Storage Modulus Of Nanocomposites Research Articles

Improvements in the thermomechanical and electrical behavior of hybrid carbon-epoxy nanocomposites

• Chemical functionalization on reinforcements produces good dispersion in epoxy matrix. • Slight amounts of hybrid reinforcement generate better performance than only one nanomaterial. • Hybrid nanocarbons contribute outstandingly in the thermomechanical and electrical properties. • Raman mapping on composites fracture surface evidenced the contribution of nanomaterials. In this work, polymeric composites of epoxy matrix reinforced with 1D and 2D nanocarbon allotropes are reported. Hybrid 3D nanostructures formed from 1D multi-walled carbon nanotubes and 2D graphene derivatives improve the electrical and thermomechanical response of the synthesized nanocomposites. Additionally, oxygenated moieties in the surface of the sp 2 carbon allotropes positively influences the dispersion of nanomaterials in the matrix and promote better interfaces among the polymeric matrix and reinforcements. Raman spectroscopy detects the different interactions of polymeric chains with carbon nanomaterials in different loads. Furthermore, Raman mapping shows the carbon dispersion regions and the influence on the final mechanical properties of the materials. The viscoelastic response evaluated by Dynamical Mechanical Analysis shows improvements of up to 138% in the storage modulus of nanocomposites with oxidized nanostructures in comparison to neat epoxy. 3D nanostructures changed the insulating nature of epoxy when the carbon nanomaterials formed the interconnected network. Some nanocomposites show an abrupt change from the insulator epoxy resin toward a semiconductor response, mainly in hybrids reinforced with pristine multi-walled carbon nanotubes and reduced graphene oxide. The TEM images of the nanocomposites showed interconnections between the 1D-2D hybrid carbon nanomaterials, which suggest a synergetic effect.

Improving the Mechanical Properties of Thermoplastic Polyolefins Using Recycled Low-Density Polyethylene and Multi-Walled Carbon Nanotubes

Thermoplastic polyolefin (TPO) has gained considerable attention because of having a combination of rubbery and thermoplastic properties and ease of production. Their excellent weather resistance, low density, and relatively low cost make them attractive materials for the automotive, electrical, footwear industries and membranes for water treatment. Their main shortcomings are poor mechanical properties, especially at low temperatures because of the opposing trends of stiffness and toughness. In this paper, recycled low density polyethylene (RLDPE) was integrated with ethylene-propylene-diene rubber (EPDM) incorporating very low content of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) to improve the mechanical properties of the produced TPO nanocomposite. TPO has been prepared through the combination of 40, 50, and 60 wt.% RLDPE and 40, 50, and 60 wt.% EBDM. The improved TPO composition was then reinforced with 0.1, 0.3, and 0.5 wt.% MWCNTs-COOH to produce TPO nanocomposites. The compounding of TPO and its nanocomposites was done by melt mixing followed by heat pressing. Mechanical and thermal behaviors of the TPO nanocomposites were investigated. Tensile tests showed that the TOP (60-40) is the best improved concentration; the storage modulus of nanocomposites was enhanced by increasing MWCNTs-COOH concentration. In addition, modulus, stress/strain and toughness of TPO were enhanced by adding 0.5 wt.% MWCNTs-COOH. Thus, MWCNTs-COOH reinforced TPO due to not only its large aspect ratios but also due to its interaction with both the TOP matrix and the combatibilizer. The results of microstructural investigations of the prepared TPO nanocomposite using FTIR and TGA confirmed the interaction between MWCNTs-COOH and TPO matrix

Mechanical and thermomechanical properties of vinyl ester/polyurethane IPN based nano-composites

Interpenetrating polymer networks of vinyl ester (VE) resin and polyurethane (PU) were synthesized using blend ratio of 93:7(w/w). Two sets of nanocomposites based on i) pure vinyl ester and ii)VE/PU IPN(93VE), were prepared with organically modified silica nanoparticle (OMS) as filler by 1, 2, 3 and 5% weight of the matrix resin. All the nanocomposites were characterized in terms of mechanical and thermomechanical properties.VE/silica nanocomposite with 2% filler (VES2) showed improvement in ultimate tensile strength by 83.5% and toughness by 42% compared to that of VE resin itself. The IPN based nanocomposite, 93VES2, exhibited 31.14%, 10.8% and 18%greater tensile strength, Young’s modulus and toughness respectively in comparison to that of the base 93VE IPN. IPN based nanocomposites were tougher than VE based nanocomposites. Storage modulus of nanocomposites was lower than that of 93VE and VE matrix system. Higher tanδmaxof the 93VE/OMS nanocomposites than that of the 93VE matrix was indication of more elastic nature of the later. Smaller size of dispersed domains was found in SEM micrographs for IPN based nanocomposites than that in micrographs of VE based nanocomposites of corresponding composition.

Effect of Surface Modification on Multi-Walled Carbon Nanotubes and their Reinforced Nylon Composites

In this study, a series of nanocomposites were prepared by melt-blending method using Nylon (Nylon12, PA12) and multi-walled carbon nanotubes (MWCNTs) with various contents such as 0.0 wt.%, 0.5 wt.%, 1.0 wt.%, 3.0 wt.%. In order to improve the dispersion of MWCNTs in composites, the MWCNTs were first acid treated by the HNO3 solution to functionalize the carboxylic groups on the surface. Subsequently, this acid treated MWCNTs were reacted with Polyetheramine (Jeffamine® M2070) and Polyethylenimine under mild conditions, respectively, to obtain the chemically modified MWCNTs (M-M2070 and M-PEI). The amide groups formed on these chemically modified MWCNTs will enhance the compatibility of MWCNTs and Nylon. The effects of different modification methods on the thermal properties, mechanical properties and electrical resistance of these Nylon12/MWCNTs composites were investigated. The results showed that M-M2070 and M-PEI dispersed in Nylon12 homogeneously, and can improve the mechanical and thermal properties of the composite materials effectively. The DMA analysis revealed that the storage moduli of nanocomposites were increased with increasing MWCNTs content. Among all, the nanocomposites containing 3wt% of M-M2070 and M-PEI were shown increased storage moduli 48.2% and 29.8%, respectively. TGA analysis showed that pyrolysis temperature of neat Nylon12 was 412.7 °C, and was increased about 43 °C by addition of M-M2070 and 36.7 °C by addition of M-PEI. Moreover, the surface resistance of neat Nylon12 was 1.68×1014 ohm/sq, and was decreased to 1.33×105 and 4.34×106 ohm/sq by addition of 3wt% M-M2070 and M-PEI, respectively. The resistance values of these nanocomposites have achieved the level of static dissipation, and can prevent the harm of static electricity.

Effect of microstructure uncertainty and testing frequency on storage and loss moduli of injection molded MWCNT reinforced polyamide 66 nanocomposites

The viscoelastic behavior of multiwall carbon nanotube (MWCNT) reinforced polyamide 66 (PA 66) was evaluated to investigate the effect of CNT content and loading frequency on dynamic moduli (i.e. storage modulus E′ and loss modulus E″) and damping factor tanδ. PA 66/CNT disk samples with five different CNT contents ranging from 3 wt % to 15 wt % were manufactured by injection molding. Testing was performed over the frequency range of 0.1–100 Hz at room temperature. Dynamic mechanical analysis results show that the mechanical properties are highly functions of tested frequency and the improvement on loss and storage modulus of nanocomposites with the addition of CNT is highly dependent on tested frequencies. The variability in loss modulus is significantly higher than the variability in the storage modulus indicating the correlation of loss modulus with uncertainties present in nanocomposite microstructure while storage modulus is essentially independent of microstructure for a given reinforcement content.

Modification of chitosan-Fe3O4 microspheres with isophorone diisocyanate and formation of polyurethane/mchitosan-Fe3O4 antimicrobial polymer

ABSTRACTPolyurethane/modified chitosan-Fe3O4 (PU/mCS-Fe3O4) nanocomposites were prepared by incorporating chitosan-Fe3O4 (CS-Fe3O4) into PU through chemical grafting using isophorone diisocyante (IPDI). The isocyanate group of IPDI was introduced on the surface of CS-Fe3O4 nanocomposites. The chemical functionalities of the CS-Fe3O4 and mCS-Fe3O4 were verified by Fourier-transform infrared and X-ray diffraction. The structure and properties were confirmed by scanning electron microscope, vibrating sample magnetometer, thermogravimetric analysis, atomic force microscope, and tensile testing. The experimental results indicate that thermal stability, tensile strength, and storage modulus of nanocomposites were improved with the increasing content of mCS-Fe3O4. Meanwhile, PU/mCS-Fe3O4 nanocomposites have less cytotoxicity and good antibacterial activities againstEscherichia coli and Staphylococcus aureus.

Influence of fullerene-like tungsten disulfide (IF-WS 2 ) nanoparticles on thermal and dynamic mechanical properties of PP/EVA blends: Correlation with microstructure

Abstract Compatibilized and non-compatibilized polypropylene/ethylene vinyl acetate copolymer (PP/EVA) blends loaded with 5 wt% of fullerene-like tungsten disulfide nanoparticles (IF-WS2) as an inorganic nano-filler were prepared by melt mixing process and their thermal and dynamic mechanical properties were determined. TEM investigations revealed that the IF-WS2 nanoparticles were mainly located within the EVA phase of the blend. Also, microstructure of blends studied by SEM showed that incorporation of IF-WS2 into the blends led to reduction of dispersed domain size attributed to reduction of interfacial tension due to the filler presence. Melting temperature of PP loaded with 5 wt% of IF-WS2 was increased up to 13 °C as compared to the neat PP. Addition of IF-WS2 and PP-g-MAH as compatibilizer to PP/EVA blend increased melting and crystallization temperatures determined by DSC. DMTA studies showed that addition of IF-WS2 into the blends had no positive effect on the storage modulus of nanocomposites while, their loss modulus were higher than that of the neat PP. Moreover, the β transition temperature of PP phase in the blends loaded with IF-WS2 and compatibilizer was about 6 °C higher than the neat PP. The thermo-oxidative and thermal degradation behavior of developed nanocomposites determined by thermal gravimetric analysis (TGA) showed that thermal stability of nanocomposites was improved and their rate of degradation was reduced which were attributed to network-like structure formation of nano-fillers in the blends.

The relationship between rheological behavior and microstructure of nanocomposite based on PA6/NBR/clay

Microstructure, rheological properties and their relationships of PA6/NBR/nano‐clay nanocomposite have been investigated. Scanning electron microscopy (SEM) and transmission electron microscopy imaging techniques were used to study micro‐structure. The nano‐clay dispersion was measured by small angle X‐ray diffraction. Frequency sweep, steady shear, startup shear transient, and startup shear free transient experiments were carried out to study rheological characteristics of nanocomposite. SEM micrograph revealed that nano‐clay decreased the size of rubber droplets to a half in comparison with samples without nano‐clay. Storage modulus of nanocomposite containing 7% wt nano‐clay exhibited frequency independent behavior because of physical network which formed in matrix, in contrast to pure PA6 which showed terminal storage modulus at low frequencies. Shear thinning at high shear rates was observed by addition of rubber to PA6 matrix caused by deformation of rubber droplets. Nano‐clay orientation in shear flow field accelerated non‐Newtonian behavior in steady shear experiment. Transient shear viscosity studies were used for measurement the strength of nano‐clay physical network. It was found that network breakdown is more stress consuming factor in comparison with nano‐particle orientation and hydrodynamic forces. Elongation transient viscosity studies showed that critical Hencky strain for linear–nonlinear viscoelastic transition shifted to higher strains by increasing nano‐clay concentration. POLYM. COMPOS., 39:2403–2410, 2018. © 2016 Society of Plastics Engineers

Thermal and dynamic mechanical properties of PP/EVA nanocomposites containing organo-modified layered double hydroxides

Abstract In this study, organo-modified layered double hydroxides (LDH) as nanoparticleswere used to prepare hybrid nanocomposites based on polypropylene (PP), ethylene vinyl acetate copolymer (EVA) blend in presence of a maleated polypropylene (PP-g-MA) as compatibilizer via a one-step melt mixing process. Transmission electron microscope (TEM) was employed to determine localization of LDH nanoparticles in the blend nanocomposites. Microstructures of the nanocomposites were studied by means of scanning electron microscopy (SEM). Thermo-mechanical properties of nanocomposites were investigated by dynamic mechanical thermal analysis (DMTA). Differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) were also used to investigate crystallization behavior and degradation process of the nanocomposites, respectively. The results showed that, LDH nanoparticles in the exfoliated and/or intercalated states were mainly localized in the EVA phase. The average particles size of EVA domains was reduced in presence of LDH and PP-g-MA. The storage modulus of nanocomposites was controlled by combination of LDH and PP-g-MA. The crystallization studies revealed that 5wt%LDH and PP-g-MA increased crystallization temperature to 133.4 °C while addition ofLDH in absence of the compatibilizer decreased the crystallization temperature to 122.7 °C.Investigation of thermal degradation behavior of samples indicated that presence of LDH and PP-g-MA in PP/EVA blendsimprovedinitial degradation temperature of nanocomposites by about 43% compared to the neat PP.

Preparation and characterization of novel modified halloysite-Fe3O4-Ag/polyurea nanocomposites with antibacterial property

ABSTRACTFirst, modified halloysite-Fe3O4 nanotubes (mHNT-Fe3O4) were synthesized. Second, mHNT-Fe3O4-Ag was synthesized by reduction process. Third, mHNT-Fe3O4-Ag was covalently incorporated into the polyurea (PUA) matrix and the mHNT-Fe3O4-Ag/PUA nanocomposites were prepared. The mHNT-Fe3O4-Ag was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, UV-vis absorption spectra, transmission electron microscopy, thermogravimetric analysis, and dynamic mechanical analysis. The experimental results shown that thermal stability, tensile strength, and storage modulus of nanocomposites were improved with the increasing of the content of mHNT-Fe3O4-Ag. Meanwhile, mHNT-Fe3O4-Ag/PUA nanocomposites had excellent magnetic properties and good antibacterial property.

Effect of halloysite nanotube on microstructure, rheological and mechanical properties of dynamically vulcanized PA6/NBR thermoplastic vulcanizates

ABSTRACTDynamically vulcanized thermoplastic vulcanizate (TPV) nanocomposites based on polyamide-6 (PA6) and acrylonitrile butadiene rubber (NBR) reinforced by halloysite nanotubes (HNT) were prepared via a direct melt mixing process. The effects of HNT on the physical, mechanical, and rheological properties of nanocomposites were investigated. The prepared PA6/NBR/HNT nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning colorimeter (DSC), dynamic mechanical thermal analysis (DMTA), and rheological measurements. The morphology study of prepared nanocomposites shows that the introduction of HNT into the PA6 phase causes a decrease in the size of NBR droplets. The mechanical measurements revealed that Young’s modulus of TPV nanocomposites increased with the HNT loading up to 54%. DMTA results show that the introduction of 10 wt% of HNT into the PA6/NBR TPV leads to a 30% increase in storage modulus. The rheological measurements revealed that the storage modulus of nanocomposites has an increase of more than 200% in the presence of 7 wt% of HNT loading. Analytical stiffness modeling of Young’s modulus of the TPV nanocomposites was investigated using Hui–Shia and Wu models. Both models have some deviations from experimental results and been modified to predict Young’s modulus of the nanocomposites containing HNT with more precisions. The viscosity behavior of TPV nanocomposites was studied using a Carruea–Yasuda model and showed that the yield stress of nanocomposites increases with higher HNT loadings, indicating the formation of a nanotube network along with NBR phase network.

Mechanical, thermo‐mechanical, thermal, and swelling properties of EPDM‐organically modified mesoporous silica nanocomposites

Ethylene‐propylene‐diene terpolymer nanocomposites has been developed using organically modified mesoporous silica nanoparticles by solution blending method. Hydrophilic mesoporous silica nanoparticles (MCM‐41) of ∼100 nm in sizes were synthesized via a template‐directed method, functionalized with trimethylchlorosilane (TMS) to produce hydrophobic silica (OS). The X‐ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analysis suggest that OS are homogeneously dispersed in the EPDM matrix and can maintain its pore structure effectively in the nanocomposites. The EPDM/OS nanocomposite exhibits a significant improvement in mechanical and thermal properties with respect to neat EPDM. A significant increase in tensile strength (TS) approximately 200% was observed at very low wt% of organosilica content in the nanocomposite. Dynamic mechanical analysis also exhibits the improvement in storage modulus for nanocomposites. Thermogravimetric analysis shows a thermal stability enhancement by approximately 25°C of EPDM nanocomposites containing 3 wt% OS when 25% weight loss was selected as point of comparison. The solvent uptakes in nanocomposites were comparable with the porous sites and free volume in EPDM matrix on OS incorporation. POLYM. COMPOS., 38:E371–E380, 2017. © 2015 Society of Plastics Engineers

Toughened polyester cellulose nanocomposites: Effects of cellulose nanocrystals and liquid epoxidized natural rubber on morphology and mechanical properties

Unsaturated polyester resin (UPR) has been modified with a liquid epoxidized natural rubber (LENR). The addition of LENR improves the toughness, but it is inevitably accompanied by a significant loss in stiffness, yield strength, and thermal resistance. Incorporation of a rigid material into the LENR–UPR blend, such as cellulose nanocrystal (CNC), provided a ternary polyester nanocomposites with desire mechanical properties. In the present work, the effects of different CNC and LENR content on the nanocomposite morphology and mechanical properties were examined. Morphological studies revealed that the size of the rubber particles is independent of the rubber content due to the chemical interaction of rubber and matrix; however, the size of the LENR particles increased with increasing CNC content. Tensile tests indicated that the blend’s tensile strength and elastic modulus could be further improved by incorporation of the CNCs. The high crystallinity and surface area of CNCs were the main factors for improvement of tensile properties of the blend. Moreover, the impact energy of the UPR improved when it was modified with the LENR, and even further improvement was achieved with the CNC addition to form nanocomposites. Dynamic mechanical thermal analysis (DMTA) showed that the storage modulus of nanocomposites with 1.5wt% rubber content was lower than those with 4.5wt% LENR; however, both samples showed a higher storage modulus than the neat UPR and the unfilled blend. The glass transition temperature (Tg) of the UPR decreased with the LENR addition, but improved with the addition of CNCs. The nanocomposites prepared with a higher LENR content displayed better mechanical properties than those with low LENR content.

UV-cured clay/based nanocomposite topcoats for wood furniture. Part II: Dynamic viscoelastic behavior and effect of relative humidity on the mechanical properties

Topcoat constituting multi-layer coatings for wood furniture used in high humidity environments, like bathrooms, must have not only good barrier properties, but also good mechanical properties. Three different types of commercial organoclays, namely Cloisite 10A (C10A), Cloisite 15A (C15A) and Cloisite 30B (C30B), were chosen in this study as reinforcing agents. These nanoparticles were dispersed (1 and 3wt% into the formulation) into a commercial epoxy acrylate oligomer by means of a three roll mill. Samples obtained from free standing UV-cured coatings were used for mechanical assessments. Mechanical tests were performed in both dynamic and static mode in order to investigate the viscoelastic behavior and tensile properties of coatings. Results from dynamic mechanical analysis have shown that all nanocomposite coatings have higher (72–75°C) glass transition temperature compared to that observed (71°C) in unreinforced coatings. The restriction of polymer chains mobility, due to the presence of layered silicate nanoparticles, has been used to explain the increase of glass transition temperature related to the decrease of the free volume. The storage modulus for nanocomposites containing 3wt% of C10A, C15A and C30B was found to be slightly higher than that observed in pure coatings. The analysis of tensile stress–strain curves has revealed that tensile properties are affected by relative humidity (RH) due to the plasticization effect of humidity. In fact, results have shown that regardless of the organoclay type, the increase of RH decreases both Young's modulus and tensile strength while increasing maximum strain. We believe that low interfaces between photocrosslinked polymer chains and organoclays explain the lack of any effect of organoclays on both storage and Young's moduli. Among samples from each type of UV-cured coating tested at 0, 20 and 80% of RH, regardless of the organoclay type and content, only samples tested (tensile tests in static mode) at RH=80% were broken. SEM images obtained from the fractured surface of these samples have shown that unreinforced UV-cured coatings and nanocomposite coatings are respectively characterized by smooth and rough fracture surface.

Preparation of poly(butylene terephthalate)/modified organoclay nanocomposite via in-situ polymerization

Nanocomposites of poly(butylene terephthalate) (PBT)/modified montmorillonite organoclay were prepared via in-situ polymerization of terephthalic acid and butanediol in the presence of different clay content. Cloisite 30B, a commercially available amino modified montmorillonite, was modified with 3-aminopropytriethoxysilane (APS) through a silylation reaction. Morphology and properties of all samples were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1HNMR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The extent of clay layers in samples was confirmed by XRD. Results of XRD and TEM showed that an exfoliation structure was produced in nanocomposites. Studies of crystallization showed that the presence of nanoclay leads to an increase in the crystallization rate and enhances the thermal stability of nanocomposites. Crystallization kinetics were described by the Avrami equation. Crystal growth was spherulitic. According to dynamic mechanical analysis (DMA), storage modulus of nanocomposites was remarkably improved compared with homo PBT. Moreover, a shrinkage test was carried out. Results showed a reduction in shrinkages along and across the flow direction that means a decrease in free volume. Flammability based on the UL-94 test was applied to study the flame retardancy effect of nanoclay on the samples.

Nanoindentation and dynamic mechanical properties of PP/clay nanocomposites

Polypropylene/clay nanocomposites were prepared by melt blending technique. A PP homopolymer was melt blended with commercial nanoclay masterbatch at different concentration (5, 10 and 15 wt% of nanoclay) using Laboratory Mixing Extruder (LME). The morphology of the nanocomposites was characterized using Scanning Electron Microscope (SEM). The viscoelastic and thermo-mechanical properties were analyzed via Dynamic Mechanical Analysis (DMA). The morphological analysis showed that the nanoclay was well distributed in the PP matrix. The DMA analysis showed an increase in storage modulus of nanocomposites which indicates an enhancement of stiffness and thermal stability of the prepared nanocomposite samples. In addition, a nanoindentation test was performed to determine the dynamic nanomechanical properties of two nanocomposites samples (NS-5 and NS-15). Load sweep test results showed that NS-15 has a slightly higher storage and loss modulus than that of NS-5. Both the samples also showed a decreasing modulus as a function of depth, indicating the presence of a stiffer surface layer in the samples. Frequency sweep tests were also performed on each sample, and display a moderate viscoelasticity with modulus values that increased slightly as a function of frequency. Load-controlled ramping force scratch test was also carried out and the results showed that NS-15 had a greater elastic recovery than sample NS-5 as well as a greater overall scratch resistance.

The Influence of Crysnanoclay Addition on Mechanical and Thermal Properties of Thermoplastic Polyurethane Elastomeric with Polycarbonate Nanocomposites

A series of crysnanoclay-loaded thermoplastic polyurethane (TPU) elastomer/polycarbonate (PC) nanocomposites have been prepared using twin screw extruders. The physicomechanical properties such as tensile behaviors, flexural properties and impact strength of the composites have been reported. Significant improvement in tensile modulus and flexural modulus were noticed for nanocomposites. The thermal characteristics of nanocomposites have been determined by thermogravimetric analysis (TGA) techniques. Thermal degradation kinetic parameters such as energy of activation (Ea) have been calculated from TGA thermograms for the nanocomposites using three mathematical models namely; Coats–Redfern, Horowitz – Metzger and Broido's methods and the results are compared. The effect of crysnanoclay on the storage modulus (E′), loss modulus (E″), and damping factor (tan δ) as a function of temperature have been measured by dynamic mechanical analysis (DMA). The storage moduli of nanocomposites have been increased after incorporating crysnanoclay in polymer matrix.

EFFECT OF COAGULATING SKIM NR PARTICLES AS NR–CLAY NANOCOMPOSITE: PROPERTIES AND STRUCTURE

Abstract New materials of skim NR–clay nanocomposites were prepared by a coagulating method using several organoclays, i.e., dodecyl ammonium–montmorillonite, Cloisite 15A, Cloisite 20A, and Cloisite 25A, which were modified by dodecyl ammonium chloride, dimethyl dehydrogenated tallow quaternary ammonium chloride, dimethyl dehydrogenated tallow quaternary ammonium chloride, and dimethyl hydrogenated tallow 2 ethylhexyl quaternary ammonium methyl sulfate, respectively. X-ray diffraction revealed that the intercalated nanocomposites were formed depending on the type and content of organoclays, and the excellent dispersion of clay in rubber matrix could be confirmed by transmission electron microscopy micrographs. In addition, thermal stability of the coagulated skim rubber–organoclay nanocomposites was improved as shown by the thermogravimetric analysis. The mechanical properties and dynamic-mechanical thermal analysis revealed that hardness and storage modulus of nanocomposites were improved and the glass transition temperature of nanocomposites increased as compared with that of the pure skim NR. Thus, not only recovery of this significant fraction of the lost rubber material but also reinforced skim rubber particles were obtained by the use of a coagulating method using several organoclays.

Characterization of bionanocomposites based on medium chain length polyhydroxyalkanoates synthesized by Pseudomonas oleovorans

Medium chain length polyhydroxyalkanoates ( mcl-PHA) have been produced by fed-batch cultivation of Pseudomonas oleovorans. Using octanoic acid as the sole carbon substrate, a copolymer of 3-hydroxyoctanoate and 3-hydroxyhexanoate monomer units was accumulated up to 38 wt. % of cell mass. Mcl-PHA based nanocomposites have then been prepared using Cloisite 15A as nanofiller and characterized. Wide angle X-ray diffraction and rheological analysis of the nanocomposites highlighted their morphologies, which can be considered as well-intercalated structures. The thermal characteristics of mcl-PHA are not significantly affected by the nanofiller incorporation. On the contrary, the storage moduli of nanocomposites are greatly enhanced with increasing clay fraction due to the degree of dispersion of the nanoplatelets in the polymer matrix.

Synthesis and characterization of linseed oil‐based nanocomposites

AbstractThe nanocomposites from conjugated linseed oil, acrylic acid, and divinylbenzene are synthesized using modified montmorillonite clay and characterized for thermal properties. The wide angle X‐ray diffraction results clearly show the distortion of the platy nanolayers of the nanofiller in the polymer matrix as the peak due to the clay disappears in the nanocomposite samples. The dynamic mechanical analysis results show the enhanced storage modulus and transition temperature compared with the pristine polymer. At the glass transition temperature, the storage modulus of nanocomposites is in the range of 17–79 MPa, whereas the pristine polymer shows a storage modulus of 2.1 MPa. The melting peak temperature ranges from 230 to 260°C, which is further confirmed by thermogravimetric analysis (TGA) results. The samples are stable up to 200°C and show a two‐stage degradation. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers