Compatibilizer effect on Organosilicate reinforced NBR nanocomposites

Nanocomposites of intercalated and exfoliated organosilicates in acrylonitrile butadiene rubber (NBR) were prepared by a two-stage melt blending method. The dispersion and interlayer space of organosilicates in these nanocomposites were examined by X-ray diffraction, transmission electron microscopy and field emission scanning electron microscopy. Dramatic enhancements in the mechanical and thermal properties of NBR were found by incorporating less than ten parts of organosilicates. In particular, the addition of 10 phr of the organosilicate in NBR provided more than a 360% increase in tensile strength, a two-fold increase in M500, a 93% increase in tear strength and a relative enhancement in elongation at break, as compared to the neat NBR. The degradation temperature for NBR with ten parts loading of organosilicate was 25 °C higher than that of the neat NBR. In addition, the relative vapor permeability of nanocomposites containing 15 phr of layered silicates was reduced, as compared to the neat NBR.     

Synergistic effect of compatibilizer in organo‐modified layered silicate reinforced butadiene rubber nanocomposites

We have prepared nanocomposites of intercalated and exfoliated organosilicates in butadiene rubber (BR) by using a two‐stage melt blending process. We used X‐ray diffraction and transmission electron microscopy to examine, respectively, the intergallery spacing of the organosilicates and their dispersion in the BR. Marked enhancements in the mechanical and thermal properties of BR occurred when it incorporated <10 parts of organosilicates and the loading ratio of the organosilicate to dicarboxylic acid‐terminated butadiene oligomer was approximately three. In particular, the addition of 10 parts of organosilicate and 3 parts of compatibilizer in the BR led to a more than four‐fold increase in the tensile strength, a 150% increase in modulus at 100% elongation (M100), and 232 and 410% enhancements in the tear strength and elongation at break, respectively, relative to those of neat BR. The degradation temperature for the BR nanocomposite containing only a 10‐part loading of organosilicate was 51°C higher than that of neat BR; these increases reduced, however, to 9–13°C upon the addition of the CTB compatibilizer. In addition, the relative water vapor permeabilities of the BR nanocomposites containing 10 parts of organosilicate—both in the presence and absence of the compatibilizer—reduced to 20% of that of the neat BR. POLYM. ENG. SCI. 46:80–88, 2006. © 2005 Society of Plastics Engineers     

High‐performance nanocomposites based on arcylonitrile‐butadiene rubber with fillers of different particle size: Mechanical and morphological studies

Acrylonitrile‐butadiene rubber (NBR) nanocomposites with layered silicate (LS), calcium phosphate (CP), and titanium dioxide (TO) of different particle size were prepared in an open two‐roll mixing mill at different filler loading in presence of sulphur as vulcanizing agent. The layered silicate (LS) filled system showed outstanding enhancement in mechanical properties in comparison with nanocalcium phosphate (CP) and titanium dioxide (TO). The variations in properties can be attributed to the extent of intercalation/exfoliation, which was highly influenced by the filler size. The layered silicate filled system at 20 phr showed nearly 349% increase in tensile strength compared to pure NBR whereas an increase of 110% and 84% were shown by CP and TO filled systems respectively. The modulus enhancements were in the order of 200%, 63% and 22%, respectively compared to the unfilled system. The increase in tear resistance was in the order of 230%, 115%, and 41% respectively for the filled systems in comparison with unfilled NBR. The significant enhancements in mechanical properties were supported by the morphological analysis. POLYM. COMPOS., 31:1515–1524, 2010. © 2009 Society of Plastics Engineers     

Evaluation of mechanical,thermal, electrical,and transport properties of MWCNT‐filled NR/NBR blend composites

Carbon nanotube based polymer nanocomposites found versatile applications and hence studying its reinforcing effect on NR/NBR blend system is a promising step in developing flexible elastomer gadgets. In this study, attempts have been made to prepare multi‐walled carbon nanotube (MWCNT)‐filled nanocomposites of NR/NBR blends. Raman spectra and transmission electron microscopic analysis indicate that there has been a finer and uniform dispersion of carbon nanotubes within the polymer matrix. Mechanical properties like tensile strength, tear resistance, abrasion loss and compression set of pure and blend samples showed an improvement with the increase in the dosage of MWCNT from 0.5 to 4 phr. 70/30 NR/NBR blend with 4 phr of MWCNT showed an improvement of 83% in tensile strength and 72% in tear strength compared to pure NBR. This is attributed to the uniform dispersion, high surface area, nano level interaction, and compatibility of MWCNT with the polymeric molecular chains. MWCNT is acting as a compatibilizing agent as is manifest from the increased negative values of free energy. Electrical conduction and thermal stability of the mixes were increased with the concentration of MWCNT due to the increase in the interfacial interaction resulting from the pi‐pi interaction with the nanotubes. POLYM. ENG. SCI., 58:961–972, 2018. © 2017 Society of Plastics Engineers     

Structure and properties of nitrile rubber (NBR)–clay nanocomposites by co‐coagulating NBR latex and clay aqueous suspension

Nitrile rubber (NBR)–clay nanocomposites were prepared by co‐coagulating the NBR latex and clay aqueous suspension. Transmission electron microscopy showed that the silicate layers of clay were dispersed in the NBR matrix at the nano level and had a planar orientation. X‐ray diffraction indicated that there were some nonexfoliated silicate layers in the NBR–clay nanocomposites. Stress–strain curves showed that the silicate layers generated evident reinforcement, modulus, and tensile strength of the NBR–clay nanocomposites, which were significantly improved with an increase in the amount of clay, and strain‐at‐break was higher than that of the gum NBR vulcanizate when the amount of clay was more than 5 phr. The NBR–clay nanocomposites exhibited an excellent gas barrier property; the reduction in gas permeability in the NBR–clay nanocomposites can be described by Nielsen's model. Compared with gum NBR vulcanizate, the oxygen index of the NBR–clay nanocomposites increased slightly. The feasibility of controlling rubber flammability via the nanocomposite approach needs to be evaluated further. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3855–3858, 2003     

Structure‐property relationships in copolyester elastomer‐layered silicate nanocomposites

While the field of polymer–clay nanocomposites is reaching maturity, some parts of the studied systems still present researchers with possibilities for the improvement of material properties. This study entails the understanding of the relationships in copolyester elastomer/organically modified layered silicate nanocomposite and the structure–property relationships within the system of the nanocomposite. A series of these nanocomposites was prepared via twin‐screw extrusion melt compounding. The experiments included the following three types of synthetic organosilicates: high aspect ratio Somasif (ME100) fluoromica and two lower aspect ratio Laponite synthetic hectorites, (WXFN) and (WXFP). These organosilicates were modified with quaternary octadecyltrimethylammonium bromide (ODTMA) and were used to prepare the nanocomposites. The nanocomposite structure on a micro‐ and nanometre scales was evaluated by two techniques, such as X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The mechanical properties of the nanocomposites were examined to determine the impact aspect ratio of the nanofiller and wt % loading have on performance. The addition of the 2 wt % high aspect ratio of ME100‐ODTMA, in particular, showed statistically improved tensile strength, tear resistance, creep resistance, and water vapor permeation barrier enhancement. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41742.     

Preparation,morphology, and properties of organo‐montmorillonite/nitrile butadiene rubber nanocomposites

Organo‐montmorillonite/nitrile butadiene rubber (OMMT/NBR) nanocomposites were prepared by co‐coagulating process, and then were combined with rubber ingredient and vulcanized by traditional rubber mixing procedure. The SEM micrographs of the nanocomposites showed uniform dispersion of the OMMT particles in NBR. The ATR‐FTIR spectra illustrated the existence of montmorillonite in the nanocomposites. The XRD patterns further indicated the structure of nanocomposites, and confirmed an effective intercalation of NBR in the interlayer space of the OMMT. Moreover, the tensile strength and elongation at break of nanocomposites tended to increased rapidly with increasing OMMT loading, due to the reinforcing properties of OMMT to NBR. In addition, the TGA and DTA curves demonstrated the thermal performance of the nanocomposites enhanced. Furthermore, the addition of OMMT accelerated the vulcanization process. POLYM. COMPOS., 34:1809–1815, 2013. © 2013 Society of Plastics Engineers     

Preparation and properties of acrylonitrile–butadiene copolymer hybrid nanocomposites with organoclays

Acrylonitrile–butadiene rubber (NBR) hybrid nanocomposites with organoclays were prepared by melt mixing, and their properties were compared with those of conventional rubber compounds filled with carbon black and silica. Based on X‐ray diffraction and transmission electron microscopy, the NBR nanocomposites obtained were found to form generally an intercalated structure, although they formed an exfoliated structure when the organoclay content was low enough, <2 parts per 100 rubber. The NBR nanocomposite showed a simultaneous improvement in ultimate strength and stiffness, which is generally in a trade‐off relation in rubbery materials. A characteristic fracture morphology of ‘laminated board‐type’ was observed for NBR nanocomposites instead of typical ‘cross‐hatched’ morphology in conventional rubber composites. The NBR nanocomposites also showed much higher hysteresis and tension set. Copyright © 2003 Society of Chemical Industry     

Preparation and characteristics of nitrile rubber (NBR) nanocomposites based on organophilic layered clay

The effect of clay modification on organo‐montmorillonite/NBR nanocomposites has been studied. Organo‐montmorillonite/NBR nanocomposites were prepared through a melt intercalation process. NBR nanocomposites were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), dynamic mechanical thermal analysis (DMTA) and a universal testing machine (UTM). XRD showed that the basal spacing in the clay increased, which means that the NBR matrix was intercalated in the clay layer galleries. On TEM images, organo‐montmorillonite (MMT) particles were clearly observed, having been exfoliated into nanoscale layers of about 10–20 nm thickness from their original 40 µm particle size. These layers were uniformly dispersed in the NBR matrix. The DMTA test showed that for these nanocomposites the plateau modulus and glass transition temperature (T_g) increased with respect to the corresponding values of pure NBR (without clay). UTM test showed that the nanocomposites had superior mechanical properties, ie strength and modulus. These improved properties are due to the nanoscale effects and strong interactions between the NBR matrix and the clay interface. Copyright © 2003 Society of Chemical Industry     

Enhanced mechanical properties of nanocomposites at low graphene content based on in situ ball milling

In this study, epoxy‐based nanocomposites with low content mechanically exfoliated graphene were successfully prepared via one‐step in situ ball milling method. The effect of graphene on mechanical properties of the nanocomposites was investigated. The results showed that samples with loadings less than 0.1% weight of mechanically exfoliated graphene increased by 160% in tensile strength and 65% in Young's modulus. The experimental value of Young's modulus was also compared with the predictions of the well‐established Halpin‐Tsai model. In addition, the adding of graphene did not decrease the impact strength of epoxy. The microstructural results showed that the as‐prepared graphenes were single‐ and few‐layer graphene sheets and preserved perfect structure. Thus enhancements of mechanical properties in the nanocomposites could be ascribed to the strong interfacial interaction between the stiff graphene nanosheets and the epoxy matrix. POLYM. COMPOS. 37:1190–1197, 2016. © 2014 Society of Plastics Engineers     

Morphology and properties of PVC/clay nanocomposites via in situ emulsion polymerization

PVC/Na⁺–montmorillonite (MMT) nanocomposites were prepared via a simple technique of emulsion polymerization at several different MMT clay concentrations. X‐ray diffraction and transmission electron microscopy studies revealed the formation of a mixture of intercalated and exfoliated nanostructure. Tensile testing results showed that the tensile modulus of the nanocomposites increased with the addition of clay, while the tensile strength decreased little. The notched impact strength of the nanocomposites was also improved. For systems containing clay in the range of 2.1 to 3.5 wt %, the impact strength was almost two times as large as that of pure PVC. However, those mechanical properties began to decrease with the continuously increasing amount of clay. The fracture surface of pure PVC and the nanocomposites was observed by scanning electron microscope. Thermal properties of the nanocomposites were found to increase as a result of clay incorporation. The glass transition temperatures of the PVC/clay nanocomposites were nearly identical to that of pure PVC. The Vicat softening points exhibited a progressively increasing trend with the clay content added. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 277–286, 2004     

The influence of zinc ferrites nanoparticles on the thermal,mechanical, and magnetic properties of rubber nanocomposites

The interest to ferrite nanoparticles (NPs) is thriving because of their unique applications in life industry. Doping of rubber composites by nanoparticles results in a novel characteristics which is not exist either in the ferrite or rubber alone. In this study, zinc ferrite NPs have been synthesized via sol–gel technique. These nanoferrites embedded into acrylonitrile butadiene rubber (NBR) at different concentrations. The morphology and structure of zinc ferrite and zinc ferrite NPs doped NBR were investigated using X‐ray diffraction and transmission electron microscopy. The influence of zinc ferrite NPs loading on the thermal stability showed that the zinc ferrite enhanced the thermal stability and reduced the rate of thermal degradation of rubber nanocomposites. The effect of zinc ferrite NPs on the mechanical properties of NBR showed that the hardness, tear strength, and tensile stress are improved. The magnetic measurements of these nanocomposites showed that the saturation magnetization is enhanced as the concentration of zinc ferrite NPs increased into NBR nanocomposites. The EPR spectra of zinc ferrite NPs doped NBR indicated that the increase in zinc ferrite NPs content resulted in an increase in the g‐factor and line width. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Preparation,structure and properties of nitrile–butadiene rubber–organoclay nanocomposites by reactive mixing intercalation method

The nanocomposites of nitrile–butadiene rubber (NBR) and organo‐montmorillonite modified by hexadecyltrimethyl ammonium bromide (HMMT) were prepared by the reactive mixing intercalation method in the presence of the resorcinol and hexamethylenetetramine complex (RH). The structure of the NBR–RH–HMMT nanocomposites was characterized by XRD, TEM, FTIR, determination of crosslinking density, and so on. The results showed that the d‐spacing of HMMT increased substantially with RH addition and the layers of HMMT were dispersed in rubber matrix on a nanometer scale. The mechanical properties of the NBR–RH–HMMT nanocomposites were far superior to those of NBR–HMMT composites, and the glass transition temperature of NBR–RH–HMMT nanocomposite was higher than that of NBR. The reactive mixing intercalation method by introducing RH could enhance the interface combination between the rubber and the organoclay through the interactions of RH with NBR and modified clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1905–1913, 2006     

Thermoplastic polyurethane and nitrile butadiene rubber blends with layered double hydroxide nanocomposites by solution blending

Polymer blending coupled with nanofillers has been widely accepted as one of the cheaper methods to develop high‐performance polymeric materials for various applications. In the present work, dodecyl sulfate intercalated Mg? Al‐based layered double hydroxide (DS‐LDH) was used as nanofiller in the synthesis of polyurethane blended with nitrile butadiene rubber (PU/NBR; 1:1 w/w) nanocomposites, which were subsequently characterized. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the partial dispersion of Mg? Al layers in PU/NBR blends at lower filler content followed by aggregation at higher filler loading. In comparison to the neat PU/NBR blend, the tensile strength (156%) and elongation at break (21%) show maximum improvement for 1 wt% filler loading. The storage and loss moduli, thermal stability and limiting oxygen index of the nanocomposites are higher compared to the neat PU/NBR blend. Glass transition temperature and swelling measurements increase up to 3 wt% DS‐LDH loading in PU/NBR compared to either neat PU/NBR or its other corresponding nanocomposites. XRD and TEM analyses indicate the partial distribution of DS‐LDH in PU/NBR blends suggesting the formation of partially exfoliated nanocomposites. The improvements in mechanical, thermal and flame retardancy properties are much greater compared to the neat blend confirming the formation of high‐performance polymer nanocomposites. Copyright © 2009 Society of Chemical Industry     

Curing and barrier properties of NBR/organo-clay nanocomposite

Organo-montmorillonite/NBR nanocomposites were prepared by a melt intercalation process. The characteristics of NBR nanocomposites were characterized by oscillating-disk rheometer, water-vapour transmission and transmission electron microscopy (TEM). Changes in cure characteristics resulting from changes in clay content and the addition of silane coupling agent were investigated. The study confirmed that organo-montmorillonite/NBR nanocomposites cure characteristics, viz minimum torque, maximum torque, scorch time and curing time, change according to the change in clay content and the addition of silane coupling agent. Of the water-vapour transport properties, the clay content and silane content are the dominating factors in determining the individual water-vapour permeability of these NBR nanocomposites. TEM analysis provided clear evidence for the homogeneous dispersion of clay in the NBR matrix without regard to increases in clay content. Copyright © 2004 Society of Chemical Industry     

Fabrication,Characterization and Dielectric Studies of NBR/Hydroxyapatite Nanocomposites

Nitrile rubber (NBR) based nanocomposite consists of different concentrations of hydroxyapatite nanoparticles (HA) were prepared and characterized by FTIR, UV and X-ray diffraction studies. The surface morphology of the nanocomposites were analyzed using SEM and optical microscopy. The glass transition temperature and thermal stability of NBR and its nanocomposites were done by DSC and TGA respectively. The electrical properties such as AC conductivity, dielectric constant and dielectric loss tangent were investigated in the frequency range of 10²–10⁶ Hz at room temperature. The FTIR spectra confirmed the interfacial interaction between NBR and the HA nanoparticles. The shift in the UV peak with broadness of composite indicates the formation of nanoparticles within the macromolecular chain of NBR. XRD pattern ascertained the ordered arrangement of nanoparticles with a decrease in the amorphous nature of parent polymer. Both the glass transition temperature and the thermal stability of the nanocomposites were higher than pure NBR and the glass transition temperature improved with the increase in concentration of nanoparticles in NBR composite indicating the strong interfacial adhesion between the polymer and nanoparticles. From DSC studies, thermodynamic parameters such as enthalpy and entropy change of the composites were also evaluated. AC conductivity of the nanocomposite was much greater than NBR and the magnitude of conductivity enhanced with the addition of nanoparticles. The observed enhancement in dielectric constant and dielectric loss tangent of composite with the increase in concentration of nanoparticle was attributed to the increase in number of interfacial interaction between the polymer and the nanoparticles.     

Morphology and properties of thermoplastic polyurethane nanocomposites incorporating hydrophilic layered silicates

Hydrophilic layered silicate/polyurethane nanocomposites were prepared via twin screw extrusion and solvent casting. Good dispersion and delamination was achieved regardless of processing route, illustrating that the need for optimised processing conditions diminishes when there is a strong driving force for intercalation between the polymer and organosilicate. Evidence for altered polyurethane microphase morphology in the nanocomposites was provided by DMTA and DSC. WAXD results suggested that the appearance of an additional high temperature melting endotherm in some melt-compounded nanocomposites was not due to the formation of a second crystal polymorph, but rather due to more well-ordered hard microdomains. Solvent casting was found to be the preferred processing route due to the avoidance of polyurethane and surfactant degradation associated with melt processing. While tensile strength and elongation were not improved on organosilicate addition, large increases in stiffness were observed. At a 7 wt% organosilicate loading, a 3.2-fold increase in Young's modulus was achieved by solvent casting. The nanocomposites also displayed higher hysteresis and permanent set.     

Mechanical,thermal, and transport properties of nitrile rubber–nanocalcium carbonate composites

The article describes the properties of acrylonitrile butadiene copolymer (NBR)–nanocalcium carbonate (NCC) nanocomposites prepared by a two‐step method. The amount of NCC was varied from 2 phr to 10 phr. Cure characteristics, mechanical properties, dynamic mechanical properties, thermal behavior, and transport properties of NBR–NCC composites were evaluated. For preparing NBR nanocomposites, a master batch of NBR and NCC was initially made using internal mixer. Neat NBR and the NBR–NCC masterbatch was compounded with other compounding ingredients on a two roll mill. NCC activated cure reaction upto 5 phr. The tensile strength increased with the nanofiller content, whereas NBR–NCC containing 7.5 phr exhibited the highest modulus. The storage modulus (E′) increased up to 5 phr NCC loading; the reinforcing effect of NCC was seen in the increase of modulus which was more significant at temperatures above T_g. The effect of nanofiller content and temperature on transport properties was evaluated. The solvent uptake decreased with NCC content. The mechanism of diffusion of solvent through the nanocomposites was found to be Fickian. Transport parameters like diffusion, sorption, and permeation constants were determined and found to decrease with nanofiller content, the minimum value being at 7.5 phr. Thermodynamic constants such as enthalpy and activation energy were also evaluated. The dependence of various properties on NCC was supported by morphological analysis using transmission electron microscopy. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

水滑石/丁腈橡胶纳米复合材料的制备及性能研究

采用乳液复合法制备水滑石(LDHs)/丁腈橡胶(NBR)纳米复合材料,并对其结构和性能进行研究。结果表明:复合材料中LDHs均匀分散在NBR基体中;与NBR胶料相比,LDHs/NBR复合材料的物理性能和气体阻隔性能明显提高;当LDHs/NBR用量比为1/20且LDHs用量为1份时,LDHs/NBR复合母胶/溴化丁基橡胶并用胶的气体阻隔性能较好。     

Determination of the glass transition temperature of polymer/layered silicate nanocomposites from positron annihilation lifetime measurements

The glass transitions of acrylonitrile-butadiene rubber (NBR)/organoclay nanocomposites with various silicate contents were investigated using positron annihilation lifetime spectroscopy (PALS). The nanocomposites were prepared through melt intercalation of NBR with various concentrations of organoclay (OC30B) modified with the organic modifier, methyl tallow bis(2-hydroxyethyl) quaternary ammonium (MT2EtOH), i.e., Cloisite^® 30B. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) measurements of the NBR/OC30B nanocomposites showed that the NBR chains were intercalated between the silicate layers, thereby increasing the gallery heights of the organosilicates. The glass transition temperature of NBR was determined using differential scanning calorimetry (DSC). However, it seemed to be very difficult to clearly resolve the very small differences in T_gs caused from various loading of nanosized silicate in NBR/OC30B nanocomposites. Hence, we performed positron annihilation lifetime spectroscopy (PALS) on NBR/OC30B nanocomposites containing various amounts of OC30B (1-10 wt%). Significant changes in the temperature dependencies of free volume parameters (i.e., lifetimes and intensities) were observed at the transition temperature, T_g,PALS, and the T_g,PALS values were found to increase with increasing organoclay content in the samples. These observations are consistent with PALS having a higher sensitivity in the detection of very small changes in free volume properties. The present findings thus highlight the usefulness of PALS for studying phase transition phenomena in polymeric materials with nanoscale structural variations.