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.     

淀粉对蒙脱土/丁腈橡胶纳米复合材料结构和性能的影响

采用蒙脱土水悬浮液/橡胶乳液共混-共凝复合技术制备蒙脱土/丁腈橡胶纳米复合材料时,在蒙脱土水悬浮液和丁腈胶乳的混合体系中加入淀粉,考察了淀粉用量对蒙脱土/丁腈橡胶纳米复合材料结构和性能的影响。结果表明,淀粉的加入有利于蒙脱土片层形成剥离型结构。当蒙脱土用量为5份、淀粉用量为10份时,蒙脱土几乎呈完全剥离状态;随着淀粉用量的增加,该复合材料的邵尔A硬度、100%定伸应力、拉伸强度、扯断伸长率和撕裂强度均有所提高。     

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。     

Preparation of natural rubber-montmorillonite nanocomposite in aqueous medium: evidence for polymer-platelet adhesion

Nanocomposites of natural rubber latex and layered silicates are prepared by a mild dispersion shear blending process. The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) show that clay particles are well dispersed in the dry latex and the platelets have a preferential orientation, forming translucent nanocomposites. These show tensile mechanical properties analogous to those obtained with vulcanized rubber as well as an increased solvent resistance, which is expected considering that there is significant adhesion between clay lamellae and rubber. Nanocomposite swelling is strongly anisotropic. Natural rubber properties may thus be strongly modified by nanocomposite formation producing unprecedented combinations of properties.     

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     

Acrylonitrile butadiene nanocomposites containing different clays by latex compounding method

Considering elastomers nanocomposites, most of the works are focused on natural rubber, styrene butadiene rubber and rubber blends, while few of them deal with nitrile butadiene rubber (NBR). This article presents the reinforcing effect of two raw sodic montmorillonites (Mts) and one organoclay on NBR matrix prepared by the latex compounding method. Raw Mts increase the mechanical properties of neat matrices. A pseudoplastic behavior is observed with the incorporation of clays into the NBR latex, indicating interactions between polymer chains and clay sheets, in agreement with the results of zeta potential analysis. X‐ray diffraction evaluates changes in the interlayer distance of the clay, indicating the NBR intercalation phenomenon in all cases. Matrices with different clay proportions present variations in the mechanical properties, depending if the aggregation phenomenon is promoted. Morphological analysis of clays and nanocomposites as well as thermal analysis were performed. The variation in mechanical properties after an aging process was studied, evaluating the effects on the tensile strength, ultimate strain and 300% modulus. POLYM. ENG. SCI., 59:736–744, 2019. © 2018 Society of Plastics Engineers     

Natural rubber-based nanocomposites by latex compounding with layered silicates

Natural rubber (NR) based nanocomposites with 10 wt% natural and synthetic layered silicates were produced via the latex compounding method. As layered silicates, sodium bentonite (natural) and sodium fluorohectorite (synthetic) were selected in addition to a non-layered inert filler (English India clay or commercial clay) as reference material. The nanocomposites were prepared by compounding the dispersions of clays and other latex chemicals necessary for vulcanization. The vulcanized nanocomposites were subjected to mechanical, thermal and swelling tests. The silicate dispersion was studied by transmission electron microscopy. Layered silicates outperformed the reference material (commercial clay) in all aspects. This was attributed to the intercalation/exfoliation of the silicates and to the formation of a skeleton ‘(house of cards)’ silicate network in the NR matrix.     

Using maleic anhydride grafted poly(lactic acid) as a compatibilizer in poly(lactic acid)/layered‐silicate nanocomposites

The goal of this work was to prepare exfoliated poly(lactic acid) (PLA)/layered‐silicate nanocomposites with maleic anhydride grafted poly(lactic acid) (PLA–MA) as a compatibilizer. Two different layered silicates were used in the study: bentonite and hectorite. The nanocomposites were prepared by the incorporation of each layered silicate (5 wt %) into PLA via solution casting. X‐ray diffraction of the prepared nanocomposites indicated exfoliation of the silicates. However, micrographs from transmission electron microscopy showed the presence of intercalated and partially exfoliated areas. Tensile testing showed improvements in both the tensile modulus and yield strength for all the prepared nanocomposites. The results from the dynamic mechanical thermal analysis showed an improvement in the storage modulus over the entire temperature range for both layered silicates together with a shift in the tan δ peak to higher temperatures. The effect of using PLA–MA differed between the two layered silicates because of a difference in the organic treatment. The bentonite layered silicate showed a more distinct improvement in exfoliation and an increase in the mechanical properties because of the addition of PLA–MA in comparison with the hectorite layered silicate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1852–1862, 2006     

Mechanical,thermal, and barrier properties of NBR/organosilicate nanocomposites

Nanocomposites of intercalated and exfoliated organosilicates in acrylonitrile butadiene rubber (NBR) were prepared by a solution‐blending method. The dispersion and intergallery spacings of organosilicates in these nanocomposites were examined by transmission electron microscopy and X‐ray diffraction. Dramatic enhancements in the mechanical and thermal properties of NBR are found by incorporating less than ten parts of organosilicate. In particular, the addition of ten parts of organosilicate provided a more than sixfold increase in tensile strength, a twofold increase in M500, and 168% and 39% enhancements in tear strength and elongation at break compared with pure NBR. The degradation temperature for NBR with ten‐parts' loading of organosilicate was 25°C higher than that of pure NBR. In addition, the relative vapor permeability of the NBR nanocomposites for water and methanol were 85% and 42% lower, respectively, than that of pure NBR. Polym. Eng. Sci. 44:2117–2124, 2004. © 2004 Society of Plastics Engineers.     

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.     

Preparation and characterization of poly(styrene‐b‐butadiene‐b‐styrene)/montmorillonite nanocomposites

With some polymerizable small molecules grafting onto the montmorillonite surface, we disposed the clay through in‐situ emulsion polymerization, and the structure of the modified montmorillonites were studied through Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD). The nanocomposites of poly(styrene‐b‐butadiene‐b‐styrene) (SBS)/montmorillonite with excellent mechanical properties were prepared by mixing SBS and the modified montmorillonite on the double rollers at 150°C. The exfoliation of the layered silicates was confirmed by XRD analysis and transmission electron microscopy (TEM) observation. After mechanical kneading of the molten nanocomposites, the exfoliation structure of the silicates is still stable for polystyrene macromolecules grafting onto the silicates. Upon the addition of the modified montmorillonite, the tensile strength, elongation at break and tear strength of the nanocomposites increased from 22.6 MPa to 31.1 MPa, from 608% to 948%, from 45.32 N/mm to 55.27 N/mm, respectively. The low‐temperature point of glass‐transition temperature (T_g) of the products was about −77°C, almost constant, but the high‐temperature point increased from 97°C to 106°C. In addition, the nanocomposites of SBS and modified montmorillonites showed good resistance to thermal oxidation and aging. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Novel hybrid of clay,cellulose, and thermoplastics. I. Preparation and characterization of composites of ethylene–propylene copolymer

The present study is aimed to prepare hybrid materials by incorporating layered silicates and microcrystalline cellulose into thermoplastic polymer. Using ethylene–propylene (EP) copolymer as thermoplastic polymer matrix and maleated EP (MEP) copolymer as compatibilizer, three types of composites were prepared by (i) melt mixing of cellulose with thermoplastics [I], (ii) melt mixing of clay with thermoplastics [II], and (iii) melt mixing of cellulose with the thermoplastic clay nanocomposites [III]. They were characterized by X‐ray diffractometry (XRD), differential scanning calorimetry, thermogravimetric analysis, and Fourier transform infrared spectroscopy. Instron was used to measure the mechanical properties. The composites [II] and [III] that contain layered silicates were intercalated nanocomposites as confirmed by XRD and transmission electron microscopy. The improvement in tensile properties was observed in cellulose–fiber‐reinforced composites with increasing cellulose content. In nanocomposites [II] and [III], the tensile modulus was improved. The resistance of the cellulose composites [I] for water absorption decreased with increasing content of cellulose fibers. The incorporation of layered silicates reduced the water absorption of cellulose composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2672–2682, 2007     

累托石/丁腈橡胶纳米复合材料的结构与性能

用乳液共混共凝法制备了累托石／丁腈橡胶(NBR)复合材料,分别进行了透射电镜分析和X射线衍射分析,研究了其力学性能和气体阻隔性能。结果表明,累托石以厚度为10．00nm左右的晶束均匀分散于NBR中;累托石／NBR复合材料属于隔离型纳米复合材料;与传统的炭黑／NBR复合材料和白炭黑／NBR复合材料相比,累托石／NBR纳米复合材料具有高的邵尔A型硬度和300％定伸应力．尤其是其气体阻隔性能得到了显著提高。     

橡胶纳米复合材料研究进展

橡胶纳米复合材料因其优异的性能而目前材料科学研究的热点。本文论述了橡胶／粘土、橡胶／纳米SiO2、氢化NBR／丙烯酸金属盐、橡胶／纳米炭黑和白炭黑、橡胶／纳米纤维等橡胶基纳米复合材料的制备方法、机理、力学性能、工业应用领域等,讨论了层状硅酸盐粘土的表面修饰,提出了插层剂的选择原则,评价了各种合成技术的优缺点及工业价值,提出了橡胶纳米复合材料的发展趋势。     

Nitrile butadiene rubber/hindered phenol nanocomposites with improved strength and high damping performance

A hindered phenol (AO-80) was studied to prepare rubber nanocomposites with nitrile butadiene rubber (NBR). The NBR/AO-80 rubber nanocomposites were successfully developed by applying the adopted preparation procedure/conditions, especially by introducing mechanical kneading of the NBR/AO-80 composites at a temperature higher than the melting point of AO-80, followed by the crosslinking of NBR molecules during the subsequent hot-pressing/vulcanization process. The nanocomposites consisted of two phases: (1) the AO-80 enriched phase (nanoparticles with the average size of approximately 20 nm) and (2) the NBR enriched phase (matrix). The generation and uniform distribution of the nanoparticles were attributed to the high temperature mechanical kneading process, the strong intermolecular interactions between AO-80 and NBR molecules, and the formation of a three-dimensional NBR network. The morphological, structural and mechanical properties of the composites were systematically investigated in each preparation step using SEM, TEM, DSC, XRD, FT-IR, DMTA and a tensile tester. The results indicated that the prepared NBR/AO-80 rubber nanocomposites had single relaxation transitions, improved tensile strengths, high dynamic mechanical loss values, and reasonably good stabilities. The NBR/AO-80 rubber nanocomposites are expected to have important applications as a high performance damping material.     

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     

Effect of sample thickness on the mechanical properties of injection-molded polyamide-6 and polyamide-6 clay nanocomposites

The effect of the thickness on the mechanical properties of injection-molded specimens of pure polyamide-6 (PA6) and polyamide-6 clay nanocomposites (PA6-NC) with 5 wt% of layered silicates was investigated. Plates of 0.5, 0.75, 1 and 2 mm thickness were characterized in the injection direction using Dynamic Mechanical Analysis under torsion and tension respectively, and tensile tests. The fracture surfaces were analyzed by Scanning Electron Microscopy. In contrast with PA6, PA6-NC showed thickness effect and clear differences in the mechanical and thermomechanical properties between skin and core, especially in the 2 mm thick samples. Increasing thickness in PA6-NC led to a reduction of tensile modulus and yield stress. In the fracture surface of the thicker tensile specimens the formation of a sheet-like structure was observed. Multiple voiding in the core causing initial failure in this region and a stiffer skin with a better orientation of the layered silicates in the injection direction are two important elements of a micromechanical model proposed in this paper to explain the fracture mechanism in PA6-NC.     

黏土/天然橡胶纳米复合材料的制备及性能

利用乳液插层法制备了黏土／天然橡胶纳米复合材料,研究了该复合材料的力学性能、应力应变行为、耐磨性、气体阻隔性和耐老化性能。结果表明,黏土／天然橡胶纳米复合材料与高耐磨炭黑(N330)、白炭黑增强橡胶相比,邵尔A型硬度、定伸应力和撕裂强度较高,拉伸强度相当。黏土、N330以及白炭黑对天然橡胶的拉伸结晶有影响,填料用量对材料拉伸强度的影响存在最佳值。黏土／天然橡胶纳米复合材料具有良好的耐磨性、气体阻隔性和耐老化性能。     

Biodegradable polyester layered silicate nanocomposites based on poly(ϵ‐caprolactone)

Nanocomposites based on biodegradable poly(?‐caprolactone) (PCL) and layered silicates (montmorillonite, MMT) were prepared either by melt interaction with PCL or by in situ ring‐opening polymerization of ?‐caprolactone as promoted by the so‐called coordination‐insertion mechanism. Both non‐modified clays (Na⁺ ‐MMT) and silicates modified by various alkylammonium cations were studied. Mechanical and thermal properties were examined by tensile testing and thermogravimetric analysis. Even at a filler content as low as 3 wt% of inorganic layered silicate, the PCL‐layered silicate nanocomposites exhibited improved mechanical properties (higher Young's modulus) and increased thermal stability as well as enhanced flame retardant characteristics as a result of a charring effect. It was shown that the formation of PCL‐based nanocomposites depended not only on the nature of the ammonium cation and related functionality but also on the selected synthetic route, melt intercalation vs. in situ intercalative polymerization. Interestingly enough, when the intercalative polymerization of ?‐caprolactone was carried out in the presence of MMT organo‐modified with ammonium cations bearing hydroxyl functions, nanocomposites with much improved mechanical properties were recovered. Those hybrid polyester layered silicate nanocomposites were characterized by a covalent bonding between the polyester chains and the clay organo‐surface as a result of the polymerization mechanism, which was actually initiated from the surface hydroxyl functions adequately activated by selected tin (II) or tin (IV) catalysts.     

Nitrile rubber/organomontmorillonite nanocomposites produced by solution and melt compounding: Effect of the polarity of the quaternary ammonium intercalants

A comparative study of the development of nitrile rubber (NBR) based nanocomposites was performed; two organomontmorillonites (Cloisite 15A and Cloisite 30B) and two procedures for clay dispersion (melt blending and solution intercalation) were used. The nanocomposites were cured with a system based on dicumyl peroxide in the presence of m‐phenylenebismaleimide as a coagent for curing. The dispersion of the organoclay inside the NBR matrix was investigated with transmission electron microscopy and X‐ray diffraction. All the cured systems displayed a combination of intercalated, partially exfoliated clay platelets and confined, deintercalated clay; the degree of dispersion depended on the amount of clay, the type of intercalant, and the intercalation procedure. The highest amount of intercalated/exfoliated clay was obtained with a previous dispersion of the clay (Cloisite 30B) in an NBR solution. All the nanocomposites presented outstanding tensile strength and creep response, and this indicated a reinforcing effect of the layered silicates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011