. Therefore, this paper intends to study the ideal amount of nanoclays to obtain the best impact performance. Nanoclays Cloisite 30B were dispersed in the epoxy system of at 1.5%, 3% and 6% in weight. For better dispersion and interface adhesion matrix/clay, nanoclays were previously subjected to a silane treatment appropriate to the epoxy resin. The laminates manufactured with epoxy resin filled by 6wt.% of nanoclays shown the best performance in terms of elastic recuperation and penetration threshold. The opposite tendency was observed for the displacement at peak load. However marginal benefits can be found when compared the results obtained for laminates filled by 3% and 6% of nanoclays.

Effect of the nanoclay types on the rheological response of unsaturated polyester-clay nanocomposites

The rheological behavior of styrene-free unsaturated polyester resin–nanoclay (Cloisite 15A and 30B) nanocomposites at various nanoclay contents prepared by melt mixing was investigated. To investigate the effect of shear and diffusion induced phenomena as well as nanoclay surface modification on the rheological behavior, samples were prepared at two different temperatures of 40°C (cold mixed) and 150°C (hot mixed) and tested in a range of 40–120°C using dynamic rheometry. Viscosity–temperature curves for the cold mixed samples showed a decrease in viscosity with increasing temperature followed by the formation of a plateau with onset temperature which depends on the nanoclay type and content. The results of small angle X-ray scattering and transmission electron microscopy analysis were in agreement with the formation of a physical network in which nanoclay particles act as the nodes, whereas polymer chains serve as the links. It is believed that for the cold-mixed samples, higher shear forces break the nanoclay stacks associations efficiently, and hence more nanoparticles are available for polymer chains to form the network. In this context, the initial d-spacing was much more effective than the nanoclay modification type. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.

The Influence of Nanofillers on the Mechanical Properties of Carbon Fibre Reinforced Methyl Methacrylate Composite

The influence of different types of nanofillers – carbon nanotubes (CNT) and organically modified nanoclay – on the flexural properties and nail penetration resistance of carbon fiber reinforced methyl methacrylate (MMA) composite have been investigated. An ultrasonic mixing was used to distribute various content of nanofillers (0.7 wt.% – 3.0 wt.%) in MMA resin. Scanning electron microscopy and X-ray diffraction analyses confirmed formation of intercalated MMA clay nanocomposites. Two different stacking sequences, [0/90]3 or [0/90/45]2, and two types of carbon fibre, with or without epoxy binder, were used for composites preparation. The composites with stacking sequence of [0/90]3 show higher resistance to the mechanical loading. Epoxy binder increases fibre adhesion interaction with MMA resin, however, almost does not influences on the fibre reinforced composite strength properties. The results demonstrated that only low content (up to 1 wt.%) of organically modified nanoclay Cloisite 10A increases the carbon fibre reinforced composites resistance to flexure and nail penetration. The low content of CNT also increases flexural stress and modulus, but decreases resistance to the nail penetration.DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2434

Curing studies of bisphenol a based bismaleimide and cloisite 15a nanoclay blends using differential scanning calorimetry and model‐free kinetics

AbstractBlends of 2,2‐bis[4‐(4‐maleimidophenoxy phenyl)]propane [bismaleimide (BMIX)] with different proportions (1, 2, 3, 4, 5, 7, and 9%) of the nanoclay Cloisite 15a were prepared with ultrasonication. Fourier transform infrared studies reveal the existence of interactions between the clay particles and the imide rings in BMIX. The difference in the melting characteristics and the decrease in the curing window caused by the incorporation of the clay particles in BMIX, as evidenced by detailed differential scanning calorimetry investigations, confirmed the existence of interactions between the nanoclay particles and BMIX molecules. The Flynn–Wall–Ozawa, Vyazovkin, and Friedman kinetics methods were used to calculate the activation energies (Ea's) for the curing of the BMIX materials.Eafor the polymerization varied, depending not only on the amount of clay loaded in the BMIX but also on the extent of the curing reaction. Because of the loss of interaction between the clay platelets and the imide rings of BMIX, a decrease inEaat higher reaction extents was noted when there was lower clay loadings (1–4% Cloisite 15a) in BMIX. A reversal in the previous behavior was noted at higher clay loadings (7 and 9% Cloisite 15a) in BMIX and was attributed to the restriction of the molecular mobility due to the presence of increased concentrations of clay platelets and the decreased availability of reaction sites for polymerization. These two opposing factors played were equal at the optimum level of Cloisite 15a loading (5%) in BMIX, which was reflected in the constancy ofEavariation noted with increasing reaction extent. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013