Styrene Emulsion Research Articles

DEVELOPMENT OF HYDROGENATED SBR-BASED VULCANIZATE WITH SUPERIOR TIRE TREAD PERFORMANCE

ABSTRACT Currently, the tire industry is exploring eco-friendly tires with improved rolling resistance, traction, abrasion resistance, and fatigue properties. The present study investigates the potentiality of the hydrogenated styrene butadiene rubber (HSBR), a special and modified grade of styrene butadiene rubber (SBR) as a tyre tread material. The rheological, mechanical, dynamic mechanical, abrasion resistance, fatigue resistance, aging resistance and ozone resistance properties of the developed HSBR-based composites were critically evaluated and compared with those of conventional rubbers such as natural rubber (NR), emulsion styrene butadiene rubber (ESBR) and solution styrene butadiene rubber (SSBR) based composites. Interestingly, the HSBR-based vulcanizates exhibited superior modulus, tensile strength, abrasion resistance, fatigue crack growth resistance, resistance to thermo-oxidative aging, and ozone resistance as compared to the conventional SBR–based vulcanizates. The modulus at 300% elongation of the HSBR-based vulcanizate was approximately 74% and 11% higher than that of the ESBR- and SSBR-based composites, respectively, whereas the improvements in tensile strength were approximately 88% and 64% and the improvements in abrasion resistance were approximately 250% and 200% than that of the ESBR and SSBR vulcanizates, respectively. The tensile strength and fatigue resistance characteristics of the HSBR vulcanizate were also nearly similar to those of the NR vulcanizate. The findings demonstrate that HSBR can be a potential tire tread material with robust physico-mechanical properties and durability.

Use of vegetable oils as an alternate to naphthenic oil for extension of emulsion styrene butadiene rubber

Various petroleum based mineral oils like Distillate Aromatic Extract (DAE), Treated Distillate Aromatic Extract (TDAE), Residual Aromatic Extract (RAE) and Naphthenic oils are used for extension of emulsion polymerized Styrene Butadiene Rubber (E-SBR). Vegetable oils are alternate to these petroleum oil from sustainability point of view as vegetable oils have no Polycyclic Aromatic (PCA) content. They improve abrasion resistance leads to less rubber particulates spread in the environment and reduce rolling resistance leads to lower fuel consumption. However, introduction of few vegetable oils leads to slow down the cure reaction due to high unsaturation to saturation ratio. Presence of high fatty acid content in vegetable oils help in better rubber-filler interaction. In the present research, vegetable origin oils as such without any modification (Decas, Palmolein, Groundnut, Soybean, Mustard and Coconut) extended Styrene Butadiene Rubber (OE-SBR) were characterized in standard American Society for Testing and Materials (ASTM) compound recipe for various processing, different vulcanizate and other performance properties. Curative’s dosages were adjusted in the recipe of vegetable oil extended SBR’s to achieve the 300% modulus value like naphthenic oil. Vegetable oil extended Emulsion Styrene Butadiene Rubber (E-SBR) grades (Prepared with Palmolein and Coconut oils) were showing comparable rheometric and stress-strain properties, high reinforcement index (around 5%), better rubber-filler interaction parameter (around 12%), better abrasion resistance (around 23%) and comparable tanδ value @0°, 30° and 60°C as compared to naphthenic oil extended SBR based compound.

Double hydrophilic thermo-sensitive macro-RAFT agents as stabilizers and control agents in styrene emulsion polymerization

Double hydrophilic thermo-sensitive macro-RAFT agents as stabilizers and control agents in styrene emulsion polymerization

Vegetable oil extended emulsion styrene butadiene rubbers for passenger car radial tire tread application

Currently emulsion polymerized Styrene Butadiene Rubber (E-SBR) is extended with various petroleum based mineral oils like Distillate Aromatic Extract (DAE), Treated Distillate Aromatic Extract (TDAE), Residual Aromatic Extract (RAE) and Naphthenic oils. It is obvious that introduction of vegetable oil should result in almost zero Polycyclic Aromatic Content (PCA) content and therefore, are environmentally friendly, renewable, and sustainable. In the present work, vegetable oil extended Styrene Butadiene Rubber (OE-SBR) were characterized for chemical properties and found that all the properties were meeting the specification requirements of mineral oils extended grades. These rubbers were also evaluated in standard Passenger Car Radial (PCR) tire tread compound recipe for various processing, different vulcanizate and other performance properties. The developed grades with vegetable oils required less mixing energy (around 10% for master batch and 15% for final batch) and shown better flow behavior (around 15% power law index and 20% activation energy reduction), better carbon dispersion (around 20%), high reinforcement index (around 15%), better rubber-filler interaction parameter (around 20%), better abrasion resistance (around 20%) and lower tanδ value @60°C (around 15%) as compared to TDAE oil extended SBR based compound. This may help to improve life of a PCR tire and reduction in fuel consumption of the vehicle.

To explore extension of emulsion styrene butadiene rubber with modified vegetable oils

To explore extension of emulsion styrene butadiene rubber with modified vegetable oils

Effect of zinc dimethacrylate concentrations on properties of emulsion styrene butadiene rubber/butadiene rubber blends

ABSTRACT The influence of zinc dimethacrylate (ZDMA) on the properties of emulsion styrene butadiene rubber/butadiene rubber (ESBR/BR) blends was studied. Results revealed that torque difference, hardness, strengths, and total/ionic crosslink densities increased; whereas the elongation at break and covalent crosslink density reduced with increasing ZDMA. As ZDMA increased, the ionic crosslink density of the blends gradually increased. Optimum tensile and tear strength of the compound were observed at 12.5 phr of ZDMA. At 5 and 7.5 phr of ZDMA, the blends showed significant good healing efficiency, supported by the characterization tests such as scanning electron microscopy (SEM) and manual video measuring machine (VMM). Fourier-transform infrared spectroscopy (FTIR) analysis showed the presence of ZDMA in the blends. The dynamic ionic bond of ZDMA contributed to the self-healing properties in the blends. The zinc ions pair constituted the ion multiplet and ionic clusters, forming an ionic supramolecular network.

A rapid synthesis of nanofibrillar cellulose/polystyrene composite via ultrasonic treatment

A new method of the synthesis of nanofibrillar cellulose/polystyrene composite based on ultrasonic treatment of styrene emulsion in cellulose-water solution was elaborated. A new approach does not require additional heating and proposes a significantly faster synthesis (15 min, 45 °C) of the target composite compared to the methods described previously. A comprehensive analysis did not reveal any significant differences between mechanical, physical and biodegradable properties of the composite obtained by ultrasonic method and that one obtained by conventional thermal method, which requires much higher temperature (above 75 °C) and reaction duration (from 3 h).

EFFECTS OF EVEN FUNCTIONAL GROUP DISTRIBUTION IN EMULSION STYRENE–BUTADIENE RUBBER PREPARED BY REVERSIBLE ADDITION–FRAGMENTATION CHAIN TRANSFER POLYMERIZATION ON THE PROPERTIES OF SILICA-FILLED COMPOUNDS

ABSTRACT Recently, considerable attention has been paid to the development of new functionalized polymers to improve the fuel efficiency of vehicles by reducing the rolling resistance of tires to adhere to strict CO2 emission regulations. Accordingly, multifunctionalized (MF) reversible addition–fragmentation chain transfer (RAFT) emulsion styrene–butadiene rubbers (ESBR) were synthesized, in which chain-end and in-chain functionalization were performed simultaneously by introducing a third monomer (glycidyl methacrylate; GMA) using RAFT polymerization. Compared with GMA ESBR, in which GMA is introduced as a third monomer by conventional radical polymerization (CRP), there was an even distribution of GMA per chain in the MF-RAFT ESBR. After preparing the silica-filled compounds, vulcanizate structure analysis and mechanical property evaluation of the compounds were performed. The MF-RAFT ESBR prepared by RAFT polymerization exhibited superior in-chain functionalization efficiency compared with GMA ESBR prepared by CRP because of the even distribution of GMA and higher crosslink density. Consequently, MF-RAFT ESBR compound showed superior silica dispersion, abrasion resistance, and lower rolling resistance compared with the GMA ESBR compound.

Wet Friction of Rubbers Containing DAE or TDAE Process Oil in ESBR and ESBR/BR Blends

AbstractThe inevitable need to replace conventional high aromatic process oils with new safe ones has made it critically important to investigate the extent of tire wet grip modification by process oils’ aromatic content. Here, direct measurement of wet friction is conducted on emulsion styrene butadiene rubber (ESBR) and ESBR/butadiene rubber (BR) rubber blends containing either safe treated distillate aromatic extract (TDAE) or the conventional distillate aromatic extract (DAE) oils. Interestingly, the results reveal that the wet coefficient of friction for rubbers with TDAE is comparable or even better than rubbers with the DAE. This stands in contrast with previous predictions founded on indirect methods such as the values of loss factor tan δ at 0°C. Analysis of temperature dependent dynamic properties exhibits similar values of tan δ at 0°C for two oil types; however, a higher level of loss tangent for TDAE is found near the glass transition temperature. It is hypothesized that the frequency of loading imposed by the microtexture of the concrete counterface may have dictated the temperature range in which the TDAE can surpass the DAE in terms of the wet grip performance. The difference in the wet grip of rubbers having two oils is more pronounced for the ESBR/BR blend system.

Effect of polyethylenimine on properties of emulsion styrene butadiene rubber/butadiene rubber blends

The purpose of this study was to evaluate the effect of polyethylenimine (PEI) on the properties of emulsion styrene butadiene rubber (ESBR)/butadiene rubber (BR) blends. PEI with molecular weight (Mw) of 800, 2,000, 25,000, and 270,000 g/mol with various ratios was successfully incorporated into ESBR/BR blends via rubber compounding method. Study showed almost 100% decrease in scorch time, ts2 in lower Mw PEI (800 and 2000 g/mol), compared to higher Mw PEI (25,000 and 270,000 g/mol) in ESBR/BR blends. PEI incorporated ESBR/BR blends showed an overall improvement in terms of tensile strength. Lower Mw PEI induced better tensile strength with an optimum value at 1.22 MPa, while higher Mw PEI induced better tear strength and self-healing ability. Incorporation of 5 phr PEI 270,000 g/mol in the blend successfully achieved the optimum self-healing efficiency of 71.5% at 160°C for 1 h. Phase separation occurred between higher Mw viscous PEI with rubber matrix at crack region to promote thermal self-healing. PEI molecules were found to be accumulated and assembled on the interface of the rubber chain from scanning electron microscopy (SEM) images. It was suggested weak physical bond interaction such as Van der Waals holding both rubber chains and PEI together, without any changes in the rubber chain backbone.

Enhancing mechanical performance and wet‐skid resistance of emulsion styrene butadiene rubber/natural rubber latex composites via in‐situ hybridization of silanized graphene oxide and silica

AbstractThe wet skid resistance and thermal conductivity of “green tire” are the focus of research. In this work, through the use of different types of silane coupling agents, the surface of SiO2 and graphene oxide (GO) were grafted with amino and epoxy groups, respectively. The in‐situ generated SiO2 was grafted to the surface of GO by ring‐opening reaction of amino and epoxy groups. The emulsion styrene butadiene rubber/natural rubber latex (ESBR/NRL) composites were prepared by gas assisted spray flocculation process to improve the dispersion performance of hybrid filler. Because the surface of the hybrid filler contains amino and epoxy groups, it can be added as a reactive compatibilizer into the ESBR/NRL composites to improve the interface compatibility and synergistic reinforcement effect. Compared with the composites filled with SiO2, the composites filled with hybrid filler have excellent wet skid resistance and mechanical properties. When the mass ratio of GO to SiO2 is 3:10, the mechanical properties and wet skid resistance of rubber composites increase by 96.7% and 20.6%, respectively. Our preparation method of hybrid filler and flocculation process of rubber composites have broad application prospects in “green tire.”

LIQUID POLYBUTADIENE EXTENDED ESBR/SILICA WET-MASTERBATCH COMPOSITES FOR IMPROVING ABRASION RESISTANCE AND DYNAMIC PROPERTIES OF TIRE TREAD COMPOUNDS

ABSTRACT Silica wet-masterbatch (WMB) is a well-known technique for manufacturing high-content, highly dispersed silica-filled compounds. Emulsion styrene–butadiene rubber (ESBR)/silica WMB offers several advantages, including excellent silica dispersion and reduced hysteresis, as compared with conventional dry masterbatch (DMB) compound. However, because of the residual emulsifiers in ESBR latex, it can exhibit a decrease in the crosslink density and reductions in its mechanical properties. Moreover, the abrasion resistance cannot be significantly enhanced because of the tradeoff between the improvement in silica dispersion and decrease in crosslink density. Accordingly, the objective of this study was to improve the silica dispersion and abrasion resistance of ESBR/silica WMB compounds by using liquid polybutadiene rubber (LqBR) extended WMB. In detail, three types of LqBR were emulsified to LqBR emulsions, and three types of LqBR extended WMBs were produced by co-coagulating ESBR latex, silane-modified silica, and the LqBR emulsion. A thorough characterization was conducted with emphasis on the silica content, cure characteristics, mechanical properties, abrasion resistance, and dynamic viscoelastic properties. Based on the results, silane-terminated LqBR extended WMB vulcanizate showed a 58% improvement in the 300% modulus, 48% reduced DIN abrasion loss, and a 23% improvement in dynamic properties.

Investigation of Polystyrene-Based Microspheres from Different Copolymers and Their Structural Color Coatings on Wood Surface

Six kinds of polystyrene (PSt)-based colloidal microspheres were synthesized by adding acrylic acid (AA), methyl methacrylate (MMA), and butyl acrylate (BA) as comonomers in styrene emulsion polymerization. The structurally colored coatings on a wood surface were self-assembled by thermally assisted gravity deposition of these microspheres. Chemical compositions and structures of microspheres and morphological characteristics of microspheres and structural color coatings, as well as optical properties of coatings and their generated structural colors, were studied. Pure PSt microspheres had a smooth surface and uniform structure, while microspheres of copolymers had core–shell morphologies and a rough surface. Only poly(styrene-acrylic acid) (P(St-AA)) microspheres had good monodispersity and the resulting coating had a well-ordered photonic crystal structure. However, other kinds of microspheres could form short ranges of ordered amorphous photonic crystal structures and they displayed structural colors. Both the reflectivity of coatings to visible light and structural colors varied with microsphere size and self-assembly temperature.

Polystyrene latex particles bearing primary amine groups via soap‐free emulsion polymerization

AbstractPolystyrene latexes were prepared in the presence of an amino‐containing functional comonomer, N‐(3‐aminopropyl)methacrylamide hydrochloride (APMH), via soap‐free batch emulsion polymerization initiated by the cationic initiator 2,2′‐azobis(2‐amidinopropane) dihydrochloride. These latexes were characterized by studying the influence of the ionic comonomers on the polymerization kinetics, particle size, surface charge density and colloidal properties. The synthesized latexes were monodisperse with a final size between 100 and 600 nm depending on the APMH concentration. The initial polymerization rate and the particle number increased in accordance with the Smith–Ewart theory for soap‐free styrene emulsion polymerization with a hydrophilic functional comonomer. The final functionalization rate of the particles has been particularly studied with the intention of fitting the prepared latexes to be used in the immobilization of biological molecules for biological sample preparation and diagnostic applications. © 2020 Society of Chemical Industry

Hybrid styrene emulsion polymerization: bare, encapsulated and pickering morphologies

In this work, the Pickering emulsion polymerization of styrene (STY) with silica nanoparticles as stabilizers and ammonium persulfate (APS) as initiator, was studied. The effects of several co-aids, considered as modifying agents to vary the compatibility of colloidal silica (Ludox AM) between the polymer interface during the emulsion polymerization, are evaluated. Sodium vinyl benzene sulfonate, 4-vinyl pyridine, poly(ethylene glycol) methyl ether methacrylate (PEGMA), and cetyltrimethylammonium bromide (CTAB) surfactant, are appraised. The obtained emulsions range from bare, hybrid encapsulated and Pickering nanoparticles. The obtained Pickering emulsion formulation requires smaller amounts of co-aids, as compared to the reported recipes from the literature.

Polystyrene-polyaniline core-shell composite particles using a bifunctional selectively polymerizable monomer as the interfacial linkage

Polystyrene-polyaniline core-shell composites were synthesized using a bifunctional monomer (benzenaminium 4-styrenesulfonate) as the interface. For the core synthesis, the monomer allowed the stabilization of styrene emulsion polymerizations, performing the function of a conventional reactive surfactant, copolymerizing with styrene by free radical polymerization. Then, the monomer allowed the synthesis of polyaniline in the emeraldine salt form by oxidative polymerization to obtain the shell. It was found that the particle size was inversely dependent on the monomer content, as established by the classical theory of emulsion polymerization. The product obtained is a complex system in which the core is a copolymer of styrene and styrenesulfonate and the shell is polyaniline with two doping agents. The polyaniline shell presented optical and electroactive properties, characterized by UV–vis spectroscopy and cyclic voltammetry. Finally, the core-shell was evaluated for H2S detection showing promising results for the design of electrochemical sensors.

Effect of Reversible Addition-Fragmentation Transfer Emulsion Styrene Butadiene Rubber (RAFT ESBR) on the Properties of Carbon Black-Filled Compounds.

Tread is an important component that directly affects the performance of passenger car radial (PCR) tires. Styrene-butadiene rubber (SBR) is mainly used for tire tread and it includes solution styrene-butadiene rubber (SSBR) and emulsion styrene-butadiene rubber (ESBR). Although SSBR is mainly used, the manufacturing process for SSBR is more challenging than ESBR, which is environmentally friendly, but has the disadvantage of a broad molecular weight distribution. To overcome this, a reversible addition-fragmentation radical transfer (RAFT) polymerization technique is used in ESBR polymerization. An environmentally friendly RAFT ESBR with a narrow dispersity can be polymerized. Here, carbon black-filled compounds were manufactured while using RAFT ESBR, and their properties were compared to ESBR. The analysis showed a low crosslink density of RAFT ESBR, due to the high polysulfide crosslink structure. We manufactured a carbon black-filled compound with the same crosslink density and structure as the ESBR carbon black-filled compound, and the effect of the dispersity of the base polymer was investigated. RAFT ESBR showed 9% better abrasion resistance and 29% better fuel efficiency than ESBR, according to the analysis of the data. The narrow dispersity can reduce energy loss and positively influence the abrasion resistance and fuel efficiency.

Microsuspension Polymerization of Styrene Using Cellulose Nanocrystals as Pickering Emulsifiers: On the Evolution of Latex Particles.

We report a mechanistic study of the microsuspension polymerization of styrene stabilized by cellulose nanocrystals (CNCs) in its native form as well as graft-modified with copolymers of styrene and N-3-(dimethylamino)propyl methacrylamide (DMAPMAm) or N,N-(diethylamino)ethyl methacrylate (DEAEMA). Native CNCs and graft-modified CNCs were shown to form stable styrene emulsions with an average droplet diameter of 18-20 and 5-9 μm, respectively. Initiators of widely varying water solubilities [2,2'-azobisisobutyronitrile (AIBN), 2-2'-azobis(2,4-dimethylvaleronitrile) (Vazo-52), and lauroyl peroxide (LPO)] were employed for the polymerizations. The type of initiator and the type of CNC were shown to directly affect the microsuspension polymerization kinetics, particle size, and molecular weight distribution. Using AIBN and Vazo-52, submicron latex particles were observed in the final latex in addition to the desired 3-20 μm CNC-armored microsuspension particles. The resulting latex and microsuspension polystyrene particles were studied for their CNC coverage and surface charge. We found that the presence of CNCs in the aqueous phase did not lead to Pickering emulsion polymerization by heterogeneous nucleation.

Preparation of monodisperse polymer particle via an in situ charge neutralization-controlled particle coagulation mechanism in macroemulsion polymerization

Styrene emulsion polymerizations using sodium dodecyl sulfate as an anionic surfactant and in the presence of cationic initiators 2, 2′- Azobis (2-methylpropionamidine) dihydrochloride (AIBA) and 2,2′-azobis(N,N′-dimethyleneisobutyramidine) dihydrochloride (ADIBA) were studied. In this work, an explanation for in situ charge neutralization is proposed, and the effect of in situ charge neutralization on the particle size distribution of the ultimate polymer particles is discussed. Charges of cationic radicals from initiator decomposition shield the anionic charges of surfactant molecules adsorbed on the particle surface and induce particle coagulation during the early particle formation period. As the occurrence of in situ charge neutralization, the particle number decreases and the rate of micelle capture for the initiator radical is enhanced. Thus, the particle nucleation period is shortened, and monodisperse polymer particles with a diameter of ～200−300 nm are prepared using this simple emulsion polymerization process. In addition, hydrolysis of the initiator AIBA at different pH conditions is used to control particle size and stability. Compared to conventional emulsion polymerization theories, the emulsion polymerization in the presence of in situ charge neutralization presents unique kinetics.

In situ conversion monitoring of styrene emulsion polymerization by deconvolution of a single reference band near 1,000 cm−1

AbstractStyrene emulsion polymerization was performed in batch reactor using Raman spectroscopy for in situ monitoring of styrene conversion. The variation of the band of trigonal aromatic ring breathing at 1,000 cm−1 was analyzed in detail as a function of monomer conversion (wavenumber, integrated intensity, and half‐width at half‐maximum). The observed variation was described both qualitatively and quantitatively by a model assuming that the overall signal resulted from the addition of two close and distinct Gaussian signals, one originating from the monomer and the other one from the polymer repeat units. A reliable estimation of monomer conversion was obtained using the relative contributions of both components. The results were comparable to those obtained using the ratio of integrated intensities of the band at 1,000 cm−1 (overlapping signals of monomer and polymer) and the band at 1,631 cm−1 (signal specific to monomer). It was shown experimentally that information about monomer conversion could be obtained by applying linear model mixture to a single band of Raman spectrum, which provided an alternative method to the use of a ratio of integrated intensities.