Polybutadiene rubber/organoclay nanocomposites: Effect of organoclay with various modifier concentrations on the vulcanization behavior and mechanical properties

It has been reported that the cure time t₉₀, scorch time t₂, and their difference (t₉₀?t₂) of Polybutadiene rubber (BR)/organoclay nanocomposites were much reduced over those of BR. This effect can be attributed to the ammonium groups in the organoclay. The possible formation of a Zn complex in which sulfur and ammonium modifier participate may facilitate the formation of crosslinks. If this assumption is true, it is expected that the organoclay with higher ammonium modifier concentration will give larger torque difference and faster vulcanization rate to the BR/organoclay nanocomposites. The effect of organoclay with different modifier concentration on the vulcanization behavior and mechanical properties of BR/organoclay hybrid was investigated in this study. As expected, the order of the torque difference was BR/Cloisite 15A > BR/Cloisite 10A > BR/Cloisite 20A > BR/Cloisite 25A > BR/Cloisite 30B > BR/Cloisite Na⁺, and the order of vulcanization rate also showed similar trends. The organoclay with higher modifier concentration gave larger torque difference and faster vulcanization rate to the BR/organoclay nanocomposites. POLYM. ENG. SCI., 47:308–313, 2007. © 2007 Society of Plastics Engineers.     

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     

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     

Studies on preparation and properties of vinyltriethoxysilane‐grafted styrene‐butadiene rubber

Graft polymerization of vinyltriethoxysilane (VTES) onto styrene‐butadiene rubber (SBR) was carried out in latex using benzoic peroxide (BPO) as an initiator. The concentration of VTES effecting on vulcanization characteristics, mechanical properties and thermal properties of VTES‐grafted SBR (SBR‐g‐VTES) were investigated. The grafting of VTES onto SBR and its pre‐crosslinking were confirmed by attenuated total teflectance‐Fourier transform infrared reflectance and proton nuclear magnetic resonance. The mechanism of graft polymerization was studied. The results revealed that the minimum torque, optimum cure time, tensile strength, thermal decomposition temperature, and glass transition temperature (T_g) all increased with the increasing concentration of VTES. But the grafting efficiency of VTES, rate of vulcanization, and elongation at break of the SBR‐g‐VTES decreased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of organoclay reinforcement on the curing characteristics and technological properties of styrene–butadiene rubber

Rubber nanocomposites based on styrene–butadiene rubber (SBR) and organophilic layered silicate were prepared. Clay structures based on dodecyl benzene sulfonic acid (DBSA), nonyl phenol ethoxylate (NPE), and DBSA/NPE (50/50%) were prepared and characterized. The results indicate the intercalation of the used surfactants within the clay layers. Varying amount of organoclay, 2, 4, 6, 8, and 10 (phr), was added to the SBR matrix. X‐ray diffraction revealed exfoliated structure for the modified clay–SBR composites. No new component in the rubber was found by fourier transform infrared measurements (FTIR). Scanning electron microscopy showed a uniform distribution of the modified clay with mixed DBSA/NPE (6 phr) in the matrix. The rheometric characteristics and physicomechanical properties of the SBR compounds were analyzed. The effect of DBSA/NPE clay loading on aging resistance of SBR nanocomposites at 90 ± 1°C for 4 and 7 days was also investigated. Rubber nanocomposites displayed an increase in the minimum and maximum torques, acceleration of the vulcanization process, and improved mechanical properties, with organoclay content up to 6 phr. This effect was more noticeable in the presence of the treated clay with DBSA/NPE. Also incorporation of DBSA/NPE‐clay (6 phr) resulted in significant improvement of the degradation profile of the nanocomposites at 90 ± 1°C for 4 days. POLYM. COMPOS., 36:1293–1302, 2015. © 2014 Society of Plastics Engineers     

Silica‐modified SBR/BR blends

The purpose of this article is that the silica‐modified SBR/BR blend replaces natural rubber (NR) in some application fields. The styrene‐butadiene rubber (SBR) and cis‐butadiene rubber (BR) blend was modified, in which silica filler was treated with the r‐Aminopropyltriethoxysilane (KH‐550) as a coupling agent, to improve mechanical and thermal properties, and compatibilities. The optimum formula and cure condition were determined by testing the properties of SBR/BR blend. The properties of NR and the silica‐modified SBR/BR blend were compared. The results show that the optimum formulawas 80/20 SBR/BR, 2.5 phr dicumyl peroxide (DCP), 45 phr silica and 2.5 mL KH‐550. The best cure condition was at 150°C for 25 min under 10 MPa. The mechanical and thermal properties of SBR/BR blend were obviously modified, in which the silica filler treated with KH‐550. The compatibility of SBR/BR blend with DCP was better than those with benzoyl peroxide (BPO) and DCP/BPO. The crosslinking bonds between modified silica and rubbers were proved by Fourier transform infrared analysis, and the compatibility of SBR and BR was proved by polarized light microscopy (PLM) analysis. The silica‐modified SBR/BR blend can substitute for NR in the specific application fields. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Effect of 3‐aminopropyltriethoxysilane and N,N‐ dimethyldodecylamine as modifiers of Na+‐montmorillonite on SBR/organoclay nanocomposites

In this study, styrene butadiene rubber (SBR)/organoclay nanocomposites were manufactured using the latex method with 3‐aminopropyltriethoxysilane (APTES) and N,N‐dimethyldodecylamine (DDA) as modifiers. The layer‐to‐layer distance of the silicates was observed according to each manufacturing process for APTES as the modifier using the X‐ray diffraction (XRD) method. From the XRD results and the TEM images, the dispersion of the silicates impoved for both APTES‐MMT and DDA‐MMT, and the dispersion of the silicates with the DDA modifier improved more than the APTES modifier. The SBR/DDA‐MMT compound exhibited the fastest scorch time, optimal vulcanization time, and cure rate. The dynamic viscoelastic properties of the SBR/APTES‐MMT compound were measured according to the change in the strain amplitude in order determine if a covalent bond was formed between APTES and bis(triethoxysilyl‐propyl)tetrasulfide (TESPT). The mechanical properties of the SBR/DDA‐MMT nanocomposite improved more than the SBR/APTES‐MMT composite because the vulcanization effects of alkylamine and the dispersion of silicates within the rubber matrix were relatively good. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Ternary elastomer nanocomposites based on NR/BR/SBR: Effect of nanoclay composition

Elastomer nanocomposites based on natural rubber (NR), butadiene rubber (BR), and styrene butadiene rubber (SBR) containing Cloisite 15A were prepared using a two‐roll mill. Mechanical, morphological, and rheological characterization of the prepared nanocomposites was carried out in order to study the effect of different nanoclay compositions, i.e., 1, 3, 5, 7, and 10 wt %. Intercalation of the elastomer chains into the silicate layers was evidenced by d‐spacing values calculated according to the results of the X‐ray diffraction (XRD) patterns. This was directly confirmed by transmission and scanning electron microscopy (TEM and SEM). The results depict a decreasing trend in the optimum cure time (t₉₀) and scorch time (t₅) values of the nanocomposite samples with increasing nanoclay loading; where the elastic modulus (G′) and complex viscosity (η*) of the samples considerably increased. The mechanical properties of the nanocomposites show a considerable increase in the tensile modulus of NR/BR/SBR/Cloisite 15A nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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     

Combining In‐Situ Organic Modification of Montmorillonite and the Latex Compounding Method to Prepare High‐Performance Rubber‐Montmorillonite Nanocomposites

Summary: To improve the interfacial interaction in MMT‐SBR nanocomposites, one type of UOAC was introduced to in‐situ modified MMT before latex compounding with SBR. The influence of the UOAC/MMT ratio on the structure and properties of MMT/SBR nanocomposites were carefully studied by XRD, TEM, and mechanical testing. It was found that through the in‐situ organic modification, a rubber‐intercalated structure of MMT was obtained in the nanocomposites, and the amount of rubber‐intercalated structure strongly depended on the UOAC/MMT ratio. The tensile strength of MMT‐SBR nanocomposites was enhanced dramatically from 4 to 18 MPa by in‐situ organic modification of MMT.

Stress‐strain diagram of SBR/clay nanocomposites.     

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     

Mechanical,thermal, barrier,and rheological properties of poly(ether‐block‐amide) elastomer/organoclay nanocomposite prepared by melt blending

Polyether block amide (PEBA) elastomer‐organoclay nanocomposites were prepared by a melt mixing technique. The X‐ray diffraction and transmission electron microscope analysis indicated that the nanocomposite formed a partially exfoliated nanostructure in which the organoclay was dispersed uniformly throughout the matrix at the nanometer scale. The effect of organoclay on the melting temperature (T_m), glass transition temperature (T_g), crystallization temperature (T_c), and heat of fusion (ΔH_m) of the PEBA was determined by differential scanning calorimetry. Enhanced mechanical properties of the nanocomposites were observed from tensile and dynamic mechanical analysis. Thermal gravimetric analysis showed that the clay nanoparticles caused an increase in the thermal stability of the PEBA. Measurement of oxygen permeability and the degree of swelling in ASTM #3 oil indicated that the gas barrier properties and solvent resistance were greatly improved by the clay nanoparticles. Melt rheological studies revealed that the nanocomposites exhibited strong shear thinning behavior and a percolated network of the clay particles was formed. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Preparation and characterization of polyethylene–clay nanocomposites by using chlorosilane‐modified clay

Clay was modified by trimethylchlorosilane; after modification, hydroxyl groups at the edge of layers were reacted and CEC value was drastically decreased. Polyethylene–clay composites were prepared by melt compounding. Wide angle X‐ray diffraction (WAXD) and transmission electron microscopy (TEM) showed that intercalated nanocomposites were formed using organoclay ion‐exchanged from chlorosilane‐modified clay, but conventional composites formed using organoclay directly ion‐exchanged from crude clay. Dynamic mechanical analysis (DMA) of PE and PE–clay composites was conducted; the results demonstrated that nanocomposites were more effective than conventional composites in reinforcement and addition of organoclay resulted in the increase of glass transition temperature (T_g), but crude clay had no effect on T_g of PE–clay composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 676–680, 2004     

Preparation and properties of natural rubber nanocomposites with solid‐state organomodified montmorillonite

A novel organomodified montmorillonite prepared by solid‐state method and its nanocomposites with natural rubber were studied. The nanocomposites were prepared by traditional rubber mixing and vulcanizing process. The properties of solid‐state organomodified montmorillonite were investigated by Fourier‐transform infrared spectroscopy (FITR) and thermogravimetric analysis (TGA). The dispersion of the layered silicate in rubber matrix was characterized by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that the nanocomposites consisting of solid‐state organomodified montmorillonite and natural rubber are obtained. The solid‐state organomodified montmorillonite can not only accelerate the curing process, but also improve the mechanical and aging resistance properties of NR. The properties improvement caused by the fillers are attributed to partial intercalation of the organophilic clay by NR macromolecules. In addition, the dynamic mechanical analysis (DMA) results showed a decrease of tanδmax and increase of T_g when the organoclay is added to the rubber matrix, which is due to the confinement of the macromolecular segments into the organoclay nanolayers and the strong interaction between the filler and rubber matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Morphology and mechanical properties of clay/styrene‐butadiene rubber nanocomposites

Based on the character of a clay that could be separated into many 1‐nm thickness monolayers, clay styrene‐butadiene rubber (SBR) nanocomposites were acquired by mixing the SBR latex with a clay/water dispersion and coagulating the mixture. The structure of the dispersion of clay in the SBR was studied through TEM. The mechanical properties of clay/SBR nanocomposites with different filling amounts of clay were studied. The results showed that the main structure of the dispersion of clay in the SBR was a layer bundle whose thickness was 4–10 nm and its aggregation formed by several or many layer bundles. Compared with the other filler, some mechanical properties of clay/SBR nanocomposites exceeded those of carbon black/SBR composites and they were higher than those of clay/SBR composites produced by directly mixing clay with SBR through regular rubber processing means. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1873–1878, 2000     

Preparation of thermoplastic elastomer nanocomposites based on polyamide‐6/polyepichlorohydrin‐co‐ethylene oxide

This work is aimed at determining the effect of nanoclay and polyepichlorohydrin‐co‐ethylene oxide (ECO) content on the microstructure and mechanical properties of PA6/ECO thermoplastic elastomers (TPEs). TPE nanocomposites were prepared in a laboratory mixer using polyamide 6 (PA6), ECO, and an organoclay by a two‐step melt mixing process. First, the PA6 was melt blended with Cloisite 30B and then mixed by ECO rubber. X‐ray diffraction results and transmission electron microscopy image showed that the nanoclay platelets were nearly exfoliated in both the phases. The SEM photomicrograph of PA6 with ECO showed that the elastomer particles are dispersed throughout the polyamide matrix and the size of rubber particles is less than 3 μm. Introduction of organoclay in the PA6 matrix increased the size of dispersed rubber particles in comparison with the unfilled but otherwise similar blends. The nanoscale dimension of the dispersed clay results in an improvement of the tensile modulus of the nanocomposites. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Impact of various oxidation degrees of graphene oxide on the performance of styrene–butadiene rubber nanocomposites

In this work, graphene oxide (GO) with various oxidation degrees were synthesized by adjusting the dosage of oxidation agent based on a modified Hummers' method, and were then used for the fabrication of the styrene–butadiene rubber (SBR)/GO nanocomposites through latex coagulation method, followed by a high‐temperature cure process. The vulcanization characteristics, thermal stability, mechanical properties, thermal conductivity as well as solvent resistance of SBR/GO nanocomposites were investigated. The results indicated that various surface structures of GO due to oxidation degrees may lead to different dispersion states of GO in the rubber matrix, and thus greatly influenced the cure rate, mechanical properties as well as thermal conductivity of SBR/GO nanocomposites. The optimal (moderate) oxidation degree of GO was achieved at the oxidation agent (KMnO₄)/graphite weight ratio 9/5, for which case the tensile strength, tear strength, and thermal conductivity of SBR/GO nanocomposites increased by 271.3%, 112.3%, and 28.6%, respectively, compared with those of neat SBR. In addition, the mentioned nanocomposites also showed the best solvent resistance in toluene. POLYM. ENG. SCI., 58:1409–1418, 2018. © 2017 Society of Plastics Engineers     

Mechanical reinforcement in magadiite/styrene‐butadiene rubber composites

This work investigates mechanical properties of styrene‐butadiene rubber (SBR) composites incorporating magadiite (MGD), a synthetic layered silicate (Na₂Si₁₄O₂₉·9H₂O) with surface chemistry similar to precipitated silica used in tire tread formulations. Treatment with cetyltrimethylammonium (CTA⁺) expands the MGD layers and makes the interlayer face surfaces accessible to sulfur‐functional silane TESPT (Si69) and SBR, primarily during batch mixing. DMA and tensile testing of cured CMGD/SBR composites show that CTA‐treated MGD (CMGD) provides substantially higher levels of mechanical reinforcement than equivalent amounts of silica. However, CMGD/SBR composites exhibit larger loss tangent values above T_g, probably due to lower SBR‐SBR crosslink density resulting from interlayer trapping of sulfur released by Si69 during vulcanization. DMA and tensile testing also demonstrate Si69′s critical role in forming MGD‐SBR graft sites essential to mechanical reinforcement. Replacing silica with CMGD reduces composite weight without sacrificing tensile modulus, suggesting that use of CMGD in tire rubber formulations could improve vehicle energy efficiency. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44763.     

改性淀粉对炭黑填充丁苯橡胶/顺丁橡胶并用胶性能的影响

用改性淀粉替代部分炭黑填充丁苯橡胶(SBR)/顺丁橡胶(BR)并用胶,考察了改性淀粉用量及偶联剂种类对混炼胶硫化特性及硫化胶物理机械性能和动态力学性能的影响.结果表明,用改性淀粉替代部分炭黑可对SBR/BR混炼胶的硫化产生明显的延迟作用,但改性淀粉用量的变化对焦烧时间与正硫化时间影响不大;添加偶联剂KH-570或NDZ-201延迟了混炼胶的硫化过程,KH-550能大幅度地促进硫化作用,Si-69对于体系的硫化性能略有影响;随着改性淀粉用量的增加,SBR/BR硫化胶的拉伸性能、耐磨耗性均有所降低,但弹性、动态生热和滞后性能得到了明显改善,改性淀粉最佳用量为5～8份;各种偶联剂均可提高SBR/BR硫化胶的拉伸性能,硅烷偶联剂Si-69和KH-570对弹性和动态生热也略有改善,添加偶联剂KH-550改善了SBR/BR硫化胶的抗湿滑性能,但滞后性能变差,添加偶联剂KH-570或Si-69对SBR/BR硫化胶动态力学性能的影响较小,综合考虑,以添加偶联剂KH-570较好.     

Properties of high‐impact polystyrene/organoclay nanocomposites synthesized via in situ polymerization

High‐impact polystyrene (HIPS)/organically modified montmorillonite (organoclay) nanocomposites were synthesized via in situ polymerization. The effects of the organoclay on the morphology and material properties of HIPS/organoclay nanocomposites were investigated. X‐ray diffraction and transmission electron microscopy experiments revealed that intercalation of polymer chains into silicate layers was achieved, and the addition of nanoclay led to an increase in the size of the rubber domain in the composites. In comparison with neat HIPS, the HIPS/organoclay nanocomposites exhibited improved thermal stability as well as an increase in both the complex viscosity and storage modulus. The presence of intercalated organoclay drastically enhanced the gas‐barrier properties because of the increase in the tortuosity of the diffusive path for a penetrating gas molecule. Some mechanical properties, including the tensile modulus, were superior to those of conventional HIPS. Finally, the preparation of the nanocomposites with a minimal loss of impact properties was proposed through changes in the synthetic procedure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008