Solution Mechanochemical Approach for Preparing High-Dispersion

Apr 10, 2019 - China's clean-air efforts could hike emissions elsewhere. Regional clean-air efforts in China's national capital region could boost air...
0 downloads 0 Views 4MB Size
Download PDF
Article Cite This: Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

pubs.acs.org/IECR

Solution Mechanochemical Approach for Preparing High-Dispersion SiO2‑g‑SSBR and the Performance of Modified Silica/SSBR Composites Wei Gao, Jianmin Lu,* Wenna Song, Jianfang Hu, and Bingyong Han* State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, People’s Republic of China

Downloaded via ROBERT GORDON UNIV on April 21, 2019 at 11:24:37 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

S Supporting Information *

ABSTRACT: This paper reports a simple, high-efficiency, and green approach for preparing high-dispersion silica-g-solution styrene butadiene rubber (SiO2-g-SSBR) through a solution mechanochemical reaction in a laboratory planetary ball mill. The condensation reaction between the hydroxyl groups on the silica surface and the siloxane groups of SSBR-g3-mercaptopropyltriethoxysilane (MPTES) was verified. The results revealed that the chemical modifications of silica through an SSBR polymer matrix weakened the strong filler−filler interactions and enhanced the weak filler−polymer interfacial interactions simultaneously. Because of the dual role of SSBR-g-MPTES as a dispersant and rubber matrix, the modified silica showed high dispersion in the SSBR composites regardless of the compounding, storage, or vulcanization period. Additionally, the dispersion of modified silica was superior to that of silica modified through bis(γ-triethoxysilylpropyl)-tetrasulfide (Si-69). Compared with the unmodified silica/SSBR composite, the performance of the composites was obviously improved, the rolling resistance decreased by 28.4%, wet skid resistance increased by 63.9%, and tensile strength increased by 40.4%. filler networks without enhancing filler−rubber networks during the mixing process. Thus, filler−filler networks tend to form again during storage and at the onset of vulcanization.22,23 To enhance filler−rubber networks and restrain filler−filler networks simultaneously, researchers have combined the wet masterbatch method with a strategy that entails grafting rubber polymers onto silica.16,20 Maya et al.16 prepared natural rubber (NR)−silica composites with epoxidized NR (ENR) as a coupling agent, and they found that the mechanical properties and filler−polymer interactions of the composites were improved compared with those of NR−silica composites with and without the Si-69. Wang et al.20 prepared NR−ENR− silica composites through the wet masterbatch method and found that the silica dispersion, filler−polymer interactions, and dynamic mechanical properties of the composites were superior to those of composites obtained through the traditional compounding process. However, their modifications focused on only NR in latex form. Solution-polymerized styrene butadiene rubber (SSBR) is a crucial synthetic rubber that is widely applied in green tires,6,24 but it has rarely been discussed.

1. INTRODUCTION Because of increasing energy shortage and environmental problems, high-performance “green tires” have attracted considerable attention. Environmentally friendly and nonpetroleum-based silica can provide excellent properties in tires, such as low rolling resistance and high wet traction.1−3 Therefore, silica is broadly applied in “green tires”.4−6 However, due to the considerable difference in polarity between rubber matrices and silica, strong filler−filler interactions and weak filler−polymer interactions hinder the improvement of filler dispersion and the comprehensive enhancement of composites performance.2,7−11 Therefore, to improve the reinforcing effect of silica and the performances of composites, the aforementioned problems must be overcome. To date, in addition to rubber matrix functionalization and silica surface modification,12 the development of new compounding methods is crucial to the improvement of filler dispersion and filler−polymer interfacial interactions. The wet masterbatch method, which can reduce energy consumption13,14 and dust pollution14,15 during mixing, has received increasing attention.14−21 Studies have combined the wet masterbatch method with a strategy of filler surface modification by using silane coupling agents (SCAs)14,18 and surface-active agents (SAAs).18 Although SCAs or SAAs can reduce the polarity of silica through chemical reactions or physical adsorption, they engender only limited improvements in silica dispersion. This is because they restrain only filler− © XXXX American Chemical Society

Received: Revised: Accepted: Published: A

December 29, 2018 April 5, 2019 April 10, 2019 April 10, 2019 DOI: 10.1021/acs.iecr.8b06458 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research

2.3. Preparation of SiO2-g-SSBR Masterbatches. A KEQ-2L laboratory planetary ball mill (Qidong Honghong Instrument Equipment Factory, China) was used to prepare SiO2-g-SSBR masterbatches with various SSBR-g-MPTES contents. Several ZrO2 balls with various diameters (4, 40, and 80 balls with diameters of 10, 6, and 3 mm, respectively) served as the milling media. Silica and the SSBR-g-MPTES solution were added to the mill pot in sequence. The mass ratio of SSBR-g-MPTES to silica was set to 5%, 8%, and 10% (e.g., 3 g of SSBR-g-MPTES for every 30 g of silica). Subsequently, cyclohexane was added to the mill pot to dilute silica to a concentration of 10% (e.g., 10 g of silica in 90 g of cyclohexane). The rotation and revolution speeds of the grinding vial were set at 500 and 290 rpm, respectively. The mixture was ground for 4 h and then spray dried to obtain masterbatches, namely, SiO2-g-SSBR-5 masterbatch, SiO2-gSSBR-8 masterbatch, and SiO2-g-SSBR-10 masterbatch; where the final digits represent the mass ratio of SSBR-g-MPTES to silica (for example, SiO2-g-SSBR-10 indicates that the mass ratio of SSBR-g-MPTES to silica was 10%). To characterize the modified silica, some of the masterbatches were extracted in a Soxhlet extractor by using toluene for 72 h to get rid of the ungrafted SSBR-g-MPTES, and they were subsequently dried in an oven at 70 °C for 36 h. The physically mixed SiO2/SSBR (a:b) were also prepared by ball milling according to the above method, where a:b is the mass ratio of silica to SSBR. Some of the physically mixed SiO2/SSBR (a:b) samples were also extracted in a Soxhlet extractor by using toluene for 72 h. 2.4. Preparation of SSBR/SiO2-g-SSBR Composites. Each SiO2-g-SSBR masterbatch was blended with SSBR2564S and other required ingredients in a 6 in. two-roll mill according to the traditional blending way. The corresponding formulations are presented in Table S1. The compounds were vulcanized at 160 °C and 15 MPa for an optimum cure time, which was determined by the P3555B2 Disc Vulkameter. The composites were prepared from various SiO2-g-SSBR masterbatches, namely, MR-1, MR-2, and MR-3. In addition, SSBR/SiO2 composites without and with the silane coupling agent Si-69 were prepared using the formulations in Table S1, namely, R-1 and R-2. 2.5. Measurements. 1H nuclear magnetic resonance (1H NMR) was conducted using an ARX-400 (400 MHz) with CDCl3 serving as the solvent. The molecular weights and distribution of SSBR were analyzed through gel permeation chromatography (GPC) on an Alliance2690 system (Waters, USA). The SSBR was run in tetrahydrofuran at 30 °C (1.0 mL/min). Polystyrene standards were used for calibration. Differential scanning calorimetry (DSC) was performed using a Mettler-Toledo DSC instrument. The temperature was varied from −80 to 30 °C under nitrogen atmosphere. The heating rate was 10 °C/min. Fourier transform infrared spectroscopy (FTIR) was conducted using a Vertex Fourier transform infrared spectrometer (Bruker Corp., USA). An automated surface area and pore size analyzer (ASAP; Quadrasorb SI, Quantachrome Instruments Co., Ltd., USA) was employed to measure the specific surface area (SSA) of silica through the Brunauer−Emmett−Teller (BET) method with nitrogen adsorption at 196 °C. The silica was degassed at 85 °C for 20 h before adsorption. The weight loss of silica was measured using a Q5000-TA Instruments from 40 to 800 °C under nitrogen atmosphere. The heating rate was 10 °C/min. The cure characteristics of the silica/SSBR composites were measured using an MR-C3 rotorless rheometer at 160 °C and

To address the mentioned research gap, this study developed a simple, high-efficiency, and green approach for preparing SSBR-grafted silica (SiO2-g-SSBR) masterbatches through a solution mechanochemical reaction in a laboratory planetary ball mill. Ball milling can disperse silica to an approximate primary particle size25−28 and break up the secondary structure (aggregations and agglomerates) resulting from the strong interactions among silica, which can prevent the modification of silica occurring only on the exterior of the agglomerates.27,28 3-Mercaptopropyltriethoxysilane (MPTES), a widely used silane coupling agent, can react with hydroxyl groups on silica surface.29,30 Moreover, it has good solubility in cyclohexane. Therefore, sulphydryl-containing MPTES was selected as a modifier to prepare in-chain siloxane-functionalized SSBR (SSBR-g-MPTES) via thiol−ene click. A condensation reaction between siloxane groups of SSBR-gMPTES and hydroxyl groups on silica surface was achieved through a mechanochemical process under high impact and friction condition. Because of the dual role of SSBR-g-MPTES as a dispersant and rubber matrix, the SiO2-g-SSBR-filled SSBR composites exhibited improvements in mechanical properties and dynamic mechanical properties. Moreover, the dynamic mechanical properties, namely, rolling resistance and wet skid resistance, of the composites were slightly better than those of composite filled with silica modified by Si-69.

2. EXPERIMENTAL SECTION 2.1. Materials. Styrene (St) (analytical grade) and cyclohexane (industrial grade) were purchased from Beijing Chemical Reagents Co. (Beijing, China). Styrene and cyclohexane were dried over calcium hydride and distilled in dry nitrogen. Butadiene (Bd) (polymerization grade) was provided by Beijing Yanshan Petrochemical Corp. (Beijing, China) and used as received. N,N-Dimethyltetrahydrofurfurylamine (DMTHFA) was synthesized in our laboratory. In addition, 3-mercaptopropyltriethoxysilane (MPTES) (reagent grade), n-butyllithium (n-BuLi), and lauroyl peroxide (LPO) (≥97%) were bought from Aldrich Chemical Co. (USA) and used as received. Commercial SSBR2564S (styrene content: 26.8 wt %) was purchased from Dushanzi Petrochemical Corp. (Xinjiang, China). The silica of Ultrasil VN3 (CTAB specific surface area is 175 m2/g) was supplied by Degussa Chemical. Other reactants were commercially available and used as received. The SSBR polymer was prepared according to the conventional anionic polymerization method (see Supporting Information). 2.2. Thiol−Ene Click Reaction for Grafting MPTES onto SSBR. The thiol−ene click reaction for grafting MPTES onto SSBR (synthesized in our laboratory, as described in Supporting Information) was conducted as described subsequently. A 0.3 g (1.26 mmol) amount of MPTES was added into the solution of 15 g of SSBR in 200 mL of cyclohexane. The mixed solution was stirred for 10 min, after which 0.17 mL of LPO solution (25 g/L in cyclohexane) was added. All reactants were added to the glass reactor, followed by heating the mixed solution up to 80 °C and then stirring it for 1 h. At the end of the thiol−ene click reaction, ethanol was added to the solution dropwise to precipitate the polymer. After filtration, all products were redissolved and reprecipitated in cyclohexane three times to separate ungrafted MPTES. Finally, the acquired SSBR-g-MPTES was dissolved in cyclohexane (0.1 g/mL) for later use. B

DOI: 10.1021/acs.iecr.8b06458 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research

3.2. Grafting of SSBR-g-MPTES onto Silica through Ball Milling. A mechanochemical reaction is a chemical reaction induced by mechanical energy (e.g., friction, impact, shear, or compression), which results from the collision and/or attrition of grinding media.35 Therefore, such a reaction is a vital complement to traditional mature reactions induced by thermal or irradiative energy. A planetary ball mill, an essential instrument for achieving mechanochemical reactions, can generate high friction and impact during milling.35 Grinding silica using a planetary ball mill not only reduces the particle size of materials but also leads to the formation of radical and charged species such as silyl Si•, siloxyl Si−O•, Si+ cations, and Si−O− anions.27,28,36,37 Condensation reactions between silanol groups and readily hydrolyzable siloxane groups essentially entails nucleophilic substitution and releases water or alkyl alcohol. In the absence of catalysts, condensation reactions between silica and alkoxysilane-functionalized SSBR can be achieved at 85 °C under stirring conditions.38 Mechanochemical activation enables the achievement of chemical reactions at lower temperature than those used in traditional methods.39−41 Moreover, a planetary ball mill engenders a higher energy entry and chemical yield than do stirring and heating.42−44 Therefore, a condensation reaction between SSBR-g-MPTES and silica by using a planetary ball mill is theoretically feasible. Scheme 1 presents the grafting mechanism of silica. Before ball milling, the silica/SSBR-g-MPTES/cyclohexane in the mill pot were distributed in two phases. The sediment at the bottom of the mill pot was silica, and the supernatant was the solution of SSBR-g-MPTES in cyclohexane. By contrast, the emulsion in the mill pot was in a homogeneous state after ball milling. Moreover, the mill pot temperature after ball milling was higher than that before ball milling. Figure 2 presents the FTIR spectra of silica, SSBR-g-MPTES, SiO2-gSSBR-5, and physical mixed SiO2/SSBR before and after extraction. A strong absorbance was observed at 1099 cm−1, which was attributed to Si−O−Si stretching. In addition, absorption peaks were noted at 3422 and 1630 cm−1, which were assigned to surface hydroxyl groups.45 The peaks observed at 703 and 1465 cm−1 were assigned to benzene ring absorption, and that observed at 2922 cm−1 was attributed to the stretching vibration of methylene bonds. To verify the ungrafted molecules can be removed by a 72-h extraction process, the spectra of physically mixed SiO2/SSBR (100:5) before and after extraction were also studied. As shown in Figure 2, the physically mixed SiO2/SSBR (100:5) showed similar peaks to SiO2-g-SSBR-5. However, the peaks related to SSBR molecules disappeared after extraction, indicating that the ungrafted molecules can be removed by an extraction process. Similar observations were also reported in other literature.28,46 The peaks, which were related to SSBR molecules, were still observed for SiO2-g-SSBR-5 sample after extraction, demonstrating successful grafting of SSBR-gMPTES onto the silica surface. Furthermore, the position of the Si−OH absorption peak shifted from 1630 to 1642 cm−1 after grafting, a phenomenon called “blue shift.” Moreover, the position of the Si−OH absorption peak was at 1630 cm−1 in the physically mixed SiO2/SSBR (100:5) sample, indicating that the blue shift was originated due to grafting of SSBR-gMPTES onto silica. This blue shift phenomenon can be explained by the elimination of hydrogen bonds.4,47 The agglomeration and poor dispersion of silica were attributed to the hydrogen bonds. Therefore, the modification of silica by

1.67 Hz. The Payne effect was analyzed through an RPA 2000 instrument (Alpha, USA) at 60 °C. For the compounds, the strain range was from 0.28% to 400% at 1 Hz. For the vulcanizates, the strain range was from 0.28% to 41.99% at 10 Hz. The silica flocculation extent during vulcanization was calculated by measuring the change of storage modulus of the composite before and after vulcanization using RPA 2000 instrument (Alpha, USA). The dispersion of silica was examined using a transmission electron microscopy (TEM) instrument (Tecnai G2 20). The accelerating voltage was 200 kV. Ultrathin samples were cut using a microtome at −100 °C. The cross-link densities of all vulcanizates were analyzed through swelling experiments, with toluene serving as the solvent31 (see Supporting Information). The mechanical properties of the composites were measured using a CMT4104 electrical tensile tester in accordance with ASTM D638. The crosshead speed was 500 mm/min. The dynamic mechanical properties of the composites were measured using a VA3000 dynamic mechanical thermal analyzer (DMTA) in tension mode at 10 Hz. The temperature was varied from −80 to 80 °C. The heating rate and strain amplitude were 3 °C/min and 0.1%, respectively.

3. RESULTS AND DISCUSSION 3.1. Synthesis of SSBR-g-MPTES. The thiol−ene click reaction was used to graft MPTES onto SSBR, with LPO serving as an initiator. The 1H NMR spectra of SSBR and SSBR-g-MPTES are illustrated in Figure 1. A peak was

Figure 1. Typical 1H NMR spectra of SSBR and SSBR-g-MPTES.

observed at 3.80−3.92 ppm after grafting, which was attributed to the methylene protons in −Si−(OCH2CH3)3, indicating successful grafting of MPTES onto SSBR. The characteristics of SSBR and SSBR-g-MPTES are shown in Table S2. The grafting percentage (ratio of the weight of grafted MPTES to that of SSBR) of MPTES based on SSBR was calculated from the 1H NMR spectrum by using eq S9, and the calculated grafting percentage was 0.81%. The thiol−ene click reaction mainly occurred between the 1,2-polybutadiene units and sulfhydryl,32−34 and approximately 0.39% of the 1,2polybutadiene units reacted with MPTES in the experiment. The measurements revealed nearly 9 MPTES molecules in each SSBR-g-MPTES. Because of the low grafting percentage, the glass transition temperature variation was not obvious after grafting (Figure S1). C

DOI: 10.1021/acs.iecr.8b06458 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research Scheme 1. Diagram of SSBR-g-MPTES Grafted onto Silica by Ball Milling

Figure 3. SSA-BET values of silica, SiO2-g-SSBR-5, SiO2-g-SSBR-8, and SiO2-g-SSBR-10.

Figure 2. FTIR spectra of silica, SSBR-g-MPTES, SiO2-g-SSBR-5, and physical mixed SiO2/SSBR before and after extraction.

SSBR-g-MPTES through the solution mechanochemical reaction was determined to be beneficial to the dispersion of silica in composites. Figure 3 shows the SSAs of silica, SiO2-g-SSBR-5, SiO2-gSSBR-8, and SiO2-g-SSBR-10 measured using the BET method.48 The SSAs of modified silica exhibited a clear decreasing trend because the grafted SSBR macromolecules blocked access of nitrogen to the pore area of silica.11,13 The SSA of SiO2-g-SSBR-10 decreased by 75.9% compared with that of silica. This was in accordance with Jana’s work reporting that the polymer coated on carbon black made a reduction in the BET surface area of carbon black.11 Under the same modifier dosage, the SSA of SiO2-g-SSBR-8 decreased by 33.8% compared with that of silica modified by silane coupling agent,13 indicating a much larger coverage area of porous silica by SSBR-g-MPTES than the silane coupling agent.11 Thermogravimetric analysis was conducted to calculate the grafting percentage of modified silica, and Figure 4 illustrates the TGA results. To ensure consistency in the treatment processes, all samples were dried in a vacuum oven in advance. The TGA curve of silica indicated two zones of weight loss

Figure 4. TGA curves of silica, SSBR, SSBR-g-MPTES, SiO2-g-SSBR5, SiO2-g-SSBR-8, SiO2-g-SSBR-10, and physical mixed SiO2/SSBR before and after extraction.

(Figure 4). In the first zone (40−143 °C), silica exhibited a considerable decrease in weight loss; the weight loss value was considerably higher than those of the modified silica, which D

DOI: 10.1021/acs.iecr.8b06458 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research

after grafting as the SSBR-g-MPTES content increased, as shown in Figure 5c−e. In addition, the dispersion of grafted silica was more uniform than that of silica displayed in Figure 5b. The obvious improvement in the silica dispersion was due to the improved interfacial interaction resulting from the covalent bonding interfaces formed during the solution mechanochemical reaction. This study created plots of the storage modulus (G′) versus strain of all composites, as illustrated in Figure 6, to examine filler−filler networks. Payne revealed that filler−filler networks are destroyed and G′ decreases rapidly only when the strain exceeds a small critical value, a phenomenon commonly called the Payne effect.51 A low Payne effect signifies weak filler−filler networks and strong filler−polymer interactions. In this study, a considerably high starting G′ value and an evident Payne effect were observed for the R-1 composites (Figure 6), indicating that extremely strong filler−filler networks existed in R-1 due to the weak interfacial interaction. The filler−filler networks were damaged considerably after SSBR-g-MPTES was chemically grafted onto the silica surface. For example, the initial G′ value of the MR-1 compound decreased by 70.1%, and the Payne effect decreased considerably. The first derivative dG′/dε can be applied to measure the dependence of G′ on strain.32 As displayed in Figure 7, the G′ values of the SSBR/SiO2-g-SSBR compounds were much less dependent on strain compared with those of the SSBR/SiO2 compounds, further signifying that the filler−filler networks were damaged after silica grafting. As shown in Figure 6(a) and 6(b), the Payne effects observed for the SSBR/SiO2-g-SSBR composites were less obvious than those observed for the R-2 composites. For the SSBR/SiO2-g-SSBR compounds, the initial G′ values of MR-1, MR-2, and MR-3 were 239.79, 229.84, and 266.62 KPa, respectively, as presented in Figure 6a. For the SSBR/ SiO2-g-SSBR vulcanizates, the initial G′ values of MR-1, MR-2, and MR-3 were 963.56, 949.79, and 1099.85 KPa, respectively, as illustrated in Figure 6b. Specifically, the SSBR/SiO2-g-SSBR composites can be ordered as follows with respect to the initial G′ values: MR-3 > MR-1 > MR-2. In addition to the filler− filler networks, composites typically include filler−rubber networks,49,50,52,53 and both types of filler networks can increase the initial G′.7,31,49,50,52 For MR-1 and MR-2, the filler−filler networks were dominant, and the initial G′ values decreased as the SSBR-g-MPTES content increased. By contrast, for MR-3, the filler−rubber networks were dominant, and the initial G′ values increased with the SSBR-g-MPTES content. Figure 8 illustrates tan δ−strain amplitude plots for all vulcanizates. At low strains, the internal friction loss could primarily be attributed to the viscous nature of rubber chains.54 For the R-2 and SSBR/SiO2-g-SSBR vulcanizates, although the effective deformable rubber fractions increased because of the improvement of filler dispersion, the enhanced interfacial interaction restricted the mobility of macromolecular chains.49,50 Therefore, the tan δ values of the R-2 and SSBR/SiO2-g-SSBR vulcanizates were similar to those of the R1 vulcanizate at low strains. At high strains, the internal friction loss could primarily be attributed to the filler−filler and filler− polymer frictions. For the R-1 vulcanizate, the poor dispersion of silica and weak interfacial interaction resulted in strong filler−filler friction and filler−polymer friction. Thus, the tan δ values of the R-1 vulcanizate increased considerably with the strain. For the R-2 and SSBR/SiO2-g-SSBR vulcanizates, at high strains, the improved silica dispersion and enhanced

resulted from removal of a high amount of physisorbed water. The weight loss of silica in the second zone (143−800 °C) was due to the silanol groups dehydroxylation and chemically combined water.27,28 SSBR-g-MPTES and SSBR were mostly decomposed between 220 and 470 °C. For modified silica, the weight loss between 300 and 580 °C was mainly attributed to the combustion of grafted SSBR-g-MPTES.10 It meant that the grafting percentages (ratio of the weight of grafted SSBR-gMPTES to that of unmodified silica) of SSBR-g-MPTES based on silica observed for SiO2-g-SSBR-5, SiO2-g-SSBR-8, and SiO2-g-SSBR-10 were 4.5%, 6.1%, and 6.9%, respectively. The grafting percentages increased with the amount of SSBR-gMPTES, indicating that the solution mechanochemical method was beneficial to the condensation reactions between SSBR-gMPTES and silica. To further rule out that the weight loss between 300 and 580 °C was not caused by the ungrafted molecules, the TGA curves of physically mixed SiO2/SSBR (100:10) before and after extraction were also analyzed. The results showed that SSBR molecules were removed by an extraction process, and the TGA curve of the physically mixed SiO2/SSBR (100:10) after extraction was similar to that of silica. Combining the SSA of silica, the grafting densities, which were calculated by using eq S10, observed for SiO2-g-SSBR-5, SiO2-g-SSBR-8, and SiO2-g-SSBR-10 were 2.0 × 10−3, 2.7 × 10−3, and 3.1 × 10−3 SSBR/nm2, respectively. These grafting densities of our SiO2-g-SSBR are similar to those of modified silica prepared through ball milling.27,28 3.3. Dispersion of SiO2-g-SSBR in SSBR Matrix. The homogeneous dispersion of nanosized filler in composites is crucial to the improvement of the properties of the silica/SSBR composites.14,47 To study the dispersion of SiO2-g-SSBR in the SSBR matrix, five types of compounds and vulcanizates were prepared in this study, and Table S1 shows the corresponding formulations. The vulcanizates were examined through TEM, and Figure 5 depicts the TEM micrographs, indicating the dispersion of

Figure 5. TEM images of (a) R-1, (b) R-2, (c) MR-1, (d) MR-2, and (e) MR-3 vulcanizates.

silica in the SSBR/SiO2 and SSBR/SiO2-g-SSBR vulcanizates. The dark phases in the TEM micrographs represent silica particles.13,14,49,50 Figure 5a reveals a high number of silica aggregates and voids, indicating the poor dispersion of unmodified silica in the composite due to the weak interfacial interaction. The number of aggregates decreased continuously E

DOI: 10.1021/acs.iecr.8b06458 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research

Figure 6. Payne effect study of SSBR/SiO2 and SSBR/SiO2-g-SSBR composites: (a) compounds and (b) vulcanizates.

modification through SSBR-g-MPTES by using the solution mechanochemical reaction was beneficial to the reduction of rolling resistance. The rolling resistance of MR-1, MR-2, and MR-3 decreased by 26.9%, 28.4%, and 34.2%, respectively, compared with that of R-1. Bohm’s work showed that filler−filler networks were formed by a flocculation during storage, molding, and the first few minutes of vulcanization.23 In order to quantify the extent of silica flocculation during vulcanization at high temperature, the differences in ΔG′ between compounds and vulcanizates, δΔG′, were calculated.29,56 The ΔG′ was the difference between the G′ at 0.28% strain and 41.99% strain. As presented in Table S3, the δΔG′ values, indicating the extent of silica flocculation,29,56 of R-1, R-2, MR-1, MR-2, and MR-3 composites were 927.82, 666.25, 493.01, 479.83, and 581.88 KPa, respectively. These results indicated that silica modification through the SSBR matrix could effectively inhibit the formation of filler−filler networks during vulcanization at high temperature. This phenomenon can be attributed to the following reasons: (1) improvement of steric hindrance of SiO2-g-SSBR,57,58 (2) improvement of affinity between SiO2-gSSBR and the SSBR matrix,57,58 and (3) improvement of interfacial interaction through covalent bond formation. 3.4. Performance of SSBR/SiO2-g-SSBR Composites. Figure 9 and Table S4 present the vulcanization characteristics of all of the composites. The torque values of the SSBR/SiO2-

Figure 7. First-derivative curves of SSBR/SiO2 and SSBR/SiO2-gSSBR compounds for storage modulus vs strain.

Figure 8. Dependence of tan δ on strain for SSBR/SiO2 and SSBR/ SiO2-g-SSBR vulcanizates.

interfacial interaction led to a steady increase in tan δ values with the strain. Moreover, due to the gradual improvement in interfacial interaction, at high strains, the tan δ values decreased continuously as the SSBR-g-MPTES content increased. A tan δ value at 7% strain is usually used as the index to evaluate the rolling resistance of composites.49,55 As illustrated in Figure 8, the composites can be ordered as follows with respect to the tan δ values at 7% strain: R-1 > R-2 > MR-1 > MR-2 > MR-3. This indicates that silica

Figure 9. Vulcanization characteristics of SSBR/SiO2 and SSBR/ SiO2-g-SSBR composites. F

DOI: 10.1021/acs.iecr.8b06458 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research g-SSBR composites were lower than that of the R-1 composite (Figure 9) because of the reduction of filler−filler networks.45 However, the torque values of the SSBR/SiO2-g-SSBR composites increased with the SSBR-g-MPTES content due to the improved interfacial interaction.50 The amount of hydroxyl groups on the silica surface that can react with the accelerators was reduced. Therefore, the optimum cure times (t90) observed for the SSBR/SiO2-g-SSBR composites were lower than that observed for the R-1 composite (Table S4). The scorch times (t10) of the SSBR/SiO2-g-SSBR composites were similar to that of the R-1 composite (Table S4), which indicated that the silica modification through SSBR-g-MPTES by using the solution mechanochemical reaction had little effect on the onset of vulcanization. The cross-link densities of the SSBR/SiO2 and SSBR/SiO2g-SSBR vulcanizates were measured using the equilibrium swelling method, and Table 1 shows the results. The cross-link

mechanical properties of the vulcanizates. It was precisely because the highest cross-link density, the highest tensile strength, and the lowest elongation at break among all of the vulcanizates were observed for R-2 vulcanizate. The temperature dependence of the dynamic mechanical properties of all vulcanizates is displayed in Figure 11 and summarized in Table S6. In general, strong filler−filler networks increase the number of rubber matrices trapped in silica aggregates, which reduces the mobility of rubber matrices and leads to high G′ values in rubbery regions.13,38,61,62 As revealed in Figure 11a, the G′ values of the SSBR/SiO2-g-SSBR vulcanizates were lower than those of the R-1 and R-2 vulcanizates in the rubbery region, indicating improved silica dispersion in the SSBR/SiO2-g-SSBR composites. These results were in accordance with the TEM and RPA results. However, the G′ values of the SSBR/SiO2-g-SSBR vulcanizates increased slightly with the SSBR-g-MPTES content. This resulted from the improved interfacial interaction between silica and polymer.47,50 The destruction of the filler−filler networks could be ignored because of the comparatively low strain in the DMTA experiments.32 Therefore, the relaxation of macromolecular chain segments can be the primary source of internal friction loss in the glass transition zone. Improved silica dispersion helps to reduce the number of rubber matrices trapped in filler−filler networks and improve the effective volume of the rubber matrices,13,63 resulting in increasing the tan δ value at Tg (tan δmax)64 due to an increase in rubber fractions involved in chain segment relaxation.47,54 As displayed in Figure 11b, the tan δmax values of the SSBR/ SiO2-g-SSBR vulcanizates were higher than those of the SSBR/ SiO2 vulcanizates, demonstrating that the filler−filler networks of the SSBR/SiO2-g-SSBR vulcanizates were weaker than those of the SSBR/SiO2 vulcanizates. However, because of the improved interfacial interaction, the tan δmax values decreased slightly as the SSBR-g-MPTES content increased (Table S6),47,50 a finding determined to be consistent with the results in Figure 11a. A relatively high hysteresis value at 0 °C (tan δ (0 °C)) is favorable for wet skid resistance.65 The tan δ (0 °C) values of the SSBR/SiO2-g-SSBR vulcanizates were higher than that of the R-1 vulcanizate, indicating that the silica modification through SSBR-g-MPTES by using the solution mechanochemical reaction was beneficial to the improvement of wet skid resistance. The wet skid resistance of MR-1, MR-2, and MR-3 increased by 26.6%, 63.9%, and 2.3%, respectively, compared with that of R-1 (Table S6). The wet skid resistance of the SSBR/SiO2-g-SSBR vulcanizates was slightly superior to that of the R-2 vulcanizate.

Table 1. Crosslink Densities of SSBR/SiO2 and SSBR/SiO2g-SSBR Vulcanizates samples

R-1

R-2

MR-1

MR-2

MR-3

cross-linking density (10−4 mol/cm3)

2.00

3.18

2.24

2.34

2.65

densities of the SSBR/SiO2-g-SSBR vulcanizates were higher than that of the R-1 vulcanizate and increased continuously with the SSBR-g-MPTES content. Furthermore, among the vulcanizates, the R-2 exhibited the highest cross-link density because the sulfur elements from Si-69 participated in the cross-linking reaction. Figure 10 and Table S5 present the mechanical properties of all vulcanizates. The tensile strength and tear strength of the

Figure 10. Stress−strain curves of SSBR/SiO2 and SSBR/SiO2-gSSBR vulcanizates.

4. CONCLUSIONS Mechanochemical activation achieved through ball milling engendered a condensation reaction between siloxane groups of SSBR-g-MPTES and hydroxyl groups on silica surface. SSBR-g-MPTES was successfully grafted onto silica, and the maximum grafting percentage was 6.9%. The strong filler−filler networks were damaged in modified silica (SiO2-g-SSBR). Moreover, chemical modifications of silica through SSBR matrices improved the filler−rubber interfacial interaction, which contributed to the effective inhibition of filler−filler network reformation during storage and at the onset of vulcanization. Because of the dual role of SSBR-g-MPTES as a dispersant and rubber matrix, the SiO2-g-SSBR with a small

SSBR/SiO2-g-SSBR vulcanizates were improved compared with those of the R-1 vulcanizate (Table S5). For instance, the tensile strength and tear strength of the MR-2 vulcanizate increased by 40.4% and 25.1%, respectively, compared with those of the R-1 vulcanizate (Table S5). This was because the improved interfacial interaction and silica dispersion led to external force transfer through the silica−rubber interface59 and lengthened the propagation paths of tear cracks.38,60 In addition, the improved cross-link densities of the SSBR/SiO2g-SSBR vulcanizates were determined to be beneficial to the G

DOI: 10.1021/acs.iecr.8b06458 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research

Figure 11. DMTA plots of SSBR/SiO2 and SSBR/SiO2-g-SSBR vulcanizates.

■

SSA showed excellent dispersion regardless of the compounding, storage, or vulcanization period. Furthermore, the dispersion of modified silica improved as the grafting percentage increased and was even superior to that of silica modified through Si-69. The SSBR/SiO2-g-SSBR composites exhibited relatively low vulcanization torque values, short cure times, and improved performance. For the modified silica/ SSBR composites at a grafting percentage of 6.1%, the rolling resistance decreased by 28.4%, wet skid resistance increased by 63.9%, and tensile strength increased by 40.4% compared with the unmodified silica/SSBR composite. This simple, highefficiency, and green approach for silica modification is expected to provide a practical and profound method for fabricating green tires.

■

(1) Bhattacharyya, S. K.; Parmar, B. S.; Chakraborty, A.; Dasgupta, S.; Mukhopadhyay, R.; Bandyopadhyay, A. Exploring Microcrystalline Cellulose (MCC) as a Green Multifunctional Additive (MFA) in a Typical Solution-Grade Styrene Butadiene Rubber (S-SBR)-Based Tread Compound. Ind. Eng. Chem. Res. 2012, 51, 10649−10658. (2) Suzuki, N.; Ito, M.; Yatsuyanagi, F. Effects of Rubber/Filler Interactions on Deformation Behavior of Silica Filled SBR Systems. Polymer 2005, 46, 193−201. (3) Xu, T.; Jia, Z.; Wu, L.; Chen, Y.; Luo, Y.; Jia, D.; Peng, Z. Influence of Acetone Extract from Natural Rubber on the Structure and Interface Interaction in NR/Silica Composites. Appl. Surf. Sci. 2017, 423, 43−52. (4) Qu, L.; Yu, G.; Wang, L.; Li, C.; Zhao, Q.; Li, J. Effect of FillerElastomer Interactions on the Mechanical and Nonlinear Viscoelastic Behaviors of Chemically Modified Silica-Reinforced SolutionPolymerized Styrene Butadiene Rubber. J. Appl. Polym. Sci. 2012, 126, 116−126. (5) Tang, Z.; Huang, J.; Wu, X.; Guo, B.; Zhang, L.; Liu, F. Interface Engineering toward Promoting Silanization by Ionic Liquid for HighPerformance Rubber/Silica Composites. Ind. Eng. Chem. Res. 2015, 54, 10747−10756. (6) Xu, T.; Jia, Z.; Luo, Y.; Jia, D.; Peng, Z. Interfacial Interaction Between the Epoxidized Natural Rubber and Silica in Natural Rubber/Silica Composites. Appl. Surf. Sci. 2015, 328, 306−313. (7) Fröhlich, J.; Niedermeier, W.; Luginsland, H.-D. The Effect of Filler-Filler and Filler-Elastomer Interaction on Rubber Reinforcement. Composites, Part A 2005, 36, 449−460. (8) Gurovich, D.; Macosko, C. W.; Tirrell, M. The Influence of Filler-Filler and Filler-Polymer Interactions on the Physical Properties of Silica-Filled Liquid Polyisoprene. Rubber Chem. Technol. 2004, 77, 1−12. (9) Li, X.; Cao, Z.; Zhang, Z.; Dang, H. Surface-Modification in Situ of Nano-SiO2 and its Structure and Tribological Properties. Appl. Surf. Sci. 2006, 252, 7856−7861. (10) Li, D.; Liu, Q.; Yu, L.; Li, X.; Zhang, Z. Correlation between Interfacial Interactions and Mechanical Properties of PA-6 Doped with Surface-Capped Nano-Silica. Appl. Surf. Sci. 2009, 255, 7871− 7877. (11) Raut, P.; Swanson, N.; Kulkarni, A.; Pugh, C.; Jana, S. C. Exploiting Arene-Perfluoroarene Interactions for Dispersion of Carbon Black in Rubber Compounds. Polymer 2018, 148, 247−258. (12) Rostami, M.; Ranjbar, Z.; Mohseni, M. Investigating the Interfacial Interaction of Different Aminosilane Treated Nano Silicas with a Polyurethane Coating. Appl. Surf. Sci. 2010, 257, 899−904. (13) Li, Y.; Han, B.; Liu, L.; Zhang, F.; Zhang, L.; Wen, S.; Lu, Y.; Yang, H.; Shen, J. Surface Modification of Silica by Two-Step Method and Properties of Solution Styrene Butadiene Rubber (SSBR)

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.iecr.8b06458. Synthesis of SSBR; formulations of SSBR/SiO2-g-SSBR composites; cross-link density measurement; synthesis of SSBR-g-MPTES; grafting density of SSBR; filler flocculation in SSBR/SiO2 and SSBR/SiO2-g-SSBR composites; curing characteristics of SSBR/SiO2 and SSBR/SiO2-g-SSBR composites; mechanical properties of SSBR/SiO2 and SSBR/SiO2-g-SSBR vulcanizates; internal friction loss of SSBR/SiO2 and SSBR/SiO2-gSSBR vulcanizates (PDF)

■

REFERENCES

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. ORCID

Jianmin Lu: 0000-0002-8642-2700 Bingyong Han: 0000-0001-8313-575X Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (Grant nos. 51473010 and 51373009) and National Basic Research Program of China (Grant no. 2015CB654701). H

DOI: 10.1021/acs.iecr.8b06458 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research Nanocomposites Filled with Modified Silica. Compos. Sci. Technol. 2013, 88, 69−75. (14) Gui, Y.; Zheng, J.; Ye, X.; Han, D.; Xi, M.; Zhang, L. Preparation and Performance of Silica/SBR Masterbatches with High Silica Loading by Latex Compounding Method. Composites, Part B 2016, 85, 130−139. (15) Prasertsri, S.; Rattanasom, N. Mechanical and Damping Properties of Silica/Natural Rubber Composites Prepared from Latex System. Polym. Test. 2011, 30, 515−526. (16) Maya, K. S.; Rani, J.; Varkey, J. K.; George, B. Epoxidised Natural Rubber as a Coupling Agent in in-Situ Precipitated SilicaNatural Rubber Composites. J. Rubber Res. (Kuala Lumpur, Malays.) 2006, 9, 204−216. (17) Lightsey, J. W.; Kneiling, D. J.; Long, J. M. Silica Wet Masterbatch: A New Process for Pre-Dispersion of Silica in Emulsion Polymers. Rubber World 1998, 218, 35−42. (18) Zheng, J.; Ye, X.; Han, D.; Zhao, S.; Wu, X.; Wu, Y.; Dong, D.; Wang, Y.; Zhang, L. Silica Modified by Alcohol Polyoxyethylene Ether and Silane Coupling Agent Together to Achieve High Performance Rubber Composites Using the Latex Compounding Method. Polymers 2018, 10, 1−17. (19) Prasertsri, S.; Rattanasom, N. Fumed and Precipitated Silica Reinforced Natural Rubber Composites Prepared from Latex System: Mechanical and Dynamic Properties. Polym. Test. 2012, 31, 593−605. (20) Wang, Y.; Liao, L.; Zhong, J.; He, D.; Xu, K.; Yang, C.; Luo, Y.; Peng, Z. The Behavior of Natural Rubber-Epoxidized Natural RubberSilica Composites Based on Wet Masterbatch Technique. J. Appl. Polym. Sci. 2016, 133, 43571. (21) Yin, C.; Zhang, Q.; Gong, D. Preparation and Properties of Silica/Styrene Butadiene Rubber Masterbatches by Latex CoCoagulating Technology. Polym. Compos. 2013, 35, 1212−1219. (22) Böhm, G. G. A.; Nguyen, M. N. Flocculation of Carbon-Black in Filled Rubber Compounds. 1. Flocculation Occurring in Unvulcanized Compounds during Annealing at Elevated-Temperatures. J. Appl. Polym. Sci. 1995, 55, 1041−1050. (23) Böhm, G. G. A.; Tomaszewski, W.; Cole, W.; Hogan, T. Furthering the Understanding of the Non Linear Response of Filler Reinforced Elastomers. Polymer 2010, 51, 2057−2068. (24) Sun, Z.; Huang, Q.; Wang, Y.; Zhang, L.; Wu, Y. Structure and Properties of Silicone Rubber/Styrene-Butadiene Rubber Blends with in Situ Interface Coupling by Thiol-Ene Click Reaction. Ind. Eng. Chem. Res. 2017, 56, 1471−1477. (25) Castrillo, P. D.; Olmos, D.; Amador, D. R.; González-Benito, J. Real Dispersion of Isolated Fumed Silica Nanoparticles in Highly Filled PMMA Prepared by High Energy Ball Milling. J. Colloid Interface Sci. 2007, 308, 318−324. (26) Pantaleón, R.; González-Benito, J. Structure and Thermostability of PMMA in PMMA/Silica Nanocomposites: Effect of HighEnergy Ball Milling and the Amount of the Nanofiller. Polym. Compos. 2010, 31, 1585−1592. (27) Lin, J.; Chen, H.; Yao, L. Surface Tailoring of SiO 2 Nanoparticles by Mechanochemical Method Based on Simple Milling. Appl. Surf. Sci. 2010, 256, 5978−5984. (28) Lin, J.; Chen, H.; Yuan, Y.; Ji, Y. Mechanochemically Conjugated PMHS/Nano-SiO2 Hybrid and Subsequent Optimum Grafting Density Study. Appl. Surf. Sci. 2011, 257, 9024−9032. (29) Robertson, C. G.; Lin, C. J.; Bogoslovov, R. B.; Rackaitis, M.; Sadhukhan, P.; Quinn, J. D.; Roland, C. M. Flocculation, Reinforcement, and Glass Transition Effects in Silica-Filled Styrene-Butadiene Rubber. Rubber Chem. Technol. 2011, 84, 507−519. (30) Zheng, M.; Lu, Y.; Dong, L.; Guo, P.; Deng, Q.; Li, W.; Feng, Y.; Huang, F. Immobilization of Candida Rugosa Lipase on Hydrophobic/Strong Cation-Exchange Functional Silica Particles for Biocatalytic Synthesis of Phytosterol Esters. Bioresour. Technol. 2012, 115, 141−146. (31) Qiao, H.; Wang, R.; Yao, H.; Wu, X.; Lei, W.; Zhou, X.; Hu, X.; Zhang, L. Design and Preparation of Natural Layered Silicate/BioBased Elastomer Nanocomposites with Improved Dispersion and Interfacial Interaction. Polymer 2015, 79, 1−11.

(32) Qu, L.; Wang, L.; Xie, X.; Yu, G.; Bu, S. Contribution of SilicaRubber Interactions on the Viscoelastic Behaviors of Modified Solution Polymerized Styrene Butadiene Rubbers (M-S-SBRs) Filled with Silica. RSC Adv. 2014, 4, 64354−64363. (33) Lotti, L.; Coiai, S.; Ciardelli, F.; Galimberti, M.; Passaglia, E. Thiol-Ene Radical Addition of L-cysteine Derivatives to Low Molecular Weight Polybutadiene. Macromol. Chem. Phys. 2009, 210, 1471−1483. (34) Schapman, F.; Couvercelle, J. P.; Bunel, C. Low Molar Mass Polybutadiene Made Crosslinkable by Silane Moities Introduced via Addition of Thiol to Double Bond: 3. Synthesis and Kinetic Study. Polymer 1998, 39, 4955−4962. (35) Leonardi, M.; Villacampa, M.; Menéndez, J. C. Multicomponent Mechanochemical Synthesis. Chem. Sci. 2018, 9, 2042− 2064. (36) Cocco, O.; Garroni, S.; Enzo, S.; Pia, G.; Meloni, P.; Delogu, F. Ball Milling of Silica-Based Pyroclastic Scoriae: Measurement of Mechanochemical Reactivity by Radical Scavenging. J. Phys. Chem. C 2018, 122, 2773−2782. (37) Hochstrasser, G.; Antonini, J. F. Surface States of Pristine Silica Surfaces: I. ESR Studies of Es′ Dangling Bonds and of CO2− Adsorbed Radicals. Surf. Sci. 1972, 32, 644−664. (38) Liu, X.; Zhao, S.; Zhang, X.; Li, X.; Bai, Y. Preparation, Structure, and Properties of Solution-Polymerized Styrene-Butadiene Rubber with Functionalized End-Groups and its Silica-Filled Composites. Polymer 2014, 55, 1964−1976. (39) Ye, G.; Troczynski, T. Mechanochemical Activation-Assisted Low-Temperature Synthesis of CaZrO3. J. Am. Ceram. Soc. 2007, 90, 287−290. (40) Mergen, A. Mechanochemical Synthesis of MgTa2O6 Ceramic. Ceram. Int. 2009, 35, 1151−1157. (41) James, S. L.; Adams, C. J.; Bolm, C.; Braga, D.; Collier, P.; Frišcǐ ć, T.; Grepioni, F.; Harris, K. D. M.; Hyett, G.; Jones, W.; Krebs, A.; Mack, J.; Maini, L.; Orpen, A. G.; Parkin, I. P.; Shearouse, W. C.; Steed, J. W.; Waddell, D. C. Mechanochemistry: Opportunities for New and Cleaner Synthesis. Chem. Soc. Rev. 2012, 41, 413−447. (42) Tullberg, E.; Peters, D.; Frejd, T. The Heck Reaction under Ball-Milling Conditions. J. Organomet. Chem. 2004, 689, 3778−3781. (43) Watanabe, H.; Hiraoka, R.; Senna, M. A Diels-Alder Reaction Catalyzed by Eutectic Complexes Autogenously Formed from Solid State Phenols and Quinines. Tetrahedron Lett. 2006, 47, 4481−4484. (44) Stolle, A.; Szuppa, T.; Leonhardt, S. E. S.; Ondruschka, B. Ball Milling in Organic Synthesis: Solutions and Challenges. Chem. Soc. Rev. 2011, 40, 2317−2329. (45) Hosseini, S. M.; Torbati-Fard, N.; Kiyani, H.; RazzaghiKashani, M. Comparative Role of Interface in Reinforcing Mechanisms of Nano Silica Modified by Silanes and Liquid Rubber in SBR Composites. J. Polym. Res. 2016, 23, 1−10. (46) Somaratne, M. C. W.; Liyanage, N. M. V. K.; Walpalage, S. Contribution of Hydrogen and/or Covalent Bonds on Reinforcement of Natural Rubber Latex Films with Surface Modified Silica. J. Appl. Polym. Sci. 2014, 131, 40380. (47) Li, Y.; Han, B.; Wen, S.; Lu, Y.; Yang, H.; Zhang, L.; Liu, L. Effect of the Temperature on Surface Modification of Silica and Properties of Modified Silica Filled Rubber Composites. Composites, Part A 2014, 62, 52−59. (48) Brunauer, S.; Emmett, P. H.; Teller, E. Adsorption of Gases in Multimolecular Layers. J. Am. Chem. Soc. 1938, 60, 309−319. (49) Qiao, H.; Chao, M.; Hui, D.; Liu, J.; Zheng, J.; Lei, W.; Zhou, X.; Wang, R.; Zhang, L. Enhanced Interfacial Interaction and Excellent Performance of Silica/Epoxy Group-Functionalized Styrene-Butadiene Rubber (SBR) Nanocomposites without Any Coupling Agent. Composites, Part B 2017, 114, 356−364. (50) Qiao, H.; Xu, W.; Chao, M.; Liu, J.; Lei, W.; Zhou, X.; Wang, R.; Zhang, L. Preparation and Performance of Silica/Epoxy GroupFunctionalized Bio-Based Elastomer Nanocomposite. Ind. Eng. Chem. Res. 2017, 56, 881−889. I

DOI: 10.1021/acs.iecr.8b06458 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research (51) Payne, A. R. The Dynamic Properties of Carbon Black-Loaded Natural Rubber Vulcanizates. Part I. J. Appl. Polym. Sci. 1962, 6, 57− 63. (52) Shen, J.; Liu, J.; Gao, Y.; Li, X.; Zhang, L. Elucidating and Tuning the Strain-Induced Non-Linear Behavior of Polymer Nanocomposites: a Detailed Molecular Dynamics Simulation Study. Soft Matter 2014, 10, 5099−5113. (53) Wang, M. Effect of Polymer-Filled and Filler-Filler Interactions on Dynamic Properties of Filled Vulcanizates. Rubber Chem. Technol. 1998, 71, 520−589. (54) Wu, Y.; Zhao, Q.; Zhao, S.; Zhang, L. The Influence of in Situ Modification of Silica on Filler Network and Dynamic Mechanical Properties of Silica-Filled Solution Styrene-Butadiene Rubber. J. Appl. Polym. Sci. 2008, 108, 112−118. (55) Lei, W.; Zhou, X.; Russell, T. P.; Hua, K.; Yang, X.; Qiao, H.; Wang, W.; Li, F.; Wang, R.; Zhang, L. High Performance Bio-Based Elastomers: Energy Efficient and Sustainable Materials for Tires. J. Mater. Chem. A 2016, 4, 13058−13062. (56) Kim, K.; Seo, B.; Lee, J.-Y.; Choi, B.-J.; Kwag, G.-H.; Paik, H.-J.; Kim, W. Reduced Filler Flocculation in the Silica-Filled StyreneButadiene-Glycidyl Methacrylate Terpolymer. Compos. Interfaces 2015, 22, 137−149. (57) Pourhossaini, M. R.; Razzaghi-Kashani, M. Grafting HydroxylTerminated Polybutadiene onto Nanosilica Surface for Styrene Butadiene Rubber Compounds. J. Appl. Polym. Sci. 2011, 124, 4721−4728. (58) Dubois, C.; Rajabian, M.; Rodrigue, D. Polymerization Compounding of Polyurethane Fumed Silica Composites. Polym. Eng. Sci. 2006, 46, 360−371. (59) Godard, P.; Bomal, Y.; Biebuyck, J. J. Influence of Interactions on the Tensile Behavior of Polystyrene Filled with Calcium Carbonate. J. Mater. Sci. 1993, 28, 6605−6610. (60) Peng, Z.; Kong, L.; Li, S.; Chen, Y.; Huang, M. Self-Assembled Natural Rubber/Silica Nanocomposites: its Preparation and Characterization. Compos. Sci. Technol. 2007, 67, 3130−3139. (61) Aso, O.; Eguiazábal, J. I.; Nazábal, J. The Influence of Surface Modification on the Structure and Properties of a Nanosilica Filled Thermoplastic Elastomer. Compos. Sci. Technol. 2007, 67, 2854−2863. (62) Evans, L. R.; Fultz, W. C. Tread Compounds with HighlyDispersible Silica. Rubber World 1998, 219, 38−45. (63) Murphy, L. J.; Wang, M.; Mahmud, K. Carbon-Silica Dual Phase Filler, a New Generation Reinforcing Agent for Rubber Part I. Characterization. Kautsch. Gummi Kunstst. 1998, 51, 348−360. (64) Robertson, C. G.; Lin, C. J.; Rackaitis, M.; Roland, C. M. Influence of Particle Size and Polymer-Filler Coupling on Viscoelastic Glass Transition of Particle-Reinforced Polymers. Macromolecules 2008, 41, 2727−2731. (65) Takino, H.; Nakayama, R.; Yamada, Y.; Kohjiya, S.; Matsuo, T. Viscoelastic Properties of Elastomers and Tire Wet Skid Resistance. Rubber Chem. Technol. 1997, 70, 584−594.

J

DOI: 10.1021/acs.iecr.8b06458 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX