Increase In Nanoclay Content Research Articles

Assessment of nanocomposites based on unsaturated polyester resin/nanoclay under impact loading

AbstractThe aim of this study is to investigate the performance of nanoclay reinforced unsaturated polyester (UP) resin under impact loads. Nanocomposite specimens containing nanoclay in 0, 1.5, and 3 (wt%) were prepared by melt mixing method. X‐ray diffraction, transmission electron microscopy analysis, scanning electron microscope photographs, and viscosity changes in liquid state resin confirmed exfoliation and intercalation of the nanoclay in the UP resin system used. Tensile modulus showed an increase with increase in nanoclay content. However, the tensile strength and elongation at break exhibited reducing performance with increase in nanoclay content. Izod impact test results indicated better performance for the specimens containing nanoclay reinforcements, with 1.5 (wt%) of nanoclay specimens showing the highest value. High velocity impact tests were carried out using gas gun in velocity range of 20–100 m/sec and harden steel hemispherical tip projectile with diameter of 8.7 mm and weight of 11.54 g. Results for high velocity impact test indicated better performance by the specimens containing nanoclay, with 1.5 (wt%) nanoclay showing the highest attained value. Damage assessments of impact area for all specimens showed spalling type brittle failure with punch out and sever fragmentation pattern. Copyright © 2011 John Wiley & Sons, Ltd.

Structural correlations to sliding wear performance of PA-6/PP-g-MA/nanoclay ternary nanocomposites

Abstract Ternary nanocomposites were fabricated based on an optimized impact modified PA-6/PP-g-MA blend composition with varied concentrations (0–6 wt.% at a step of 2 wt.%) of organoclay, Cloisite 30B™. The structural attributes such as state of intercalation/exfoliation/crystalline organization (by TEM and XRD), mechanical attributes such as storage-modulus ( E ′)/loss-tangent (tan δ ) (by DMA) and sliding wear performance on a pin-on-disc set up have been investigated for the nanocomposites. The wear performance as a function of sliding speed, normal load, sliding distance, and nanoclay loading have been analyzed following Taguchi method and parametric optimization has been carried out for wear resistance maximization. The wear resistance showed a correlation to the fraction of immobilized polymer chains due to incorporation of nanoclay into the PA-6 based blend matrix. Scanning electron microscopy of worn surface morphology has revealed a transition in the wear mechanism with the increase in nanoclay content.

Cell Structure Evolution and the Crystallization Behavior of Polypropylene/Clay Nanocomposites Foams Blown in Continuous Extrusion

In this study, linear homopolypropylene/clay (HPPC) nanocomposite foams with a high expansion ratio of about 18 and a high cell density of about 1.7 × 108 cells/cm3 were produced using an extrusion foaming method with CO2 as the physical blowing agent. The result was much better than pure HPP foams with expansion ratios of 1.7−2.2 and cell densities of 103−105 cells/cm3 obtained even at the same foaming conditions. The nanoclays had a half-exfoliated structure in the HPP matrix, and their presence dramatically affected the viscoelastic properties of HPP melt and foaming behaviors. It was found that the introduction of a small amount of nanoclay significantly increased the cell morphology of HPP foams at low die temperatures, where the cell wall was very thin and cell distribution was uniform. With an increase in nanoclay content of up to 5 wt %, cell morphology was improved gradually at broader die temperatures. Based on the cell morphology results, a suitable foaming window for clay content and die tempe...

Influence of nanoclay and coupling agent on the physical and mechanical properties of polypropylene/bagasse nanocomposite

AbstractIn this work, the effects of nanoclay (1–4 wt %) and coupling agent (2 and 4 wt %) loading on the physical and mechanical properties of nanocomposites are investigated. Composites based on polypropylene (PP), bagasse flour, and nanoclay (montmorillonite type) was made by melt compounding and then compression molding. When 1–3 wt % nanoclay was added, the tensile properties increased significantly, but then decreased slightly as the nanoclay content increased to 4%. The impact strength was 6% lower by the addition of 1 wt % nanoclay, it was decreased further when the nanoclay content increased from 1 to 4%. Finally, the water absorption of PP/bagasse composites was lowered with the increase in nanoclay content. Additionally, the coupling agent, 4 wt % MAPP, improved the mechanical and physical properties of the composites more than the 2 wt % MAPP. From these results, we can conclude that addition of nanoclay enables to achieve better physical and mechanical properties in conventional composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Study on Preparation and Properties of Acrylonitrile‐Butadiene‐Styrene/Montmorillonite Nanocomposites

Acrylonitrile‐butadiene‐styrene (ABS)/organically modified montmorillonite nanocomposites were prepared by melt blending in an internal mixer, and their morphology, rheological behaviors and mechanical properties were characterized using X‐ray diffraction (XRD), capillary rheometer and tensile, flexural and impact tests. X‐ray diffraction studies revealed the presence of intercalated structure for the prepared nanocomposites and good dispersion of clay layers at low levels of its loading. From the rheological investigations it was observed that the prepared nanocomposites and their pristine counterpart have shear‐thinning behavior, obeying the power law equation. At low shear rates, the steady shear viscosity and shear stress of the nanocomposites increase with increasing of nanoclay content. However, at high shear rates they behave similar to pure ABS. It was shown that the flow activation energy (E) values increase with increasing of nanoclay content. Mechanical tests showed that the flexural moduli of the nanocomposites increase with increase of nanoclay loading, but the flexural strength and the tensile and impact properties decrease with increase of nanoclay content.

Study on Steady Shear, Morphology and Mechanical Behavior of Nanocomposites based on Polyamide 6

Nanocomposites of two different grades of polyamide 6 (PA6) with organically modified nanoclay were prepared via melt compounding in a twin‐screw extruder. The rheological behavior, morphology and mechanical properties of the nanocomposites were studied using a capillary rheometer, x‐ray diffraction (XRD), tapping‐mode atomic force microscopy (AFM), and tensile and flexural tests. XRD patterns indicate that the organically modified layered silicate was well dispersed in the PA6 matrix. From the AFM images the surface roughness of PA6 slightly increases with addition of organoclay. The rheological studies showed that the prepared nanocomposites have shear thinning behavior, obeying the power law equation. Addition of organoclay increases the shear stress and shear viscosity. At high rate of shear deformation the viscosity of nanocomposites are comparable to those of the pure polyamides. The activation energy of flow decreases with increasing nanoclay content. For most of the prepared nanocomposites the activation energy values increase with increasing shear rate. The tensile strength and flexural modulus and strength of the nanocomposites increase with increase of nanoclay content, but the extension at yield decreases with increasing clay loading.

Analysis of surface degradation of epoxy nanocomposite due to tracking under AC and DC voltages

The tracking phenomenon, a carbonaceous process, in epoxy nanocomposite material has been studied under the AC and DC voltage in the present work. It was observed that the tracking is more severe under the DC voltages, especially under positive DC voltage when compared to negative DC voltage. The leakage current during the tracking studies was measured and moving average technique was used to characterize the trend of current flow. It was noticed that an increase in nanoclay content to epoxy resin shows a reduction in magnitude of leakage current flow during tracking test. It was also observed that the magnitude of leakage current is more under negative DC voltage compared with positive DC/AC voltage. The magnitude of leakage current and the tracking time shows inverse relationship as evident from the present study. A drastic reduction in contact angle was observed for the specimens subjected to tracking test. It was confirmed that surface discharges also cause permanent damage to the insulating material. The WAXD studies indicated that up to 5 wt% of nanoclay in epoxy resin resulted in exfoliated structure. The TEM studies were carried out on the nanocomposite structures. The TG–DTA results showed that a maximum degradation of epoxy resin occurs at around 300 °C. From the EPR study it is realized that, in the tracking formed zone the spin concentration is more in epoxy nanocomposites indicating that tracking as a damage generating process.

Understanding the thermal, mechanical and electrical properties of epoxy nanocomposites

In the present work, the electrical, mechanical and thermal properties of epoxy nanocomposite materials were studied. The electrical insulation characteristics were analyzed through short time breakdown voltage test, accelerated electrical ageing test, and by tracking test. The breakdown voltage increases with increase in nano-clay content up to 5 wt%, under AC and DC voltages. The volume resistivity, permittivity and tan( δ) of the epoxy nanocomposites were measured. The Weibull studies indicate that addition of nanoclay upto 5 wt% enhances the characteristic life of epoxy nanocomposite insulation material. The tracking test results indicate that the tracking time is high with epoxy nanocomposites as compared to pure epoxy. Ageing studies were carried out to understand the surface characteristic variation through contact angle measurement. The hydrophobicity of the insulating material was analysed through contact angle measurement. The diffusion coefficients of the material with different percentage of clay in epoxy nanocomposites were calculated. The exfoliation characteristics in epoxy nanocomposites were analyzed through wide angle X-ray diffraction (WAXD) studies. The thermal behaviour of the epoxy nanocomposites was analyzed by carrying out thermo gravimetric-differential thermal analysis (TG-DTA) studies. Heat deflection temperature of the material was measured to understand the stability of the material for intermittent temperature variation. The dynamic mechanical analysis (DMA) results indicated that storage modulus of the material increases with small amount of clay in epoxy resin. The activation energy of the material was calculated from the DMA results.

A study on nanostructured laminated plates behavior under low-velocity impact loadings

The influence of montmorillonite (MMT) silicate layers on glass-fiber-epoxy laminated composites behavior has been investigated by low-velocity impact and X-ray diffraction tests. The glass-fiber-epoxy-nanoclay laminate composites have 16 layers and 65% fiber volume fraction is manufactured by vacuum-assisted wet lay-up. Fibers have a plain-weave configuration with density of 200 g/m 2, while the epoxy resin system is made of diglycidyl ether of bisphenol A resin with aliphatic amine as the curing agent. The nanoclay (Nanomer I30E) is dispersed into the epoxy system in a 1%, 2%, 5% and 10% ratio in weight with respect to the matrix. X-ray diffraction tests indicate that rather than exfoliated, these nanostructures are mostly in intercalated form, with a possible presence of immiscible nanosystems at 10% concentration. The methodology used for the impact test is based on the ASTM D5628-01 standard. The results have shown that for the four edges clamped condition not only the delamination phenomenon is reduced, but also the damping is increased during the rebounds. Moreover, for the 20 J impact energy condition the energy absorption by delamination increases close to 48%, while for larger energies, i.e. 60 J, the average improvement into energy absorption is around 15%. Even for larger energies close to total perforation, i.e. 80 J, the use of nanoclays leads to an average increase in energy absorption by delamination close to 4%. Finally, the failure mechanism seems to be affected by the nanoclay presence, as the interlaminar failure shifts to a mostly intralaminar failure with the increase of nanoclay content.