Triethoxysilylpropyl Disulfide Research Articles

Preparation of high‐performance and low‐rolling resistance tire tread compound based on hydrogen‐bonded self‐assembled graphene/carbon nanotube‐silica hybrid

AbstractGraphene/carbon nanotubes and silica hybrids (CTGS) with high dispersion and strong interface were prepared by hydrogen bond self‐assembly technique using green modifiers Tween‐80 (TW) and Oleylamine (YA) as “molecular bridge.” CTGS was added into natural rubber (NR) as an effective functional filler to prepare high‐performance, low‐rolling resistance, and antistatic tire tread. In the vulcanization process of NR filled with CTGS (CTGS/NR), CTGS can participate in the rubber vulcanization, and co‐vulcanization is a catalyst for constructing the strong interfacial interactions between CTGS and rubber. The extreme dispersion of CTGS hybrid in NR and the strong interfacial interaction between CTGS and NR are the basis for obtaining excellent comprehensive properties of CTGS/NR composites. The results show that compared with NR filled with silica modified by triethoxysilyl propyldisulfide (ST@SiO2/NR), NR filled with carbon nanotubes and silica hybrid (CTGS4) using YA as the molecular bridge (CTGS4/NR) has the best comprehensive performance. Its tensile strength increased from 27.41 to 30.18 MPa, increasing by 10.1%, the rolling resistance decreased from 0.098 to 0.087, decreasing by 11.2%, and the conductivity increased by three orders of magnitude (increasing from 2.321 × 10−7 S∙m−1 to 4.111 × 10−5 S∙m−1) indicating excellent electrostatic conductivity for CTGS hybrid with carbon nanotubes loading as low as 0.6 wt%. CTGS hybrid is expected to be a new functional filler for rubber, especially good for green tires with high‐performance, low‐rolling resistance, and antistatic performances.

Saccharide-containing conjugates as eco-friendly coupling agents for silica reinforced rubber compounds

Silica reinforced rubber is used as a tire tread compound due to its desirable viscoelastic properties. To achieve proper silica dispersion in rubber compound, silane-based coupling agents are required. In this study, we synthesize saccharide-containing molecules and investigate their uses as green coupling agents for the development of environmentally friendly tires. Two saccharide conjugates are prepared: maltose-polybutadiene (Mal-PB) by coupling reaction between alkyne-functionalized Mal and azide-functionalized PB; and maltose-cystamine-maltose (Mal-Cys-Mal) by reductive amination of the reducing end of Mal. Both conjugates are used in place of bis(triethoxysilylpropyl)disulfide (TESPD) for rubber compounding. We find that Mal-PB serves as a good compatibilizer for silica/rubber interface but cannot bridge silica fillers to rubber chains due to lack of sulfur element. Mal-Cys-Mal shows better potential as a coupling agent. The rubber compound prepared with Mal-Cys-Mal shows increased bound rubber content and improved silica dispersion, and the resulting vulcanizate shows modestly improved viscoelastic properties and much improved tensile properties. Overall both saccharide conjugates reported can effectively enhance silica dispersion in rubber compounds, and the sulfur-containing Mal-Cys-Mal has the potential to replace TESPD as a greener coupling agent for tire tread formulation.

Effect of feldspar filler on physical and dynamic properties of SBR/CB based tire tread compounds: Effect of addition method of silane coupling agent

In this work, the effects of using feldspar (FLD) as an alumina-silicate inorganic filler, with carbon black (CB) as a novel binary filler system, on the properties of SBR compounds were investigated for tire applications. The bis(triethoxysilylpropyl) disulfide (TESPD) was used for modification of FLD. The SBR hybrid composites were produced by replacing 10 phr of CB filler with neat FLD and functionalized FLD (F-FLD). The TESPD was added directly to the rubber mixture including neat FLD. The SBR composite which has only CB filler (50CB) was found to have the highest damping parameter (tan δ) value at 60°C. On the other hand, the composites loaded with the CB and the FLD fillers exhibited relatively lower tan δ at the same temperature showing lower rolling resistance meaning better fuel saving performance. The lowest rolling resistance was achieved for the 40CB-10F-FLD most probably due to its stronger interaction with the SBR elastomer molecules through the silane agent-assisted crosslinks of the F-FLD. As another dynamic property, the storage moduli at −20°C were found to be lower for the SBR hybrid composites as compared to that of the 50CB composite, exhibiting enhanced winter traction performance of the composites having FLD filler together with CB. The composites containing only 10 phr of FLD and F-FLD, on the other hand, exhibited very low tensile strength values which are not acceptable for tire tread materials.

EFFECTS OF SILANE AGENTS AND CURING TEMPERATURES ON VULCANIZATE STRUCTURES

ABSTRACT Silane coupling agents are commonly used in silica-filled rubber compounds to hydrophobize the silica surface and improve filler–rubber interaction. The coupling agent bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT) is the most widely used coupling agent. The tetrasulfide is more reactive than the disulfide in bis[3-(triethoxysilyl)propyl]disulfide (TESPD) due to its low decomposition energy, resulting in more coupling reaction with rubber molecules. Meanwhile, vulcanization temperature affects chemical networks. Polysulfide is vulnerable to heat, so it can be easily broken to form shorter crosslinks. Compounds with TESPD or TESPT were vulcanized at 160 and 180 °C. In addition to the decomposition, the reactivity of the silanes was confirmed from the cure characteristics of the compounds without the curatives. TESPD could also cause a coupling reaction without the curatives such as TESPT known to release free sulfur. By analyzing vulcanizate structures, total crosslink density was separated into chemical crosslink density and filler–rubber networks. Applying TESPT or vulcanizing at 180 °C increased the filler–rubber networks, and the higher vulcanization temperature decreased the chemical crosslink density. By correlating physical properties, effects of the vulcanizate structures on performance of tread compounds were investigated. The filler–rubber interaction was dominant for wet traction and mechanical properties in tensile test. The chemical crosslink density affected rolling resistance.

Effect of the functional group of silanes on the modification of silica surface and the physical properties of solution styrene-butadiene rubber/silica composites

ABSTRACTSilica compounds were prepared using non-functionalized solution styrene-butadiene rubber (SSBR) to investigate effect of the functional group of silanes on the silica modification and properties of SSBR/silica compounds. Bis-[3-(triethoxysilyl)propyl]disulfide (TESPD), 3-mercaptopropyltriethoxysilane (MPTES), 3-aminopropyltriethoxysilane (APTES), vinyltriethoxysilane (VTES), and 3-chloropropyltriethoxysilane (CPTES) were used as silane agents. Bound rubber contents and vulcanizate structures were analyzed, and physical properties, cure characteristics and viscoelasticities were evaluated. MPTES and TESPD have chemically reactive functional groups with rubber chain. Particulary, as thiol group is more reactive than disulfide, the filler–rubber interaction is outstanding when applying MPTES. The bound rubber content of the MPTES applied compound was 30% higher. Vulcanizate structure analysis exhibited that the filler–rubber interaction of the MPTES applied compound is more than twice as high. As amino group of APTES can form hydrogen bonds with other amino or silanol groups on silica surface, strong filler–filler interaction which leads to easy agglomeration and accelerator adsorption, resulting in flocculation and marching. VTES cannot hydrophobize silica surface owing to its short carbon chain. Therefore, the compounds that apply APTES or VTES had high Payne effect, indicating poor silica dispersion. CPTES has polar functional group but behaves as covering agent because of its weak interaction with rubber.

CHARACTERIZATION OF SILICA MODIFIED WITH SILANES BY USING THERMOGRAVIMETRIC ANALYSIS COMBINED WITH INFRARED DETECTION

ABSTRACT Tire treads with reduced rolling resistance and increased wet grip can be achieved by coupling hydrophilic silica to hydrocarbon rubber by using an alkoxysilane. The silica surface was modified by reaction with a wide range of coupling and non-coupling silanes. The chemistry and extent of these silanizations were elucidated using thermogravimetric analysis (TGA) combined with infrared detection. The silane grafting efficiencies were typically 52–72%, but efficiencies were lower with the bulkier 3-(di-(tridecyloxypenta(ethyleneoxy))ethoxysilyl)propyl mercaptan. However, the silica surface coverage increases with increasing size of the silane. Grafting efficiencies were lower with higher silane loadings. In the TGA, ethoxy and methoxy groups are displaced from the grafted silanes mainly at moderate temperatures (up to about 495 °C) to form siloxane bridges. Over a similar temperature range, the weaker S–S bonds present in bis(3-triethoxysilylpropyl) tetrasulfide (TESPT)- or bis[3-(triethoxysilyl)propyl] disulfide (TESPD)-modified silica are cleaved, leading to weight losses from TESPT or TESPD bound at one end to the silica and from TESPT bound at both ends. The remaining weight losses from bound silanes occurred mainly at higher temperatures. In the commercial silanized silica Coupsil 8113, TGA indicates that about two of three ethoxy groups in each triethoxysilane were lost during the silanization process.

Influence of the silanes on the crosslink density and crosslink structure of silica-filled solution styrene butadiene rubber compounds

The effects of three silane coupling agents, triethoxy(octyl)silane (TEOS), bis[3-(triethoxysilyl)propyl]disulfide (TESPD), and bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT) on the filler-rubber interaction, crosslink density and crosslink structure of the silica-filled solution styrene butadiene rubber (SSBR) vulcanizates were studied. High dispersion silica, 7000GR, was used as the filler, and the loading range was varied from 0 to 60 phr. Crosslink density was measured by the swelling method. Experimental results showed that Kraus plot can be applicable to the silica-filled SSBR vulcanizates to separate filler-rubber interaction from the measured swelling data. Filler-rubber interaction increased by increasing sulfur rank in the silane as TEOS < Silica without silanes < TESPD < TESPT. Sulfurless silane, i.e. TEOS, only worked as a covering agent for hydrophobating silica surface. Silica without silane show high filler-rubber interaction than TEOS system because chain-end functionalized SSBR was used in this study. Unfilled system showed similar amounts of poly, di, and mono-sulfidic crosslinks. On the contrary to this, all of the silica-filled vulcanizates showed high mono-sulfide contents due to longer cure time.

Mechanistic aspects of silane coupling agents with different functionalities on reinforcement of silica‐filled natural rubber compounds

Silane coupling agents containing different specific functionalities are studied to gain understanding of their roles in silica‐filled natural rubber (NR) compounds. Five different silane coupling agents, that is bis‐(triethoxysilylpropyl) tetrasulfide (TESPT), bis‐(triethoxysilylpropyl) disulfide (TESPD), octyltriethoxysilane, vinyltrimethoxysilane, and bis‐(trimethyl‐silylmethyl) tetrasulfide (TMSMT), are comparatively investigated, by taking the most commonly used TESPT as a reference. The results reveal that alkoxy‐based silanes can effectively reduce the filler–filler interaction and lower compound viscosity owing to the effect of silane‐to‐silica hydrophobation which contributes to better compatibility between silica and NR. The alkoxy‐silanes with a sulfur moiety, that is TESPT and TESPD, show more pronounced improvement in overall properties as a result of filler–rubber interactions. The use of TMSMT which has no alkoxy groups but contains only a sulfur moiety elucidates that there are three reaction mechanisms involved in systems with sulfur‐alkoxy‐based silane. These are as follows: (1) the silane‐to‐silica or silanization/hydrophobation reaction; (2) the silane‐to‐rubber or coupling reaction; and (3) rubber–rubber crosslinking originating from active sulfur released by the polysulfide‐based silane TESPT. These simultaneous reactions are temperature dependent, and show an optimum level at a dump temperature of approximately 140–150°C, as depicted by filler–filler and filler–rubber interactions, as well as mechanical properties of such compounds. POLYM. ENG. SCI., 55:836–842, 2015. © 2014 Society of Plastics Engineers

Fabrication of hollow core carbon spheres with hierarchical nanoarchitecture for ultrahigh electrical charge storage

A simple and reproducible sol–gel synthesis strategy was developed to fabricate hollow core carbon spheres (HCCSs) with hierarchical nanoarchitecture through the hydrolysis, self-assembly and co-condensation of bis-[3-(triethoxysilyl)propyl]disulfide (TESPDS) and octadecyltrimethoxysilane (C18TMS). This synthesis route allows one to fabricate thioether-bridged organosilica (TBOS) with tailored spherical structure and particle size which can be further converted to HCCS upon calcination under N2 flow. It is assumed that hydrophobic octadecyl chains of hydrolyzed C18TMS first form a micelle-like self-assembly structure with hydrophilic trihydroxysilyl groups as heads, and a reactive core is then expanded by the base-catalyzed co-condensation of TESPDS and/or C18TMS over the C18TMS self-assembly structure. The organic moieties of TESPDS and C18TMS not only serve as a porogen during the formation of TBOS but also as a carbon precursor for transformation of TBOS into HCCS during the carbonization. Due to its unique hierarchical nanostructure composed of hollow macroporous core and meso/microporous shell, which facilitates fast mass transport, along with large surface area for electrical charge storage, the HCCS for the first time exhibits ultrahigh specific capacitance and energy, good cycling performance and rate capability.

Concentration Effects of Organosilane (TESPD) on Mechanical Properties of Silica Filled Silicone Rubber/Natural Rubber Compounds

Abstract The concentration effects of the silane coupling agent bis (triethoxysilylpropyl) disulfide (TESPD) on mechanical properties of silica-filled silicone rubber (SR)/natural rubber (NR) compound are investigated upon torque maximum value, tensile strength, tensile modulus and hardness. The compounds are cured with a conventional vulcanization system. The concentration range of the TESPD used is 1 to 17 phr. The optimum concentration of the TESPD is found to be 13 phr in the SR/NR compound. The degree of dispersion of silica in the rubber matrix is also examined by scanning electron microscopy (SEM).

SYNTHESIS OF 3-HEXANOYLTHIO-1-PROPYLTRIETHOXYSILANE AND ITS COUPLING EFFECT ON SOLUTION POLYMERIZED STYRENE-BUTADIENE RUBBER/SILICA COMPOUNDS

A novel coupling agent,3-hexanoylthio-1-propyltriethoxysilane(HXT),was synthesized through the reaction of 3-triethoxysiyl-1-propanethiol and hexanoyl chloride.HXT or bis-(triethoxysilylpropyl)disulfide(TESPD)as coupling agent were incorporated into solution polymerized styrene-butadiene rubber(SSBR)/silica(SiO_2)compounds.Dynamic rheological properties of the compounds were investigated by using an advanced rheomitric expended system(ARES).It is found incorporation of silane coupling agent into SSBR/SiO_2 compounds improved the elastic properties and wakened the Payne effect due to the surface modification of SiO_2 particles and the improved dispersion of the particles in the SSBR matrix.Compared with TESPD,HXT provides rubber compounds with higher critical strain value of Payne effect and lower storage modulus.In this aspect,HXT performs better than TESPD.This might be attributed to the combined effects of better rubber-filler interaction and better filler dispersion which are obtained when TESPD is replaced with HXT.

Ethylene–propylene–diene terpolymer/silica compound modification with organosilane [bis(triethoxysilylpropyl)disulfide] and improved processability and mechanical properties

AbstractBifunctional silane [bis(triethoxysilylpropyl)disulfide (TESPD)] was added to a silica‐containing ethylene–propylene–diene terpolymer mold compound, and its effects with respect to the vulcanization properties, processability, and physical properties were investigated. The addition of TESPD caused reduced heat generation during mixing, low minimum torque, low drop temperature, and low extrusion pressure buildup in the extruder. It also caused a high vulcanization torque, high torque rise, high torque maximum, and high elongational modulus. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Reduction of volatile organic compound emission. II. Use of alkoxy‐modified silsesquioxane for compounding silica‐filled rubbers

AbstractA class of alkoxy‐modified silsesquioxane (AMS) containing less than 5 wt % of latent alcohol that can be used for compounding silica‐filled rubbers is described. The AMS derived from octyl‐triethoxysilane (OTES) behaves as a good shielding agent in silica‐filled rubber to significantly reduce the compound Mooney viscosity and filler flocculation. The co‐AMS prepared from OTES and 3‐mercaptopropyl‐trimethoxysilane yielded an effective shielding and coupling agent for reinforcing the silica‐filled vulcanizates. The alcohols released as volatile organic compounds (VOC) are quantified during compounding and processing along with the compound properties of silica‐filled vulcanizates containing various silicon compounds such as bis‐(triethoxysilyl propyl) disulfide (TESPD), a polyhedral oligomeric silsesquioxanes (POSS), OTES, AMS, or co‐AMS. Dynamic mechanical properties such as dependences of hysteresis on temperature (HTD) and storage modulus on strain (MSD) are discussed. Stronger HTD and weaker MSD were found in stocks containing co‐AMS or a combination of AMS and a coupling agent when compared with that with TESPD. Stronger HTD and weaker MSD may benefit a tire compound with lower rolling resistance, more stable handling performance, as well as better wet traction. More importantly, the VOC released during the manufacture of rubber articles are significantly reduced in stocks containing AMS (or co‐AMS) when compared with those with a silane. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Measurement of the condensation temperature of nanosilica powder organically modified by a silane coupling agent and its effect evaluation

AbstractThe proper condensation temperatures of nanosilica powder modified by silane coupling agents such as 3‐methacryloxypropyl trimethoxy silane (MEMO), [3‐(2‐aminoethyl)aminopropyl] trimethoxy silane (AMMO), and bis[3‐(triethoxysilyl)propyl] disulfide (TESPD) were measured with Fourier transform infrared. Moreover, the structure and properties of solution‐polymerized styrene–butadiene rubber (SSBR) filled with nanosilica powder that was organically modified by the three silane coupling agents at different temperatures were investigated. The results showed that the proper condensation temperatures of nanosilica powder modified by MEMO, AMMO, and TESPD were about 80, 80, and 100°C, respectively. Compared with SSBR filled with silica powder, SSBR filled with silica powder modified by a silane coupling agent exhibited not only better filler‐dispersion and mechanical properties but also lower internal friction loss in a selected range of strains. Furthermore, when the organic modification was carried out at the proper condensation temperature, the improvement of the modification effect became more obvious. Among these silane coupling agents, AMMO presented the most remarkable modification effect for nanosilica. The mechanism of modification for silica powder and its enhancement of the properties of SSBR were examined. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Moisture Effects on TESPD-Silica/CB/SBR Compounds

Abstract Moisture was treated on a silica surface and it was added into bis(triethoxysilylpropyl)disulfide (TESPD)/carbon black (CB)/S-SBR compound and mixed in an internal mixer. The effects of moisture were investigated with respect to the temperature rise during mixing, processability, cure characteristics, and mechanical properties and two-pass (2P) mixings were compared with conventional three-pass (3P) mixings. Addition of the moisture treated silica into the compound lowered the heat generation during mixing, lowered the drop temperature, decreased the scorch time, lowered the heat build up, lowered the tanδ (E″/E′), increased the Mooney viscosity, increased the torque rise (MH-ML), increased the elongation modulus, increased the blow out time, and increased the deformation%. The properties of each compound were gradually increased with the level of moisture and the 2P mixing procedure generated less heat during mixing and exhibited better mechanical properties than the 3P mixing one. The addition of water molecules improved the silane reaction with silica surface via improved hydrolysis and resulted in an increased level of cross-linking. It also seemed hydrolyzes the benzothiazolesulfenamide accelerator and resulted in a faster scorch and an increased cure rate.

Temperature effects of silane coupling on moisture treated silica surface

AbstractMoisture and temperature effects were investigated on silica/(triethoxysilylpropyl) disulfide (TESPD)/carbon black (CB)/S‐SBR compounds with respect to processability, vulcanization characteristics, physical properties, and alcohol residues. The moisture‐treated compounds exhibited lower rates of viscous heat generation during mixing, lower discharging temperatures (drop temperatures), lower Mooney viscosities, shorter cure times (Tc‐90), higher torque rises (MH − ML), less heat build ups (HBU), and equal or less alcohol residues than the control. As the drop temperatures of the compound were increased, decreased temperature differences between mixer sensor (set drop) and real (proven) temperatures, increased the scorch times (Ts‐2), decreased the cure times (Tc‐90), increased the tensile moduli, and decreased the alcohol residues remaining in the compound. The higher temperature drop compounds (160 and 176°C) exhibited no reversion behavior; however, the lower temperature (120 and 140°C) drop compounds exhibited marching behavior. The treatment of moisture on the silica surface influenced the hydrolysis reaction to the silane and improved coupling on the silica surface. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95:623–633, 2005

Reactive Batch Mixing for Improved Silica-Silane Coupling

Abstract Moisture (55 wt%) treated silica compounds, bis(triethoxysilylpropyl)disulfide(TESPD)/silica/carbon black/S-SBR was processed in a batch mixer and they were investigated with respect to the alcohol residue level in silane, the processability, the vulcanization characteristics, and the mechanical properties. Treatment of moisture on the TESPD/silica/carbon black/S-SBR compound showed a lower alcohol level than untreated material. The alcohol level was low at high drop temperatures. The probe temperatures of the moisture treated compound were lower than the drop temperature, while that of the untreated compound was higher than the drop one. The vulcanization properties of the compounds were changed by treatment of moisture and this improved the mechanical properties of the compounds. The treatment of moisture on silica surface increased the hydrolysis reaction of the alkoxy silane and the hydrolyzed silane improved the coupling reaction with the hydroxyl group on silica surface during reactive batch processing. It also reduced the rate of temperature rise during batch processing due to the latent heat of the moisture and the endothermic reaction between silica and silane. At the vulcanization stage, it seemed to further increase the coupling reaction between silica and silane. The steric hindrance theory of an alkoxy silane has to be reconsidered with a large amount of moisture treated silica/TESPD/CB/S-SBR compound system.

Moisture effects on improved hydrolysis reaction for TESPT and TESPD-silica compounds

The moisture(55 wt%)-treated silica compounds, bis(triethoxysilylpropyl)disulfide (TESPD)/silica/carbon black (CB)/SBR and bis(triethoxysilylpropyl)tetrasulfide (TESPT)/silica/CB/SBR, have been processed in a batch mixer and they are investigated with respect to the alcohol residue level in silane, the processability, the vulcanization characteristics, and the mechanical properties. The alcohol level is low at the moisture treated compounds. The TESPD compounds show lower alcohol level than the TESPT ones on moisture treated and untreated compounds. The probe temperatures of the moisture treated compounds are lower than the drop temperature, while those of the untreated compounds are higher than the drop ones, respectively. The vulcanization properties of the compounds are changed by the moisture treatment and this improves the physical properties of the compounds. The moisture treatment on silica surface increases the hydrolysis reaction of the alkoxy silane and the hydrolyzed silane improved the coupling reaction with the hydroxyl group on silica surface during reactive batch processing. It also reduces the rate of temperature rise during batch mixing due to the latent heat of the moisture and the endothermic reaction between silica and silane. At the vulcanization stage, it seems to further increase the coupling reaction between silica and silane. The steric hindrance theory of an alkoxy silane (TESPT) has to be reconsidered with a large amount of moisture treated silica/TESPD/CB/S-SBR compound system.

THE OCCURRENCE OF SUCROSE IN RELATIVELY LARGE AMOUNTS IN A NEW SEEDLING GRAPE

Zinc ions contatining surfactant (ZB) were added into the silica treated with silanes bis(triethoxysilylpropyl) tetrasulfide (TESPT), and bis(triethoxysilylpropyl)disulfide (TESPD) and its effects on natural rubber (NR) compounds were investigated based on processability, rheology, mechanical properties and silica dispersion. Addition of the ZB increased the mechanical property, torque between maximum and minimum, modulus, and density of the compounds; and reduced the cure time, viscosity, tan δ values, heat generation during mixing, reversion, ODR minimum torque, maximum tensile stress, maximum elongation%, abrasion loss, and swell ratios. The most significant improvement was found from the blowout (BO) experiment with the addition of the ZB. The ZB effects were more significant at higher concentration.