基于X射线衍射法研究改性脱硫灰基生态橡胶的制备过程及机理

脱硫灰作为半干法脱硫技术主要副产品,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。橡胶作为广泛应用的聚合物材料,在橡胶制备加工过程中需大量使用填料改善其力学性能、加工性能和填充增容。炭黑与白炭黑作为常用的橡胶填料,其不仅生产工艺繁杂,而且对能源和资源消耗量大,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填料,既是固体废弃物高附加值利用又是资源可持续发展的重要途径之一,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。以该课题组前期取得的研究成果为基础,创新性以改性脱硫灰取代部分炭黑制备改性脱硫灰基生态橡胶。利用XRD对改性脱硫灰基生态橡胶制备过程各阶段的生产物质进行测试,即丁苯橡胶密炼胶制备阶段、改性脱硫灰基生态橡胶密炼胶制备阶段和改性脱硫灰基生态橡胶制备阶段,从微观层面揭示丁苯橡胶密炼胶制备过程、改性脱硫灰基生态橡胶密炼胶制备过程和改性脱硫灰基生态橡胶制备过程,阐明硫化过程中丁苯橡胶密炼胶与改性脱硫灰的结合机理。同时采用SEM对丁苯橡胶密炼胶与改性脱硫灰基生态橡胶密炼胶的微观形貌进行测试,以进一步佐证所获得的相关机理。结果表明:改性脱硫灰加入丁苯橡胶密炼胶后,改性脱硫灰基生态橡胶密炼胶的最大转矩F max大幅下降、最小转矩F L保持稳定、ΔF=F max-F L显著下降,同时焦烧时间t 10与正硫化时间t 90均缩短。硫化诱导期为0~387 s、硫化反应期为387~1586 s和硫化平坦期为1586~1800 s。在硫化诱导期形成非交联网络结构、硫化反应期前期形成基本交联网络结构、硫化反应期后期完善交联网络结构和硫化平坦期保持交联网络结构。以期为高附加值的脱硫灰资源化利用提供一定理论依据和技术支持。     

Thermoplastic Elastomers Based on High-Impact Polystyrene/Waste Styrene Butadiene Rubber Powder Blends Enhanced by Styrene–Butadiene–Styrene Block Copolymer and Aromatic Oil

Thermoplastic elastomers (TPEs) based on high-impact polystyrene (HIPS)/waste styrene–butadiene rubber powder (WSBRP) blends were prepared by melt-compounding; they were enhanced by incorporation of styrene–butadiene–styrene block copolymer (SBS) and aromatic oil (AO). The effects of SBS and AO dosage on the mechanical properties, Mullins effect and morphological properties of the blends were investigated. Experimental results showed that the incorporation of SBS and AO in the HIPS/WSBRP blends could improve the mechanical properties significantly. Compared with that of HIPS/WSBRP blends, the elongation at break had a maximum value with 9 phr SBS and 15 phr AO loading, being improved by about 220%. The Mullins effect results showed that a softening effect appeared obviously after the first loading–unloading cycle, while the residual deformation and internal friction loss of the HIPS/SBS/AO/WSBRP TPEs were much lower than those of the HIPS/WSBRP blends, indicating the improvement of elasticity.     

Effect of Rubber Content of ABS on the Mechanical Properties of ABS/Clay Nanocomposites

One approach to improve the impact strength of acrylonitrile–butadiene–styrene (ABS)/clay nanocomposites is to increase rubber content. To investigate the effect of the rubber content of ABS on the mechanical properties of the ABS/clay nanocomposites, other parameters were fixed and ABS/clay nanocomposites containing various rubber contents were prepared in this study. Also the effect of the UV stabilizer on the mechanical properties of ABS/clay nanocomposite was studied. For addition of 3 wt% clay, ABS nanocomposite with 35 wt% content of rubber displayed the highest reinforcement ratio for tensile properties and impact strength.     

About the cure kinetics in natural rubber/styrene Butadiene rubber blends at 433 K

Vulcanized blends of elastomers are employed in several goods mainly to improve physical properties and reduce costs. One of the most used blends of this kind is that composed by natural rubber (NR) and styrene butadiene rubber (SBR). The cure kinetic of these blends depends mainly on the compound formulation and the cure temperature and time. The preparation method of the blends can influence the mechanical properties of the vulcanized compounds.     

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.     

Dynamically Vulcanized Nitrile Butadiene Rubber/Acrylonitrile-Butadiene-Styrene Terpolymer Blends Compatibilized by Styrene-Butadiene-Styrene Block Copolymer

Thermoplastic vulcanizates (TPVs) based on nitrile butadiene rubber (NBR)/ acrylonitrile-butadiene-styrene (ABS) blends were prepared by dynamic vulcanization, and then compatibilized by styrene-butadiene-styrene block copolymer (SBS). The effects of SBS compatibilizer on mechanical properties, Mullins effect, and morphological properties of the TPVs were investigated systematically. Experimental results indicated that SBS had an excellent compatibilization effect on the dynamically vulcanized NBR/ABS TPVs. The tensile strength increased from 9.4 to 15.8 MPa and the elongation at break went through a maximum value when the dosage of SBS was only 1 phr. Mullins effect results showed that the compatibilized NBR/ABS TPV had relatively lower residual deformation and internal friction loss than the NBR/ABS TPV, indicating the improvement of elasticity. Morphology studies showed that the vulcanized NBR particles were dispersed evenly in the TPVs and the dimensions of NBR particles were decreased remarkably with the incorporation of SBS compatibilizer.     

Carboxylated acrylo nitrile butadiene rubber latex/kaolin nanocomposites: preparation and properties

Carboxylated nitrile butadiene rubber (XNBR)–based nanocomposites with varying amounts of nanokaolin were produced by latex stage mixing. Sonication of the unmodified kaolin and the technique adopted for the preparation of the composite have helped to get a uniform dispersion of clay in XNBR matrix. Nanokaolin caused enhancement in the mechanical properties of the composites. Proper dispersion of the clay particles, partial exfoliation/intercalation of clay, and interaction of clay with the polar rubber latex made nanokaolin good reinforcing filler in XNBR latex. Swelling studies conducted in methyl ethyl ketone showed a decrease in the swelling index and solvent uptake confirming the hindrance exerted by clay and the possible clay–rubber interaction. Increase in complex modulus obtained from the strain sweep analysis is a further evidence for better rubber filler interaction. The composites were characterized by the scanning electron microscopy, X-ray diffraction analysis, and atomic force microscopy.     

Fracture toughness of the epoxy/ATPEI-CTBN-ATPEI triblock copolymer/NMA blend system

The shortcoming of epoxy resin is the brittleness of this material though it shows excellent chemical, mechanical and electric properties. To improve fracture toughness of epoxy resin, rubbery materials that show high values in toughness but low values in glass transition temperature and mechanical properties, and thermoplastics that show high values in thermal and mechanical properties but relatively small increase in toughness were blended with epoxy. ATPEI-CTBN-ATPEI triblock copolymer, which consists of rubbery and thermoplastics blocks, was synthesized, and the triblock copolymer was blended with epoxy resin. The effects of parameters such as contents of the triblock copolymer, cure temperature, and contents of catalyst on the morphology of the blend systems were studied. From 30 wt% of the contents of the triblock copolymer, fracture toughness and impact energy absorption of the blend systems were increased significantly. This was due to the generation of nodular morphology in the system.     

Effect of Methyl Methacrylate Graft Acrylonitrile–Butadiene-Styrene on Morphology and Properties of Polycarbonate/Acrylonitrile–Butadiene-Styrene Blend

In order to improve the compatibility of polycarbonate (PC) and acrylonitrile– butadiene–styrene (ABS), a new type of reactive compatibilizer, methyl methacrylate graft acrylonitrile–butadiene–styrene (MABS) tetramer, was synthesized. The structure and properties of PC/ABS (70/30) blend with various MABS ratios were studied in terms of their mechanical and morphological properties. The results indicated that with the addition of MABS, the glass transition temperature (T_g) of the PC and ABS phases were closer to each other. Addition of MABS decreased the domain size of the ABS dispersed phase, making the dispersed phase well distributed, and the interfacial cohesiveness was enhanced. Notched impact strength and elongation at break of the PC/ABS (70/30) blend increased remarkably with the addition of MABS, with a small drop in the tensile strength.     

Performance and Mechanism of Epoxy Resin for Reinforcement of Styrene–Butadiene Rubber

Styrene–butadiene rubber (SBR) vulcanizates reinforced by epoxy resin (EP) have been synthesized by an in-situ vulcanization and curing process. The influences of synthetic parameters, such as the contents of EP, carbon black, and types of compatilizers, on the microstructures, vulcanization, and mechanical properties of SBR have been investigated. It was found that EP in SBR exists in the form of a fibrillar interpenetrating network, which is important for the enhancement of mechanical properties of SBR. The experimental results showed that when the percentage of EP was in the range of 10–20%, the composite materials had the best comprehensive performance. In comparison with pure SBR, the tear strength and the tensile stress at 300% elongation of SBR-EP composite were increased significantly. The method can be applicable for other rubber vulcanizates to improve their mechanical properties.     

Thermal,flexural, and impact strength studies on phenolic novolac resin/acrylonitrile–butadine rubber blends

Phenolic novolac resin was modified with nitrile rubber (NBR) using resol as compatibilizer. These systems were characterized by differential scanning calorimetry, flexural and impact strength. The resin was prepared by varying percentage of NBR. The curing behavior of unmodified and NBR-modified phenolic resin has been studied. The results reveal that the exothermic heat of cure for NBR-modified system increases due to the participation of the double bond of butadiene. In addition, the impact strength and flexural strain increase with increasing percentage of NBR in the phenolic resin matrix.     

Effect of Compression Pressure on the Ethylene Propylene Diene Terpolymer (EPDM)/Acrylonitrile Butadiene Copolymer (NBR) Rubber Blends Filled with Different Types of Carbon Black

Blends of ethylene-propylene diene terpolymer/acrylonitrile butadiene copolymer (EPDM/NBR) loaded with different types [(N326-HAF) and (N774-SRF)] and ratios of carbon black (CB) fillers were prepared. The mechanical properties of the EPDM/NBR rubber blends unloaded and loaded with different ratios of CB were investigated. Among the blends, the one with 75% EPDM and 25% NBR, both loaded and unloaded with CB, were found to exhibit the highest tensile strength and elongation at break. The observed changes in the mechanical properties of the blends were correlated to the morphology as observed by scanning electron microscopy. The changes of the electrical resistivity of the rubber blend composites during compression were investigated. The experimental results were explained from the position that an external pressure induces either an increase or decrease of the resistivity of the blend composites according to whether annihilation or creation of effective conductive paths occurs, respectively.     

Dynamic Mechanical Properties of Phenolic Resin/Chlorinated Butyl Rubber Composites

Chlorinated butyl rubber composites were prepared by a compounding and vulcanizing process using phenolic resin (PF) as the vulcanizing agent and carbon black as filler. Instead of using the conventional vulcameter method to determine the vulcanizing parameters, the vulcanization temperature and time were obtained by differential scanning calorimetry (DSC) and tensile testing, respectively. Dynamic mechanical analysis (DMA) showed that, higher PF content resulted in higher E′ and lower tanδ, and variations of E′ and tanδ with temperature were consistent with the time-temperature equivalence principle. It is proposed that chlorinated butyl rubber using phenolic resin as the vulcanizing agent could be used as potential damping materials in the temperature range 20–100°C and frequencies 0.1–100 Hz.     

基于傅里叶红外光谱的钢渣代炭黑环保型复合橡胶的补强机理及性能研究

以铁水脱硫渣作为研究对象,利用铁水脱硫渣作为橡胶填料取代部分炭黑与丁苯橡胶进行复合,制备铁水脱硫渣/丁苯橡胶。利用多种方法测试铁水脱硫渣/丁苯橡胶的性能,采用傅里叶变换红外光谱仪测试硫化过程中不同阶段铁水脱硫渣的结构组成。结果表明：利用铁水脱硫渣部分替代炭黑,可达到补强效果与降低补强剂成本的目的。铁水脱硫渣/丁苯橡胶的正硫化时间(t₉₀)为25.08 min,其焦烧期为0~15 min、热硫化期15~25 min和硫化平坦期25~45 min。在焦烧期铁水脱硫渣可以提供碱环境,利于增加丁苯橡胶流动性;在热硫化期与硫化平坦期,铁水脱硫渣中Ca₂SiO₄能够持续加速发生水化反应生成C-S-H凝胶,达到对丁苯橡胶补强的效果。另外,铁水脱硫渣可以避免铁水脱硫渣/丁苯橡胶过硫化期的出现。     

Effects of Chemical Structure of Phenolic Resin on Damping Properties of Acrylate Rubber-Based Blends

Two types of acrylate rubber (AR)-based damping blends were prepared by using two types of phenolic resins (PF), a resole resin (RR) and a novolac resin (NR), as organic fillers. The structure and damping properties of the AR/RR and AR/NR blends obtained by hot-pressing were characterized and compared by Fourier transform infrared spectrum, scanning electron microscopy, differential scanning calorimetry, and dynamic mechanical analysis. The results showed that the chemical structures of PF and the hot-pressing process had a significant effect on the damping properties of the AR-based composites. The loss peak of AR/RR shifted to a lower temperature accompanied with a gradually reduced peak intensity with the increase of RR content. In contrast, hot-pressed AR/NR showed great improvement in damping properties, which can broaden the effective damping temperature region and an increase in the temperature of the loss peak. It was thus concluded that NR with linear structure and abundant phenolic hydroxyl groups, which can create effective hydrogen bonds with an AR matrix, even after hot-pressing, makes it a promising NR to choose as an organic additive in ARs to prepare advanced damping blends.     

Preparation and Evaluation of the Morphology,Flammability, and Mechanical Properties of the Acrylonitrile‐Butadiene‐Styrene/Poly (vinyl chloride) Blends

Blends of two grades of acrylonitrile‐butadiene‐styrene (ABS) with three different compounds of poly (vinyl chloride) (PVC) were prepared via melt processing and their morphology, flammability, and physical and mechanical properties were investigated. SEM results showed that the ABS/PVC blend is a compatible system. Also, it can be inferred from fracture surface images that ABS/PVC blends are tough, even at low temperatures. It was found that properties of these blends significantly depend on blend composition and PVC compound type; however, the ABS types have only a small effect on blend properties. On blending of ABS with a soft PVC compound, impact strength, and melt flow index (MFI) increased, but tensile and flexural strength decreased. In contrast, blending of ABS with a rigid PVC compound improved fire retardancy and some mechanical properties and decreased MFI and impact strength.     

Damping Properties of Ethylene-Vinyl Acetate Rubber/Nitrile Butadiene Rubber Blends

The damping and mechanical properties of ethylene-vinyl acetate rubber (EVM)/nitrile butadiene rubber (NBR) blends, with BIPB (bis (tert-butyl peroxy isopropyl) benzene) as curing agent, were investigated by DMA. It was proved by mechanical performance, DMA and crosslink density data that a chemical crosslinking reaction occurred between EVM and NBR. A new tan δ peak appeared between 40°C and 60°C in EVM/NBR = 80/20, which we suggest was due to a new molecular chain generated between EVM and NBR. Thus, the effective damping temperature range (EDTR) of EVM/NBR = 80/20 was widened from 31.6°C of EVM and 31.7°C of NBR to 40.7°C. The addition of sulfur, as a curing agent for NBR, greatly raised the height of the damping peak of EVM/NBR blend, but only slightly widened the EDTR at a cost of deterioration of mechanical performance. Zinc diacrylate (Zn (Ac)₂), as a possible graft addition to the blends, enlarged the damping peak of EVM/NBR, especially widening the EDTR of EVM/NBR = 80/20 to 50.9°C, but with a decline of mechanical properties. PVC was partially miscible with EVM/NBR blends and dramatically widened the EVM/NBR = 80/20 EDTR to 62.4°C.     

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.     

羧基丁苯胶乳中结合苯乙烯含量的红外光谱测定法

本文介绍了用红外光谱法测定羧基丁苯胶乳中结合苯乙烯含量的方法，通过该方法分别选择１４９５ｃｍ~（－１）作为苯乙烯的芳烃Ｃ＝Ｃ伸缩振动特征吸收带和９７０ｃｍ~（－１）作为丁二烯的反式Ｃ＝Ｃ非平面摇摆振动特征吸收带。结果求得直线回归方程，相关系数，相对标准偏差，精度范围等。本方法简单、快速、选择生强，已成功地应用于羧基丁苯胶乳中结合苯乙烯含量的测定。     

NMR relaxation and NMR imaging of elastomers in the course of thermal aging

A complex aging regime occurs in the course of thermal aging of elastomers. Depending on the type and the content of the rubber filler materials, temperature, chemical environment (normally air), and time, a different aging process can be observed also by nuclear magnetic resonance (NMR) [1–6]. The methods used are the common spin-echo ¹H-NMR, including variable echo times and parameter-selective NMR-¹H-imaging (material properties imaging). The decay of the echo-magnetization is discussed on the basis of a single-chain model with a distribution of dipolar interactions. This model is based on the influence of a very fast, but anisotropic, local motion, as well as larger and slower motions, which are able to diminish the residual dipolar interaction. Carbon-black-filled natural rubber, as well as silica and carbon-black-filled E-SBR (emulsion-polymerized styrene butadiene rubber) and S-SBR (solution-polymerized SBR) are the systems under investigation, with the results showing some characteristic features of the course of aging observable by NMR.