Triethoxysilylpropyl Tetrasulfide Research Articles

COOPERATIVE EFFECTS OF EPOXIDE FUNCTIONAL GROUPS ON NATURAL RUBBER AND SILANE COUPLING AGENTS ON REINFORCING EFFICIENCY OF SILICA

ABSTRACTPolar functionality attached onto natural rubber has a significant impact on the reinforcing efficiency of silica. Parallel studies involving various levels of epoxidation on natural rubber (ENR) in the absence of bis-(triethoxysilylpropyl) tetrasulfide (TESPT) coupling agent, as well as a combination of ENRs with different loadings of TESPT, provide a better understanding of the various factors that influence the properties of silica-filled ENR compounds. Based on the overall properties, the best possible combination to optimize processability, to reduce filler–filler interaction, and improve vulcanization rate as well as vulcanizate properties, is to use ENR with an epoxide content in the range of 20–30 mol%, together with a small portion of TESPT, that is, 2–4 wt% relative to the silica content. This leads to a reduction of approximately 60–80% of TESPT when compared with the conventional NR compounds, where the optimal loading of TESPT was 9.0 wt% relative to the silica content.

Reactivity of Bis[3-(triethoxysilyl)propyl] Tetrasulfide (TESPT) Silane Coupling Agent over Hydrated Silica: Operando IR Spectroscopy and Chemometrics Study

The presence of physisorbed water during the silanization of silica is well-known for strongly influencing the silane reactivity at the interface. In this work, the reactivity of bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT), widely used in the rubber industry, on hydrated precipitation silica was investigated by time-resolved operando FTIR spectroscopy and chemometrics. The predominating reaction scheme is elucidated in conditions representative of industrial mixing process at the molecular scale. Based on multivariate curve resolution analysis and a quantitative kinetic model, it is shown that TESPT chemisorption is governed by two competitive reaction routes both producing only ethanol in the gas phase: (i) direct grafting reaction between an ethoxy moiety and a silica surface silanol and (ii) silane hydrolysis followed by co-condensation with a vicinal silane species. Reactions involving silanol–silanol condensation with production of water were not found to be significant. Although several types...

Preparation and characterization of EPDM/silica composites prepared through non-hydrolytic sol-gel method in the absence and presence of a coupling agent

Ethylene propylene diene monomer (EPDM) rubber composites containing in situ generated silica particles was prepared through a non-hydrolytic sol-gel (NHSG) method with silicon tetrachloride as precursor. The silica particles were homogenously dispersed in the EPDM matrix, but there were agglomerates at high silica contents. The swelling experiments showed a decrease in the crosslinking density of the vulcanized rubber due to the presence of the silica particles for both the composites prepared in the presence and absence of a coupling agent, bis-[-3-(triethoxysilyl)-propyl]-tetrasulfide (TESPT). Unlike the composites prepared through a hydrolytic sol-gel (HSG) method with TEOS as precursor, the TESPT did not seem to take part in the sol-gel reaction. The presence of TESPT influenced the interaction and dispersion of the silica particles in the EPDM matrix, which gave rise to increased thermal stability of the EPDM when compared to the composites prepared in the absence of TESPT. However, ethylene chloride and TESPT evaporated from the samples at temperatures below the EPDM decomposition range. The values of the Nielsen model parameters, that gave rise to a good agreement with the experimentally determined Young’s modulus values, indicated improved dispersion and reduced size of the silica aggregates in the EPDM matrix. There was also good agreement between the storage modulus and Young’s modulus values. The filler effectiveness (Factor C) indicated a mechanical stiffening effect and a thermal stability contribution by the filler, while the damping reduction (DR) values confirmed that the EPDM interacted strongly with the well dispersed silica particles and the polymer chain mobility was restricted. The tensile properties, however, were in some cases worse than those for the samples prepared through the HSG method in the presence of TEOS.

STUDYING NR/ORGANO-MONTMORILLONITE NANOCOMPOSITES WITH SILANE COUPLING AGENTS VIA NETWORK VISUALIZATION TEM

ABSTRACT Organo-montmorillonite (OMMT) increases the elastic modulus of elastomers such as natural rubber (NR) by a very large amount at low strains, but this decreases as the rubber is extended. Silane coupling agents, widely used with silica-filled rubbers, were added to NR/OMMT nanocomposites to increase the effects of OMMT on modulus at high strains. Both bis(triethoxysilylpropyl)tetrasulfide (TESPT) and 3-mercaptopropyl di(tridecan-1-oxy-13-penta(ethylene oxide))ethoxysilane (MPDES) increase tensile modulus significantly at strains greater than 30%. The coupling agents strengthen the rubber–filler interface, reducing cavitation around OMMT particles and preventing NR molecules from sliding at the interface. Evidence for a stronger rubber–filler interaction is provided by measurements of bound rubber content and use of network visualization transmission electron microscopy (NVTEM). OMMT also affects the dynamic properties of NR differently from other fillers. One aspect of this is the appearance of a peak in tan δ between 20 °C and 60 °C, attributed to the glass transition of intercalated and adsorbed NR molecules. The intensity of this peak is diminished by the addition of TESPT or MPDES, implying that they are restricting the intercalation of the rubber between the clay sheets. The coupling agents also have a small effect on vulcanization behavior compared with that of OMMT.

Reinforcement of EPDM rubber with in situ generated silica particles in the presence of a coupling agent via a sol–gel route

Ethylene propylene diene monomer rubber (EPDM)-silica (SiO2) composites were prepared by means of an in situ sol–gel process with tetraethoxysilane (TEOS) as precursor and bis-[-3-(triethoxysilyl)-propyl]-tetrasulfide (TESPT) as coupling agent. Homogenous dispersion of the silica particles was observed in all cases, as well as good adhesion between the filler and the matrix. The swelling and gel content results indicated that the number of crosslinks decreased, while the network was still extensive enough to maintain the high gel content. These results indicate that the coupling agent acted as a bridge between the hydrophilic silica and the hydrophobic rubber and enhanced the rubber-silica interactions. This enhanced interaction gave rise to increased thermal stability of the EPDM. The values of the Nielsen model parameters, which gave rise to good agreement with the experimentally determined Young's modulus values, indicate improved dispersion and reduced size of silica aggregates in the EPDM matrix. Good agreement was found between the storage modulus and Young's modulus values. The filler effectiveness (Factor C) indicated a mechanical stiffening effect and a thermal stability contribution by the filler, while the damping reduction (DRNorm) values confirmed that the EPDM interacted strongly with the well dispersed silica particles, and the polymer chain mobility was restricted.

Optimization of Epoxidation Degree and Silane Coupling Agent Content for Silica-Filled Epoxidized Natural Rubber Tire Tread Compounds

Parallel studies on the influence of epoxide contents in epoxidized natural rubbers (ENRs) in the absence of bis-(triethoxysilylpropyl) tetrasulfide (TESPT) coupling agent, as well as a combination of ENRs with different loadings of TESPT on the properties of ENR compounds, are carried out in this work. The results suggests that the best possible combination to optimize processibility and to improve reinforcement efficiency is to utilize ENR with an epoxide content in the range of 20 30 mol%, together with 2 4 wt% relative to the silica content of TESPT. This leads to a reduction of TESPT when compared to the conventional natural rubber compounds.

Property Enhancement of Silica-Filled Natural Rubber Compatibilized with Epoxidized Low Molecular Weight Rubber by Extra Sulfur

The properties of both compounds and vulcanizates of silica-filled natural rubber (NR) compatibilized with epoxidized low molecular weight natural rubbers (ELMWNRs) consisting of 12 and 28 mol% epoxide are investigated. The ELMWNRs with a molecular weight range of 50,000 to 60,000 g/mol are produced by depolymerization of epoxidized natural rubber (ENR) latex using periodic acid, and then used as compatibilizer in a range of 0 to 15 phr in virgin NR. The compounds with LMWNR without epoxide groups, and with bis-(triethoxysilylpropyl) tetrasulfide (TESPT) coupling agent are also prepared for comparison purpose. Incorporation of ELMWNRs lowers Mooney viscosity and Payne effect to the level closed to that of silica/TESPT compound, and clearly enhances the modulus and tensile strength of vulcanizates compared to the compounds with no compatibilizer and LMWNR. The higher epoxide groups content results in the better tensile properties but somewhat less than the compound with TESPT. Addition of extra sulfur into the compounds with LMWNR and ELMWNRs to compensate for the sulfur released from silane molecule in the silica/TESPT system shows small influence on Mooney viscosity, but remarkably enhances 300% modulus, tensile strength and loss tangent at 60°C as a result of the better network formation.

Effect of silane coupling agent on filler and rubber interaction of silica reinforced solution styrene butadiene rubber

In the present article, the influence of bis-(triethoxysilylpropyl)-tetrasulfide (TESPT) content on the viscoelastic behavior of silica filled Solution Styrene Butadiene Rubber (SSBR) was carefully studied in terms of loss tangent spectrum and bound rubber content. The results showed that both relative tan δ area and tan δmax of filled SSBR with TESPT were detected to present maximum value at 2.5 wt% TESPT(with respect to silica loading). Larger tan δ area and tan δmax meant more chains participating in the glass transition in the present system, which is reflected by the variation of effective filler volume with TESPT content. The interaction between filler and rubber can be improved remarkably when a little amount of TESPT up to 2.5 wt% was incorporated, whereas as the TESPT content exceeds 2.5 wt% the filler–rubber interaction was weakened, which was also proven by TEM images and Payne effect. The bound rubber content of this SSBR system studied presents the same tendency as tan δmax. Once TESPT linked with rubber chains, the condensation reaction between silica and SCA is somewhat hindered because of the difficulty in diffusion of large molecules after SCA is chemically bonded with rubber molecules. The network structure of the filled SSBR was analyzed by applying elasticity model. The consecutive increase of crosslink density compensated the reduction of topological tube-like constrains and thus tensile strength continued to ascend with TESPT content, but sacrificed the ultimate strain. POLYM. COMPOS., 34:1575–1582, 2013. © 2013 Society of Plastics Engineers

Bis[3-(triethoxysilylpropyl)]tetrasulfide에 의한 실리카 입자의 표면개질 반응과 SBR 나노 복합체 응용

In this study, we performed surface modification of silica nanoparticles with bis[3-(triethoxysilylpropyl)]tetrasulfide (TESPT) silane coupling agent to study the effects of treatment temperature, treatment time, and amount of TESPT used on the silanization degree with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), elemental analysis (EA) and solid state and cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance spectroscopy (NMR). We found peak area of isolated silanol groups at decreased, but peak area of asymmetric stretching of TESPT at increased with the amount of TESPT from FTIR measurements. We also used universal testing machine (UTM) to study mechanical properties of styrene butadiene rubber (SBR) nanocomposites with 20 phr (parts per hundred of rubber) of pristine and TESPT modified silicas, respectively. The tensile strength and 100% modulus of modified silica/SBR nanocomposite were enhanced from 5.65 to 9.38MPa, from 1.62 to 2.73 MPa, respectively, compared to those of pristine silica/SBR nanocomposite.

Reactivity of sulfide-containing silane toward boehmite and in situ modified rubber/boehmite composites by the silane

The silanization reaction between boehmite (BM) nanoplatelets and bis-[3-(triethoxysilyl)-propyl]-tetrasulfide (TESPT) was characterized in detail. Via such modification process, the grafted sulfide moieties on the BM endow reactivity toward rubber and substantially improved hydrophobicity for BM. Accordingly, TESPT was employed as in situ modifier for the nitrile rubber (NBR)/BM compounds to improve the mechanical properties of the reinforced vulcanizates. The effects of BM content and in situ modification on the mechanical properties, curing characteristics and morphology were investigated. BM was found to be effective in improving the mechanical performance of NBR vulcanizates. The NBR/BM composites could be further strengthened by the incorporation of TESPT. The interfacial adhesion of NBR/BM composites was obviously improved by the addition of TESPT. The substantially improved mechanical performance was correlated to the interfacial reaction and the improved dispersion of BM in rubber matrix.

Microstructure and properties of styrene‐butadiene rubber based nanocomposites prepared from an aminosilane modified synthetic lamellar nanofiller

ABSTRACTIn this work, a novel nanocomposite series based on styrene‐butadiene rubber (SBR latex) and alpha‐zirconium phosphate(α‐ZrP) lamellar nanofillers is successfully prepared. The α‐ZrP lamellar filler is modified at the cation exchange capacity by γ‐aminopropyltrimethoxysilane and the filler surface modification is first discussed. A significant improvement of the mechanical properties is obtained by using the surface modified nanofillers. However, no modification of the gas barrier properties is observed. The impact of addition of bis(triethoxysilylpropyl)tetrasulfide (TESPT) as coupling agent in the system is discussed on the nanofiller dispersion state and on the filler–matrix interfacial bonding. Simultaneous use of modified nanofillers and TESPT coupling agent is found out with extraordinary reinforcing effects on both mechanical and gas barrier properties and the key factors at the origin of the improvement of these properties are identified. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1051–1059

Mechanical and dynamic mechanical properties of natural rubber blended with waste rubber powder modified by both microwave and sol–gel method

AbstractWaste rubber powder (WRP) was modified by microwave, sol–gel method, and both microwave and sol–gel method, respectively. The mechanical and dynamic mechanical properties of natural rubber (NR)/modified WRP composite were investigated. The influence of bis‐(3‐(triethoxysilyl)‐propyl)‐tetrasulfide (TESPT) content on curing characteristics and mechanical properties of vulcanizate was also studied. The results showed that NR/WRP modified by both microwave and sol–gel method composite owned the best mechanical properties. Rubber processing analyzer was used to characterize the interaction between silica and rubber chains and the dispersion of silica. With increase of TESPT content, the Payne effect decreased. Scanning electron microscopy indicated the coherency and homogeneity of in situ generated silica filled vulcanizate. Dynamic mechanical analyzer showed that NR/WRP modified by both microwave and sol–gel method composite with 5 phr TESPT exhibited the lower tan δ at temperature range of 50–80°C, compared with composite without TESPT and the higher tan δ at temperature of 0°C, compared with the conventional modification of WRP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Reinforcement of Solution Styrene Butadiene Rubber by Silane Functionalized Halloysite Nanotubes

We describe a nanocomposite based on solution styrene butadiene rubber (SSBR) and naturally occurring tube-like nanoparticles called halloysite nanotubes (HNT). Highly hydrophilic HNT nanotubes were modified by different silane coupling agents namely diethoxydimethyl silane (DMS) and bis[3-(triethoxysilyl)­propyl]tetrasulfide (TESPT) to ensure good dispersion of these nanoparticles in the hydrophobic SSBR matrix. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to characterize the functional groups on the surface of the HNT after the silane modification. Contact angle measurements, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were also carried out to understand the extent of modification. The reinforcing effect of modified HNT in SSBR matrix was perceived from both static and dynamic mechanical properties. The tensile strength and elongation at break of the modified HNT filled SSBR nanocomposites are found to be much higher than that of pristine HNT (pHNT) filled nanocomposites. In addition, transmission electron microscopic analysis unveiled the fact that, owing to more rubber-filler interaction modified HNT dispersed in a very fine state as compared with pHNT.

Synthesis of novel thiol-functionalized mesoporous silica nanorods and their sorbent properties on heavy metals

Novel thiol-functionalized mesoporous silica nanorods (MSNRs) were synthesized through a base co-condensation method, in which two organoalkoxysilanes, tetraethoxylsilane (TEOS) and bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT), were used as silica precursors simultaneously. TESPT was firstly used for both morphology control and inner surface functionalization of mesoporous silica hybrid materials. The microstructures as well as porous character of the MSNRs were characterized by means of SEM, XRD, TEM and N2 sorption measurements. Infrared spectrum analysis and heavy metal ions (Ag+ and Cd2+) adsorption measurements were carried out to confirm the functionalized framework of MSNRs.

Nanoscale gold intercalated into mesoporous silica as a highly active and robust catalyst

Stable gold/mesoporous silica nanocomposites (with Au nanoparticles intercalated in the walls of mesoporous silica) were successfully synthesized by the hydrothermal method and applied as catalysts. A challenging issue associated with intercalation and the use of coordinating agents is the effect of the coordinating agent on the mesoporous silica structure and periodicity. This investigation is targeted at elaborating the effect of the coordinating agent on the resulting mesoporous structure. The amount of Au coordinating agent bis[3-(triethoxysilyl)propyl]-tetrasulfide (TESPTS) was systematically altered to synthesize a range of materials with varying Au loadings and morphologies. These materials were characterized by N2 adsorption–desorption, x-ray diffraction, transmission electron microscopy and UV–visible spectroscopy. The structures of the catalysts were found to range from mesoporous to vesical- and foam-like upon varying the TESPTS/polymer template (P123) ratio. Additionally, the sizes of Au nanoparticles increased by increasing the amount of TESPTS. The catalytic properties of the resulting materials were examined using oxidation of benzyl alcohol and reduction of 4-nitrophenol as probe reactions. The intercalated systems demonstrated high activity and more importantly were robust and readily reusable. This approach to imparting stability to nanoscale materials may be much more broadly applicable and expand the types of environments in which they can be utilized.

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

AbstractIn 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

Effectively reinforcing roles of the networked silica prepared using 3,3′-bis(triethoxysilylpropyl)tetrasulfide in the physical properties of SBR compounds

The networked silica having pre-fabricated networks among silica particles is a new concept for the reinforcement of rubber compounds. The networked silica was designed to improve the fuel efficiency of tires while eliminating the disadvantages such as precure and ethanol production that arise in the conventional reinforcing system using coupling reagents. The networked silica was prepared using bis(triethoxysilylpropyl)tetrasulfide (TESPT) as a connecting chemical at various loading levels. The styrene–butadiene rubber (SBR) compounds reinforced with the networked silica exhibited low filler–filler interaction and high rubber–filler interaction due to the entanglements between the rubber molecules and the connecting chains of the networked silica. The increased physical interaction improved the elastic properties and wear resistance, while lowering the rolling resistance of the rubber compounds, resulting in long tire service life and high automobile fuel efficiency. The enhanced physical properties of the SBR compounds reinforced with the networked silica supported their promising potential as reinforcing fillers for tire manufacture. The networked silica can readily replace the conventional silica-reinforced system, without requiring major modification of the processing conditions.

Highly Ordered Lamellar Mesostructure of Nanocrystalline PbSO4 Prepared by Hydrothermal Treatment

A lamellar PbSO4 mesophase with well-crystallized walls was synthesized using sodium dodecyl sulfate (SDS) as a template and bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPTS) as a structure-stabilizing agent through hydrothermal treatment method. The obtained layered mesostructure was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM), energy-dispersive X-ray spectroscopy (EDS), and IR spectrum. The photoluminescence properties of the products were also investigated. The sample gives two UV emission bands centered at 340 and 360 nm and four visible light emission bands in the range of 400−500 nm using an excitation wavelength of 270 nm. The results have demonstrated that TESPTS with more hydrophobic character could be responsible for the formation of this stabilized lamellar PbSO4 mesophase. A possible formation mechanism for the lamellar PbSO4 mesostructure was also proposed. Such lamellar mesostructures could provide a useful precursor for potential applications of PbSO4.

The influence of in situ modification of silica on filler network and dynamic mechanical properties of silica‐filled solution styrene–butadiene rubber

AbstractThe influence of in situ modification of silica with bis‐(3‐(triethoxysilyl)‐propyl)‐tetrasulfide (TESPT) on filler network in silica filled solution SBR compound was investigated. In situ modification greatly increased the bound rubber content. TEM observation of silica gel showed that bridging and interlocking of absorbed chains on the surface of silica particles formed the filler network. Rubber processing analyzer (RPA) was used to characterize the filler network and interaction between silica and rubber by strain and temperature sweeps. In situ modification improved the dispersion of silica, and in the meantime, the chemical bonds were formed between silica and rubber, which conferred the stability of silica dispersion during the processing. Compared to the compound without in situ modification, the compound with in situ modification of silica exhibited higher tan δ at low strains and lower tan δ at high strains, which can be explained in terms of filler network in the compounds. After in situ modification, DMTA results showed silica‐filled SSBR vulcanizate exhibited higher tan δ in the temperature range of −30 to 10°C, and RPA results showed that it had lower tan δ at 60°C when the strain was more than 3%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Silica‐Ethylene Propylene Diene Monomer Rubber Networking by In Situ Sol‐Gel Method

Triethoxysilyl‐grafted ethylene propylene diene monomer rubber (EPDM) was prepared with the silane coupling agent, bis‐[‐3‐(triethoxysilyl)‐propyl]‐tetrasulfide (TESPT), and thus modified rubber has been treated by an in situ sol‐gel method with the objective to grow silica particles inside the rubber matrix. TESPT grafted EPDM rubber, filled with the silica particles grown by making use of the described method, was found to exhibit excellent physical properties, despite the fact that the fraction of silica fillers in this material is found to be very low. In particular, thus produced filled rubber has higher reinforcing efficiency that is attributed to the formation of a rubber‐silica network. In addition, better silica dispersion is observed in the shear modulus measurements at low dynamic deformation amplitudes, which is in qualitative agreement with the ‘Payne’ effect that quantifies the ability of fillers to promote the formation of rubber‐filler networks. No such effect of network formation was observed when an in situ sol‐gel experiment was performed in the absence of TESPT. TEM observations showed that even if the amount of silica fillers in rubber is as small as 5 phr or less, the uniform mono‐dispersed distribution of the silica primary particles is still the main factor responsible for the reinforcement of the rubber matrix.