Distillate Aromatic Extract Research Articles

Influence of high cis-1,4-liquid polydienes on properties of carbon-black filled composites

High cis-1,4 liquid polybutadiene (cLBR) and polyisoprene (cLIR) with narrow molecular weight distribution were prepared by the chain-transfer coordination polymerization. The effects of cLBR and cLIR on the physical and dynamic mechanical properties of carbon-black filled composites containing single polybutadiene (PBR) or a blend of PBR/polyisoprene (PIR), were investigated. The results showed that cLBR and cLIR effectively ameliorated filler dispersion compared with the treated distillate aromatic extract (TDAE) oil. The wet skid resistance and rolling resistance of vulcanized PBR/PIR composites plasticized with 5 phr cis-1,4 liquid rubbers were significantly improved. Therefore, a new type of plasticizers cLBR and cLIR that are environmental benign and highly compatible with matrix rubbers, has been discovered to replace the conventional TDAE oil used in fabricating the “green” tyres.

TDAE aromatic oil preference for polymer blends: An analysis of S-SBR, BR, and miscible S-SBR/BR systems

This study assesses the impact of Treated Distillate Aromatic Extract (TDAE) oil, at concentrations of 0–20 parts per hundred rubber (phr), on the glass transition temperature (Tg) of High Vinyl/Low Styrene Styrene-Butadiene Rubber (HVLSS-SBR), polybutadiene rubber (BR), and their blends with weight ratios of 70/30 and 50/50. Using Dynamic Mechanical Analysis, Broadband Dielectric Spectroscopy, and Positron Annihilation Lifetime Spectroscopy, we found that TDAE modifies Tg and fractional free volume (Fv) differently across materials. In HVLSS-SBR, TDAE reduced Tg by approximately 10 °C and increased Fv by 0.8 %. In BR, TDAE raised Tg by 5–7 °C without altering Fv. The 70/30 blend showed no Tg change but a 0.6 % Fv increase. For the 50/50 blend, one Havriliak-Negami equation indicated a Tg rise of 2–3 °C and a 0.4 % Fv increase. A two-equation analysis revealed a 6 °C Tg increase and 0.9 % Fv boost in the BR-rich phase, versus a 2 °C rise and 0.3 % Fv uptick in the HVLSS-SBR-rich phase. The sequence of compatibility, influenced by TDAE, is crystalline BR > amorphous BR > HVLSS-SBR >70/30 blend >50/50 blend. This study provides valuable insights into the behavior of TDAE oil in rubber blends and can serve as a basis for further research in this field.

Exploring the Impact of Bio-Based Plasticizers on the Curing Behavior and Material Properties of a Simplified Tire-Tread Compound.

The tire industry needs to become more sustainable to reduce pollution and fight climate change. Replacing fossil ingredients in a tire-tread compound with bio-based alternatives is an approach to create a more sustainable product. For instance, the plasticizer can be replaced, which is a petroleum-based ingredient used in relatively high amounts in the rubber. This approach was followed in the current study. Three plant-based plasticizers were selected as potential substitutes for treated distillate aromatic extract (TDAE) in a simplified tire-tread compound formulation, namely, sunflower oil, coconut oil, and cardanol. Additionally, squalane was used as a TDAE replacement to further investigate the possible interactions between plasticizers and other compound ingredients. Squalane (C30H62) is a fully saturated substance, containing six methyl groups but no additional chemical functional groups. Therefore, it was expected that squalane would result in limited interactions within the studied system. All alternatives to TDAE showed an increased cure rate and decreased scorch time, except squalane. This indicates that the three bio-based plasticizers might interact with the vulcanization system. For example, they could function as an additional coactivator of the curing system and/or shield the silica surface. A severe decrease in maximum torque and an increase in elongation at break were obtained for cardanol and sunflower oil. Both plasticizers also resulted in lower crosslink densities compared to the other compounds. A model study with the bio-plasticizers and sulfur verified that the unsaturation in the cardanol and sunflower oil reacted with the crosslinking agent. This leads to less sulfur available for the curing reaction, explaining the low maximum torque. The tan δ curves showed that all replacements resulted in a decrease in the glass transition temperature of the compound. Although all oil alternatives displayed promising results, none of them are suitable as a direct substitute for TDAE in a tire-tread compound due to its ability to interact additionally with other rubber ingredients and contribute in this form to the reinforcement of the compound.

Influence of silane-modified palm oil as a green processing oil in silica-reinforced SBR/BR compounds for tire tread applications

This study focuses on the usage of silane-modified palm oil (Si-m-PO) to replace petroleum-based processing oils, i.e., distillate aromatic extract (DAE) and treated distillate aromatic extract (TDAE), in silica-reinforced styrene butadiene rubber/butadiene rubber (SBR/BR) compounds for green tire tread products. The preparation of a novel processing oil based on Si-m-PO was successful on the laboratory scale, as verified by nuclear magnetic resonance, where the grafting efficiency of silane in oil molecules was 58%. Among the different types of processing oils, the presence of Si-m-PO in the compounds resulted in lower filler-filler interactions than the ones with TDAE and unmodified PO but higher than DAE. The Si-m-PO showed an effective reduction in filler–filler interaction compared to unmodified PO, possibly because the Si-m-PO could cover silica surfaces via silane linkage, leading to hydrophobicity of silica surfaces. Overall, the compounds containing Si-m-PO represented higher mechanical properties than the other oils. Furthermore, the Si-m-PO provided the same level concerning rolling resistance and enhanced wet traction, when compared to unmodified PO. Therefore, Si-m-PO can be applied as a biobased processing oil in tire tread applications.

The influence of palm oil-derived plasticizers and lubricants on the rheological and mechanical properties of styrene butadiene rubber

Researchers have recently focused on green processing aids made from plants and vegetables to avoid the high concentration of polycyclic aromatic hydrocarbons (PAHs) from petroleum-based processing oils, which is hazardous to human health. This paper focuses on the effect of lubricants and plasticisers produced from palm oil on the rheological, mechanical and thermal aging properties of styrene-butadiene rubber (SBR). These lubricants and plasticisers are known as glycerol trioleate (GTO), n-butyl stearate (NBS), ethylene bis-steramide (EBS), ethylene bis-oleamide (EBO), pentaerythritol tetrastearate (PETS) and stearyl stearate. The abrasion performance, visual inspection appearance, and cure characteristics of the lubricants and plasticisers on SBR were examined and compared to processing oil-treated distillate aromatic extract (TDAE), paraffin wax, microcrystalline wax, polyethylene (PE) wax, epoxidised soybean oil (ESBO), and stearic acid. It discovered that rubber compounds based on GTO, stearic acid, and EBS exhibited better abrasion resistance and cure properties than rubber compounds based on processing oil. These samples were selected and subjected to mechanical properties, thermal aging effects analysis and comparison with processing oil. Tensile strength shows that SBR with EBS (22.49 MPa) and EBS with GTO (EBS/GTO; 21.25 MPa) are closely similar to SBR compounds with processing oil (21.02 MPa). The findings imply that EBS and EBS/GTO, green plasticisers and lubricants, are viable alternatives to petroleum-based processing oils while being cost-effective for tire production.

Vulcanization kinetics and reinforcement behaviour of natural rubber-carbon black composites: Addition of Shea-butter versus aromatic oil as plasticizers

This work is a comparative study between Shea butter (SB) and treated distillate aromatic extract oil (TDAE) as plasticizers in the vulcanization of natural rubber (NR)- carbon black (CB) vulcanizates (—CB—S—NR—). The plasticized —CB—S—NR— composites extended scorch (Ts2) and optimum (T90) curing times. The delays in crosslinking reaction were suspected to be due to the increased viscosity (ML) and insulation of the reacting species (NR, CB, Sulfur and other curing aids) by the films of plasticizers. This effect increased the activation energy (Ea (KJ/mol)) for vulcanization. The —CB—S—NR— without plasticizer SB (SBO), showed higher ML, crosslinking density index (ΔM), rheological strength (MH) and low cure reversion properties than others. In comparison, the SB loaded —CB—S—NR— composites showed improvement in ML, ΔM, T90, with lowers Ea (KJ/mol) than TDAE samples. Also, the SB compounds exhibited higher Young's modulus Eo(MPa) than SBO and TDAE compounds. For instance, the Eo(MPa) of SB5 was over 7 and 1200 % higher than SBO and STD5 respectively. However, —CB—S—NR— filled with TDAE generally showed higher strength(MPa), attributed to stronger CB—NR interactions. Therefore, environmentally friendly SB could replace petroleum based oils for compounding rubbers.

Effect of Dilution on the Crystallization Kinetics of Neodymium-Based Rare Earth Polybutadiene Rubber.

The crystallization behavior of neodymium-based rare earth polybutadiene rubber (Nd-BR) is studied in the presence of small-molecule treated distillate aromatic extract (TDAE) and high-molecular-weight polybutadiene-isoprene copolymer rubber (BIR). Pronounced inhibitory effects on the crystallization of Nd-BR are exhibited by both materials, as evidenced by reductions in the crystallization temperature (Tc), melting point (Tm), and corresponding enthalpy change. It is found that, at equal concentrations, a greater influence on the crystallization rate is exerted by TDAE oils, whereas nucleation inhibition is more potently affected by BIR. Incomplete crystallization during cooling is exhibited by Nd-BR when the TDAE oil concentration reaches 40 parts per hundreds of rubber (PHR) (31 wt.%), or BIR achieves a 60 wt.% concentration; subsequently, a noticeable cold crystallization phenomenon is observed upon heating. Insights into the isothermal crystallization kinetics are offered by the data, which reveal that the Avrami index n value for Nd-BR predominantly ranges between 2.5 and 3.0. A decrease in the n value is induced by a small amount of TDAE oil, while a noticeable decline in the n value is observed only when the BIR concentration is 60 wt.%. A correlation between the crystallization activation energy, the concentration of TDAE oil and BIR, and the crystallization temperature is established; a negative activation energy is recorded, and a decrease in the crystallization rate is noted when both concentrations are low and the crystallization temperature exceeds -50 °C. In contrast, positive activation energy and an increase in the crystallization rate are observed when the BIR concentration reaches 60%, and the crystallization temperature resides between -50 °C and -70 °C.

Effect of functionality and loading procedure of liquid butadiene rubber on properties of silica-filled tire tread compounds

This study explores the utilization of liquid butadiene rubber (LqBR) as a processing aid in tire tread compounds, as a replacement for treated distillate aromatic extract (TDAE) oil, which is known to contribute to the extraction of organic materials during tire aging. Additionally, the influence of the silane-terminated functional group in LqBR and the procedure of LqBR addition are investigated. The results demonstrate a significant reduction in organic extraction when employing silane-terminated LqBR as a processing aid. Moreover, the performance of tire tread compounds is comparable or even superior to those incorporating TDAE oil, particularly when 80 % silane-terminated LqBR is added after the mixing of silica and coupling agent. The enhanced performance is attributed to homogeneous silica dispersion and robust filler-rubber interaction. These findings offer valuable insights into the optimization procedure for developing tire tread compounds utilizing functionalized LqBR as a processing aid, with the aim of improving tire tread applications.

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.

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.

Optimized End Functionality of Silane-Terminated Liquid Butadiene Rubber for Silica-Filled Rubber Compounds.

As the world is shifting from internal combustion engine vehicles to electric vehicles in response to environmental pollution, the tire industry has been conducting research on tire performance to meet the requirements of electric vehicles. In this experiment, functionalized liquid butadiene rubber (F-LqBR) with triethoxysilyl groups at both ends was introduced into a silica-filled rubber compound as a substitute for treated distillate aromatic extract (TDAE) oil, and comparative evaluation was conducted according to the number of triethoxysilyl groups. The results showed that F-LqBRs improved silica dispersion in the rubber matrix through the formation of chemical bonds between silanol groups and the base rubber, and reduced rolling resistance by limiting chain end mobility and improving filler-rubber interaction. However, when the number of triethoxysilyl groups in F-LqBR was increased from two to four, self-condensation increased, the reactivity of the silanol groups decreased, and the improvement of properties was reduced. As a result, the optimized end functionality of triethoxysilyl groups for F-LqBR in silica-filled rubber compound was two. The 2-Azo-LqBR with the optimized functionality showed an improvement of 10% in rolling resistance, 16% in snow traction, and 17% in abrasion resistance when 10 phr of TDAE oil was substituted.

Utilization of palm oil as an alternative processing oil in carbon black-filled natural rubber compounds

Due to the toxicity of distillate aromatic extract (DAE), palm oil (PO) being environmental friendliness, renewability, and sustainability, was used as an alternative processing oil in this study. The properties of carbon black-filled natural rubber compounds containing PO were investigated and compared with the DAE-added rubber compound. The results revealed that the presence of PO in the rubber compound gave the same degree of filler–filler interactions but higher filler-rubber interactions compared with the one with DAE. Payne effect as referred to filler-filler interactions of the rubber compounds with DAE and PO was 191 and 189 kPa, respectively. In addition, the presence of PO not only accelerated the vulcanization reaction but also reduced the crosslink density within the rubber matrix. The crosslinking type of PO-added rubber compounds consisted only of polysulfidic linkages, whereas the DAE-added rubber compound contained various crosslinking types, i.e., mono-, di-, and polysulfidic linkages. On the other hand, the presence of PO in rubber compounds promoted a positive effect on elastic properties, as indicated by the temperature scanning stress relaxation (TSSR) index and tan δ at 60 °C. The TSSR index of rubber compounds with DAE and PO was 0.69 and 0.71, respectively. Given the low tan δ at 60 °C of the PO-added rubber compounds, PO promoted a low rolling resistance when applied in tire applications, providing tires with safe energy.

Enhancement of the properties of carbon-black-filled natural rubber compounds containing soybean oil cured with peroxide through the addition of coagents

Due to the hazard of the commercial rubber processing oil such as distillate aromatic extract (DAE), many rubber researchers play attention to find the green alternatives. Vegetable oils seem to gain a lot of attraction for this. It is not just only due to their environmentally friendly nature but also their abundance and affordable cost. The use of soybean oil (SBO) for the carbon black-filled rubber compounds was focused here and comparatively discussed with the use of DAE. Furthermore, this work also proposed the way to improve the mechanical properties and environmental endurance of the rubber compounds containing SBO by adding coagents. There were two types of coagent including trimethylolpropane trimethacrylate (TMPTMA) and triallyl isocyanurate (TAIC) used here. It was found that the cure time, cure rate index, and cure reaction rate constant of SBO-added rubber compounds with and without coagents were higher than those of DAE-added rubber compounds, whereas the activation energy of SBO-added rubber compounds was lower than the one with DAE. Without coagent, the mechanical properties of rubber compounds with DAE and SBO are equal. However, the addition of coagents improved the mechanical properties of rubber compounds containing SBO. The modulus at 100% strain, modulus at 200% strain, and tensile strength of TMPTMA-added rubber compounds increased by 41%, 48%, and 15%, respectively, whereas the rubber compounds with TAIC increased by 7%, 8%, and 20%, respectively, when compared to the one with SBO alone. Interesting, the SBO-added rubber compounds with and without coagents showed better thermal aging and ozone resistances than the DAE-added rubber compounds. All results showed that the presence of coagents especially TMPTMA gave the SBO-added rubber compound with the superior performance to the DAE-added rubber compound and the SBO-added rubber compound without coagent.

ADHESION AND HYSTERETIC FRICTION OF TIRE TREAD RUBBERS HAVING PROCESS OILS WITH DIFFERENT AROMATIC CONTENT

ABSTRACT The extent of modification of wet grip of tire tread rubber by safe aromatic process oils has been the subject of controversy, as this property has conventionally been judged by indirect methods such as the loss factor at 0 °C. The present work aims to directly measure the dry and wet frictional behavior of rubbers containing various loadings of distillate aromatic extract (DAE) or treated distillate aromatic extract (TDAE) and to elucidate the contributions resulting from the adhesion and the hysteretic terms of friction. Physico-mechanical tests including rubber hardness, rubber–substrate work of adhesion, rubber–oil compatibility, hysteretic properties, and the rubber glass transition temperature were evaluated to disclose the underlying friction mechanisms. Interestingly, TDAE-containing rubbers presented a comparable or even better hysteretic friction not only at low oil loadings but also at high oil levels. As the loss factor properties of DAE and TDAE are very close to each other and there is the possibility of a crossover point within the frictional zone, care must be exercised not to merely rely on the values of tanδ at 0 °C in judging the preference of DAE or TDAE with regard to the wet grip performance.

Performance Enhancement of Polymerized, Functionalized Solution Styrene–Butadiene Rubber Composites Using Oligomeric Resin towards Extremely Safe and Energy-Saving Tires

Polymerized, functionalized solution styrene–butadiene rubber (F-SSBR) is a new type of polymerized styrene–butadiene rubber solution containing specific terminal groups, which can be used in treads for high performances. However, the wet skid resistance related to safety, the rolling resistance to energy consumption, and the wear resistance to service life are often contradictory and form the performance “magic triangle”. In this work, oligomeric resins, including Coumarone resin, C9 resin, C5/C9 resin and a styrene-α-methyl styrene copolymer (SSC), were used as tire functional additives and selected to replace treated distillate aromatic extract (TDAE) to improve the performances of silica-filled F-SSBR composites. The C9 resin, C5/C9 resin and SSC could enhance the modulus at 300% and tensile strength of the F-SSBR composite. The four resins could improve the wet skid resistance and wear resistance of the composites. However, Coumarone resin caused poor silica dispersion in the F-SSBR matrix and eventually, the lower modulus, higher loss factor at 60 °C and the higher heat buildup in the composite were comparative to the composite with TDAE. Furthermore, the synergistic effect of the C5/C9 resin and SSC was found to improve the mechanical performance of the composites and it resulted in higher tensile strength and modulus, and a lower heat buildup, compared to the case when only TDAE was used. It is noted that the properties “magic triangle” was broken by the C5/C9 resin and SSC, and the C5/C910T15 increased the wet skid resistance by 21.7%, fuel-saving rate by 2.3%, and wear resistance by 8.3%, while S20T5 increased the wet skid resistance by 30.4%, fuel-saving rate by 7%, and wear resistance by 25% compared with CG.

Unfilled Natural Rubber Compounds Containing Bio-Oil Cured with Different Curing Systems: A Comparative Study

This study focuses on the properties of unfilled natural rubber compounds containing bio-oils cured with a peroxide curing system and then discusses the comparisons to those cured using the sulfur system from our previous work. Two types of bio-oils, i.e., palm oil and soybean oil, were used, and distillate aromatic extract (DAE)-based petroleum oil was employed as a reference. The bio-oils caused no significant change in the vulcanization of rubber compounds cured using peroxide. However, the compounds containing bio-oils and cured with sulfur showed a faster vulcanization than the ones with DAE. The bio-oils strongly affected the crosslink density of rubber compounds in both curing systems. The use of bio-oils caused a low crosslink density due to the possible implication of curing agents to bio-oil molecules. The properties of rubber compounds dependent on the different levels of crosslink density were also investigated. The results revealed that when the crosslink density increased, the modulus, tensile strength, and hardness of the rubber compounds increased and the elongation at break and compression set decreased. The use of bio-oils in the rubber compounds cured with different curing systems gave low modulus at 300% strain, tensile strength, and hardness but high elongation at break and compression set when compared to the ones with DAE. However, no significant change was observed for the compression set of the rubber compounds cured using sulfur. With the presence of bio-oils, the properties of rubber compounds cured with sulfur system deteriorated less than those of the ones cured with peroxide.

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.

Influence of liquid polybutadiene on crosslinking network and mechanical properties of SSBR/BR

AbstractThe treated distillate aromatic extract (TDAE) is widely used in tread compounds. However, polycyclic aromatic hydrocarbons (PAHs) contained in TDAE is serious harm to the environment and human. In this paper, liquid polybutadiene (LPB) of different brands was used to replace TDAE to plasticize solution polymerized styrene‐butadiene rubber/cis‐1,4‐polybutadiene rubber (SSBR/BR). The effects of liquid polybutadiene instead of TDAE on crosslinking network and mechanical properties of matrix rubber were studied. LPB could participate in vulcanization reaction (different from TDAE). The results showed that LPB effectively reduced the critical strain amplitude of Payne effect (ameliorated filler dispersion) compared with TDAE plasticizing SSBR/BR. The degree of crosslinking decreased slightly, but there was no significant difference in rolling resistance and wet skid resistance at the same sulfur content. Changing the sulfur content, the wet skid resistance of tread and tensile strength of SSBR/BR vulcanizate plasticized by LPB were significantly improved, and the effect of LPB with high 1,2‐vinyl content was better. In a word, LPB as a new environmental protection plasticizer can be used to effectively replace the TDAE plasticizing SSBR/BR.

Elucidation of the accelerated sulfur vulcanization of bio oil‐extended natural rubber compounds

AbstractThe elucidation of the role of bio‐oils on the accelerated sulfur vulcanization of natural rubber (NR) compounds is discussed in this study. Two types of bio‐oil, palm oil and soybean oil, were studied in direct comparison with a distillate aromatic extract oil (DAE) as a reference. The scorch and cure times of the bio‐oil‐extended NR compounds were shorter than those containing DAE. The use of bio‐oils gave a higher cure reaction rate constant along with a lower activation energy than the use of DAE. The attenuated total reflectance‐Fourier transform infrared spectroscopy analysis revealed that the fatty acid segment of the bio‐oils can react with zinc oxide to give zinc carboxylate, which is then involved in and promotes the vulcanization reaction. The use of bio‐oils to increase the rate of vulcanization strongly influenced the crosslink density of the obtained NR vulcanizates, yielding NR vulcanizates with a lower crosslinking density. It is proposed here that the bio‐oils might consume the curing agent via the reaction between their own unsaturated fatty acid and sulfur. This was supported by the increased viscosity of the oils after exposure to sulfur at a high temperature. The tensile strength and elongation at break of the bio‐oil‐extended NR compounds were lower and higher, respectively, than the NR extended with DAE oil due to the lower crosslink density of the bio oil‐extended NR vulcanizates.

Effect of the Epoxide Contents of Liquid Isoprene Rubber as a Processing Aid on the Properties of Silica-Filled Natural Rubber Compounds.

In this study, we examined the feasibility of using epoxidized liquid isoprene rubber (E-LqIR) as a processing aid for truck and bus radial (TBR) tire treads and investigated the effects of the epoxide content on the wear resistance, fuel efficiency, and resistance to extraction of the E-LqIRs. The results confirmed that, compared to the treated distillate aromatic extract (TDAE) oil, the E-LqIRs could enhance the filler–rubber interactions and reduce the oil migration. However, the consumption of sulfur by the E-LqIRs resulted in a lower crosslink density compared to that of the TDAE oil, and the higher epoxide content decreased the wear resistance and fuel efficiency because of the increased glass-transition temperature (Tg). In contrast, the E-LqIR with a low epoxide content of 6 mol% had no significant effect on the Tg of the final compound and resulted in superior wear resistance and fuel efficiency, compared to those shown by TDAE oil, because of the higher filler–rubber interactions.