Effects of overhalogenation of a synthetic vulcanized styrene–butadiene rubber sole on its adhesion behavior

The effects of halogenating the same synthetic vulcanized styrene–butadiene rubber (R2) (used as a sole material in the shoe industry) twice (double halogenation) using solutions of trichloroisocyanuric acid (TCI) in MEK were studied. The R2 rubber was treated with 0.5 and 2 wt% TCI/MEK solutions and after 1 h re-treated with additional 0.5 (0.5 + 0.5 wt% TCI/MEK) and 2 wt% TCI/MEK (2 + 2 wt% TCI/MEK) solutions. The results obtained were compared with those obtained by treating the R2 rubber once with 1 and 4 wt% TCI/MEK solutions. The surface modifications produced by the double halogenation of the R2 rubber were analyzed using advancing and receding contact angles (variations in wettability), XPS and ATR-IR spectroscopy (characterization of chemical modifications) and SEM (morphological modifications). T-peel tests on doubly halogenated R2 rubber/polyurethane adhesive joints were carried out to quantify the adhesion properties of the treated R2 rubber. The degree of chlorination was higher with increasing amount of chlorinating agent. Furthermore, the most efficient removal of hydrocarbon substances from the R2 rubber surface was obtained by double halogenation and by increasing the TCI concentration. Similar trends in surface chemistry of the R2 rubber were obtained using 0.5–2 wt% TCI/MEK, with or without double halogenation. On the other hand, by comparing the effects of treatments with 0.5 + 0.5 wt% TCI/MEK and 1 wt% TCI/MEK or with 2 + 2 wt% TCI/MEK and 4 wt% TCI/MEK, less effective removal of zinc stearate and less degree of chlorination were obtained by double halogenation although similar outermost surface modifications were produced. The second application of the TCI/MEK solution on the already halogenated R2 rubber dissolved the unreacted TCI and/or the isocyanuric acid crystals on its surface. The mechanical properties of the treated R2 rubber decreased because it became stiffer. Higher and relatively similar peel strength values were obtained in all adhesive joints prepared using treated R2 rubber. A cohesive failure in the rubber close to the chlorinated layer was always obtained.     

Chemical modification of styrene–butadiene–styrene (SBS) rubber by reactive grafting with maleic anhydride

A procedure to increase the adhesion of block styrene-butadiene-styrene (SBS) rubber consisting of the reactive grafting with maleic anhydride (MA) in the presence of an organic peroxide radical initiator is proposed. The influence of the reactive grafting on the surface properties of SBS has been studied with special emphasis on the improvement of the adhesion to polyurethane adhesive. The grafting of MA onto SBS was carried out in the presence of different concentrations of 2,5-dimethyl-2,5-di(tertbutyl peroxy) hexane (DBPH) as initiator to generate oxygen radicals by thermal decomposition, which induce the grafting reaction. The modification process was performed in the molten state using a Brabender mixer to premix the reactants and a hot press to initiate the functionalizing reaction. ATR-IR and XPS spectroscopies were employed to verify the grafting of MA on SBS. The changes in wettability on the modified SBS rubber were determined by contact angle measurements. Adhesion properties were evaluated from T-peel tests of SBS rubber/polyurethane adhesive joints. Reasonable extents of MA grafting on SBS were obtained (evidenced by the presence of a weak carbonyl vibration at 1700 cm^-1 in the ATR-IR spectra and by the carbon- oxygen band at a binding energy of 287.0 eV in the XPS spectra). The higher the DBPH amount, the higher the MA amount grafted onto the SBS surface. The maximum grafting level was obtained using 2 wt% MA. Grafted species seemed to be mainly concentrated on the surface of the SBS-molded sheets. The wettability of the modified rubber increased with respect to the original polymer, new carbon-oxygen moieties were created and the C/O ratio increased. A noticeable enhancement in peel strength values was observed, which was ascribed to the creation of interfacial interactions between the polyurethane and the SBS rubber surfaces.     

Thermal and mechanical enhancement of styrene–butadiene rubber by filling with modified anthracite coal

Anthracite is the highest rank of coal with a layered structure similar to that of graphite. Here, styrene–butadiene rubber/modified anthracite (MA) composites were prepared and analyzed. The microstructure and dispersion of the anthracite were improved by ball milling with the modifier bis-(γ-triethoxysilylpropyl)-tetrasulfide (KH-Si69). The particle size of the modified coal was decreased significantly to ~3 μm, while surface interactions with the modifier yielded enhanced lamellar morphology and hydrophobic surfaces. The anthracite lamellae were well dispersed in the rubber matrix, providing good reinforcement; the tensile strength of the composite exceeded that of a composite with carbon black (CB) N660 filler (16.65 vs. 14.68 MPa). Moreover, low-level CB or silica compositing further promoted the dispersion of coal particles in the rubber, effectively enhancing the mechanical reinforcement behavior of the coal particles as well as the thermal stability of the rubber composite. Notably, it led to a 10.63% improvement in tensile strength and a 9.96 °C increase in the 5% mass loss temperature compared to the composite with a single MA filler. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48203.     

Preparation and characterization of natural rubber/ultrafine full-vulcanized powdered styrene–butadiene rubber blends

In this paper, natural rubber (NR)/ultrafine full-vulcanized styrene–butadiene powdered rubber (UFPSBR) blends were prepared and studied for the first time. Scanning electron microscopy and thermogravimetric analysis were employed to characterize UFPSBR. Equilibrium swelling method was used to determine the crosslink density of NR/UFPSBR vulcanizates. The results on mechanical properties showed that when NR/UFPSBR ratio was 100/5, the formulation exhibited favorable performances compared to pure NR vulcanizates. The heat build-up temperature also decreased after adding UFPSBR into the NR formulation. In dynamic mechanical analysis, in the temperature range of ?10 to ?5 °C, loss factor (tanδ) values of NR/UFPSBR vulcanizates showed an increasing trend over the given temperature range and exhibited a peak value at approximate ?5 °C. This indicates that wet traction and rolling resistance of samples were improved after UFPSBR was added in NR. This research demonstrates that UFPSBR can be incorporated into a conventional NR formula to successfully improve the comprehensive performances and dynamic mechanical properties of NR formula.     

Phosphorylated cardanol prepolymer-grafted carboxylated styrene–butadiene rubber for better processing with enhancing silica filler dispersion

Cardanol is a byproduct of cashew industry of semiforest origin. It is cheap and available in humongous amount and acts as a multifunctional additive in rubber compounds. It can be oligomerized with orthophosphoric acid to make phosphorylated cardanol prepolymer (PCP). Hence, cardanol has been chemically grafted on to the backbone chain of carboxylated styrene–butadiene rubber (XSBR) by employing melt grafting technique in presence of peroxide initiator to include multifunctional properties. The PCP-grafted XSBR (PCP-g-XSBR) was characterized by using Fourier transform infrared spectroscopy and ¹H-NMR techniques and optimize the grafting conditions such as percent of grafting and grafting efficiency by using Taguchi methodology. PCP-g-XSBR was compounded with silica filler for a comparative study in terms of processing behavior with XSBR. The cure characteristics such as the cure rate and the optimum cure time of the unfilled PCP-g-XSBR compounds were determined by oscillating disc rheometer. The thermal analysis of PCP-g-XSBR vulcanizate exhibits slightly better thermal stability as well as plasticization effect. Morphological behaviors also display the less cracked and filled fracture surfaces with better filler dispersion in PCP-g-XSBR vulcanizate. The mechanical properties of the compounded PCP-g-XSBR vulcanizates also improve compare to XSBR vulcanizates. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47528.     

Chemical modification of styrene–butadiene–styrene co-polymer by grafting of N-carbamyl maleamic acid

A styrene–butadiene–styrene (SBS) block co-polymer was functionalized using different amounts of N-carbamyl maleamic acid (NCMA) and benzoyl peroxide as initiator. NCMA, which is a bifunctional monomer, was synthesized in our laboratories. The concentration of NCMA used in the functionalization of SBS ranged from 0.5 to 3% (w/w) based on the co-polymer mass. Benzoyloxy radicals generated from the thermal decomposition of benzoyl peroxide initiated the grafting reaction. The concentration of the initiator was kept constant at 0.076% (w/w). FT-IR spectroscopy was used to determine the amount of NCMA effectively grafted onto the SBS. The maximum amount of monomer grafted was about 0.3% (w/w) when the SBS was modified with 1% (w/w) NCMA. The effect of grafting on the surface properties and the adhesion to polyurethane adhesive of the modified SBS were evaluated. Contact angle values were obtained using liquid droplets. When the concentration of the NCMA used in the grafting reaction was 1% (w/w), the contact angles with water on original and modified SBS were 95° and 77°, respectively. Adhesion properties were evaluated by standard peel tests employing a commercial polyurethane adhesive. The modified SBS having the largest amount of NCMA displayed a T-peel strength value 5-times higher than the corresponding value measured with the original SBS.     

Structure–property relationships of silica/silane formulations in natural rubber,isoprene rubber and styrene–butadiene rubber composites

The mechanical performance of natural rubber (NR), synthetic poly-isoprene rubber (IR), and styrene–butadiene rubber (SBR) composites filled with various silica/silane systems is investigated. The results are analyzed by referring to micro-mechanical material parameters, which quantify the morphological and structural properties of the polymer and filler network. These are obtained from fits with the dynamic flocculation model (DFM) describing the strongly nonlinear quasi-static stress–strain response of filler-reinforced elastomers as found from multihysteresis measurements of the investigated compounds. We focus on the reinforcement mechanisms of silica compounds with coupling and covering silane, respectively. The fitted material parameters give hints that the coupling silane provides a strong chemical polymer–filler coupling, which is accompanied by improved strength of filler–filler bonds for all three rubbers types. This may result also from the chemical coupling of short chains bridging adjacent silica particles. It implies larger stress values for the coupling silane and, in the case of NR and IR, a more pronounced “Payne effect” compared to the covering silane. In contrast, for SBR, the coupling silane delivers a lower Payne effect, which is explained by differences in the compatibility between rubber type and silane-grafted silica surface. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48435.     

Thermal decomposition kinetics of dynamically vulcanized polyamide 6–acrylonitrile butadiene rubber–halloysite nanotube nanocomposites

Thermally stable thermoplastic elastomer nanocomposites based on polyamide 6 (PA6), acrylonitrile butadiene rubber (NBR), and halloysite nanotubes (HNTs) were dynamically vulcanized, and their nonisothermal decomposition kinetics were examined. The Friedman, Kissinger–Akahira–Sunose (KAS), Ozawa–Wall–Flynn (FWO), and modified Coats–Redfern (m-CR) isoconversional models were used to obtain information about the kinetics of the thermal decomposition of PA6–NBR–HNTs in terms of the activation energy per partial mass loss monitored through thermogravimetric analyses performed at different heating rates. An erratic trend was due to the Friedman model, especially for systems having higher HNT loadings, whereas the KAS, FWO, and m-CR models revealed very similar meaningful thermal decomposition kinetics. A relatively high activation energy corroborating a reliable thermal stability was obtained by the addition of HNTs to PA6–NBR, and the resistance against decomposition was higher for systems containing more HNT. This signified the role of the HNTs as thermal stability modifiers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47483.     

Effects of modified silica on the co-vulcanization kinetics and mechanical performances of natural rubber/styrene–butadiene rubber blends

Rubber blends are widely used for combining the advantages of each rubber component. However, to date, how to determine and distinguish the vulcanization kinetics for each single rubber phase in rubber blends during the co-vulcanization process is still a challenge. Herein, high-resolution pyrolysis gas chromatography–mass spectrometry (HR PyGC-MS) was employed for the first time to investigate the vulcanization kinetics of natural rubber (NR) and styrene–butadiene rubber (SBR) in NR/SBR blends filled with modified silica (SiO₂). The reaction rates of crosslinking of each rubber phase in NR/SBR were calculated, which showed that the crosslinking rates of NR were much lower than those of SBR phase in the unfilled blends and blends filled with unmodified and silane modified silica. Interestingly, the vulcanization rates of NR and SBR phase were approximately same in the vulcanization accelerator modified silica filled blends, showing better co-vulcanization. In addition, the vulcanization accelerator modified silica was uniformly dispersed and endowed rubber blends with higher mechanical strength compared to the untreated silica. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48838.     

Carbon black reinforced thermoplastic vulcanisates based on ethylene–vinyl acetate copolymer/styrene–butadiene rubber blends

Thermoplastic vulcanisates (TPVs) based on ethylene–vinyl acetate copolymer (EVA)/styrene–butadiene rubber (SBR) blends were prepared by dynamic vulcanisation, with the TPVs being reinforced by carbon black (CB). Experimental results indicated that the mechanical properties of dynamically vulcanised EVA/SBR blends were enhanced remarkably by the incorporation of CB. Morphology study showed that the SBR particles with average diameter of 20?μm were dispersed evenly on the etched surface of EVA/SBR/CB TPVs. The Mullins effect could be observed in the stress–strain curves of EVA/SBR TPVs and EVA/SBR/CB TPVs during the uniaxial loading–unloading cycles. Compared with EVA/SBR TPVs, CB reinforced EVA/SBR TPVs had the relatively higher stress, residual deformation and internal friction loss.     

The effect of styrene–butadiene latex carboxylation on adhesion

Styrene–butadiene latices are widely used as binders in pigmented coatings for the paper and board industry. White pitch deposition, which is one type of surface fouling, is a well-known problem at paper machines using coated broke as a raw material. The main component of white pitch is latex, such as styrene–butadiene. The viscoelastic properties of styrene–butadiene latex have been found to affect on white pitch formation, but the effect of carboxylation has not been studied extensively. Carboxylation has traditionally performed to latices in order to increase colloidal stability, but it has also effect on mechanical properties of the latices.In this paper, we studied the adhesion potential of three styrene–butadiene latices by using a cylindrical probe tack method under dry and aqueous conditions while varying the carboxylation degree of the latex. Adhesion potential was measured using low and high energy surfaces as adherents. The results show that carboxylation influences adhesion potential of latices in both dry and aqueous environments.     

Effect of silica reinforcement on natural rubber and butadiene rubber vulcanizates by a sol–gel reaction with tetraethoxysilane

The effect of silica reinforcement was studied for natural rubber (NR) and butadiene rubber (BR) vulcanizates by a sol–gel reaction with tetraethoxysilane at different temperatures. The formation of silica in the rubber vulcanizates was investigated analytically with Fourier transform infrared spectroscopy and energy-dispersive X-ray analysis. The variations of the mechanical and dynamic properties were measured in the NR and BR vulcanizates with silica filling. The hardness of the rubber vulcanizates increased with silica filling in the rubber matrix. The tensile strength and elongation at break decreased with silica filling in the NR vulcanizates. The moduli at 50, 100, and 300% elongation increased with silica filling in the rubber matrix. The storage modulus of silica-filled rubber vulcanizates became higher than that of pure rubber vulcanizates. The temperature dependence of the loss modulus also increased with silica filling. The temperature dependence of the loss tangent was maintained, regardless of silica filling in the BR vulcanizates. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Application of hygrothermally decomposed polyurethane in rubber recipes Part 2–Influence of hygrothermally decomposed polyester–urethane on cure characteristics and viscoelastic behaviour of styrene/butadiene rubber

Abstract

Hygrothermally decomposed polyester–urethane (HD PUR) was mixed at concentrations up to 20 pphr with a styrene/butadiene rubber (SBR), using an efficient vulcanisation system. Changes in the cure behaviour were followed by vulcametry, plate–plate rheometry, and differential scanning calorimetry. It was found that the degree of crosslinking was increased by the incorporation of HD PUR, which acts as an accelerator in SBR stocks. Increasing crosslinking resulted in higher stiffness and strength and was accompanied by a reduction in elongation at break and swelling index.     

Synthesis of emulsion styrene butadiene rubber by reversible addition–fragmentation chain transfer polymerization and its properties

Emulsion polymerization is generally used to synthesize styrene butadiene rubber (SBR), and the molecular weight of this rubber can be easily increased. However, the broad molecular weight distribution (MWD) of SBR increases energy loss and adversely affects the dynamic viscoelastic properties. To overcome this disadvantage, reversible addition–fragmentation chain transfer (RAFT) polymerization, which is a type of living polymerization, is applied to emulsion polymerization for preparing RAFT emulsion SBR (ESBR). The molecular weight and microstructure of RAFT ESBR are compared to those of commercially available ESBR 1502 by gel permeation chromatography and proton nuclear magnetic resonance spectroscopy. The aforementioned two polymers are used to prepare unfilled ESBR compounds, which are compared in terms of key physical properties (abrasion resistance, mechanical properties, and dynamic viscoelastic properties). It is confirmed that various physical properties of RAFT ESBR are improved due to its narrow MWD. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47069.     

The interplay between the fragility and mechanical properties of styrene–butadiene rubber composites with unmodified and modified sago seed shell powder

Reinforcing rubber with natural fillers from agrarian wastes is a new area of interest in developing rubber composite technologies. Lignocellulosic material from sago seed shell is one of the important promising natural fillers having 37% cellulose used to reinforce styrene–butadiene rubber (SBR) for enhancing its mechanical properties. Moreover, chemically or physically modified natural fillers play a significant role in enhancing the properties of SBR like morphological, thermal, and electrical characteristics. In this investigation, the changes encountered in molecular mobility, glassy dynamics, thermal stability, flexibility, and tensile strength of SBR on reinforcing with unmodified and modified sago seed shell powder were studied using broadband dielectric spectroscopy (BDS) in conjunction with thermogravimetric analysis, and mechanical properties. BDS has been successfully employed to investigate the relaxation phenomena and glass/rubbery transition in SBR, as well as its composites with unmodified and modified sago seed shell powder over the frequency (10⁻¹ to 10⁷ Hz) and wide temperature range (−100 to 150°C). Experimental data were analyzed in terms of electric modulus formalism and were suited well with the Havriliak Nigami equation. The incorporation of filler and its nature (unmodified or modified it with polyaniline, PANI) greatly influenced the morphological pattern, miscibility, and mode of interaction with the rubber matrix of SBR, which owed a path to diverse charge transport mechanism in the composites. The mechanical properties of all the composites were in good correlation with the steepness index obtained from BDS. The tensile strength, tear strength, and hardness of SBR increased slightly on loading with unmodified cellulose, whereas with modified cellulose causes substantial enhancement in its tensile strength.     

Supercapacitive properties of electrodeposited polypyrrole on acrylonitrile–butadiene rubber as a flexible current collector

Flexible sheets consisting of acrylonitrile–butadiene rubber (NBR) and vapor-grown carbon fiber (VGCF) are newly prepared varying the composition (VGCF 10–30 wt%) for use as a current collector of supercapacitor electrodes. The electrical conductivity of as-prepared VGCF/NBR current collector can be enhanced as the content of VGCF increases. The VGCF/NBR current collector is then electrodeposited with pyrrole using a potentiodynamic cyclic voltammetry to yield a polypyrrole (PPy)/VGCF/NBR composite electrode. Cyclic voltammetry result for the PPy/VGCF/NBR composites shows that the sample with 30 wt% VGCF achieves a maximum specific capacitance (125.8 F g^?1) at 5?mV?s^?1 and reaches a lower specific capacitance at higher scan rates. In addition, the flexibility of supercapacitor electrode of PPy can also be established with a comparable capacitance value by using the NBR-based current collector.     

Preparation of dispersible nanosilica surface-capped by hexamethyl disilazane via an in situ surface-modification method and investigation of its effects on the mechanical properties of styrene–butadiene/butadiene rubber

Silica has been established as one of the most promising materials in green tires. The filler–rubber interactions can increase the comprehensive performance of rubber composites. In this study, sodium silicate was used as the silicon source and hexamethyl disilazane (HMDS; molecular formula: C₆H₁₉NSi₂) was used as a modifier to synthesize dispersible silica (DNS) via an in situ surface-modification method. The effects of the HMDS-capped silica on the properties of rubber–matrix composites made of styrene–butadiene rubber (SBR) and high-cis-polybutadiene rubber (BR9000 or BR) were investigated with Zeosil 1165MP (Z1165-MP; a commercial highly dispersible silica produced by Rhodia for the production of green tires in the rubber industry) as a reference. The results show that the SBR–BR–DNS composite was before the SBR–BR–Z1165-MP composite in increasing the tear strength and elongation at break and reducing the compression heat buildup. On the basis of the resulting properties, the reinforcing behaviors in the rubber–matrix composites were analyzed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47763.     

Infrared dichroism and birefringence studies of silica-filled styrene–butadiene rubbers

Infrared and birefringence measurements are used to characterize the orientational behavior of silica-filled styrene–butadiene copolymers. The orientational data are correlated with the results of equilibrium swelling measurements. On the other hand, the role played by a silane couling agent bis(3-triethoxysilylpropyl)tetrasulfide (TESPT), or “Si69”) on rubber/silica system is discussed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1006–1012;2001