Preparation and characterization of polypropylene/solid‐state organomodified montmorillonite nanocomposites

A novel organomodified montmorillonite prepared by solid‐state method and its nanocomposites with polypropylene were studied. The interaction between modifying agent and montmorillonite was investigated by X‐ray diffraction (XRD) analysis, contact angle determination, and Fourier‐transform infrared spectroscopy. The results showed that the modifying agent behaves as an effective intercalating agent, enlarging the interlayer spacing of montmorillonite and making montmorillonite more hydrophobic. Polypropylene/solid‐state organomodified montmorillonite composites were prepared by melt‐mixing method. The dispersion of the silicates was investigated by XRD analysis and transmission electron microscopy. It was found that the nanocomposites are formed with solid‐state organomodified montmorillonite and polypropylene. The thermogravimetric analysis and differential scanning calorimetry results showed that the organoclay could enhance the thermal stability and decrease the relative crystallinity of polypropylene. Mechanical and rheological tests indicated that the organoclay improves the mechanical properties but has no obvious effect on rheological properties of polypropylene. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Effect of organoclay loading level on mechanical properties,thermomechanical behavior,and heat build‐up of natural rubber/organoclay nanocomposites

Sodium‐montmorillonite nanoclay was modified with octadecylamine and compounded with natural rubber (NR) by dry mixing method. The effects of organoclay loading level on mechanical properties, thermal–mechanical behavior, and heat build‐up of NR/organoclay nanocomposites were investigated. Temperature scanning stress relaxation technique was used to characterize the thermal–mechanical behavior of the composites. The morphological properties were assessed by X‐ray diffraction and transmission electron microscopy. Loading levels of organoclay below 5 phr gave improved mechanical properties and heat build‐up, along with exfoliated clay structure in the nanocomposites. On the other hand, with loading levels above 7 phr the organoclay tended to agglomerate, and X‐ray diffraction revealed an intercalated structure. In these cases, the excess residual organoclay caused significantly increased stress relaxation and heat build‐up. Unmodified sodium‐montmorillonite as filler did not significantly affect the mechanical and heat build‐up properties of NR vulcanizates. POLYM. COMPOS., 37:1735–1743, 2016. © 2014 Society of Plastics Engineers     

Structure and flammability properties of NR‐organoclay nanocomposites

The nanocomposites of natural rubber (NR) and organoclay modified by tributyl phosphate (TMMT) were prepared by the mixing intercalation method and the structure and the flammability properties of them were studied. The structure of the NR‐TMMT nanocomposites were characterized by X‐ray diffraction, transmission electron microscopy, fourier transform infrared spectroscopy and the results show that the d‐spacing of TMMT increase substantially with tributyl phosphate addition and the layers of TMMT disperse in rubber matrix on a nanometer scale. The flammability properties of them were demonstrated by cone calorimeter and indicate that the NR‐TMMT nanocomposites have significantly decreased in heat release rate, mass loss rate, and smoke produce rate. The NR‐TMMT nanocomposites appears very good the flame retardant properties. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Effect of organoclay on the gas barrier properties of natural rubber nanocomposites

Natural rubber nanocomposites have been prepared with organically modified montmorillonite clay. The nanocomposites have been characterized by X‐ray diffractometry and transmission electron microscopy. The gas‐barrier properties of the nanocomposites have been studied for three different gases viz., oxygen, nitrogen, and CO₂ gases. The natural rubber–organoclay composites exhibit outstanding gas‐barrier properties compared to the neat rubber. Various models have been applied to predict the decrease in permeability in nanocomposites. All other models except Bharadwaj model give low values of calculated aspect ratio. Dynamic mechanical analysis has been carried out to investigate the role of the constrained region on the permeability of the nanocomposites. The permeability decrease of the organoclay nanocomposites is found to have good qualitative correlation with the volume of the constrained region. POLYM. COMPOS.,, 2012. © 2012 Society of Plastics Engineers     

Preparation,structure, and properties of montmorillonite/cellulose II/natural rubber nanocomposites

In this work, sodium montmorillonite clay was added, as filler, to nanocomposites of natural rubber (NR) and cellulose II (regenerated cellulose) in amounts varying from 0 to 5 phr (per hundred resin). Natural rubber (NR)/cellulose II/montmorillonite nanocomposites were prepared by co‐coagulating NR latex, montmorillonite aqueous suspension and cellulose xanthate. The clay was previously exfoliated in water, and the resulting suspension was then added to the mixture of NR latex with cellulose xanthate. Morphological, rheometric, mechanical, and dynamic mechanical properties were evaluated, and an increase in these properties was observed upon the addition of cellulose and clay nanomaterials to the rubber matrix. The results show the advantage in using cellulose as a nanopolymer as well as MMT as nanofiller. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation,characterization, and application of NR/SBR/Organoclay nanocomposites in the tire industry

The natural rubber/styrene butadiene rubber/organoclay (NR/SBR/organoclay) nanocomposites were successfully prepared with different types of organoclay by direct compounding. The optimal type of organoclay was selected by the mechanical properties characterization of the NR/SBR/organoclay composites. The series of NR/SBR/organoclay (the optimal organoclay) nanocomposites were prepared with various organoclay contents loading from 1.0 to 7.0 parts per hundreds of rubber (phr). The nearly completely exfoliated organoclay nanocomposites with uniform dispersion were confirmed by transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The results of mechanical properties measurement showed that the tensile strength, tensile modulus, and tear strength were improved significantly when the organoclay content was less than 5.0 phr. The tensile strength and the tear strength of the nanocomposite with only 3.0 phr organoclay were improved by 92.8% and 63.4%, respectively. It showed organoclay has excellent reinforcement effect with low content. The reduction of the score and cure times of the composites indicated that the organoclay acted as accelerator in the process of vulcanization. The incorporation of a small amount of organoclay greatly improved the swelling behavior and thermal stability, which was attributed to the good barrier properties of the dispersed organoclay layers. The outstanding performance of co‐reinforcement system with organoclay in the tire formulation showed that the organoclay had a good application prospect in the tire industry, especially for the improvement of abrasion resistance and the reduction of production cost. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

机械共混法制备剥离型天然橡胶蒙脱土纳米复合材料及其微观结构与力学性能

采用常规的双辊混炼法制备出了剥离型的天然橡胶/蒙脱土纳米复合材料。利用透射电子显微镜观察复合材料的亚微观形态,测试了材料的物理性能,研究了材料的应力-应变变化曲线,表征了材料的加工流动性变化,测试结果表明制备出了剥离型纳米复合材料,低填充量(小于3份)时力学性能大大提高,应力-应变明显变化,加工流动性略有不同。     

Comparative study on the natural rubber nanocomposites reinforced with carbon black nanoparticles and graphite oxide nanosheets

To achieve dramatic improvements in the performance of natural rubber (NR), the graphite oxide nanosheets (GON)‐reinforced NR nanocomposites have been prepared through solution mixing on the basis of pretreatment of graphite. The mechanical and thermal properties of GON/NR nanocomposites were characterized in contrast to the carbon black (CB)/NR nanocomposite. The mechanical properties of the GON‐reinforced NR showed a considerable increase compared to the neat NR and traditional CB/NR nanocomposite. The initial modulus of pure NR was increased for up to 53.6% when 7 wt% GON is incorporated. The modulus and strength of NR with GON appear to be superior to those of CB with the same filler content. The dispersion state of the nanofillers into NR was investigated by scanning electron microscopy and X‐ray diffraction, and the results indicated that nanofillers have been dispersed homogeneously in the NR matrix. Fourier transform infrared spectra showed possible interfacial interactions between fillers and NR matrix. Differential scanning calorimetry and thermogravimetric analysis showed that the T _g and thermal decomposition temperature of NR slightly increased with the addition of the fillers, especially for that of GON/NR nanocomposites. According to this study, application of the physical and mechanical properties of GON to NR can result in rubber products which have improved mechanical, physical, and thermal properties, compared with existing NR products reinforced with CB. POLYM. COMPOS., 38:1427–1437, 2017. © 2015 Society of Plastics Engineers     

Preparation and characterization of thermoplastic polyurethane/organoclay nanocomposites by melt intercalation technique: Effect of nanoclay on morphology,mechanical, thermal,and rheological properties

Nanocomposites based on thermoplastic polyurethane (TPU) and organically modified montmorillonite (OMMT) were prepared by melt blending. Organically modified nanoclay was added to the TPU matrix in order to study the influence of the organoclay on nanophase morphology and materials properties. The interaction between TPU matrix and nanofiller was studied by infrared spectroscopy. Morphological characterization of the nanocomposites was carried out using X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy techniques. The results showed that melt mixing is an effective process for dispersing OMMT throughout the TPU matrix. Nanocomposites exhibit higher mechanical and thermal properties than pristine TPU. All these properties showed an increasing trend with the increase in OMMT content. Thermogravimetric analysis revealed that incorporation of organoclay enhances the thermal stability of nanocomposites significantly. Differential scanning calorimetry was used to measure the melting point and the glass transition temperature (T_g) of soft segments, which was found to shift toward higher temperature with the inclusion of organoclays. From dynamic mechanical thermal analysis, it is seen that addition of OMMT strongly influenced the storage and loss modulus of the TPU matrix. Dynamic viscoelastic properties of the nanocomposites were explored using rubber process analyzer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of organoclay on the morphology,mechanical, thermal,and rheological properties of organophilic montmorillonite nanoclay based thermoplastic polyurethane nanocomposites prepared by melt blending

Polymer nanocomposites based on the thermoplastic polyurethane (TPU) and organically modified montmorillonite (OMMT) was prepared by melt intercalation technique using a laboratory internal batch mixer followed by compression molding. Varying amount of organically modified nanoclays (1, 3, 5, 7, and 9 wt%) was added to the TPU matrix to examine the influence of organoclay on nanophase morphology and structure–property relationships. The interaction between TPU matrix and nanofiller was studied by infrared spectroscopy. The morphology of nanocomposites was studied by X‐ray diffraction, transmission electron microscopy, and atomic force microscopy that shows melt mixing by a batch mixer is an effective method for dispersing OMMT throughout the TPU matrix. Thermogravimetric analysis revealed that incorporation of organoclay enhances the thermal stability of the nanocomposites significantly. Differential scanning calorimetry was employed to measure the melting point and glass transition temperature (T_g) of soft segments. The reinforcing effect of the organoclay was determined by dynamic mechanical analysis and physico–mechanical testing. The effects of nanoclay concentration and processing parameters on the dynamic viscoelastic properties of the nanocomposites were studied by a rubber process analyzer using frequency sweep. A significant increase in the viscosity and storage modulus of the nanocomposites was found with the increasing clay content. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

乳液插层法天然橡胶/蒙脱土纳米复合材料的制备及其性能

采用乳液插层法制备了天然橡胶/蒙脱土（NR/MMT）纳米复合材料,采用透射电子显微镜（TEM）研究了复合材料的亚微观形态,并对复合材料的力学性能和耐磨耗性能进行了研究。TEM结果显示,MMT片层以纳米尺寸均匀分散在NR基体中;力学性能测试结果表明,当MMT用量小于12份时,纳米复合材料的力学性能随MMT用量的增加而逐渐增大,NR/MMT纳米复合材料具有优良的力学性能;蒙脱土的加入稍微降低纳米复合材料的耐磨性。     

Thermal stability,aging properties,and flame resistance of NR‐based nanocomposite

Polymer/clay nanocomposites have some unique properties due to combination of flame resistance and improved mechanical and thermal stability properties which are important to enhance the material quality and performance. The objective of this work was to investigate the effect of organically modified montmorillonite (org‐MMT) on the thermal and flame retardant as well as hardness and mechanical properties of the nanocomposites based on the natural rubber (NR). It was shown that by the addition of 3 wt % of org‐MMT to NR, its aging hardness rise was decreased more than 55% and the ignition time was delayed about 150%. The reduction in heat release rate peak value was equal to 54% compared to the pristine NR. Addition of org‐MMT improved the thermal stability of the NR. Furthermore, nanocomposites which were calendared before curing showed much more thermal stability and fire resistance than those which contained similar amount of organoclay. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of ionic liquid on the polymer–filler coupling and mechanical properties of nano‐silica filled elastomer

The natural rubber (NR) nanocomposites were fabricated by filling ionic liquid (1‐allyl‐3‐methyl‐imidazolium chloride, AMI) modified nano‐silica (nSiO₂) in NR matrix through mechanical mixing and followed by a cure process. Based on the measurements of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), solid state nuclear magnetic resonance spectroscopy, and Raman spectroscopy, it was proved that AMI could interact with nSiO₂ through hydrogen bonds. With the increase of AMI content, the curing rate of nSiO₂/NR increased. The results of bound rubber and dynamic mechanical properties showed that polymer–filler interaction increased with the modification of nSiO₂. Morphology studies revealed that modification of nSiO₂ resulted in a homogenous dispersion of nSiO₂ in NR matrix. AMI modified nSiO₂ could greatly enhance the tensile strength and tear strength of nSiO₂/NR nanocomposites. Compared to unmodified nSiO₂/NR nanocomposite, the tensile strength of AMI modified nSiO₂/NR nanocomposite increased by 102%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44478.     

Natural rubber/poly(ethylene‐co‐vinyl acetate)‐blend‐based nanocomposites

Natural rubber (NR)/poly(ethylene‐co‐vinyl acetate) (EVA) blend–clay nanocomposites were prepared and characterized. The blend nanocomposites were prepared through the melt mixing of NR/EVA in a ratio of 40/60 with various amounts of organoclay with an internal mixer followed by compression molding. X‐ray diffraction patterns revealed that the nanocomposites formed were intercalated. The formation of the intercalated nanocomposites was also indicated by transmission electron microscopy. Scanning electron microscopy, used to study the fractured surface morphology, showed that the distribution of the organoclay in the polymer matrix was homogeneous. The tensile modulus of the nanocomposites increased with an increase in the organoclay content. However, an increase in the organoclay content up to 5 phr did not affect the tensile strength, but the organoclay reduced this property when it was increased further. This study also indicated that a low silicate content dispersed in the blend matrix was capable of increasing the storage modulus of the material. The addition of the organoclay also increased the decomposition temperature of the NR/EVA blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 353–362, 2006     

Comparative study of nanocomposites of polyolefin compatibilizers containing kaolinite and montmorillonite organoclays

This work studied the morphology and physical properties of nanocomposites of different ethylene copolymers and functionalized polyethylenes with two different types of organoclays, to assess the potential application of these fillers as reinforcing components in the design of polyethylene and other polyolefinic based nanocomposites with enhanced properties. A polyethylene‐grafted‐maleic anhydride (PEMA), a poly(ethylene‐co‐acrylic acid), a poly(ethylene‐co‐vinyl acetate), and an ionomer of poly(ethylene‐co‐methacrylic acid) containing a small fraction of polyamide 6 were used to prepare nanocomposites by melt compounding in internal mixer. Two different types of commercial clays were used to obtain nanocomposites with the same organoclay content (5 wt %), i.e., an organomodified montmorillonite and an organomodified kaolinite. The morphology was evaluated by wide angle X‐ray scattering, scanning electron microscopy, transmission electron microscopy, and optical microscopy. The thermal, mechanical and barrier properties were evaluated by differential scanning calorimetry and thermogravimetric analysis, tensile tests and oxygen transmission rate experiments, respectively. From the results, it was seen that PEMA and the ionomer are the best polymer matrices to disperse both organoclays under the conditions applied. Kaolinite and montmorillonite appeared to be dispersed in the nanorange, however, higher aspect ratio was observed for montmorillonite. The best improvements in thermal degradation and in mechanical reinforcement were shown for organomodified kaolinite nanocomposites. But the best improvements in thermo‐oxidative degradation and in oxygen barrier were seen for the nanocomposites with organomodified montmorillonite. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of organoclay reinforcement on the curing characteristics and technological properties of SBR sulphur vulcanizates

Styrene‐butadiene rubber (SBR) nanocomposites with different organoclay contents (up to 15 phr) were prepared by a melt compounding procedure, followed by a compression‐molding step in which the SBR matrix was sulfur crosslinked. The vulcanizates were characterized in respect to their curing, mechanical and viscoelastic properties, and thermal stability. The optimum cure time decreased with increasing organoclay content. This effect was attributed to the ammonium modifier present in the organoclay, which takes part in the curing reaction acting like an accelerator. The results of mechanical test on the vulcanizates showed that the nanocomposites presented better mechanical properties than unfilled SBR vulcanizate, indicating the nanoreinforcement effect of clay on the mechanical properties of SBR/organoclay nanocomposites. The addition of organoclay did not significantly change the glass transition temperature. However, the heights of tan δ value at the glass transition temperature for the nanocomposites are lower than that of the unfilled SBR. This suggests a strong interaction between the organoclay and the SBR matrix as the molecular relaxation of the latter is hampered. The temperature at which 50% degradation occurs (T₅₀) and the temperature when the degradation rate is maximum (DTG_max) showed an improvement in thermal stability, probably related to the uniform dispersion of organoclay. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of surface modification of silicon carbide nanoparticles on the properties of nanocomposites based on epoxidized natural rubber/natural rubber blends

Improvement of the properties of rubber nanocomposites is a challenge for the rubber industry because of the need for higher performance materials. Addition of a nanometer‐sized filler such as silicon carbide (SiC) to enhance the mechanical properties of rubber nanocomposites has rarely been attempted. The main problem associated with using SiC nanoparticles as a reinforcing natural rubber (NR) filler compound is poor dispersion of SiC in the NR matrix because of their incompatibility. To solve this problem, rubber nanocomposites were prepared with SiC that had undergone surface modification with azobisisobutyronitrile (AIBN) and used as a filler in blends of epoxidized natural rubber (ENR) and natural rubber. The effect of surface modification and ENR content on the curing characteristics, dynamic mechanical properties, morphology and heat buildup of the blends were investigated. The results showed that modification of SiC with AIBN resulted in successful bonding to the surface of SiC. It was found that modified SiC nanoparticles were well dispersed in the ENR/NR matrix, leading to good filler‐rubber interaction and improved compatibility between the rubber and filler in comparison with unmodified SiC. The mechanical properties and heat buildup when modified SiC was used as filled in ENR/NR blends were improved. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45289.     

Exfoliation targeted toughness enhancement in polypropylene‐blend‐ montmorillonite nanocomposites

BACKGROUND: Both exfoliated and toughened polypropylene‐blend‐montmorillonite (PP/MMT) nanocomposites were prepared by melt extrusion in a twin‐screw extruder. Special attention was paid to the enhancement of clay exfoliation and toughness properties of PP by the introduction of a rubber in the form of compatibilizer toughener: ethylene propylene diene‐based rubber grafted with maleic anhydride (EPDM‐g‐MA). RESULTS: The resultant nanocomposites were characterized using X‐ray diffraction, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis, dynamic mechanical analysis and Izod impact testing methods. It was found that the desired exfoliated nanocomposite structure could be achieved for all compatibilizer to organoclay ratios as well as clay loadings. Moreover, a mechanism involving a decreased size of rubber domains surrounded with nanolayers as well as exfoliation of the nanolayers in the PP matrix was found to be responsible for a dramatic increase in impact resistance of the nanocomposites. CONCLUSION: Improved thermal and dynamic mechanical properties of the resultant nanocomposites promise to open the way for highly toughened super PPs via nanocomposite assemblies even with very low degrees of loading. Copyright © 2008 Society of Chemical Industry     

Preparation and characterization of poly(styrene‐co‐butadiene) and polybutadiene rubber/clay nanocomposites

Poly(styrene‐co‐butadiene) rubber (SBR) and polybutadiene rubber (BR)/clay nanocomposites have been prepared. The effects of the incorporation of inorganically and organically modified clays on the vulcanization reactions of SBR and BR were analysed by rheometry and differential scanning calorimetry. A reduction in scorch time (t_s1) and optimum time (t₉₅) was observed for both the rubbers when organoclay was added and this was attributed to the amine groups of the organic modifier. However, t_s1 and t₉₅ were further increased as the clay content was increased. A reduction in torque value was obtained for the organoclay nanocomposites, indicating a lower number of crosslinks formed. The organoclays favoured the vulcanization process although the vulcanizing effect was reduced with increasing clay content. The tensile strength and elongation of SBR were improved significantly with organoclay. The improvement of the tensile properties of BR with organoclay was less noticeable than inorganic‐modified clay. Nevertheless, these mechanical properties were enhanced with addition of clay. The mechanical properties of the nanocomposites were dependent on filler size and dispersion, and also compatibility between fillers and the rubber matrix. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of cationic gemini surfactant modified Na–bentonite and its applications for rubber nanocomposites

A cationic gemini surfactant (N‐isopropyl‐N , N‐dimethyldodecan 1‐aminium bromide) was synthesized by quaternization reaction. The synthesized surfactant was characterized by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. Modified Na–bentonite (organoclay) was obtained by the intercalation of a gemini surfactant between the layers of sodium bentonite and characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), FTIR, thermogravimetry–differential thermal analysis (TGA–DTA) and differential scanning calorimetry (DSC) techniques. The results of XRD, TEM, FTIR, TGA, and corresponding DSC analysis indicate that gemini surfactant has been successfully intercalated into the clay layers. Rubber‐based nanocomposites have been prepared by incorporating various concentration of organically modified bentonite on to natural rubber/styrene–butadiene rubber (NR/SBR) rubber blend (75/25) using two roll mill. Effect of organoclay content on XRD, curing, mechanical, and scanning electron microscopy (SEM) properties of the nanocomposites are investigated. The morphological study showed the intercalation of nanoclay in NR/SBR blend chain. It was found that the organoclay decrease the optimum and scorch time of the curing reaction, increase maximum torque and the curing rate, which was attributed to the further intercalation during vulcanization process. Mechanical properties such as tensile strength, modulus and elongation at break have improved. POLYM. COMPOS., 38:396–403, 2017. © 2015 Society of Plastics Engineers