Properties of Natural Rubber Vulcanizates/Nanosilica Composites Prepared Based on the Method of In-situ Generation and Coagulation

Using the characteristics of silica sol dispersing well in water and easy formation of silica gel when the silica sol is heated, by mixing a system of concentrated natural rubber latex and silica sol, the silica sol can in-situ generate SiO₂ particles when heated. After coagulation of the mixed system, natural rubber/nanosilica composites C(NR/nSiO₂) were obtained. The composites C(NR/nSiO₂) and their vulcanizates were studied using a rubber processing analyzer (RPA), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The influence of silica contents on the C(NR/nSiO₂) vulcanizates mechanical properties, cross-linking degree, Payne effect, dissipation factor (tanδ), and the particle size and dispersion of SiO₂ in NR were investigated. The results obtained were compared with the NR/SiO₂ composites based on traditional dry mixing of bale natural rubber and precipitated silica (white carbon black). The results showed that when using a sulfur curing system with a silica coupling agent (Si69) in C(NR/nSiO₂), the vulcanizate had better mechanical properties, higher wet resistance, and lower rolling resistance than those without Si69. In the composites C(NR/nSiO₂) and their vulcanizates, the SiO₂ particles’ average grain diameter was 60 nm, and the good-dispersion of the in-situ generated SiO₂ in the rubber matrix were a significant contribution to the satisfactory properties of C(NR/nSiO₂) composites and their vulcanizates.     

Insights into the Reinforcement of Butyl Rubber by Carbon Black and Silica with the Aid of Their Dynamic Properties

Carbon black (N234) and silica (Vulksail N) with a silane coupling agent Si-69 were chosen as reinforcing fillers in butyl rubber (IIR). The rheological behavior of the IIR compounds and the dynamic mechanical properties of IIR vulcanizates were investigated with a rubber processing analyzer and dynamic mechanical analysis (DMA) to examine the filler dispersion in the rubber matrix and the interaction between filler and matrix. The data indicated that the N234 filled IIR compounds had more filler networks than those filled with silica. Filler networks first appeared at 30 phr N234 and 45 phr silica with silane coupling agent Si-69. The interaction between N234 and IIR was far stronger than that between silica and IIR. However, the silica Vulksail N filled IIR had better wet-grip and lower rolling resistance compared to the carbon black-filled IIR should IIR be chosen as a substitute of styrene-butadiene rubber (SBR) in tire tread. The reinforcing factor, R, R (related to the difference in tan d peak height at T_g for the filled and nonfilled rubbers), also demonstrated that the N234-IIR interaction was stronger than for the silica. IIR with 30 phr N234 exhibited the largest tensile strength, 20.1 MPa, for those vulcanizates examined. The tensile and tear strengths of N234 filled IIR were higher than those of IIR with similar amounts of silica. Thus, it was concluded that N234 is a more active reinforcing filler in IIR than silica (Vulksail N) even with a silane coupling agent (Si-69).     

Effect of Modified Nano-Silica on the Reinforcement of Styrene Butadiene Rubber Composites

The performance of styrene butadiene rubber (SBR) composites filled with nano-silica has been improved by surface modification of the nano-silica using silane coupling agents. The dispersion of nano-silica in SBR rubber and the bonding force of nano-silica with SBR were significantly improved, and the physical and mechanical properties of the vulcanized rubber were greatly improved. The results showed Si69 (bis-(γ- triethoxysilylpropyl)-tetrasulfide) was the best modifier among the six silane coupling agents used in the experiments, and its optimum amount was 12% (wt) of nano-silica.     

Studies on the Dielectric Behavior of Silica-Filled Butyl Rubber Vulcanizates After Cyclic Deformation

Abstract

The broadband dielectric spectroscopy (10^?3–10⁶ Hz) is used to study the effect of stress-strain cycles on the dielectric properties of butyl rubber vulcanizates filled with silica. The influence of chemical modification of the surface of the silica by silane coupling agent (Si69) also was investigated. In addition Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC) were carried out. Dielectric investigations of the samples were done after stress-strain cycles with maximum elongation 26%, 40%, 60%, and 80% from elongation at break, respectively. It was found that the dielectric properties recovered after storage at room temperature for about one year.     

Preparation of Silicon Carbide Nanoparticle/Butadiene Rubber/Silane Nanocomposites; Structural,Mechanical, Tribological and Thermal Properties

Silicon carbide nanoparticles (nano-SiC), in the amounts of 0, 3, and 5 parts per hundred of rubber (phr), were employed in a butadiene rubber (BR) based compound as a potential commercial rubber and the structure, mechanical, tribological and thermal properties of the samples were investigated. The use of 3 phr of nano-SiC, especially in the presence of silane, increased the crosslink density and improved the tensile strength (35%) and elongation at break (64%) of the BR. In addition; the abrasion resistance of the BR was improved about 120% and the coefficient of friction increased. Scanning electron microscopy (SEM) images revealed the use of silane resulted in an appropriate dispersion of the nano-SiC and improvement of its interaction with the matrix. The use of nano-SiC, especially with silane, increased the initial thermal decomposition temperature of the BR and decreased its rate of degradation.     

基于FTIR与XRD的改性脱硫灰取代部分炭黑 制备复合橡胶的补强机理研究

脱硫灰是半干法脱硫的主要副产品,其利用难度大且成本高,导致大量脱硫灰以直接堆放和填埋的方式处理,不但造成环境污染,而且浪费潜在资源。炭黑(8 000 元·t-1)与白炭黑(6 000 元·t-1)是常用的橡胶补强填料,生产工艺繁杂,消耗大量能源和资源,导致成本较高。面对上述问题,如何利用脱硫灰开发一种价格低廉的无机橡胶补强填料,既是固体废弃物高附加值利用的重要途径之一,也是橡胶企业大幅降低填料成本提高经济效益的重要途径之一。由于脱硫灰属于无机材料,橡胶属于有机材料,为了更好的降低脱硫灰界面与橡胶界面(无机界面/有机界面)的不相容性,需要对脱硫灰进行化学改性处理,以提高脱硫灰代替部分炭黑制备橡胶的力学性能。该研究创新性以硅烷偶联剂Si69、硅烷偶联剂KH550与脱硫灰制备改性脱硫灰,然后以改性脱硫灰取代部分炭黑制备复合橡胶。根据国家与行业标准测试复合橡胶的力学性能,如拉伸强度、撕裂强度和硬度。利用扫描电子显微镜(SEM)对复合橡胶的微观形貌进行测试与分析,傅里叶变换红外光谱仪(FTIR)对改性脱硫灰的组成结构进行测试与分析,X射线衍射仪(XRD)对改性脱硫灰的矿物组成进行测试与分析,以揭示硅烷偶联剂Si69与硅烷偶联剂KH550协同对脱硫灰的改性机理,以及改性脱硫灰对复合橡胶的补强机理。结果表明：采用硅烷偶联剂KH550与硅烷偶联剂Si69协同改性脱硫灰,其取代炭黑的增强效果最佳,即复合橡胶的拉伸强度为20.36 MPa、撕裂强度为45.71 kN·m-1和邵尔A硬度为66;硅烷偶联剂KH550与硅烷偶联剂Si69协同改性脱硫灰,不仅保持脱硫灰依然良好的碱性,有利于对复合橡胶起到增强效果;而且可以改善脱硫灰的表面特性与结构,提高改性脱硫灰与丁苯橡胶的无机界面/有机界面相容性。     

Silane effects on the surface morphology and abrasion resistance of transparent SiO2/UV-curable resin nano-composites

Transparent ultraviolet curable nano-composite coatings consisting of nano-sized SiO₂ and acrylate resin have been developed to improve the abrasion resistance of organic polymers. The nano-sized SiO₂ particles were surface-modified using various amounts of 3-methacryloxypropyltrimethoxysilane. The 3-methacryloxypropyltrimethoxysilane concentration effects on the surface morphology and abrasion resistance of the transparent SiO₂/ultraviolet-curable resin nano-composites were investigated using scanning electron microscopy, atomic force microscopy, and ultraviolet-visible spectrophotometer. The results showed that as the 3-methacryloxypropyltrimethoxysilane/SiO₂ weight ratio increased from 0.2 to 0.6, the dispersion, compatibility and cross-linking density between the 3-methacryloxypropyltrimethoxysilane-modified SiO₂ particles and acrylate resin were improved, leading to an increase in abrasion resistance. However, as the 3-methacryloxypropyltrimethoxysilane/SiO₂ weight ratio was increased to 1.5, the additional 3-methacryloxypropyltrimethoxysilane may exceed that needed to fill the pores with the probability of SiO₂ nano-particles existing on the coating surface was lower than that for samples with a 3-methacryloxypropyltrimethoxysilane/SiO₂ weight ratio of 0.6. This produced a decrease in abrasion resistance.     

Wet Sliding Abrasion of Natural Rubber Composites Filled with Carbon Black at Different Applied Loads

The wet sliding abrasion and abrasion behavior of carbon black (CB)-filled natural rubber (NR) composites were investigated using a Deutsche Industrie Normen (DIN) abrader and compared to their dry abrasion resistance. The results showed that water tended to lubricate the contact between the rubber and the abrader and thus the abrasion loss was reduced. At different applied loads, the abrasion mechanism of the filled vulcanizates was different. When the applied load was below the turning point, the rubber abrasion was mainly fatigue abrasion and the main factor to influence the abrasion was the dynamic loss factor tanδ of the rubber. When the applied load was above the turning point, the rubber abrasion was mainly pattern abrasion and the main factors to influence the abrasion were the mechanical properties, in particular tensile and tear strength.     

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-?lled solution styrene butadiene rubber (SSBR) vulcanizates were studied. High dispersion silica, 7000GR, was used as the ?ller, 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.     

Preparation of MPS (mercaptopropyltrimethoxysilane)-coated SiO2 nanoparticle and its effect on mechanical properties of surface treated SiO2/EVA nanocomposite

SiO₂ nanoparticles were synthesized from different three precursors, namely, TEOS (tetraethyl orthosilicate), sodium metasilicate and sodium silicate. First, SiO₂ nanoparticles were prepared by a controlled hydrolysis of TEOS. In another method, SiO₂nanoparticles were prepared by precipitation in an emulsion medium from sodium metasilicate and hydrochloric acid solution. Finally, SiO₂ nanoparticles were also synthesized from sodium silicate by an emulsion method. In this study, we concentrated on dispersion and compatibility between nanosized SiO₂ particles and EVA (ethylene vinyl acetate). Therefore, surface modification of synthesized SiO₂ nanoparticles was accomplished with MPS (3-mercaptopropyl trimethoxysilane) to enhance homogeneous dispersion and compatibility between the obtained SiO₂ nanoparticles and EVA. Finally, nanocomposites of surface treated SiO₂ nanoparticles and EVA were prepared. By inserting the MPS-coated SiO₂ nanoparticles into EVA, abrasion resistance and hardness were increased remarkably. On the other hand, insertion of SiO₂ nanoparticles barely decreased original tensile strength and elongation of EVA. Consequently, MPS-coated SiO₂/EVA nanocomposite can have an improved abrasion resistance and hardness compared with raw EVA, without decrease tensile strength and elongation. The characterization of synthesized SiO₂ nanoparticles and their nanocomposite with EVA was conducted by TEM, SEM, FTIR photography and mechanical property tests such as abrasion, hardness, tensile strength and elongation.     

A Study on the Morphology and Mechanical Properties of PVC/nano‐SiO2 Composites

Three methods were used to modify nano‐SiO₂ particles with various interfaces and interfacial interactions between the particles and Poly(vinyl chloride) (PVC) matrix. The experimental results show that direct surface treatment of nano‐SiO₂ particles with a silane coupling agent (KH‐550) is not effective for improving the mechanical properties of PVC/SiO₂ composites. Both ultrasonic oscillations and high energy vibromilling improve the interfacial interactions between SiO₂ particles and PVC matrix. With these methods, the aggregation of SiO₂ particles was inhibited and a good dispersion of SiO₂ particles in PVC matrix was obtained, which improved the mechanical properties of the PVC/SiO₂ composite. The mechanical properties of the PVC/SiO₂ composite with high energy vibromilling modified SiO₂ particles were remarkably improved. Scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), dynamic mechanical analysis (DMA), and theoretical calculations demonstrate these improvements.     

Synthesis of a New Nanosilica-Based Antioxidant and Its Influence on the Anti-Oxidation Performance of Natural Rubber

Nanosilica was modified with a silane coupling agent 3-Glycidoxypro- pyltrimethoxysilane (KH-560) and then reacted with p-aminodiphenylamine (RT) to obtain a new nanosilica-based antioxidant. Fourier transform infrared and thermogravimetric (TGA) analysis measurements confirmed the successful grafting of RT to the nanosilica surface. Scanning electron microscope analysis showed that the nanosilica-based antioxidant could be homogeneously dispersed in a natural rubber matrix. Differential scanning calorimetry and TGA were used to measure the thermal oxidative behavior of rubber vulcanizates with different types of fillers. It was found that the thermal oxidative stability of rubber vulcanizates with the nanosilica-based antioxidant was improved to a greater extent than that with other fillers examined.     

Effect of organosilane agents on the vulcanizate structure and physical properties of silica-filled solution styrene butadiene rubber compounds

Physical properties of rubber compounds are affected by the filler-rubber interaction, filler dispersion in the rubber matrix, and crosslink structure formed during vulcanization. Organosilane agents are essentially used in silica-rubber compounds to inhibit the formation of silica agglomerates and increase the formation of silica-rubber networks. Generally, organosilane agents have an alkoxysilyl alkyl sulfide structure and are classified into silane coupling and covering agents depending upon the presence of sulfur. Coupling agents have a sulfur moiety and serve as a sulfur donor during the vulcanization process, thus increasing the formation of filler-rubber and chemical crosslink networks. On the other hand, covering agents promote the hydrophobation of silica surfaces, decreasing the adsorption loss of vulcanization additives, which increases the formation of chemical crosslink networks. This implies that organosilane agents can affect the vulcanizate structure, which causes a variation in the properties of silica compounds. Therefore, in this study, the effect of coupling (bis(3-triethoxysilylpropyl)disulfide (TESPD) and bis(3-triethoxysilylpropyl)tetrasulfide (TESPT)) agents and a covering (triethoxy(octyl)silane) agent on the vulcanizate structure and properties of silica compounds was investigated and compared. In the comparative study of coupling and covering agents, the influence of sulfur donors on the formation of vulcanizate structures was investigated. In the case of the coupling agents, the effect of sulfur rank on the vulcanizate structure and properties of silica-rubber compounds was quantitatively analyzed through various characterization techniques.     

Effect of curing temperature,fibre loading and bonding agent on the equilibrium swelling of isora-natural rubber composites

Isora fibre-reinforced natural rubber (NR) composites were cured at 80, 100, 120 and 150°C using a low temperature curing accelerator system. Composites were also prepared using a conventional accelerator system and cured at 150°C. The swelling behavior of these composites at varying fibre loadings was studied in toluene and hexane. Results show that the uptake of solvent and volume fraction of rubber due to swelling was lower for the low temperature cured vulcanizates which is an indication of the better fibre/rubber adhesion. The uptake of aromatic solvent was higher than that of aliphatic solvent, for all the composites. As the fibre content increased, the solvent uptake decreased, due to the superior solvent resistance of the fibre and good fibre–rubber interactions. The bonding agent improved the swelling resistance of the composites due to the strong interfacial adhesion. Due to the improved adhesion between the fibre and rubber, the ratio of the change in volume fraction of rubber due to swelling to the volume fraction of rubber in the dry sample (V_τ ) was found to decrease in the presence of bonding agent. At a fixed fibre loading, the alkali treated fibre composite showed a lower percentage swelling than untreated one for both systems showing superior rubber–fibre interactions.     

Evaluation of Synthetic Magnesium Silicate as a New Polymer Filler

The paper reports on the performance of highly dispersed synthetic magnesium silicate as a filler of the styrene–butadiene rubber (SBR). The magnesium silicate has been precipitated and characterized by determination of particle size distribution, electrokinetic potential, nitrogen adsorption/desorption isotherms and SEM observation. At the subsequent stage of the study its surface has been modified by silane coupling agents. The unmodified and silane-grafted magnesium silicate samples have been used as fillers of SBR of standard testing composition. The vulcanizates obtained with the fillers have been tested as to their physical and mechanical performance. The vulcanizates filled with synthetic magnesium silicate have been found to show much better mechanical parameters than unfilled rubber. Modification of the synthetic magnesium silicates with silane coupling agents has further improved the mechanical characteristics of the vulcanizates.     

Effects of Replacement of Part of the Silica Reinforcement with Hybrid Modified Microcrystalline Cellulose on the Properties of their Rubber Composites

Hybrid modified microcrystalline cellulose (HMCC), with SiO₂ nanoparticles being in-situ loaded on the surface of microcrystalline cellulose (MCC), was obtained through a sol-gel process of tetraethoxysilane (TEOS) by using ammonia as catalyst. HMCC was characterized by thermogravimetric analysis and scanning electron microscopy. The results showed that the spherical nano-SiO₂ particles had been loaded successfully on the surface of the MCC with a loading ratio of approximately 10%. Then the HMCC was used in high vinyl solution-polymerized styrene butadiene rubber (SSBR)/silica compounds to replace part of the silica, and its effects on the physio-mechanical and dynamic mechanical properties of the vulcanizates were investigated. The results showed that the HMCC samples had improved physio-mechanical properties and lower heat build-up than that of MCC ones. Dynamic mechanical analysis (DMA) showed that the tanδ value of the compounds decreased at 60°C while increased obviously at 0°C, which meant that the tires would have improved wet-skid resistance while maintaining low rolling resistance when HMCC was used in tire tread compounds. As observed from scanning electron microscopy (SEM) photos, the sizes of the HMCC were in-situ decreased from 20–90 µm to 0.5–10 µm during the processing of the rubber compounds. Compared with MCC, the interfacial adhesion between HMCC and rubber was also improved greatly.     

The tribology properties of alumina/silica composite nanoparticles as lubricant additives

The as-prepared alumina/silica (Al₂O₃/SiO₂) composite nanoparticles were synthesized with a hydrothermal method and modified by silane coupling agent. The tribological properties of the modified Al₂O₃/SiO₂ composite nanoparticles as lubricating oil additives were investigated by four-ball and thrust-ring tests in terms of wear scar diameter, friction coefficient, and the morphology of thrust-ring. It is found that their anti-wear and anti-friction performances are better than those of pure Al₂O₃ or SiO₂ nanoparticles. When the optimized concentration of nanoparticle additive is 0.5 wt.%, the diameters of wear scar and friction coefficients are both smallest. Such modified composite nanoparticles can adsorb onto the friction surfaces, which results in rolling friction. Therefore, the friction coefficient is reduced.     

Interactions Between an Ionic Liquid and Silica,Silica and Silica,and Rubber and Silica and Their Effects on the Properties of Styrene-Butadiene Rubber Composites

An investigation of the effect of an ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (BMI), on the properties of silica reinforced styrene-butadiene rubber (SBR), aimed to correlate the interactions between the ionic liquid and silica, silica and silica, and silica and rubber with the macro-properties and microstructure of SBR and SBR/silica vulcanizates is described. The interaction between the ionic liquid and silica was characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), the interaction between silica and silica was characterized by a rubber processing analyzer (RPA), and the interaction between rubber and silica was characterized by the bound rubber content. The FTIR analysis revealed that BMI can react with the hydroxyl groups on the surface of silica, improving the compatibility between the rubber and silica. The RPA and bound rubber testing indicated that the interactions between silica and silica particles were weakened and the interaction between silica and rubber increased with the incorporation of BMI into the SBR rubber. The bound rubber content showed a maximum with a BMI content of 3 phr. At the same time, the dispersion of silica in SBR was improved with the incorporation of BMI. With the increase of BMI content, the curing rate was greatly improved and the crosslink density increased. BMI also increased the tensile strength and abrasion resistance of the SBR vulcanizates. Most important, the BMI significantly improved the dynamic properties of the rubber composites, especially the wet-skid resistance and rolling resistance. However, excessive BMI (beyond 3 phr) acted as a plasticizer and was detrimental to the mechanical properties, resulting in a decrease of tensile strength and abrasion resistance.     

HLDPE/organic functionalized SiO2 nanocomposites with improved thermal stability and mechanical properties

High-pressure low-density polyethylene (HLDPE)/organic functionalized SiO₂ nanocomposites were synthesized using melt-blending technique in a sigma internal mixer. The properties of the nanocomposites were studied using two different organic functional modifiers: diglycidyl ether of bisphenol-A (DGEBA) and triacetoxyvinylsilane. Reinforcing, thermal stability and toughening effects of organic functionalized nanosilica on the polymer matrix were found at loading of 2.5% nanosilica functionalized with 2.8% of DGEBA and silane coupling agent respectively. Organic functionalization on the nanosilica particle surface led to different microstructures when compared with that of the pure polymer. Organic functionalization on the nanosilica particle surface produced good interfacial adhesion and homogeneous dispersion in the polymer matrix, while the use of nanosilica resulted in aggregated silica particles in the polymer matrix. There was no significant improvement in thermal stability and mechanical properties when only nanosilica was added to the pure polymer. On the contrary, the addition of pretreated nanosilica with organic functional modifiers led to an increase of thermal stability from 313–363°C, elastic modulus and toughness from 0.12–0.18 GPa and 3.23–9.81 MJ/m³ respectively.     

Studies of structure and composition of a Pt-based basic electrode for deposition of PZT ferroelectric films on silicon substrates

In this study it has been found that a TiO₂/Ti double adhesion layer is used for SiO₂/Si substrate and a YSZ layer is used for SiO₂/Si and Si substrates to achieve high residual polarization of PZT layers on platinum. Epitaxial deposition of YSZ on Si(100) provides an atomically smooth platinum layer textured in the [100] direction. The produced PZT films are mostly textured in the [111] direction; their residual polarization is 5–15 μC/cm².