Natural Rubber/styrene Butadiene Rubber Research Articles

Enhancement of the cure behavior and mechanical properties of nanoclay reinforced NR/SBR vulcanizates based on waste tire rubber

The most important goal of this work was to investigate the different physical and mechanical properties of the nanoclay (montmorillonite, MMT)-filled 50/50 wt.% of natural rubber/styrene butadiene rubber (NR/SBR) blend containing 40 phr of waste tire rubber (WTR) in the presence of bio-resin. The MMT was added into the NR/SBR/WTR blends and processed via a two-roll mill to prepare blends at 0, 5, 10, 15, and 20 phr of nanoclay filler and a constant concentration of 10 phr of bio-resin. The morphology, rheological, percent of swelling weight, and mechanical properties of the MMT-reinforced NR/SBR/WTR blends were examined. The cure characteristics of the blends showed that MMT significantly affected the scorch and vulcanization times, torques, and curing rate of NR/SBR/WTR blends at all filler contents. Also, the findings revealed that the MMT was an efficient reinforcing material for the NR/SBR/WTR blend, improving crosslink density, tensile and tear strengths, hardness, compression set, and abrasion resistance. The tensile strength of filled NR/SBR/WTR blends achieved its maximum value (11.2 MPa) when the MMT content was 15 phr. While the elongation percent of the filled blends decreased for all MMT concentrations compared with the pristine blend. The elastic modulus and tear strength of the blends improved as the MMT loading increased. The hardness (Shore A) continued to increase with increasing MMT loading. On the contrary, the rebound resilience gradually decreased leading to improved interaction between the matrix and filler.

Effect of Morphology/Structure on the Phase Behavior and Nonlinear Rheological Properties of NR/SBR Blends.

The evolution of the morphology/structure and the nonlinear viscoelasticity of rubber blends under large amounts of strain are key scientific issues for the design and manufacture of rubber blends. The rheological responses of natural rubber/styrene-butadiene rubber (NR/SBR) blends are traced over a wide range of blend compositions to gain an insight into the effect of blend morphology on their nonlinear viscoelasticity. We also prepare NR + SBR physical blends without melt mixing to distinguish the contributions of composition and blend morphology to the viscoelastic response. The microscopic heterogeneous gel-like structure of NR/SBR blends may remarkably weaken their strain softening and improve their modulus hysteretic recovery under large strain, which may be attributed to the heterogeneous microscopic deformation for the NR and SBR phases. Furthermore, additional elastic contribution resulted from the increasing interfacial energy of domain deformation. This may provide some new insights into the effect of blend morphology on the Payne effect of rubber blends.

Mechanical and morphology characteristics of natural rubber-styrene butadiene rubber (NR-SBR) blends in the presence of natural microbentonite

Natural rubber (NR) has been the world renewable natural elastomer produced mainly in South East Asia from the sap of rubber tree (hevea brasiliensis). However it only exported to manufacturing countries for production of various engineering and specialty rubber products. Blending of the natural rubber with synthetic rubber such as styrene butadiene rubber (SBR) is a mean to improve engineering specification of the NR, especially due to exposure of mineral oils during its service life. Whereas natural microbentonite functions not only as filler but also as coagulant breaker in both SIR-10 and SBR matrices, which improves miscibility of the blends. In this work blending of Indonesian natural rubber (NR: SIR-10) with styrene butadiene rubber (SBR) were carried out in reflux reactor in xylene solution in the presence of various loading of natural microbentonite as fillers. Miscibility of the blends were measured from their mechanical properties as well as morphology of their fracture surfaces using electron microscopy (SEM). It was found that optimum loading of microbentonite in the NR/SBR (weight ratio: 50/50) blend was 3 per hundred rubber (phr), which showed good adhesion of the rubber matrices onto the filler surface and without any agglomeration.

Friction and wear study of NR/SBR blends with Si3N4Filler

The aim of this paper is to investigate mechanical and frictional properties of natural rubber/styrene butadiene rubber (NR/SBR) blends with and without silicon nitride (Si3N4) filler. The rubber is surface modified by silane coupling agent (Si-69) for enhancing hydrophobic property. The Si3N4of percentage 0 1, 3, 5 and 7, is incorporated into NR/SBR rubber compounds with 20% precipitated silica. The specimens with and without fillers are prepared as per standard for tensile and friction testing. Fourier transform infrared (FTIR) spectroscopy test is conducted and it is inferred that the coupling agent is covalently bonded on the surface of Si3N4 particles and an organic coating layer is formed. The co-efficient of friction and specific wear rate of NR/SBR blends are examined using an in-house built friction tester in a disc-on-plate (DOP) configuration. The specimens are tested to find coefficient of friction (COF) against steel grip antiskid plate under dry, mud, wet and oil environmental conditions. It is found that the increase in tensile strength and modulus at low percentage of Si3N4 dispersion. It is also observed that increase in sliding friction co-efficient and decrease in wear rate for 1% of Si3N4 dispersion in NR/SBR blends. The friction tested surfaces are inspected using Scanning Electron Microscope (SEM) and 3D non contact surface profiler.

Effect of carbon black composition with sludge palm oil on the curing characteristic and mechanical properties of natural rubber/styrene butadiene rubber compound

This study was conducted to investigate the possibility of utilizing sludge palm oil (SPO) as processing oil, with various amount of carbon black as its reinforcing filler, and its effects on the curing characteristics and mechanical properties of natural rubber/styrene butadiene rubber (NR/SBR) compound. Rubber compound with fixed 15 pphr of SPO loading, and different carbon black loading from 20 to 50 pphr, was prepared using two roll mills. The cure characteristics and mechanical tests that have been conducted are the scorch and cure time analysis, tensile strength and tear strength. Scorch time (ts5) and cure time (t90) of the compound increases with the increasing carbon black loading. The mechanical properties of NR/SBR compound viz. the tensile strength, modulus at 300% strain and tear strength were also improved by the increasing carbon black loading.

NR/SBR composites reinforced with organically functionalized MWCNTs: simultaneous improvement of tensile strength and elongation and enhanced thermal stability

Abstract Butyl acrylate-α-methyl methacrylate-glycidyl methacrylate (BA-MMA-GMA) terpolymer was successfully grafted onto carbon nanotubes (CNTs) via a facile grafting functionalization approach, affording an organically functionalized multiwalled CNTs (O-MWCNTs), which show improved mechanical and thermal properties in natural rubber/styrene-butadiene rubber (NR/SBR) composites. Under optimized conditions, the result of elongation at break of NR/SBR composites combined with 1.5 parts per hundred rubber (phr) O-MWCNTs is 450% compared to 376% of pristine NR/SBR composites, which is proportional to tensile strength due to the mixed O-MWCNTs in the rubber matrix. Transmission electron microscopy study shows that O-MWCNTs (1.5 phr) can disperse uniformly in NR/SBR/O-MWCNT composites. A scanning electron microscopy study on the fractured surface morphology of the optimized composites reveals that a BA-MMA-GMA terpolymer can interact with the rubber matrix strongly. The decreased height of the maximum tanδ peak shows that O-MWCNTs can reduce the heat buildup and damping capability of NR/SBR/O-MWCNT composites. The largest enhancement observed in the thermal degradation curves of composites is, for the first time, about 70°C, which can be attributed to enhanced interfacial interaction between MWCNTs and the rubber matrix.

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

CURE CHARACTERISTICS AND CROSSLINK DENSITY OF NATURAL RUBBER/STYRENE BUTADIENE RUBBER BLENDS

By using a semi-efficient vulcanization system, the cure characteristics and crosslink density of natural rubber/styrene butadiene rubber (NR/SBR) blends were studied with a blend ratio from 0 to 100% rubber. The scorch time, optimum cure time, and torque difference value of the blended rubber compounds were determined by using the Moving-Die Rheometer (MDR 2000). The crosslink density was determined by the Flory—Rehner approach. Results indicate that the scorch and cure times, ts2 and t90, of the NR/SBR blends increased with increasing the SBR content. Whilst, the maximum values of torque difference and crosslink density were performed by the NR/SBR blend with a blend ratio of 75/25.

Applicability of a Non-Gaussian-Type Tube Model to Filler-Reinforced Rubber Networks: Data Analysis for Carbon Black-Filled Networks

In a previous paper, the author compared the fit to natural rubber/styrene-butadiene rubber (NR/SBR) unfilled network experiments of his finite extensibility tube model for non-filled rubber networks and another model similar to it. This work extended the above comparison to the same rubber networks loaded with carbon black (CB), based on the two rubber elasticity models for unfilled rubber networks. As a result of the comparative study, our treatment was able to provide more favorable data fittings compared to the other, although there is still need for improvement. Also, this study gave a description of the Mullins softening on the assumption that the CB networks formed in the rubbers were broken up during their deformation.

Determination of characteristics of natural rubber/styrene–butadiene rubber-based elastomer material filled with mica powder and glass spheres

Different filler materials are widely used in industry both for obtaining better mechanical properties and decreasing the overall costs. In this study, several uniaxial tensile tests were conducted for 5.15% (MP1-GS1), 9.4% (MP2-GS2), and 13.4% (MP3-GS3) of glass spheres and mica powder-filled elastomer materials. In this research, the results obtained from tensile tests of samples made of natural rubber/styrene–butadiene rubber (NR/SBR)-based elastomer materials in which different amount of glass spheres (GS) and mica powder (MP) mixed were characterized using the finite element method. The values of forces and displacements obtained from the tests were transferred to ABAQUS 6.7 finite element analysis (FEA) software. Among all hyperelastic material models, Marlow’s model was found to be the most suitable one and was utilized as a material model in the FEA. Mechanical tests and the finite element results were compared with each other. Comparison of the results show that while the error percentage changed between 0.01 and 0.5% for the MP-filled samples, the error percentage changed between 0.25 and 0.5% for GS-filled samples. The effects of MP and GS filler materials on the mechanical properties of NR/SBR elastomer were compared. Maximum stress and strain values were observed in GS2 and MP2 materials.

The network and properties of the NR/SBR vulcanizate modified by electron beam irradiation

A natural rubber/styrene butadiene rubber (NR/SBR) vulcanizate filled with carbon black was modified by high-energy electron beam (EB) irradiation in this work. The crosslinked structure was studied by a special chemical probe method. The influence of EB irradiation on mechanical properties, filler network, and dynamic properties including abrasion resistance, rolling resistance, and wet skid resistance was also investigated. The results revealed that the crosslink structure significantly changed after EB treatment, indicating that the amount of poly- and di-sulfide crosslinked bonds decreased and that of mono-sulfide bonds increased. The polymer–filler interaction was enhanced after EB irradiation. An EB dose of 600kGy reduced the abrasion loss of the NR/SBR vulcanizate, and one of 300kGy reduced the rolling resistance by 11.4%. Meanwhile, EB doses below 200kGy had no obvious effect on the wet skid resistance. This EB-modified NR/SBR vulcanizate can be used to prepare high-performance tires with good abrasion resistance and low rolling resistance.

Raman spectroscopy and thermal analysis of gum and silica-filled NR/SBR blends prepared from latex system

Natural rubber/styrene-butadiene rubber (NR/SBR) blends, with and without silica, were prepared by co-coagulating the mixture of rubber latices and various amounts of well-dispersed silica suspension. An attempt to predict blend compositions was made using Raman spectroscopy in association with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was found that the intensity of each Raman characteristic peak was strongly dependent on the blend composition, but there was no significant evolution with the presence of silica. Also, TGA results revealed an improvement in thermal stability of NR/SBR blends with increasing both SBR and silica contents due to the dilution effect. Two distinct glass transition temperatures (Tg) were observed in DSC thermograms of all blends, and their Tg values were independent on both blend composition and silica content. This indicated a physical blend formation, which agreed well with no shifts in Raman peaks of the blends in comparison with those of the individual rubbers. Linear regression with R2 quality factor close to 0.99 was achieved when plotting intensity ratio at 1371/1302 cm−1 versus blend ratios. On the other hand, the peak height ratio and heat capacity ratio from TGA and DSC analysis, respectively, yielded quadratic equations as a function of blend ratios.

Effects of Carbon Nanotube on Tensile and Dynamic Mechanical Properties of NR/SBR and NR/XSBR Nanocomposites Prepared by Latex Compounding

In this study, natural rubber/styrene butadiene rubber (NR/SBR) and NR/carboxylated styrene butadiene rubber (NR/XSBR) nanocomposites with carbon nanotube (CNT) were prepared by a latex compounding method. The dry weight ratio of either NR/SBR or NR/XSBR was fixed to 80/20 and the CNT loading in each blend was varied from 0.1 to 0.4 phr. The nanocomposite latices were cast into sheets on a glass mold and then cured at 80°C for 3 h. The tensile properties (tensile strength, modulus at 300% strain, elongation at break) and dynamic mechanical properties (storage modulus, loss tangent) of the vulcanizates were then evaluated. The results showed that the addition of CNT at a very loading could enhance the tensile strength, modulus at 300% strain and storage modulus of these two rubber bends in a dose dependent manner, except that the tensile strength peaked at an optimum filler level, declining at higher filler loadings, whilst the elongation at break deteriorated. Moreover, the tensile strength and modulus at 300% strain of the NR/XSBR nanocomposites appeared to be higher than those of the NR/SBR nanocomposites at the same CNT loadings.

Effect of surface‐modified zinc oxide as cure activator on the properties of a rubber compound based on NR/SBR

AbstractZinc oxide (ZnO) and nano‐zinc oxide (nZnO) were surface modified by polyethylene glycol (PEG) and poly propylene glycol (PPG). Modification of particles were controlled by transmission electron microscopy, Brunauer, Emmett, Teller specific surface area measurement, infrared (IR) spectroscopy, and differential scanning calorimetry. IR spectra were shown that the interactions between surface modifiers and particles are hydrogen bonding. Modified particles were applied as an activator in vulcanization of natural rubber/styrene butadiene rubber (NR/SBR) blend. Dispersion of modified particles in rubber matrix was investigated by scanning electron microscopy and shown good results. Blend properties were improved by using modified particles. These improvements were due to the better hydrophobicity of modified particles, which were more compatible with nonpolar rubber matrix and caused better participation in curing process. Modification by PEG and PPG were shown better compound properties for ZnO and nZnO, respectively. Application of ZnO‐modified particles were presented better compound properties in comparison with nZnO‐modified particles. It has confirmed more effective mixing of ZnO‐modified particles in rubber matrix by using ordinary mixers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Fly‐ash particles and precipitated silica as fillers in rubbers. II. Effects of silica content and Si69‐treatment in natural rubber/styrene–butadiene rubber vulcanizates

AbstractThis article explored the possibility of using silica from fly‐ash particles as reinforcement in natural rubber/styrene–butadiene rubber (NR/SBR) vulcanizates. For a given silica content, the NR : SBR blend ratio of 1 : 1 (or 50 : 50 phr) exhibited the optimum mechanical properties for fly‐ash filled NR/SBR blend system. When using untreated silica from fly‐ash, the cure time and mechanical properties of the NR/SBR vulcanizates decreased with increasing silica content. The improvement of the mechanical properties was achieved by addition of Si69, the recommended dosage being 2.0 wt % of silica content. The optimum tensile strength of the silica filled NR/SBR vulcanizates was peaked at 10–20 phr silica contents. Most mechanical properties increased with thermal ageing. The addition of silica from fly‐ash in the NR/SBR vulcanizates was found to improve the elastic behavior, including compression set and resilience, as compared with that of commercial precipitated silica. Taking mechanical properties into account, the recommended dosage for the silica (FASi) content was 20 phr. For more effective reinforcement, the silica from fly‐ash particles had to be chemically treated with 2.0 wt % Si69. It was convincing that silica from fly‐ash particles could be used to replace commercial silica as reinforcement in NR/SBR vulcanizates for cost‐saving and environment benefits. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

A New Approach to Improved Properties of Rubber Vulcanizates Containing White Molybdates

ABSTRACT Incorporation of fillers in rubber results in a profound effect on rheological and mechanical properties of the formed composites. Fillers are customarily classified into organic and inorganic. The latter class includes calcium carbonate, talc, barium sulfate, kaolin, silica, etc. Molybdates are inorganic, nontoxic white pigments combined with reasonable pricing range and controlled solubility. The purpose of this study was to employ white molybdates and study their role as reinforcing fillers that can replace traditional carbon black, or semi-reinforcing furnance black (SRF), with both natural rubber (NR) and a blend of natural rubber-styrene butadiene rubber (NR-SBR), to show the modification of rheometric characteristics, tensile strength, strain at break, hardness, Young's modulus, swelling in toluene, thermal oxidative aging, and calculation of the rubber-filler interaction after the addition of such fillers.

Fatigue and Mechanical Properties of NR/SBR and NR/NBR Blend Vulcanizates

One of the important considerations in the selection of a polymer blend for a practical application is how it resists crack growth and/or failure from a material flaw, under static or fatigue conditions. The blending of two or more rubbers is a useful technique to improve certain properties not inherent in a single rubber. In the present work, fatigue and mechanical failure tests have been performed to evaluate the behaviour of blend vulcanizates of natural rubber/styrene butadiene rubber (NR/SBR) and natural rubber/butadiene acrylonitrile rubber (NR/NBR). It has been found that the fatigue life and the strain energy varies linearly with blend composition in the compatible blend (NR/SBR), but they deviate from linearity in the case of the incompatible blend (NR/NBR). These results are in good agreement with the mechanical property measurements for the various compatible and incompatible blends studied.

Natural rubber-styrene butadiene rubber latex blends: Time-dependent rheological behavior and film formation

This article focuses mainly on the effect of maturation time on the rheological behavior of unvulcanized natural rubber (NR)–styrene butadiene rubber (SBR) latex blends. Viscosity shows a composition-dependent behavior with maturation time. It was found that there is a marginal decrease in viscosity for all the systems with maturation time except for the 70/30 NR–SBR blend. In this blend, there is a sharp decrease in viscosity with maturation time. This is associated with the exchange of stabilizers with one another until an equilibrium is reached; that is, all the particles of the blend are stabilized with random mixture of stabilizers. The structural build up observed in 70/30 NR–SBR blend was found to be diminished as the maturation time increases. At equilibrium, there is no further exchange of stabilizers. The behavior of this blend has been explained with the help of a schematic model. The effects of blend ratio and surface active agents on the viscosity were also studied. In addition, the time-dependent flow behavior of prevulcanized latex blends was evaluated as a function of vulcanizing systems and prevulcanization time. There is a regular increase in viscosity with prevulcanization time. However, after 3 h, the viscosity of almost all blends levels off, indicating that the curing reaction is complete within this time. Finally, the morphological changes occurred during film formation of the blends were studied using scanning electron microscopy. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1473–1483, 1998