Organoclay Platelets Research Articles

New stable waterborne amorphous polylactic acid/organoclay nanocomposites prepared using emulsification solvent evaporation method

AbstractWater based polylactic acid (PLA)‐surface modified montmorillonite (MMt) nanocomposites as biobased formulations for paper coating were successfully developed using emulsification solvent evaporation method. Electrostatic and steric stabilization mechanisms have contributed to the production of stable emulsions up to 5 months at 23 ± 1°C, revealing strong repulsive forces generated between the nanoparticles as confirmed by zeta potential (ζ) and dynamic light scattering (DLS) analysis. MMt particles were fully encapsulated by PLA as demonstrated by transmission electron microscopy (TEM) micrographs. Meanwhile the film formation process highlighted the importance of emulsifier's type and solubility in the polymer matrix, as no films were obtained when sodium oleate was used alone compared with continuous, homogeneous, and free‐standing films obtained when the combination Tween 80 (80 wt%)—sodium oleate (20 wt%) was used. Scanning electron microscopy (SEM) micrographs of the cross‐section's surfaces showed homogeneous dispersion of the MMt particles with no clusters or agglomerates formed. Thermal analyses using differential scanning calorimetry and thermogravimetric analysis (DSC‐TGA) showed an overall reduction in the glass transition temperature (Tg) and the thermal stability of neat PLA, whoever this reduction was recovered when MMt was added due to the confinement effect. Thickened PLA and PLA/MMt emulsions using 1 wt% xanthan gum showed a non‐Newtonian behavior and shear thinning flow with suitable viscosity values for paper coating applications.Highlights Development of stable PLA/organoclay nanocomposite aqueous dispersions. Steric and electrostatic mechanisms provided excellent stability. Full encapsulation of organoclay platelets in nanometric PLA particles. Formation of free‐standing films from PLA/organoclay emulsions. Thickened PLA/organoclay emulsions using Xanthan gum for paper coatings.

Study on the formation mechanism of a flat rheology by poly(diethylenetriamine dimer acid amide) and organoclay in nonaqueous drilling fluids over a wide temperature range

This work aims to establish the relationship between the morphology and rheology changes affected by the addition of Flat-rheology modifier (FRM) to organoclay (OC)/white oil dispersions between 2 and 65 °C to analyze the flat-rheology formation mechanism in nonaqueous drilling fluids. The FRM used in this work is poly(diethylenetriamine dimer acid amide), and the OC is organo-montmorillonite. Temperature-controlled rheological tests confirmed that FRM addition to dispersions with low OC loadings (lower than 3.0 wt%) results in a relatively constant gel strength from 2 to 65 °C. This could be explained by the morphology variations in the dispersions generated by the FRM. Based on macroscopic settlement, particle size distribution, optical microscopy, transmission electron microscopy (TEM) and wide-angle X-ray scattering (WAXS) results, FRM molecules were inserted into and enlarged the interlayer space between OC platelets, thus reducing the particle size and improving the dispersion stability. Subsequently, the original card house network formed by OC particles was destroyed, and a new network with a larger volume fraction was formed by the highly dispersed platelets and FRM molecules. The increase in network volume fraction and extension of FRM molecular carbon chains with increasing temperature inhibit network strength deterioration. As a result, the rheological properties at 65 °C remained similar to those at 2 °C, thereby forming a flat rheology.

The ultrasonic-assisted synthesis of tetrafunctional acrylated epoxy clay nanocomposite

The acrylation of a tetrafunctional epoxy resin was carried out through the reaction with acrylic acid in the presence of two different organoclays under ultrasonic irradiation. As reinforcing agents, two different kinds of commercial organoclays, namely Cloisite 15A and Cloisite 30B, were used individually in nanocomposite fabrication. The acrylation reaction of epoxy resin in addition to curing processes was monitored by Fourier transform infrared spectroscopy. The main advantage of the ultrasonic process was a significant reduction in reaction time as low as 8 min. Thermal and mechanical properties of the UV-cured samples were investigated by means of differential scanning calorimetry, dynamic mechanical thermal analysis and the film hardness. The clay dispersion was characterized through X-ray diffraction patterns coupling with the images of two microscopic techniques. The enhancements in nanocomposite glass transition temperature, thermal stability and mechanical properties may be attributed to proper dispersion of organoclay platelets as evidenced in transmission electron microscopy. However, the nanocomposite films reinforced with the Cloisite 30B exhibit more pronounced improvements in the final properties of the nanocomposite film.

Thermally stable low‐density polyethylene/polyhydroxybutyrate pairs: Synergy between organomodified nanoclay and LDPE‐g‐MAH

ABSTRACTNanocomposites of low‐density polyethylene/polyhydroxybutyrate (LDPE/PHB) containing organomodified montmorillonite (OMMT) and/or LDPE grafted maleic anhydride (LDPE‐g‐MAH) were prepared with a wide range of composition ratios using a vertical co‐rotating twin‐screw microCompounder. To infer the effect of OMMT and LDPE‐g‐MAH on the thermal stability of prepared nanocomposites, all samples were characterized by thermogravimetric analysis while changing clay and compatibilizer contents. Accordingly, two commonly used kinetic models (Coats–Redfern and Horowitz–Metzger) were employed to correlate the thermal stability of the samples with kinetic parameters, including activation energy and pre‐exponential factor. Furthermore, morphological features of LDPE/PHB in the presence or absence of OMMT and LDPE‐g‐MAH were studied using scanning electron microscopy, transmission electron microscopy, and wide‐angle X‐ray diffraction analysis. It was found that for a specific OMMT composition ratio (1 wt %), the thermal stability is enhanced due to an exfoliated structure. However, for samples containing more organoclay (>=3 wt %), the thermal stability was reduced showing the competition between the barrier effect of organoclay platelets and the catalyzing effect of ammonium salts. Moreover, when using LDPE‐g‐MAH as compatibilizer, it acted as a good coupling agent in all compositions in LDPE major phase systems in contrast to PHB major phase samples. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45922.

A combined experimental and theoretical approach to quantitative assessment of microstructure in PLA/PP/Organo-Clay nanocomposites; wide-angle x-ray scattering and rheological analysis

Abstract A rheological study and morphological investigation using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and wide angle x-ray scattering (WAXS) techniques were performed on the single step melt processed poly (lactic acid) (PLA)/polypropylene (PP)/organoclay counterpart blend nanocomposites prepared via a micro-compounder. Two types of organoclay, Cloisite 30B and 15A were used for the preparation of the nanocomposites. Using a thermodynamic approach and with the aid of experimental techniques, it was indicated that both types of organoclay tend to localize within the PLA phase. Accordingly, in PLA-rich blends, 30B organoclay was localized in the matrix while in the PP-rich system the organoclay (15A) was mainly concentrated within the dispersed phase and also at the interface. In analyzing the WAXS results, two quantities, derived from Bragg and Scherrer's equations, in order to quantify the extent of interaction of organoclay with the different media and also partitioning of clay within the blend components. By that means, it was indicated that WAXS technique owns a great potential to predict organoclay morphology within the blend nanocomposites. Using the weighted relaxation spectrum of blends and implementation of Palierne emulsion model the interfacial tension of PLA/PP counterpart blends was determined. Despite the weak interaction of organoclay with the PP and also the low content of PLA in the PP-rich blend, the 25/75 PLA/PP blend represented substantial enhancement in elasticity as a result of organoclay loading. This behavior was attributed to the created network-like structure of organoclay platelets around the dispersed particles of PLA. Moreover, the applicability of fractional Zener model, to get the best fit to the melt rheological material functions using the genetic algorithm approach, and dependency of the fitting parameter of that model to the blend ratio and organoclay content, were evaluated.

Processing and properties of poly(ester–urethane)/modified montmorillonite nanocomposite foams derived from novel diol and tolylene-2,4-diisocyanate

In this attempt, we have designed novel poly(ester–urethane) (PEU) using poly(di(ethylene glycol)/trimethylolpropane-alt-adipic acid), tolylene-2,4-diisocyanate, and novel diol. Later, PEU has been employed for the fabrication of nanocomposites and foams with hydroxyl-modified montmorillonite (MMT-OH) via in situ polymerization. Afterward, structure and physical properties of PEU/MMT-OH nanocomposites and foams have been explored using various techniques. Physical characteristics of nanocomposites and foams seemed to be dependent upon polyurethane structure, modification of layered silicate and physical interaction between matrix and organoclay platelets. Field emission scanning electron microscopy revealed distorted honeycomb morphology of PEU/MMT-OH 1–5 foams, while PEU/MMT-OH 1–5 nanocomposites depicted dispersed MMT-OH in the matrix. Increased cell density in nanocomposite foams was also observed relative to pure PEU foam. PEU/MMT-OH 5 (5 wt% MMT-OH) foam showed improved tensile strength of 58.1 MPa relative to PEU/MMT-OH 1 foam (56.8 MPa). The density of the foams was also increased (0.7–1.7 g cm−1) with clay loading. The 10% thermal decomposition temperature of PEU/MMT-OH 1–5 foams measured by thermogravimetric analysis was in the range of 431–465°C. Percentage of water absorption was also measured for the foam materials. Dynamic mechanical thermal analysis of PEU/MMT-OH 5 foam with 5 wt% nanofiller showed higher glass transition temperature ( Tg) of 129°C relative to PEU/MMT-OH 1 ( Tg 116°C). UL 94 and limiting oxygen index results showed that PEU/MMT-OH 1–5 foam had increased nonflammability (V-0 rating) with the clay loading. Silicate layers of MMT-OH were well exfoliated in PEU matrix due to chemical reaction between the hydroxyl of MMT-OH and functional groups of PEU. The morphology, mechanical, thermal, and flame retardant properties of PEU/MMT-OH 1–5 foams were found to be superior to those of PEU/MMT-OH 1–5 nanocomposites.

Morphology and mechanical properties of PA6/organoclay nanocomposites toughened by bulk rubber and core-shell rubber

Reactive bulk rubber (EOR-g-MA) and reactive core-shell rubber (ABS-g-MA) are selected as toughening agents to toughen PA6 nanocomposites. The two blends are designed with 20 wt-% rubber phase and 3 wt-% organoclay. X-ray diffraction, transmission electron microscopy and scanning electron microscopy were used to evaluate the degree of exfoliation of organoclays and morphology of the nanocomposites. The organoclay platelets are well exfoliated in the nanocomposites. At the same time, the size of the elastomer particles and interfacial adhesion between polyamide 6 and elastomers are dramatically affected by the existence of organoclay. ABS-g-MA is found to promote the toughness efficiency of PA6 than does EOR-g-MA, which reveals higher impact strength and elongation at break. However, tensile strength and Young's modulus of PA6 blends based on EOR-g-MA elastomer are higher than those based on ABS-g-MA elastomer.

Highly exfoliated epoxy/clay nanocomposites: Mechanism of exfoliation and thermal/mechanical properties

Highly exfoliated epoxy/clay nanocomposites have been fabricated via a new “acetone-clay slurry compounding” approach. Transmission electron microscopy (TEM) observation displayed the clay platelets uniformly dispersed and highly exfoliated in the entire epoxy matrix. The mechanism of exfoliation has been explored by monitoring the change of morphology of organoclay during each stage of processing with X-ray diffraction (XRD). It revealed that organoclay platelets had exfoliated in epoxy prepolymer prior to the curing reaction. Differential scanning calorimeter (DSC) test indicated that incorporation of organoclay resulted in a significantly increase in Tg of the resultant nanocomposites, which is attributed to the highly exfoliation structure and the stronger interfacial interaction. Flexural tests performed at both room temperature(RT) and higher temperature (80°C) showed the flexural strength of the nanocomposites decreased slightly with increasing clay loading at RT, while it exhibited a remarkably enhancement with increasing clay content at 80°C.

Rheological, morphological and thermal properties of pickering-like EVA/organoclay nanocomposites

Pickering-like ethylene vinyl acetate copolymer (EVA)/organoclay nanocomposites were prepared by melt mixing with two different compatibilizers: polyethylene-grafted maleic anhydride and ethylene propylene diene monomer-grafted maleic anhydride. The linear dynamic viscoelasticity, transient and intermittent shear flows, thermal stability, and dispersion state of organoclays were investigated in detail. Before taking rheological measurements, transmission electron microscopy (TEM) and X-ray diffraction were employed to evaluate organoclay intercalation and exfoliation in the nanocomposites. Interestingly, TEM micrographs showed that organoclay platelets were trapped at the interface and bent around the compatibilizer droplets, such as in Pickering emulsions. The intermittent shear flow experiments indicate that structural reorganization during the rest period upon cessation of the initial transient occurred in the EVA/Cloisite 20A nanocomposites, while there was very little evidence of such a state for the EVA/Cloisite 30B nanocomposites. Addition of the compatibilizers to the nanocomposites leads to an increase in overshoot peak both in the initial transient flow and during intermittent shear flow after a rest time. Thermogravimetric analysis and real time Fourier transform infrared spectroscopy indicated that organoclays retard thermal degradation depending on organoclay concentration. The results of micro-scale cone calorimetry showed that the peak of the heat release rate and total heat release of the EVA/organoclay nanocomposites decreased dramatically compared with those of pure EVA, and both compatibilizers could considerably improve the thermal stability and remarkably delayed thermal oxidative degradation of nanocomposites.

Highly filled organoclay/phenolic resin nanocomposite as an ablative heat shield material

The successful return of space vehicles to the Earth’s atmosphere depends largely on the provision made for reducing the aerodynamic heat transfer to its structure. Regarding this, using charring ablative composites is more effective and economic than other methods. Some limitations are associated with the ablative composites, such as weakness of composite char structure which results in easy mechanical corrosion leading to faster surface erosion of insulator. Polymer nanocomposites, especially highly filled systems, show interesting mechanical and thermal properties. In this work, high-filled organoclay/asbestos/phenolic nanocomposite samples were prepared as prototypes. The morphology, mechanical and ablation performance of these nanocomposites were investigated and compared with those of their composite counterparts. Furthermore, toughening mechanism of such highly filled nanocomposite system was studied and its capability as ablative heat shield was discussed. The results showed that the ablation performance of the highly filled polymeric nanocomposite, with exfoliated morphology, was higher than that of the composite counterpart; up to 35 % reduction in erosion rate and above 300 % decrease in temperature in depth. These nanocomposites preserved their strength and modulus in spite of high loading of clay and showed higher toughening in comparison with composite counterpart. The toughening mechanism of the highly filled polymeric nanocomposite was distinguished as crack branching due to flake shape and strength of organoclay platelets.

Effect of matrix morphology on mechanical and barrier properties of polypropylene nanocomposite films containing preferentially aligned organoclay platelets

The objective of this research was to study and optimize the effect of matrix morphology on the desirable mechanical and barrier properties of polypropylene/organoclay (PP/clay) nanocomposite films. Nanocomposites with different organoclay contents and three different matrix morphologies were compared with neat PP under identical conditions. The degree of organoclay dispersion was controlled through the use of a compatibilizer, maleic anhydride grafted polypropylene (PP-g-MA). The nanocomposite films were first prepared by melt casting and then subjected to annealing and re-crystallization. Organoclay platelets in all films were found to align parallel to the film plane. Crystalline PP in as-prepared films was found to have a preferred orientation with the lamellae normally lying perpendicular to the machine direction. Upon annealing, the stacks of parallel lamellae, aligned perpendicular to the machine direction and the film surface, tend to be more orderly than in as-prepared films (see models). No crystal orientation was found in re-crystallized films. A clear increase in elastic modulus and tensile strength with increasing organoclay content was observed. Relative oxygen permeability (ROP) of nanocomposite films decreased with increasing amount of organoclay. The effect of matrix morphology is as follows: annealed films display the highest elastic modulus, tensile strength and ROP, followed by as-prepared and re-crystallized films.

The Aggregation Process as a Cause of Large-Scale Disorder in Nanocomposites of Polymer/Organoclay

It has been shown that organoclay platelets aggregation in packets (tactoids) results in large-scale disorder intensification. It reduces the nanofiller anisotropy degree. In its turn, this factor decreases essentially the nanocomposites reinforcement degree. The interfacial adhesion role in anisotropy level definition has been shown.

Structural characterization of high-density polyethylene nanocomposites: effect of compatibilizer type and high aspect ratio organoclay platelets

This research focuses on the possibility of improving properties of high-density polyethylene-based nanocomposite films for packaging applications, using a high aspect ratio layered silicate named fluoromica. Three different compatibilizers [ethylene vinyl acetate copolymer and two grades of maleic anhydride grafted high-density polyethylene (HDPE-g-MA) with different melt flow indices] were examined to explore the effects of compatibilizer polarity and molecular weight on the state of nanoclay dispersion. Owing to the direct correlation between nanocomposites morphology and rheological behavior, a quite extensive survey of the role of different material variables was carried out via measuring rheological properties in linear viscoelastic region. Percolation threshold ( $$\phi_{\text{p}}$$ ) were determined by analyzing the improvement in dynamic viscosity in low-frequency region and also, by means of a predicted mathematical model obtained from experimental design. It was found that the HDPE-g-MA compatibilizers result in lower $$\phi_{\text{p}}$$ and better clay dispersion, particularly in the case of high MFI resin. Microstructural characterization of the samples was studied by X-ray diffraction and transmission electron microscopy as well.

Synthesis and Characterization of New Poly(amide-imide)/organoclay Nanocomposites Derived from N,N′-(4,4′-diphtaloyl)-bis-L-α-aminophenyl Acetic Diacid and 1,2-Bis(4-aminophenoxy)ethane

AbstractIn this study, a series of polymer/clay nanocomposites (PCNs) materials consisting of organic poly(amide-imide) (PAI) and organo-modified clay content varying from 0 to 10 mass%, were successfully prepared by solution dispersion technique. At first, the reactive organoclay was prepared by using protonated L-phenylalanine amino acid as a swelling agent for silicate layers of montmorillonite/Na+ (MMT/Na+) via ion-exchange reaction. Then, poly(amide-imide) used as a matrix of nanocomposite was prepared through the polymerization reaction of N,N′-(4,4′-diphtaloyl)-bis-L-α-aminophenyl acetic diacid and 1,2-bis(4-aminophenoxy)ethane in a medium of N-methyl-2-pyrrolidone (NMP) / triphenyl phosphite (TPP) / calcium chloride (CaCl2) / pyridine (py). This polymer was end-capped with amine end groups near the completion of the reaction to interact chemically with organoclay. Finally, PAI/organoclay nanocomposite films containing 1%, 3%, 5% and 10% of organoclay were prepared via solution intercalation method through blending of organoclay with the PAI solution. The resulting nanocomposite films were characterized by FT-IR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). XRD and TEM results revealed the formation of exfoliated and intercalated organoclay platelets in the PAI matrix. TGA results indicated that the addition of organoclay into the PAI matrix increases in the thermal decomposition temperatures of the resulted nanocomposites.

The role of flow‐induced microstructure in rheological behavior and nonisothermal crystallization kinetics of polyethylene/organoclay nanocomposites

The evolution of polyethylene/organoclay nanocomposite microstructure via shear and extentional flow fields was studied by tracing rheological behavior and nonisothermal crystallization kinetics. Although studying microstructure formed through flow fields, two phenomena were noticed: the breaking of three‐dimensional (3D) network containing filler–filler, filler–matrix, and matrix–matrix interactions, and organoclay platelets orientation. Utilizing nonlinear viscoelastic measurements and thermal analyses, it was proven that clay alignment was present only in large enough shear flows and all elongational flows. It was observed that regardless of the type of flow field and its magnitude, due to the breaking of 3D network, the extent of crystallization can be increased. The half‐lives of the crystallization of film samples and those samples subjected to large enough shear rates for clay platelets to be aligned decreased, proving the effect of clay orientation on crystallization rate increment. Based on endotherms observed through melting behavior studies of samples, it was proven that in elongation and large amplitude shear flows, clay orientation had resulted in forming thicker crystalline lamellae, likely because of forcing the adjacent polymer chains to align with the clay platelets. POLYM. ENG. SCI., 54:1839–1847, 2014. © 2013 Society of Plastics Engineers

Effect of water‐assisted extrusion and solid‐state polymerization on the microstructure of PET/Clay nanocomposites

An melt‐mixing process has been used to prepare Poly(ethylene terephthalate) (PET)/clay nanocomposites with high degree of clay delamination. In this method, steam was fed into a twin‐screw extruder (TSE) to reduce the PET molecular weight and to facilitate their diffusion into the gallery spacing of organoclays. Subsequently, the molecular weight (MW) reduction of the PET matrix due to hydrolysis by water was compensated by solid‐state polymerization (SSP). The effect of the thermodynamic compatibility of PET and organoclays on the exfoliated microstructure of the nanocomposites was also examined by using three different nanoclays. The dispersion of Cloisite 30B (C30B) in PET was found to be better than that of Nanomer I.28E (I28E) and Cloisite Na+. The effect of feeding rate and consequently residence time on the properties of PET nanocomposites was also investigated. The results reveal more delamination of organoclay platelets in PET‐C30B nanocomposites processed at low feeding rate compared to those processed at high feeding rate. Enhanced mechanical and barrier properties were observed in PET nanocomposites after SSP compared to the nanocomposites prepared by conventional melt‐mixing. POLYM. ENG. SCI., 54:1723–1736, 2014. © 2013 Society of Plastics Engineers

The Effects of Organoclay on the Morphology and Balance Properties of an Immiscible Polypropylene/Natural Rubber Blend

The objective of this work is to study the effects of organoclay on the morphology and balance properties between strength and toughness of a blend based on polypropylene (PP) and natural rubber (NR). This nanocomposite blend (nanoblend) was prepared by melt extrusion technique. The results obtained show that at 3wt % organoclay concentration there is a slight balance between strength and toughness of the blend. On the other hand, the results obtained by XRD analysis show that, at 3wt % of organoclay loading, there is a shift towards low angles of the (001) plane diffraction peak. This shift means an intercalation of the macromolecular polypropylene/natural rubber blend chains between the clay platelets. The SEM study reveals that at 3wt % organoclay concentration there is a uniform distribution of the elastomeric dispersed domains. TGA analysis revealed an improvement of the thermal stability of the composite containing 3wt % organoclay. DSC study shows that at 3wt % organoclay concentration, there is a decrease of the melting temperatures of the blend; this decrease can be explained by the intercalation of NR chains between organoclay platelets. This intercalation can hinder or disturb the physical transition of the intercalated PP chains. The simultaneous intercalation of PP and NR chains into organoclay galleries can be explained by the localization of the organoclay platelets at the interface between PP and NR domains as assessed by SEM examinations

Effects of organoclay on morphology and mechanical properties in acrylonitrile-butadiene-styrene/polyamide 6/ organoclay ternary nanocomposites

AbstractIn this article, polyamide 6(PA6)/organoclay masterbatch were prepared by melt mixing, and then acrylonitrile-butadiene-styrene(ABS)/polyamide 6(PA6)(70/30,w/w) nanocomposites were prepared by the melt mixing of PA6, ABS and organoclay. The effect of organoclay platelets on morphology and mechanical properties of ABS/PA6/organoclay ternary nanocomposites had been investigated by wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM), scanning electron microscopy (SEM) and mechanical properties testing. Morphology analysis revealed that organoclay platelets were selectively dispersed and exfoliated in PA6 phase, but some were located in interface of PA6 and ABS phase. The droplet size of PA6 dispersed phase were gradually reduced less than 4 phr organoclay, then the dispersed domain size became unchanged with the addition of various organoclay. It suggested the organoclay can compatibilize the ABS/PA6 blend nanocomposite. Moreover, the flexural strength and modulus increase with increasing organoclay content, but the tensile strength became maximal at 3 phr organoclay. The organoclay has no effect on impact strength of ABS/PA6 blend nanocomposite.

Morphology and mechanical properties of heterophasic PP–EP/EVA/organoclay nanocomposites

AbstractThe effect of vinyl acetat (VA) on the morphological, thermal stability, and mechanical properties of heterophasic polypropylene–(ethylene‐propylene) copolymer (PP–EP)/poly(ethylene vinyl acetate) (EVA)/organoclay nanocomposites was studied. Tailored organoclay C20A was selected to enhance the exfoliation of the clay platelets. Depending on the VA content, there were two morphological organoclay populations in the systems. Both populations were directly observed by scanning transmission electron microscopy and measured by wide‐angle X‐ray diffraction and small‐angle X‐ray scattering. The content of VA in EVA originated spherical and elongated morphologies in the resultant nanocomposites. High‐VA content led to a better intercalation of the organoclay platelets. Measurement of thermal properties suggested that higher VA decreases thermal stability in samples both with and without organoclay, although nanocomposites had higher thermal stability than samples without clay. The storage modulus increased both with nanoclay and VA content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effect of water absorption on the mechanical properties of nanoclay filled recycled cellulose fibre reinforced epoxy hybrid nanocomposites

Recycled cellulose fibre (RCF) reinforced epoxy/clay nanocomposites were successfully synthesized with different weight percentages (0%, 1%, 3% and 5%) of organoclay platelets (30B). The objective of this study was to investigate the effect of water absorption on the physical and mechanical properties of the RCF reinforced epoxy/clay nanocomposites. TEM images indicated a well-intercalated structure of nanoclay/epoxy matrix with some exfoliated regions. Water absorption was found to decrease as the clay content increased. The flexural strength, flexural modulus and fracture toughness significantly decreased as a result of water absorption. However, the properties of impact strength and impact toughness were found to increase after exposing to water. The addition of nanoclay slightly minimized the effect of moisture on the mechanical properties. SEM images showed that water absorption severely damaged the cellulose fibres and the bonding at fibres–matrix interfaces in wet composites.