丁基橡胶及卤化丁基橡胶阻尼材料的研究进展

介绍了丁基橡胶的阻尼性能及应用,阐述了丁基橡胶、氯化丁基橡胶及溴化丁基橡胶阻尼材料的研究进展。指出提高损耗因子和拓宽阻尼温域是丁基橡胶基高性能阻尼材料的研究方向,丁基橡胶与其他橡胶共混、开发合适的硫化体系和填料是提高丁基橡胶基阻尼材料性能的重要手段。     

硅橡胶和丁基橡胶共混体系的阻尼特性研究

采用机械共混法制备了硅橡胶/丁基橡胶复合材料。研究了丁基橡胶用量对复合材料力学性能、热稳定性和阻尼性能的影响。结果表明,随着丁基橡胶用量的增加,复合材料的力学性能和热稳定性出现降低的现象,但阻尼性能有显著提高。当丁基橡胶用量为100份时,与纯硅橡胶相比,复合材料的有效阻尼温域从0 ℃拓宽到近75 ℃,最大损耗因子从0.11提高到0.80,玻璃化转变温度向高温偏移了8 ℃左右。     

橡塑阻尼材料的研究进展

介绍了橡塑阻尼材料的阻尼机理,重点介绍了丁基橡胶、硅橡胶、丁腈橡胶和聚氨酯改性制备阻尼材料的最新进展及应用,指出提高损耗因子、拓宽阻尼温域及频率范围是橡塑基高性能阻尼材料的研究方向.总结了橡塑阻尼材料在未来工程应用中的应用方向和发展趋势,为橡塑阻尼材料的应用研究提供参考和建议.     

Evaluation of pyrolytic oil from used tires and natural rubber (Hevea brasiliensis)

The pyrolysis of used tires, UT, and natural rubber (Hevea brasiliensis), NR obtained from Nigerian NIG800 clonal rubber tree, was performed and the effects of process conditions on product yield were investigated. An optimum yield was attained at operating temperature of 600°C, a heating rate of 15°C?min^?1, for a feed size of 6?mm. The UT and NR gave maximum pyrolytic oil yield of 34.40 and 75.93?wt%, respectively. The pyrolytic oil was characterized using Fourier transform infrared, nuclear magnetic resonance, and gas chromatography–mass spectrometry (GC–MS). Results obtained reveal the pyrolytic oil to be a complex mixture, mainly of aliphatic and aromatic compounds, which can serve as feedstock for industrial application. Nevertheless, a comparative evaluation of the physical and chemical properties of the UT and NR pyrolytic oil showed that NR had hydrocarbon composition of 80% aliphatics, 12% aromatics (with less than 2% polycyclic aromatic hydrocarbon concentration). However, the UT pyrolytic oil had 42% aliphatic and 34% aromatic compounds (with polycyclic aromatic hydrocarbons concentrations of 18%). Also, NR pyrolytic oil had better physical properties such as density, viscosity, flash point, pour point, and higher heating value than that produced from UT in this study, and comparable with that of commercial diesel. Moreover, sulfur content, which is a limiting factor in the direct combustion of UT pyrolytic liquid, was absent in NR pyrolytic oil. Hence, it is technologically feasible for NR from H. brasiliensis to be a suitable source of pyrolytic oil than UT.     

芳纶短纤维增强硅橡胶阻尼材料的制备及性能研究

以芳纶纤维和苯基硅橡胶为原料,制得芳纶短纤维增强硅橡胶阻尼材料,研究了纤维长度、纤维用量及纤维处理方式对阻尼材料力学性能与阻尼特性的影响。结果表明,硫酸酸蚀处理可增大纤维表面粗糙度,而硅烷偶联剂则附着于纤维表面,实验所涉纤维处理方式中,γ-(甲基丙烯酰氧)丙基三甲氧基硅烷与纤维的结合最好,以其制得的阻尼材料的拉断伸长率最高,达到524%。阻尼材料的弹性模量随纤维长度的增加变化不明显,但随纤维用量的增加而略有增加。纤维长度对阻尼材料的储能模量与损耗因子的影响较小;而随着纤维用量的增加,材料的储能模量与损耗因子增加,使得材料的阻尼性能得到改善。相比于基体硅橡胶,制备的短纤维增强阻尼材料的损耗因子提高明显。     

Changes in morphology and properties of NR–NBR blends. Effect of viscosity ratio modified by liquid natural rubber and epoxidised liquid natural rubber

Abstract

Changes in rheological properties, morphology, and oil resistance in NR–NBR blends by viscosity ratio have been investigated. In this study, the viscosity ratio was modified by mechanical mastication and addition of liquid natural rubber (LNR) and epoxidised liquid natural rubber (ELNR). The results reveal that as viscosity ratio increased from 0·5 to 1·0, Mooney viscosity of the blends increased, and then decreased sharply as the viscosity ratio further increased from 1·0 to 2·0. The addition of LNR and ELNR for plasticising NR and NBR, respectively, does not significantly affect cure properties of the blends. The phase size of the NR dispersed phase depends strongly on the viscosity ratio. The high viscosity of the matrix and/or the low viscosity of the dispersed phase promote breaking up of the dispersed phase. Unexpectedly, a decrease in size of the dispersed phase by the modification of viscosity ratio via the use of low molecular weight rubber (i.e. LNR and ELNR) did not result in an improvement in oil resistance.     

稠油注空气催化氧化采油催化剂的制备与评价

注空气催化氧化采油技术是一项提高稠油采收率的创新技术,因其气源丰富、成本低,越来越受到人们关注。该文针对SZ36-1稠油,制备了5种油溶性催化氧化催化剂——过渡金属环烷酸盐,并加以筛选,得到环烷酸铜催化效果最佳。对稠油注空气催化氧化条件进行了初步评价。在催化剂用量为原油质量的0.2%,反应温度100℃,反应时间3 d的条件下,稠油酸值从3.96 mg KOH/g上升至13.50 mg KOH/g,黏度由2.004 Pa.s上升到11.48 Pa.s,尾气中φ(O2)由21.0%降至10.0%。向氧化油中分别加入氧化油质量1.2%的助剂SW-1和质量分数40%的水,保温50℃搅拌,生成大量表面活性剂,形成O/W乳化油,黏度最终降至0.067 Pa.s,总降黏率达到96.66%。     

Study on the high-temperature damping properties of silicone rubber modified by boron-terminated polysiloxane

Rubber damping materials have important applications in modern industrial systems. However, their damping temperature range is low, which is not suitable for the damping demand under high temperature conditions. At present, there is very little research on the damping performance of rubber under high temperature conditions. Silicone rubber has excellent high temperature resistance but poor damping in its application temperature range. In this study, a boron-terminated polysiloxane (PBS) was prepared by modifying hydroxy-terminated polydimethylsiloxane (PDMS-OH) with boric acid (BA). The molecular structure of PBS was confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) analysis. Rheology measurements revealed that PBS was a “shear hardening” material. Then, the silicone rubber was modified with PBS. With the introduction of boron atoms, boron and oxygen dative bonds with dynamic properties could be formed inside the silicone rubber, which played an energy dissipation role in the process of association/dissociation. Dynamic mechanical analysis (DMA) showed that the loss factor (tan δ) of modified silicone rubber was greater than 0.3 in the temperature range of 81.5°C–250°C, which was higher than the loss temperature range of conventional damping rubber. The cyclic stress–strain test also showed that the modified silicone rubber still had high dissipation coefficient (DE) at high temperature. Therefore, the PBS-modified silicone rubber prepared by this method achieved excellent damping performance under high temperature conditions.     

Noise generation and propagation control in disc brake systems using composite friction materials composed of thermoplastic elastomers as viscoelastic materials

Attempts have been made for the first time to produce a thermal sensitive friction material by the inclusion of thermoplastic elastomers (TPE) with combined plastic and rubbery properties as viscoelastic polymeric materials into the composition of the friction material for the purpose of increasing damping behavior. To evaluate the viscoelastic parameters such as loss factor (tan δ) and elastic modulus (E′) of the friction material on the molecular scale, dynamic mechanical thermal analysis was performed on the samples. Natural frequencies and mode shapes of the friction material and brake disc were determined by modal analysis. Styrene–butadiene–styrene (SBS), styrene–ethylene–butylene–styrene (SEBS) and nitrile rubber/polyvinyl chloride (NBR/PVC) blend systems have been used as TPE materials. However, NBR/PVC and SEBS were found to be more effective in preventing the noise generation and reducing the amplitude of the brake vibrations. All the friction materials containing TPEs exhibited more damping characteristics within a wide range of temperature compared with the damping characteristics of the reference sample. POLYM. COMPOS. 27:461–469, 2006. © 2006 Society of Plastics Engineers.     

Curing characteristics,mechanical properties and morphology of butyl rubber filled with ground tire rubber (GTR)

The results on testing application of ground tire rubber (GTR), as potential filler for butyl rubber, are presented. The GTR content variation, within the range of 10–90 phr, was studied with respect to the vulcanization process, static mechanical properties (tensile strength, elongation-at-break, hardness and resilience), dynamic mechanical properties and the morphology of the obtained vulcanizates. Butyl rubber was characterized by its low compatibility to other elastomers [i.e., natural rubber and styrene–butadiene rubber (SBR)—the main ingredients of tires] and low degree of unsaturation. To evaluate the impact of these factors on curing characteristics and mechanical properties of butyl rubber vulcanizates filled with GTR, the same compositions of SBR compounds, cured under identical conditions, were used as reference samples. Based on the obtained data, it can be stated that butyl rubber vulcanizates containing 30 phr of GTR as filler revealed the highest tensile strength and elongation-at-break. The microstructural analysis of a sample containing 30 phr of GTR revealed strong interactions between the butyl rubber matrix and GTR. This phenomenon resulted mainly from two factors. First, the cross-link density of the butyl rubber matrix was affected by its competition against GTR for cross-linking agents. Secondly, the migration of carbon black particles from GTR into the butyl rubber matrix had a significant impact on properties of the obtained vulcanizates.     

Viscosity Reduction of Indian Heavy Crude Oil by Emulsification to O/W Emulsion Using Polysorbate-81

Pipeline transportation is the most convenient means of transportation of crude oil continuously and economically from production site to refinery. However, transportation of heavy crude oil (HCO) through pipelines is difficult due to its high viscosity. The high viscosity of heavy crude oil is mainly due to the presence of poly-aromatic compounds like resins and asphaltenes. Emulsification of HCO using surfactant is believed to be the most favorable technique to reduce the viscosity of HCO for efficient pipeline transport. In the present study, oil-in-water (O/W) emulsion has been formulated using a non-ionic surfactant Polyoxyethylene (5) sorbitan monooleate (PS-81) at different pH, surfactant concentration, and oil content. Box–Behnken response surface method has been used to optimize two responses, apparent viscosity and emulsion stability index (ESI). The optimal values of the parameters found are 75%v/v oil content, 2.5%w/v surfactant concentration, and pH value of 7 at which experimental value of emulsion viscosity is 0.2162 Pa·s, at 150 RPM, with a reduction of viscosity by 95.8% and having ESI of 98.16 after 24 h at 30°C.     

Effect of C5 petroleum resin content on damping behavior,morphology, and mechanical properties of BIIR/BR vulcanizates

In this work, the white‐silica‐filled vulcanizates of brombutyl rubber (BIIR)/cis 1,4 polybutadiene rubbers (BR) with hydrogenated aromatic hydrocarbon (C5) petroleum resins were prepared by compression molding, and the effects of C5 petroleum resin content on the damping behaviors and mechanical properties of BIIR/BR vulcanizates were investigated by foam force rheometer, dynamic mechanical analysis (DMA), scanning electron microscopy, and mechanical measurements. The results of this study showed that, the C5 resins could retard the vulcanization, and reduce the crosslink density and Mooney viscosity of vulcanizates. The DMA curves exhibited two independent peaks of loss factor (tanδ) corresponding to the glass transition of BR and BIIR vulcanizates, respectively. The addition of C5 resin had a positive impact on the damping of BIIR/BR vulcanizates, with the increment content of C5 resin, the main tanδ peaks shifted significantly to higher temperature and the effective damping temperature range was broadened remarkably, especially in the range of the BIIR glass transition. The mechanical properties such as tensile strength and abrasion performance were influenced by the C5 resin and the changes in mechanical properties were mainly due to the decline of crosslink density and the improvement of filler dispersion. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and damping properties of (waste rubber powder)/hindered phenol composites

Waste rubber powder (WRP)/hindered phenol composites were successfully prepared by mixing tetrakis[methylene‐3‐(3‐5‐ditert‐butyl‐4‐hydroxy phenyl) propionyloxy] methane (AO‐60) into WRP for modification and recycling. The damping properties of the composites were systematically investigated through dynamic mechanical analysis. The experimental results indicate that the damping loss factor (tan δ) of WRP increases sharply from 0.366 to 0.734 via the modification process. With an increase in AO‐60, the tan δ value and the storage modulus in the glassy state gradually increase, and temperature dependence of loss peak gradually improves. The effects of the particle size of WRP, vulcanization temperature, vulcanization pressure, and vulcanization time on damping properties of the composite were investigated further. J. VINYL ADDIT. TECHNOL., 20:225–229, 2014. © 2014 Society of Plastics Engineers     

Studies on the dynamic mechanical and vibration damping properties of polyether urethane and epoxy composites

The dynamic mechanical and vibration damping properties of polyether urethane and epoxy composites have been studied. The experiment results show: the crosslink density is an important factor that influences the loss factor of polyether urethane damping materials; increasing the amount of pendant methyl of the backbone contributes to raising the value of the loss factor (tan δ) and broadens the damping temperature range; adding the planar filler can increase the shear motion and the internal dissipation in polyurethane materials. As the thickness ratio and the Young's modulus of the constraining layer increase, the composite loss factor (η) increases significantly. © 1993 John Wiley & Sons, Inc.     

Visbreaking of heavy petroleum oil catalyzed by SO/ZrO solid super-acid doped with Ni or Sn

SO₄^2-/ZrO₂ solid super-acid catalysts (SZ) doped with Ni²⁺ or Sn²⁺ (Ni²⁺/SZ, Sn²⁺/SZ) were prepared for catalytic visbreaking of heavy petroleum oil from Shengli oil field. The visbreaking reactions were carried out at 240°C and 3–4 MPa for 24 h using a heavy petroleum oil to catalyst mass ratio of 100 : 0.05. The effect of water content on viscosity of heavy petroleum oil was also investigated. Both catalysts can promote thermolysis of heavy petroleum oil and the viscosity was reduced from 0.319 Pa·s to 0.135 Pa·s for Ni²⁺/SZ and 0.163 Pa·s for (Sn²⁺/SZ) with visbreaking rates of 57.7% and 48.9%, respectively. After visbreaking, the saturated hydrocarbon content increased while aromatics, resin, asphaltene, sulfur and nitrogen content decreased. The presence of water was disadvantageous to visbreaking of heavy petroleum oil.     

丁腈橡胶阻尼材料的研究及其影响因素

丁腈橡胶是一种具有强极性的高分子弹性体,不仅具有良好的耐油性和粘接性,较其他橡胶还具有更宽的使用温度,在汽车、航空、石油、复印等行业中成为必不可少的阻尼减振材料.为了改善单一橡胶力学性能较差、有效阻尼温域较窄等弊端,使橡胶阻尼材料在实际中得到更好的应用,大量的学者对丁腈橡胶进行了不同方法的改性.本文主要综述了近年来国内...     

橡胶阻尼材料的研究进展

分析了橡胶材料的阻尼机理,重点讨论了丙烯酸酯橡胶、聚氨酯、丁基橡胶、丁腈橡胶和聚乙酸乙烯酯橡胶经过改性制备橡胶阻尼材料的研究进展,指出了橡胶阻尼材料的发展方向。     

A Simple Model for Predicting the Two-Phase Heavy Crude Oil Horizontal Flow with Low Gas Fraction

A two-phase heavy crude oil flow with low gas fraction is common in the oil transportation process. However, most of the studies of a gas–liquid flow are based on low viscosity fluid, such as water and light oil; as a result, the results cannot be introduced successfully into the mixture flow of gas and heavy crude oil. In this work, a two-phase flow of gas and heavy crude oil, which originated from the Bo-hai oilfield in China, was investigated in a horizontal pipe with 47-mm inner diameter. Data were acquired for the oil flow rate ranging from 2 m³/h to 10 m³/h, the input gas volume fraction ranging from 0.01 to 0.15, and the viscosity of crude oil ranging from 2.41 Pa·s to 0.34 Pa · s. Based on the drift-flux model, a new simplified correlation was developed to predict the void fraction and the pressure gradient. A comparison between the predicted and measured data demonstrates a reasonable agreement, and the correlation might be helpful for practical application in industry, especially in initially estimating the flow characteristic parameters.     

Water‐Based Bitumen Recovery from Diluent‐Conditioned Oil Sands

Important process development aspects leading to more efficient bitumen recovery from diluent‐conditioned oil sands by water‐based methods are discussed. Bitumen viscosity of 0.5–2 Pa·s is required at the processing temperature and can be reduced to this level by bitumen dilution with an organic solvent. Oil sand porosity, however, poses a restriction on the amount of diluent that can be accepted by the oil sand. Also oil sand‐diluent conditioning time is an important process parameter and can vary from a few minutes for oil sands with low‐viscosity bitumen to several hours if viscosity of the bitumen is high. Additionally, the bitumen separation efficiency during digestion and flotation can be enhanced by reducing the bitumen/water interfacial tension through addition, for example, of tripolyphosphate to the aqueous phase.     

Chlorinated butyl rubber/two-step modified montmorillonite nanocomposites: Mechanical and damping properties

Montmorillonite (MMT) was modified by ultrasound and castor oil quaternary ammonium salt intercalation method to prepare a new type of organic montmorillonite (OMMT). The surface structure, particle morphology, interlayer distance, and thermal behavior of the samples obtained were characterized. The modified OMMT was then added to chlorinated butyl rubber (CIIR) by mechanical blending, and a composite material with excellent damping properties was obtained. The mechanical experiment results of CIIR nanocomposites showed that the addition of OMMT improved their tensile strength, hardness, and stress relaxation rate. Compared with pure CIIR, when the content of OMMT was 5 phr (part per hundred of rubber), the tensile strength of the nanocomposite was increased by 677% and the elongation at break was also increased by 105.4%. The enhancement of this performance was mainly due to the dispersion of the nanosheets in CIIR rubber and the chemical interaction between the organoclay and the polymer matrix, which was confirmed by morphology and spectral analysis. OMMT also endowed a positive effect on the damping properties of CIIR nanocomposites. After adding 5 phr of OMMT, the nanocomposite owned the best damping performance, and the damping factor, tanδ_max, was 37.9% higher than that of pure CIIR. Therefore, the good damping and mechanical properties of these CIIR nanocomposites provided some novel and promising methods for preparing high-damping rubber in a wide temperature range.