Characteristics of nitrile–butadiene rubber layered silicate nanocomposites with silane coupling agent

Nanocomposites of organophilic montmorillonite (C18‐MMT), nitrile–butadiene rubber (NBR), and a coupling agent were produced during a melt compounding process at room temperature. During the process, it was clearly observed that organo‐MMT particles were exfoliated into nanoscale layers of approximately 1–30 nm thickness, in addition to their original 40 μm thickness. These MMT layers were uniformly dispersed in the NBR matrix. The effects of a coupling agent such as 3‐(mercaptopropyl)trimethoxy silane in C18‐MMT/NBR nanocomposites were studied. The C18‐MMT/NBR nanocomposites in the presence of the coupling agent were identified and characterized by X‐ray diffraction, transmission electron microscopy, a universal testing machine, thermogravimetric analysis, and IR spectroscopy. It was observed that an additional silane coupling agent, 3‐(mercaptopropyl)trimethoxy silane, enhanced the chemical interaction and was accompanied by the formation of Si? O? Si coupling bonds between C18‐MMT and the coupling agent and Si? C coupling bonds between NBR and the coupling agent. This work resulted in improved properties of organo‐MMT/NBR nanocomposites because of the nanoscale effects and strong interaction of the coupling bonds between NBR and organo‐MMT. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2633–2640, 2003     

Biodegradable nanocomposites based on starch/polycaprolactone/compatibilizer ternary blends reinforced with natural and organo‐modified montmorillonite

In this article, biodegradable polymer/clay nanocomposites were prepared. The matrices used were based on blends of Polycaprolactone (PCL) and Anhydride‐Functional Polycaprolactone (PCL‐gMA) with Thermoplastic Starch (TPS). Nanocomposites films based on PCL/TPS and PCL/PCL‐g‐MA/TPS blends reinforced with 1 and 3 wt % of natural montmorillonite and two organo‐modified ones were prepared by melt intercalation followed by compression molding. The study was designed focusing on packaging applications. Grafting maleic anhydride onto PCL was efficient to improve PCL/TPS compatibility but did not modify matrix/nanoclay interaction. Matrix compatibilization and nanoclays increased the Youn?s modulus and slightly decreased the maximum stress of the TPS/PCL matrix. Nanoclay functionalization improved nanoclay dispersion in the blends but it was not reflected in mechanical properties improvements. The water adsorption of the compatibilized matrix was reduced after clay incorporation. A slight decrease in the biodegradation rate was observed with the addition of nanoclay. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44163.     

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     

Overall properties of fibrillar silicate/styrene–butadiene rubber nanocomposites

The mechanical properties, heat aging resistance, dynamic properties, and abrasion resistance of fibrillar silicate (FS)/styrene butadiene rubber (SBR) nanocomposites are discussed in detail. Compared with white carbon black (WCB)/SBR composites, FS/SBR composites exhibit higher tensile stress at definite strain, higher tear strength, and lower elongation at break but poor abrasion resistance and tensile strength. Surprisingly, FS/SBR compounds have better flow properties. This is because by rubber melt blending modified FS can be separated into numerous nanosized fibrils under mechanical shear. Moreover, the composites show visible anisotropy due to the orientation of nanofibrils. There is potential for FS to be used to some extent as a reinforcing agent for rubber instead of short microfibers or white carbon black. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2725–2731, 2006     

Effect of two types of layered silicate on mechanical and barrier properties of hydrogenated acrylonitrile butadiene rubber (HNBR)/layered silicate nanocomposites

Abstract

The role of the type of layered silicate platelets, OMMT and rectorite on the mechanical properties, aging resistance and oxygen permeation properties of HNBR/layered silicate nanocomposites was investigated. The effect of peroxide vulcanising agent on the dispersion of layered silicate in the HNBR matrix was also studied. HNBR was mechanically mixed with layered silicate via melt blending method. The results of the test show remarkable improvement in tensile strength, tear strength, aging resistance and oxygen permeation properties of HNBR nanocomposites than that of unfilled HNBR. It is obvious that the OMMT filled nanocomposites have far better properties than that of rectorite filled HNBR.     

Dielectric properties of layered silicate‐reinforced natural and polyurethane rubber nanocomposites

Natural rubber (NR), polyurethane rubber (PUR), and NR/PUR‐based nanocomposites were prepared by adding a pristine synthetic layered silicate (LS; sodium fluorohectorite) in 10 parts per hundred parts rubber, following the latex compounding route. The dispersion of the LS latices in the composites was studied by means of X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The morphology‐dependent dielectric properties of the produced nanocomposites were examined using broadband dielectric spectroscopy (BDS) at ambient temperature. Besides the glass/rubber transition of the polymer matrices, interfacial polarization (IP) is evident in the produced nanocomposites. The α‐relaxation, as well as the β‐mode, in the PUR‐containing nanocomposites proved to be less affected by the presence of LSs. The obtained experimental data suggest that the LS is more compatible with and thus better intercalated by the PUR than by the NR which was prevulcanized in this case. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

High performance epoxy‐layered silicate nanocomposites

High performance epoxy‐layered silicate nanocomposites based on tetra‐glycidyl4,4'‐diamino‐dipheny1 methane (TGDDM) resin cured with 4,4'‐diaminodipheny1 sulfone (DDS) have been successfully synthesized. Fluorohectorites modified by means of interlayer cation exchange of sodium cations for protonated dihydro‐imidazolines and octadecylamine were used. Fluorohectorite exchanged with 1‐methy12‐norsteary1‐3‐stearinoacid‐amidoethy1‐dihydro‐imidazolinium ions was immiscible with the epoxy matrix. In contrast, fluorohectorites exchanged with hydroxyethy1‐dihydro‐imidazolinium (HEODI) and riciny1‐dihydro‐imidazolinium ions (RDI) favored the formation of a nanocomposite structure. This is most likely due to the presence of ‐OH groups in their molecular structure, which has a catalytic effect on the polymerization occurring between the silicate layers. The diffusion of epoxy and curing agent molecules between the silicate layers is also promoted. Microscopy observations revealed that the dispersion of the silicate aggregates on a microscale was proportional to the degree of separation of the silicate layers on a nanoscale. Decreased apparent glass transition temperature was observed in all the nanocomposites. Finally, mechanical property studies showed that epoxy‐layered silicate nanocomposite formation could simultaneously improve fracture toughness and Young's modulus, without adversely affecting tensile strength.     

Synergistic effect of plasma‐modified halloysite nanotubes and carbon black in natural rubber—butadiene rubber blend

Halloysite nanotubes (HNTs) were investigated concerning their suitability for rubber reinforcement. As they have geometrical similarity with carbon nanotubes, they were expected to impart a significant reinforcement effect on the rubber compounds but the dispersion of the nanofillers is difficult. In this work, HNTs were surface‐modified by plasma polymerization to change their surface polarity and chemistry and used in a natural rubber/butadiene rubber blend in the presence of carbon black. The aim of the treatment was to improve the rubber–filler interaction and the dispersion of the fillers. A thiophene modification of HNTs improved stress–strain properties more than a pyrrole treatment. The surface modification resulted in a higher bound rubber content and lower Payne effect indicating better filler–polymer interaction. Scanning electron microscopy measurements showed an increased compatibility of elastomers and fillers. As visualized by transmission electron microscopy, the thiophene‐modified HNTs formed a special type of clusters with carbon black particles, which was ultimately reflected in the final mechanical properties of the nanocomposites. The addition of HNTs increased loss angle. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of different dendritic‐layered silicate nanocomposites

Several dendrimer–clay nanocomposites have been prepared. Firstly, the dendrimer (DE₁)/clay nanocomposite was obtained via an in situ free radical polymerization of a double bond‐ended dendrimer (DE₁), derived from Behera's amine by using 2,2′‐azobisisobutyronitrile (AIBN), as initiator, and Cloisite 30 B, as nanofiller. Further free radical in situ copolymerization processes were conducted between DE₁, methyl methacrylate (MMA), and styrene (St). Two other dendrimer/clay nanocomposites were prepared by the reaction of second generation (G₂)–36‐acid dendrimer (DE₂) and N,N′,N′,N′‐tetrakis[2‐hydroxy‐1,1‐bis(hydroxylmethyl) ethyl]‐α,α,ω,ω‐alkane‐tetracarboxamide [6]‐10‐[6] Arborols (DE₃) with montmorillonite clay (MMT). POLYM. ENG. SCI., 53:2166–2174, 2013. © 2013 Society of Plastics Engineers     

Preparation and mechanical properties of nitrile butadiene rubber/silicate nanocomposites

Elastomer nanocomposites consisting of nitrile butadiene rubber (NBR) latex and layered silicates are prepared by a modified latex shear blending process aided with ball milling. The mode of dispersion of layered silicates in NBR is partially exfoliated and intercalated when the concentration of layered silicates is below 7.5 wt%, as evidenced by transmission electron microscopy and X-ray diffraction results. The tensile and tear mechanical properties are much higher than that of neat NBR. Specifically, the tensile and tear mechanical properties of the NBR/layered silicates increase by 200 and 60%, respectively. The decomposition temperature of the nanocomposites increases slightly.     

Synthesis and characterization of resol‐layered silicate nanocomposites

Resol‐layered silicate nanocomposites were synthesized by intercalative polymerization of phenol and formaldehyde using layered clays such as an aminoacid‐modified montmorillonite (MMT) and a commercial modified MMT (Cloisite 30B). The composites were prepared by a sequential process in which one of the reactives of the phenolic resin was reacted with the organosilicate and subsequently cured with triethylamine. The nanocomposites were studied by means of X‐ray diffraction, atomic force microscopy, and thermogravimetric analysis. Results show a strong clay composition dependence on the intercalation state. The composite of resol with 2 wt % aminoacid‐modified MMT content has the best dispersion of clay layers. Thermal stability of nanocomposites was slightly increased in comparison with the neat resol. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation and properties of novel natural rubber/organo‐vermiculite nanocomposites

Polymer‐layered silicate nanocomposites have an attracting increasing attention over recent years because of their unique mechanical, thermal, and other properties. In this article, a new kind of natural rubber (NR)/organo‐vermiculite (OVMT) nanocomposites were investigated. The vermiculite (VMT) was intercalated by cetyltrimethylammonium bromide with ball mill method. The intercalation led to an increase of the d₍₀₀₁₎ of VMT from 1.46 nm to 4.51 nm. NR/OVMT nanocomposites were prepared via a melt process in a HAAKE mixer and were analyzed by X‐ray diffraction and scanning electron microscope observations. The mechanical properties of the vulcanized nanocomposites were tested. It was found that the tensile strength and the elongation at the breaking point of the NR/OVMT nanocomposites loading 15 phr of the OVMT reached 28.4 MPa and 623.2%, respectively. The 300% modulus, tear strength, and hardness (Shore A) of the nanocomposites increased with the increase of the OVMT loading. The thermal properties of the nanocomposites were investigated by dynamic mechanical analysis, and the results showed that the storage modulus and the glass transition temperature of the nanocomposites were increased. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

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.     

Natural rubber and butadiene rubber blend using diblock copolymer of isoprene–butadiene as compatibilizer

Blends of natural rubber (NR) and butadiene rubber (BR) have been studied with or without diblock copolymers of isoprene–butadiene (BIR). It was found that NR/BR blends displayed the optimal properties at about 4 wt % of BIR from the tensile measurements of NR/BR blends. Increase of molecular weight of BIR resulted in the decrease of tensile properties, but had no significant effect on their hardness. Abrasion resistance of rubber blends containing BIR was about 30% higher than that without BIR. The molecular weight of BIR did not show a remarkable effect on the abrasion index. Differential scanning calorimetry and dynamic mechanical analyses of rubber blends suggested a two-phase structure even in the presence of BIR. © 1993 John Wiley & Sons, Inc.     

Temperature and frequency‐dependent creep and recovery studies on PVDF‐HFP/organo‐modified layered double hydroxides nanocomposites

A series of poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) loaded with various contents of layered double hydroxides (LDHs) nanoparticles were prepared via a melt mixing method. Detailed investigations on LDH dispersion state in the polymeric matrix conducted by TEM revealed intercalated/exfoliated, and agglomerated structures at low (1 wt %) and high (>3 wt %) loadings of LDH contents, respectively. Wide angle X‐ray scattering and DSC results showed that incorporation of LDH into PVDF‐HFP matrix reduced its overall crystallinity and helped to form polar crystallites, while the crystal size at 020 crystallographic directions was found to be most affected by presence and dispersion state of LDH in the matrix. TGA results showed LDH improved thermal stability of matrix however, unlike many other nanomaterials it significantly reduced the residual mass which highlights catalytic role of LDH in degradation of residual carbon char. Detailed analysis on creep and recovery data over wide range of selected temperatures revealed that the creep compliance of nanocomposites are basically controlled by crystallinity and presence of LDH at low and high temperatures, respectively. Based on obtained storage modulus and creep compliance master curves it was also found that the influence of LDH on decreasing the creep compliance and improving viscoelastic properties of PVDF‐HFP over long time period and over high frequency ranges becomes more pronounced. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46352.     

Synthesis of resol–layered silicate nanocomposites by reaction exfoliation with acid‐modified montmorillonite

Resol–layered silicate nanocomposites were prepared by the intercalative polymerization of phenol and formaldehyde in the presence of acid‐modified montmorillonite (HMMT). The nanocomposites were studied by means of X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic mechanical analysis (DMA), and rheological measurements. The exfoliation of HMMT was promoted by the intragallery reactions catalyzed by protons in the galleries of the clay, whereas the extragallery polymerization catalyzed by ammonia went on simultaneously. The nanocomposites showed higher glass‐transition temperatures in the DMA diagram compared with the resol counterparts. The impact strength was improved significantly by the incorporation of the clay. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 791–797, 2004     

Synergistic effect of carbon nanofiber decorated with iron oxide in enhancing properties of styrene butadiene rubber nanocomposites

Elastomer nanocomposites reinforced with carbon nanofiber (CNF) decorated with metal nanoparticles exhibit excellent thermal, mechanical, and magnetic properties with low volume fraction of the reinforcement. Generally, metal nanoparticles are used to modify the surface of CNF, to improve their dispersion and contact resistance in the polymer matrix. In this study, Fe₂O₃ metal nanoparticles were decorated on CNF by electrostatic attraction via a green and facile solution‐based method. Interestingly, the CNF decorated with Fe₂O₃ (CNF‐Fe₂O₃)/elastomer improved both the tensile strength and the fatigue property of plain CNF/elastomer by as much as 57.2% and 27.2%, respectively. Moreover, the CNF‐Fe₂O₃/elastomer exhibited superior thermal conductivity, a twofold enhancement compared with carbon fibers. The elastomer nanocomposites consisting of CNF‐Fe₂O₃ also exhibited enhanced magnetic properties due to synergies between the Fe₂O₃ nanoparticles and the CNF. The elastomer nanocomposites prepared with CNF‐Fe₂O₃ will open significant new opportunities for preparing advanced elastomer nanocomposites for future engineering applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45376.     

Thermal,mechanical and morphological properties of surface‐modified montmorillonite‐reinforced Viton rubber nanocomposites

Thermal, mechanical and morphological properties of surface‐modified montmorillonite (OMMT)‐reinforced Viton rubber nanocomposites were studied. The surface of montmorillonite was modified with a column chromatography technique using quaternary long‐chain ammonium salt as an intercalant, which resulted in uniform exchange of ions between montmorillonite and the ion‐exchange resin, and increased the d‐spacing to 31.5 Å. This improved d‐spacing was due to the use of an ion‐exchange column of sufficient length (35 cm) and diameter (5 cm) with maximum retention time for exchange of ions. The Viton nanocomposites reinforced with OMMT (3–12 wt%) were prepared using a two‐roll mill and moulded in a compression moulding machine. Tensile strength increased 3.17 times and elongation at break from 500 to 600% for 9 wt% loading of OMMT in comparison to pristine Viton rubber. Thermogravimetric analysis revealed that the presence of OMMT greatly improved the thermal stability. This improvement in properties with increasing OMMT loading was due to insertion of rubber chains between the OMMT plates with good wetting ability. Overall, at an optimum OMMT loading of 9 wt%, the properties of the Viton rubber nanocomposites improved, and subsequently worsened at 12 wt% due to agglomeration of OMMT as revealed by scanning electron microscopy and atomic force microscopy images. © 2013 Society of Chemical Industry     

片层硅酸盐纳米复合聚氨酯橡胶的结构及性能

将聚四氢呋喃二醇和富羟基活性蒙脱土(HMMT)进行预混插层处理,然后与甲苯二异氰酸酯(TDI)进行反应,得到层状硅酸盐复合预聚体。随后预聚体与扩链剂(DMTDA)反应制备出聚氨酯橡胶/片层硅酸盐纳米复合材料。采用材料拉伸机、X射线衍射(XRD)、透射电镜 (TEM)、差示扫描量热仪 (DSC)和热失重分析仪 (TGA) 等检测设备对聚醚型聚氨酯脲的结构与性能进行分析。结果表明：当PMMT的质量百分含量在2％时,片层硅酸盐粒子在聚氨酯基体内分散较均匀,形成了以剥离型为主、插层型为辅的复合型结构,聚醚型聚氨酯脲复合材料的拉伸强度比纯PUU提高了21%,断裂伸长率提高了12%,PUU复合材料的玻璃化转变温度(Tg)提高了5.8℃,第一失重区分解温度和最高分解温度高出纯聚氨酯17.33 ℃和13.94 ℃。无机纳米片层硅酸盐粒子的存在,聚氨酯橡胶的强度、韧性和热稳定性均得到改善。     

Exploring the role of stearic acid in modified zinc aluminum layered double hydroxides and their acrylonitrile butadiene rubber nanocomposites

The proposed study attempted to explore the role of stearic acid modification on the properties of zinc‐aluminum based layered double hydroxides (LDH) and their composites with acrylonitrile butadiene rubber (NBR). Three distinctive LDH systems were adapted for such comparison; an unmodified LDH and two stearic acid modified LDH. The use of zinc oxide and stearic acid in the rubber formulation was avoided as the modified LDH would be able to deliver the necessary activators for the vulcanization process. Emphasis was predominantly given to reconnoiter the merits of stearic acid modification on the increase in interlayer distance of the LDH. X‐ray diffraction studies and transmission electron microscope morphological investigations of LDH powders indicated that modification with stearic acid increased the interlayer spacing which would favor the intercalation of NBR polymer chains into the layered space. However, stress–strain studies indicated better mechanical properties for composites with unmodified LDH. Composites with LDH showed higher crosslinking densities than conventionally sulfur cured control compounds using zinc oxide/stearic acid as activators. This was evident from equilibrium swelling method as well as statistical theory of rubber elasticity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41539.