Influence of α‐ZrP fillers and process conditions on the morphology and the gas barrier properties of filled polyamide 6 films

Composite films based on polyamide 6 and lamellar unmodified α‐ZrP nanofillers have been prepared for low filler amounts (less than 2 wt %) using cast process or blowing process. Whatever be the filler content and the film process conditions, the lamellar nanofillers were not intercalated by the polymer chains and microcomposites were obtained. On the other hand, the matrix crystalline structure highly depended on the presence of fillers and on the film process conditions. The nature of the crystalline phase and its orientation were shown to play a major role on the film barrier properties to helium. For instance, the presence of γ crystalline phase associated to a specific orientation of the crystalline lamellae parallel to the film surface could significantly contribute to enhance barrier properties. This specific morphology was favored by the presence of α‐ZrP in the formulation but depended also on the process conditions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1734–1746, 2008     

Polypropylene/layered double hydroxide nanocomposites: Synergistic effect of designed filler modification and compatibilizing agent on the morphology,thermal, and mechanical properties

This work addresses the optimization of the morphology, thermal, and mechanical properties of polypropylene/layered double hydroxide (LDH) nanocomposites. For this, the nanofillers were modified by a calcination rehydration process using two surfactants, sodium dodecylsulfate (SDS) and sodium dodecylbenzenesulfonate, respectively. The nanofillers were characterized at each step of the modification process by thermal gravimetry, X‐ray diffraction, and Infra red spectroscopy. Furthermore, the impact of anionic modifiers on the filler surface energy and on the interactions toward water was analyzed. Polypropylene (PP)/LDH nanocomposites were then prepared by a melt intercalation process and a high molar mass maleic anhydride functionalized polypropylene (PPgMA) was introduced as a compatibilizer. The dispersion of LDH in the PP matrix was characterized and the thermal and mechanical properties of the corresponding nanocomposites were determined and discussed as a function of the filler modification, of the nanocomposite morphology, and of the filler/matrix interfacial properties. The nanocomposites prepared from SDS modified LDH and PPgMA exhibited superior properties thanks to an optimized filler dispersion state and improved interfacial interactions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 782–794     

Modification of α-ZrP nanofillers by amines of different chain length: Consequences on the morphology and mechanical properties of styrene butadiene rubber based nanocomposites

An aqueous slurry of α-ZrP lamellar nanofillers has been modified by amine type surfactants. The influence of the alkylamine chain length and of the cationic exchange rate on the nanofiller d-spacing has been analyzed. The strength of the interactions formed between the intercalating agent and the filler has been studied by Infra Red Spectroscopy (FTIR), Solid-state Nuclear Magnetic Resonance (³¹P MAS NMR) and Thermogravimetric Analysis (TGA). Different routes allowing to obtain optimized filler properties while minimizing the surfactant weight amount have been proposed from the detailed analysis of the intercalation mechanism. Styrene Butadiene Rubber nanocomposites have been prepared directly from the different slurries of modified α-ZrP. The dispersion of the organophilic α-ZrP in the SBR matrix has been characterized and the mechanical properties of the corresponding nanocomposites have been determined and discussed as a function of the filler modification, of the nanocomposite morphology and of the filler/matrix interfacial properties.     

Impact of coated calcium carbonate nanofillers and annealing treatments on the microstructure and gas barrier properties of poly(lactide) based nanocomposite films

Amorphous poly(lactide) (PLA) and nanocomposite films were prepared from melt‐blending with precipitated calcium carbonate nanofillers (PCC). Nanocomposites based on uncoated PCC (PCC‐UT), stearic acid coated PCC (PCC‐S), and poly(ε‐caprolactone) coated PCC (PCC‐P) were investigated for an inorganic content fixed to 8 wt %. Using coated nanofillers allowed preserving both PLA average molar mass and thermal stability while enhancing the nanofiller dispersion state. Poly(ε‐caprolactone) was identified as the best coating for optimized morphology and thermal properties. Maxwell law accurately described the increase in oxygen barrier properties observed for the nanocomposites based on PCC‐S. A modified Maxwell law was proposed to take account of the additional increase in barrier properties evidenced for the PLA/PCC‐P nanocomposites and assigned to the particularly strong compatibility between PCL and PLA. Different annealing conditions were investigated to respectively study the impact of physical ageing and PLA crystallization on gas permeability. Different extents of physical ageing did not significantly modify the oxygen transport properties. However, a high permeability decrease was observed for the semicrystalline nanocomposites with respect to the amorphous reference PLA film. Finally, the gain in barrier properties was shown to result from both contribution of the nanofillers and the crystalline phase. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 649–658     

New nanohybrids of poly(ε‐caprolactone) and a modified Mg/Al hydrotalcite: Mechanical and thermal properties

Novel composites based on poly(ε‐caprolactone) (PCL) and an organically modified layer double hydroxide (LDH) obtained using the melt‐extrusion technique have been characterized through structural, thermal, and mechanical analyses. Although exfoliation has not been achieved and despite the very low content of filler (from 1 to 3% by weight), significant enhancements are obtained in the physical and mechanical properties of the composites with respect to neat PCL. As a consequence, LDHs can substitute other nanofillers, in particular, cationic clays for polymeric matrices. They can be modified by a large number of organic anions, generally more numerous than the cationic ones, and can be mixed in very simple ways with polymers. This makes such nanofillers suitable to obtain new hybrid materials for a series of applications, from active food packaging to intelligent materials for biomedical device, for example, controlled drug release. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 945–954, 2007     

Payne effect in silica‐filled styrene–butadiene rubber: Influence of surface treatment

The nonlinear effect at small strains (Payne effect) has been investigated in the case of silica‐filled styrene‐butadiene rubber. The originality of this study lies in the careful preparation of samples in order to fix all parameters except one, that is, the modification of the silica surface by grafting silane (introduced at different concentrations) via reactive mixing. The organosilane can be either a coupling or a covering surface treatment with an octyl alkyl chain. A careful morphological investigation has been performed prior to mechanical characterization and silica dispersion was found to be the same whatever the type and the amount of silane. The increasing amount of covering agents was found to reduce the amplitude of the Payne effect. A similar decrease is observed for low coupling agent concentration. At higher concentrations, the evolution turns through an increase due to the contribution of the covalent bonds between the matrix and the silica acting as additional crosslinking. The discussion of the initial modulus was done in the frame of both the filler–filler and filler–polymer models. It is unfortunately not possible to distinguish both scenarios, because filler–filler and filler–matrix interactions are modified in the same manner by the grafting covering agent. On the other hand, the reversible decrease of the modulus versus strain (Payne effect) is interpreted in terms of debonding of the polymeric chains from the filler surface. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 286–298, 2007     

Viscoelastic behaviour of silica filled natural rubber composites – Correlation of shear with elongational testing

Dynamic mechanical behaviour of natural rubber-silica composites was studied by a frequency sweep method at different temperatures (40 °C,70 °C and 100 °C) using a dynamic mechanical analyzer and a rotorless rheometer, RPA, in an attempt to establish a correlation between the two. The composites with silica content up to 40 phr were studied. It was found that the dependence of dynamic modulus on the frequency as obtained from both the instruments followed a similar trend. This suggests that the dynamic mechanical properties of rubber compounds can be determined even during curing. A correlation could be arrived at between the two sets of data, making it possible to predict one set knowing the other. The impact of silane coupling agent, bis (3-triethoxysilylpropyl tetrasulphide), TESPT, on viscoelasticity was also investigated. The mechanical properties were improved in the presence of TESPT. Additionally, an increase in thermal stability was also observed in the presence of TESPT. Scanning electron micrographs showed the better filler dispersion in the case of silane-coupled silica composites.     

Elastomer Nanocomposite; Properties

Polymer nanocomposites represent a class of materials that have assumed great importance in recent years and are the focus of extensive research. Unlike plastomer nanocomposites, the elastomer nanocomposites are in the stage of infancy in respect to their applications.

In general, in polymer composites, the matrix and the filler are bonded to each other by weak intermolecular forces and covalent bonding are rarely involved. If the filler could be dispersed in the polymer matrix at the nanometre level and is able to interact with the matrix by chemical bonding, nanocomposites with significant properties improvement are obtained. These improvements can include mechanical properties (module, strength, etc.), thermal resistance, decrease in gas permeability (barrier), flammability, etc.

This paper is a review of the property improvements of different elastomers using nanofillers like silicates, carbon black, metallic powders, cellulose crystals, mixture of nanofillers, etc, with the intention of obtaining elastomer nanocomposites.     

Correlation between rheological,electrical, and microstructure characteristics in polyethylene/aluminum nanocomposites

Polyethylene (PE)/aluminum (Al) nanocomposites with various filler contents were prepared by a solution compounding method. We investigated the influence of the surface modification of Al nanoparticles on the microstructure and physical properties of the nanocomposites. The silane coupling agent octyl‐trimethoxysilane was shown to significantly increase interfacial compatibility between the polymer phase and Al nanoparticles. Rheological percolation threshold values were determined by analyzing the improvement in storage modulus at low frequencies depending on the Al loadings. Lower percolation threshold values were obtained for the composites prepared with the original nanoparticles than those prepared with the silane‐modified Al nanoparticles. A strong correlation between the time and concentration dependences of dc conductivity and rheological properties was observed in the different nanocomposite systems. The rheological threshold of the composites is smaller than the percolation threshold of electrical conductivity for both of the nanocomposite systems. The difference in percolation threshold is understood in terms of the smaller particle–particle distance required for electrical conduction when compared with that required to impede polymer mobility. It was directly shown by SEM characterization that the nanoparticle surface modification yielded better filler dispersion, as is consistent with our rheological and electrical analysis. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2143–2154, 2008     

EFFECT OF SILANE COUPLING AGENT ON THE MECHANICAL, THERMAL PROPERTIES AND MORPHOLOGY OF TREMOLITE/PA1010 COMPOSITES

Tremolite,a kind of inorganic filler,was modified with a silane coupling agentγ-methacryloxypropyl trimethoxy silane (MPS) in ethanol/ammonia solution.The graft of MPS on tremolite was confirmed by X-ray photoelectron spectroscopy (XPS),IR and thermogramitric analysis (TGA) measurements.In addition,contact angle analysis showed that particle surface property was changed from hydrophilicity to hydrophobicity after the modification.Modified tremolite and pure tremolite were blended respectively with PA1010...     

Preparation and properties of nanocomposites based on acrylonitrile–butadiene rubber,styrene–butadiene rubber,and polybutadiene rubber

Nanocomposites were prepared with different grades of nitrile rubber with acrylonitrile contents of 19, 34, and 50%, with styrene–butadiene rubber (23% styrene content), and with polybutadiene rubber with Na‐montmorillonite clay. The clay was modified with stearyl amine and was characterized by X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The XRD studies showed an increase in the gallery gap upon the modification of the filler by stearyl amine. The intercalation of the amine chains into the clay gallery gap was confirmed by the presence of some extra peaks (2928, 2846, and 1553 cm^?1) in the FTIR spectra. The clay–rubber nanocomposites were characterized by TEM and XRD. The mechanical properties were studied for all the compositions. An improvement in the mechanical properties with the degree of filler loading up to a certain level was observed. The changes in the mechanical properties, with changes in the nature and polarity of the rubbers, were explained with the help of XRD and TEM results. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1573–1585, 2004     

Effect of silane coupling agent on the polymer‐filler interaction and mechanical properties of silica‐filled NR

The effects of filler loading and a new silane coupling agent 3‐octanoylthio‐1‐ propyltriethoxysilane (NXT silane) on the polymer‐filler interaction and mechanical properties of silica‐filled and carbon black‐filled natural rubber (NR) compounds were studied. Silica (high dispersion silica7000GR, VN2, and VN3) and carbon black (N330) were used as the fillers, and the loading range was from 0 to 50 phr. The loading of NXT silane was from 0 to 6 phr. Experimental results show that the maximum and minimum torques of silica and carbon black‐filled NR increase with increasing filler loading. With increasing filler loading, the scorch time and optimum cure time decrease for carbon black‐filled NR, but increase for silica‐filled NR. The minimum torque, scorch time, and optimum cure time decrease because of the presence of NXT silane. For the carbon black and silica‐filled NR, the tensile strength and elongation at break have maximum values, but the hardness, M300, M100, and tear strength keep increasing with filler loading. The mechanical properties of silica‐filled NR were improved in the presence of NXT silane. With increasing filler loading, the storage modulus of filled NR increases, but the loss factor decreases. Carbon black shows the strongest polymer‐filler interaction, followed by VN3, 7000GR, and VN2. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 573–584, 2005     

Characterization of electron-beam-modified surface coated clay fillers and their influence on physical properties of rubbers

A novel process of surface modification of clay filler has been developed by coating this with an acrylate monomer, trimethylol propane triacrylate (TMPTA) or a silane coupling agent, triethoxy vinyl silane (TEVS) followed by electron beam irradiation. Characterization of these surface modified fillers has been carried out by Fourier-transform infrared analysis (FTIR), electron spectroscopy for chemical analysis (ESCA), wettability by dynamic wicking method measuring the rise of a liquid through a filler-packed capillary tube and water flotation test, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). Presence of the acrylate and the silane coupling agent on the modified fillers has been confirmed from FTIR, ESCA, and EDX studies, which has also been supported by TGA studies. The contact angle measurement by dynamic wicking method suggests improvement in hydrophobicity of the treated fillers, which is supported by water flotation test especially in the case of silanized clay. However, XRD studies demonstrate that the entire modification process does not affect the bulk properties of the fillers. Finally, both unmodified and modified clay fillers have been incorporated in styrene butadiene rubber (SBR) and nitrile rubber (NBR). Rheometric and mechanical properties reveal that there is a definite improvement using these modified fillers specially in the case of silanized clay compared to the control sample, probably due to successful enhancement in interaction between the treated clay and the base polymer.     

The mechanical properties and tribological behavior of epoxy resin composites modified by different shape nanofillers

Mechanical properties and tribological behavior of epoxy resin (EP) and EP nanocomposites containing different shape nanofillers, such as spherical silica (SiO₂), layered organo‐modified montmorillonite (oMMT) and oMMT‐SiO₂ composites, were investigated. The SiO₂‐oMMT composites were prepared by in situ deposition method and coupling agent modification, and transmission electron microscopy (TEM) analysis shows that spherical SiO₂ is self‐assembled on the surface of oMMT, which forms a novel layered‐spherical nanostructure. The mechanical properties test results show that oMMT obviously improves the strength of EP and SiO₂ enhances its toughness, but oMMT‐SiO₂ exhibits a synergistic effect on toughening and reinforcing EP simultaneously. A pin‐on‐disc rig was used to test friction and wear loss of pure EP and EP nanocomposites. The tribological test results prove that these nanofillers with different shapes play different roles for improving the wear resistance of EP nanocomposites. Morphologies of the worn surfaces were studied further by scanning electron microscopy (SEM) observations, and it was clarified that the EP and EP nanocomposites undergo similar wear mechanisms. Copyright © 2006 John Wiley & Sons, Ltd.     

Effect of silane coupling agent on mechanical interfacial properties of glass fiber‐reinforced unsaturated polyester composites

A silane coupling agent, γ‐methacryloxypropyltrimethoxysilane, for the surface modification of glass fibers was varied between 0.1 and 0.8 wt %. To understand the role of interfacial adhesion of glass fiber/unsaturated polyester composites, contact angles of the silane‐treated glass fibers were measured by the wicking method on the basis of the modified Washburn equation with deionized water, diiodomethane, and ethylene glycol as testing liquids. As a result, silane‐treated glass fibers led to increased surface free energy, mainly because of their increased specific or polar component. The mechanical interfacial behaviors based on the interlaminar shear strength (ILSS) of the composites determined by short‐beam tests and the critical stress‐intensity factor (K_IC) were also improved in the case of silane‐treated composites. The surface free energy and the mechanical interfacial properties especially showed the maximum value in the presence of 0.4 wt % silane coupling agent. It revealed that the increase of a specific component of the surface free energy or hydrogen bonding between the glass fibers and the coupling agents plays an important role in improving the degree of adhesion at interfaces in a composite system. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 55–62, 2003     

The effect of zirconium phosphonate with different functional groups on the structure and properties of chitosan film

Three types of zirconium phosphonate (org‐ZrP) with different functional groups (―COOH, ―SO₃H, ―NO₂) were prepared first and then added into chitosan (CS) matrix, respectively. The effect of these functional groups on structure, morphologies, and mechanical properties of chitosan films was investigated. The Fourier transform infrared spectroscopy revealed that org‐ZrP had intensely interacted with chitosan in the composites because of introducing functional groups on the fillers. The composite films filled with zirconium sulfophenylphosphonate exhibited the best mechanical properties among the three org‐ZrP fillers. These differences of reinforcement effect appeared to be caused by the difference of interfacial interactions between the org‐ZrP fillers and matrix. The stronger the interfacial interactions are, the better the reinforcement effect is. In addition, the moisture uptake (Mu) of CS/org‐ZrP‐n composite films depended on the hydrophilic property of functional groups. It was found that zirconium nitrophenyl phosphonate showed the best moisture barrier property due to its poor absorbability for water molecules. Copyright © 2014 John Wiley & Sons, Ltd.     

Preparation,characterization, and properties of novolac‐type phenolic/SiO2 hybrid organic–inorganic nanocomposite materials by sol–gel method

This article describes the preparation of novolac‐type phenolic resin/silica hybrid organic–inorganic nanocomposite, with a sol–gel process. The coupling agent was used to improve the interface between the organic and inorganic phases. The effect of the structure of the nanocomposite on its physical and chemical properties is discussed. The coupling agent reacts with the resin to form covalent bonds. The structure of the modified hybrid nanocomposites was identified with a Fourier transform infrared spectroscope. The silica network was characterized by nuclear magnetic resonance imaging (²⁹Si NMR). Results revealed that Q₄ (tetrasubstituted) and T₃ (trisubstituted) are the dominant microstructures. The size of the silica in the phenolic resin was characterized with a scanning electron microscope. The size of the particles of inorganic silica in the modified system was less than 100 nm. The nanocomposite exhibited good transparency. Moreover, the thermal and mechanical properties exhibited significant improvement. The modified hybrid composite exhibited favorable thermal properties. The temperature at which a weight loss of 5% occurred increased from 281 to 350 °C. The flexural strength increased by 6–30%. The limiting oxygen index of the nanocomposite reached 37, and the Underwriters Laboratory test was 94V‐0. Consequently, these materials possess excellent flame‐retardant properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 905–913, 2003     

A new method for crosslinking and reinforcing acrylonitrile–butadiene rubber using a silanized silica nanofiller

Using a high loading of synthetic precipitated amorphous white silica nanofiller, an acrylonitrile–butadiene rubber containing 26% by weight acrylonitrile was crosslinked and its mechanical properties were measured. The silica surfaces were pre‐treated with bis(3‐triethoxysilylpropyl)tetrasulfide (TESPT) to chemically adhere silica to the rubber. To optimize the reaction between the tetrasulfane groups of TESPT and the rubber, accelerator and activator were added. The rubber was fully crosslinked and the hardness, tensile strength, stored energy density at break, elongation at break, tearing energy, and modulus increased substantially because of the filler. The bound rubber, crosslink density, tan δ, and glass transition temperature measurements indicated a strong interaction between the filler and rubber. This new method helped to substantially reduce the use of the curing chemicals and produce a safer and more cost‐effective rubber compound without compromising the good mechanical properties of the rubber, which are essential for long service life. Copyright © 2009 John Wiley & Sons, Ltd.     

Selective localization of organoclay and effects on the morphology and mechanical properties of LDPE/PA11 blends with distributed and co‐continuous morphology

A study was made on the effect of small amounts of organically modified clay on the morphology and mechanical properties of blends of low‐density polyethylene and polyamide 11 at different compositions. The influence of the filler on the blend morphology was investigated using wide angle X‐ray diffractometry, scanning and transmission electron microscopy and selective extraction experiments. The filler was found to locate predominantly in the more hydrophilic polyamide phase. Although such uneven distribution does not have a significant effect on the onset of phase co‐continuity of the polymer components, it brings about a drastic refinement of the microstructure for the blends both with droplets/matrix and co‐continuous morphologies. In addition to the expected reinforcing action of the filler, the resulting fine microstructure plays an important role in enhancing the mechanical properties of the blends. This is essentially because of a good quality of stress transfer across the interface between the constituents, which also seems to benefit for a good interfacial adhesion promoted by the filler. Our results provide the experimental evidence for the capabilities of nanoparticles added to multiphase polymer systems to act selectively as a reinforcing agent for specific domains of the material and as a medium able to assist the refinement of the polymer phases during mixing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 600–609, 2010     

Mechanical properties of clay‐reinforced polyamide

Intercalated and exfoliated nanocomposites were prepared by extrusion and injection of polyamide‐6 and highly swollen or slightly swollen montmorillonite, respectively. The microstructure of the nanocomposites has been studied previously. In this article, we investigated the influence of the preferential orientation of the montmorillonite sheets on the mechanical properties of the nanocomposites. Dynamic mechanical analysis and tensile tests showed that the elastic modulus depends mainly on the filler loading. A parallel coupling could well account for the behavior of the nanocomposites. The calculated elastic and storage moduli of montmorillonite were set to 140 and 40 GPa, respectively. Compression tests were performed to study the anisotropy of the mechanical properties. The elastic modulus and flow strain were sensitive to the filler orientation. A Tandon–Weng approach was applied to consider the geometry of the filler. In all low‐deformation tests, no significant difference between intercalated and exfoliated systems was observed. Finally, the influence of the dispersion and exfoliation state of the filler on the ultimate properties of the nanocomposites (tensile tests) is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 272–283, 2002