Constructing a Multiple Covalent Interface and Isolating a Dispersed Structure in Silica/Rubber Nanocomposites with Excellent Dynamic Performance

Abstract

Realizing and manipulating a fine dispersion of silica nanoparticles (NPs) in the polymer matrix is always a great challenge. In this work, we first successfully synthesized N, N'-bis[3-(triethoxysilyl)propyl-isopropanol]-propane-1,3-diamine (TSPD), which was a new interface modifier, aiming to promote the dispersion of silica NPs. Through Fourier transform infrared spectroscopy, nuclear magnetic resonance analysis, and mass spectroscopy, we verified that TSPD contains together six ethoxy groups at its two ends. Then, we used this TSPD to modify the pure silica NPs, and this modified silica was abbreviated as D-MS, which is realized by the thermal gravimetric analysis examination, scanning electron microscopy analysis, and dynamic light scattering results. It was clearly observed that D-MS NPs are connected to one another but are not conglutinated tightly, exhibiting a novel predispersed structure with around 1-2 nm certain extent of interparticle distance. Next, we fabricated the following four elastomer nanocomposites such as pure silica/natural rubber (NR) composite (PS-NR), D-MS/NR composite (DMS-NR), bis-(γ-triethoxysilylpropyl)-tetrasulfide (TESPT)-modified silica/NR composite (TS-NR), and TESPT-modified D-MS/NR composite (T&DMS-NR) and found that the Payne effect is the smallest for T&DMS-NR via the combination use of the D-MS and the traditional coupling agent TESPT, which is attributed to its best dispersion state evidenced by the transmission electron microscopy results. Moreover, by measuring a series of other important mechanical performances such as the stress-strain curve, the dynamic strain dependence of the loss factor, and the heat build-up, we concluded that the T&DMS-NR system greatly exceeds those of the three other rubber composites. In general, this new approach provides a good opportunity to prepare a silica/rubber composite with excellent properties in mechanical strength and dynamic behavior by tailoring the fine dispersion of NPs.

Promoting the dispersibility of silica and interfacial strength of rubber/silica composites prepared by latex compounding

“…Therefore, the particle size distribution of Silica-MSH and Silica-MS samples both explain two peaks. [39] After ball milling modification and heating, the peak position shifts to the right because more Si-747 grafted on the silica surface. What's more, in the embedded image of Figure 3b, the average particle diameter of Silica-MS is 350.3 nm, which is 15.6 nm larger than Silica-M and 88.4 nm smaller than Silica-MSH.…”

“…Silica powders were obtained by drying in an oven at 105 C and then were removed ungrafted modifier Si-747 in the Soxhlet extractor employing absolute ethanol lasting 24 hr, reflow once every 15 min. [26,39] The extracted powders were further dried in an oven at 70 C until the mass of the sample remains constant (the mass difference of the two measurements is less than 1 mg), the dried silica powders were used for subsequent characterizations including thermo gravimetric analyzer (TGA), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), the average particle size and distribution and dibutylphthalate absorption values (DBP).…”

“…Above 110 C, the mass losses of Silica-MS and Silica-MSH samples were mainly due to degradation of Si-747. [31,39] Compared with Silica-MS, Silica-MSH sample has the higher grafting rate of Si-747 because of the 1.4% greater weight losses in 800 C. In addition, the mass losses of pure silica corresponded to degradation of surface hydroxyl above 110 C. [31,39] The graft ratio calculation shows that the graft ratio of Silica-MS and Silica-MSH separately are 2.6 and 4.1, and only 0.9% of the modifier was not grafted in Silica-MSH sample (the weight ratio of Si-747 to silica is 5%). Zheng et al [26] stirred the silica in water at high speed firstly, then added the modifier Si-747 to the silica and heat-treated it to obtain the modified silica dispersion, and the results show that the graft ratio of the modified silica is 6.7% (the weight ratio of Si-747 to silica is 10, and 3.3% of the modified is not grafted in the modified).…”

“…[26] Previous studies also showed that silica had either been treated with mechanical force alone or with a silane coupling agent alone or with grinding first and then modification, but the grafting ratio of silane coupling agent is low. [38,39] In this study, silica was simultaneously treated by ball milling and silane coupling agent accompanying by heating process, which made the higher grafting rate of modifier according to results of the thermo gravimetric analyzer (TGA) and X-ray photoelectron spectroscopy (XPS). Finally, performance test results show this method is very effective for the dispersibility of silica and the enhancement of interface strength of composites.…”

Reutilization of waste printed circuit boards nonmetallic powders in elastomer composites: Significant improvements of curing and mechanical properties

“…Rubbers are recognized as strategically important elastic materials and have been extensively applied in many fields . Generally, almost all rubber matrix need to be reinforced with inorganic fillers to fulfill the ultimate practical applications due to their poor mechanical strength . In recent years, driven by the pressure from environmental issues, some industrial wastes and by‐products such as fly ash, marble waste powder, and agricultural waste have been utilized as the alternative of commercial fillers in rubber composites.…”