环氧化天然橡胶制备反应动力学

采用适当提高反应温度、减小甲酸和过氧化氢用量的方法制备不同环氧化程度（Ｂ）的环氧化天然橡胶（ＥＮＲ）,并利用质量作用定理,从ＥＮＲ的制备基本反应式推导出ＥＮＲ的制备反应动力学方程,讨论了Ｂ与反应温度和时间及甲酸、过氧化氢用量的关系。结果表明,用过氧甲酸对ＮＲ进行环化改性制备ＥＮＲ的反应为二级反应,对ＮＲ和过氧化氢的反应则为一级反应。求出的反应速率常数ｋ４为１１２５×１０－４ｄｍ３·（ｍｏｌ·ｓ）－１,活化能为８２６７４ｋＪ·ｍｏｌ－１;Ｂ与过氧化氢用量之间为线性关系     

环氧化天然橡胶研究进展

简述了环氧化天然橡胶（ＥＮＲ）的制备工艺及工艺条件对ＥＮＲ结构和性能的影响,对ＥＮＲ的结构和稳定性控制进行了探讨,介绍了ＥＮＲ的几种化学改性及应用情况,并对今后的研究方向提出意见。     

环氧化天然橡胶的中型试验和产品应用

本研究是利用天然鲜胶乳扩大试制环氧化天然橡胶（ＥＮＲ），并研究了其透气性、耐油性、比重、玻璃化温度与环氧化程度的关系，以及纯胶配合、炭黑配合硫化胶的主要物理性能。对ＥＮＲ胶乳在玻璃纤维布和尼龙帘布表面浸胶处理．干胶在自行车和摩托车内胎、印刷胶辊等制品方面的应用进行了尝试。     

环氧化天然橡胶加工性能的研究

研究了环氧化天然橡胶的塑炼，混炼，挤出及加工流变性能。结果表明，ＥＮＲ的加工性能与天然橡胶相近，只是塑炼效果胶ＮＲ稍差。ＥＮＲ混炼生热较低，吃粉速度较快，虽然挤出口型膨胀率大于ＮＲ，但挤出物外观与ＮＲ相当。     

环氧化天然橡胶多元接枝胶粘剂粘合性能的研究

环氧化天然橡胶多元接枝胶粘剂粘合性能的研究宋刚玉黄有发（华南理工大学,广州５１０６４１）环氧化天然橡胶（ＥＮＲ）是在ＮＲ主分子链的双键中引入环氧基团的新型改性聚合物。它除保留了ＮＲ的多种优异性能外,还具有一些特殊性能,因此有着广阔的应用前景［１］。由...     

白炭黑填充的环氧化天然橡胶性能研究

研究了白炭黑用量对环氧化天然橡胶（ＥＮＲ）流变性能、弹性记忆、硫化特性、平衡应力－应变及动态力学性能的影响。试验结果表明：白炭黑填充的ＥＮＲ属非牛顿型流体；随着白炭黑用量增加，挤出膨胀减小，硫化速度加快，滞后增大；随着剪切速率增大，挤出膨胀增大。透射电镜照片表明硅烷偶联剂使白炭黑在ＥＮＲ中的分散性明显提高。     

几种配合剂对环氧化天然橡胶性能的影响

研究了氢氧化镁、氧化锌及硬脂酸对环氧化天然橡胶（ＥＮＲ）硫化特性、硫化胶的力学性能及老化性能的影响。结果表明：加入２份氢氧化镁可有效地提高ＥＮＲ的硫化速度、拉伸强度和抗热氧老化性能；氧化锌和硬脂酸对硫化胶网络的完善是不可缺少的。用差示扫描量热法（ＤＳＣ）比较了几种防老剂（防老剂Ｄ，Ｈ．ＷＳＰ，ＭＢ．４０１０，ＳＰ）在ＥＮＲ中的防护效果。结果表明防老剂Ｄ的效果最好。以防老剂Ｄ与防老剂ＭＢ并用，加入２份氢氧化镁、２份硬脂酸和５份氧化锌，不仅可缩短硫化时间，而且可大幅度提高硫化胶的拉伸强度、扯断伸长率和老化系数。     

环氧化天然橡胶

ｅｐｏｘｉｄｉｚｅｄｎａｔｕｒａｌｒｕｂｂｅｒ；ＥＮＲ　用过氧化有机酸或过氧化氢与有机酸处理，使天然橡胶形成环氧化基团结构的生胶。该胶具有抗湿滑性好、气密性优良、耐油性能佳等诸多优点。按环氧化程度的高低一般有ＥＮＲ７５，ＥＮＲ５０和ＥＮＲ２５三个品种。环氧化天然橡胶     

环氧化天然橡胶/二胺硫化胶在轮胎胎面中的应用

含二胺的环氧化天然橡胶（ＥＮＲ）与炭黑的硫化胶，其橡胶区内的ｔｇδ较低，业已证实，其潘恩效应也降低。人们推测，基于与二胺的交联和ＥＮＲ与炭黑之间强烈的相互作用；才使得这种硫化胶的ｔｇδ值较低。考察了不同二胺对轮胎胎胶料性能的影响，发现伯胺和脂肪胺改善胎面滚动阻力的效果优于叔胺和芳香胺。     

环氧化天然橡胶与配方设计

叙述了环氧化天然橡胶（ＥＮＲ）及其与ＰＶＣ，ＥＰＤＭ并用的配方设计与物理性能。     

Thermoplastic vulcanizates based on epoxidized natural rubber/polypropylene blends: Effect of compatibilizers and reactive blending

Epoxidized natural rubber (ENR) was prepared using the performic epoxidation method. TPVs based on ENR/PP blends were later prepared by melt‐mixing processes via dynamic vulcanization. The effects of blend ratios of ENR/PP, types of compatibilizers, and reactive blending were investigated. Phenolic modified polypropylene (Ph‐PP) and graft copolymer of maleic anhydride on polypropylene molecules (PP‐g‐MA) were prepared and used as blend compatibilizers and reactive blending components of ENR/Ph‐PP and ENR/PP‐g‐MA blends. It was found that the mixing torque, apparent shear stress and apparent shear viscosity increased with increasing levels of ENR. This is attributed to the higher viscosity of the pure ENR than that of the pure PP. Furthermore, there was a higher compatibilizing effect because of the chemical interaction between the polar groups in ENR and PP‐g‐MA or Ph‐PP. Mixing torque, shear flow properties (i.e., shear stress and shear viscosity) and mechanical properties (i.e., tensile strength, elongation at break, and hardness) of the TPVs prepared by reactive blending of ENR/Ph‐PP and ENR/PP‐g‐MA were lower than that of the samples without a compatibilizer. However, the TPVs prepared using Ph‐PP and PP‐g‐MA as compatibilizers exhibited higher values. We observed that the TPVs prepared from ENR/PP with Ph‐PP as a compatibilizer gave the highest rheological and mechanical properties, while the reactive blending of ENR/PP exhibited the lowest values. Trend of the properties corresponds to the morphology of the TPVs. That is, the TPV with Ph‐PP as a blend compatibilizer showed the smallest rubber particles dispersed in the PP matrix, while the reactive blending of ENR/PP‐g‐MA showed the largest particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4729–4740, 2006     

Tensile,Tear and Swelling Properties of ENR 50/SBR Blend

Abstract

Tensile strength, tear strength and swell index of epoxidized natural rubber (ENR 50) blended with styrene-butadiene rubber (SBR) was studied. The blend ratio was varied from 0–100% of ENR 50. Accelerated-sulfur conventional vulcanization system was used throughout the study. Tensile property and tear strength of the blend were determined by Monsanto Tensometer (Model T10) and toluene was used as the solvent in the swell index experiment. Results show that tensile strength and elongation at break increases with ENR 50 up to about 70% ENR 50, whereas for the tear strength, it increases steadily with increasing ENR 50, an observation which is attributed to strain-induced crystallization of ENR. Similar behavior was observed with the aged sample though its absolute value is lower than that of the unaged sample. As for the swell index, it decreases gradually with increasing ENR indicating the increase in polarity of the blend as the blend ratio of ENR 50 is increased.     

TENSILE PROPERTY OF EPOXIDIZED NATURAL RUBBER/NATURAL RUBBER BLENDS

The tensile strength and elongation at break of epoxidized natural rubber (ENR) blended with natural rubber (NR) was studied. ENR 25, ENR 50, and one grade of natural rubber (SMR L) were used as the elastomers. The composition of ENR was varied from 0% to 100% rubber. The accelerated sulfur vulcanization system was used throughout the investigation. The tensile property of unaged and aged samples was determined by using the Monsanto tensometer (T10) operating at 50 cm/min. Results show that the tensile strength and elongation at break passes through a maximum at 50% ENR for both ENR25/SMR L and ENR50/SMR L blends. This positive deviation from ideality is attributed to the mutual reinforcement of ENR and NR in the blends as a result of strain-induced crystallization. This synergistic effect is more pronounced in the case of ENR 25 due to the higher crystallinity and availability of more double bonds, which is more compatible to NR compared to ENR 50/NR blends. For the aged samples, a drop in the tensile property associated to the breakdown of the polysulfidic cross-link during aging is observed. A systematic study of the effect of sulfur concentration on the percentage retention of tensile property of the ENR blends after aging reveals that percentage retention decreases with increasing sulfur loading, which, in turn, enhances the formation of the polysulfidic cross-link; thus, more breakdown is observed in the rubber vulcanizate.     

Enhancement of electrical conductivity and other related properties of epoxidized natural rubber/carbon nanotube composites by optimizing concentration of 3‐aminopropyltriethoxy silane

Carbon nanotube (CNT)‐filled epoxidized natural rubber (ENR) composites were prepared by mixing in an internal mixer and thereafter on a two‐roll mill. Silane coupling agent, namely 3‐aminopropyltriethoxy silane (APTES), was directly incorporated in the ENR‐CNT composites during mixing of rubber and CNTs in the mixer, to perform in situ functionalization. It was found that pre‐crosslinking of ENR and APTES occurred especially at high APTES concentrations, such as 0.06 mL/(g of CNTs) and caused strong CNT agglomeration in the ENR matrix. However, the pre‐crosslinking could be reduced or avoided by decreasing the APTES concentration. In the concentration range 0.01–0.015 mL/(g of CNTs) of APTES, the APTES molecules were grafted on the CNT surfaces and generated new chemical linkages with the ENR. This improved the CNT dispersion in the ENR matrix and enhanced the composite properties. A very low approximately 0.5 phr of CNT threshold concentration for electric percolation was achieved in this type of composites. Also, three‐dimensional connected CNT networks were found to form in the ENR matrix at very low APTES levels. Thus, the electrical conductivity achieved in these composites reached the level required of conductive materials. POLYM. ENG. SCI., 57:381–391, 2017. © 2016 Society of Plastics Engineers     

Moisture-sorption properties and studies on the dilute solution behavior of epoxidized natural rubber ENR 50

Studies of the dilute solution capillary viscosity and moisture sorption of commercial samples of epoxidized natural rubber (ENR 50) were carried out. Dilute solution viscometry of ENR 50 solutions was conducted in xylene, tetrahydrofuran, and methyl ethyl ketone solvents and the degradation due to shearing and oxidation for this rubber was followed. At average elevated temperatures and high relative humidities, epoxidized natural rubber ENR 50 shows high moisture sorption. Moisture sorption measurements at 100% RH and 34°C followed by desorption show near equilibrium moisture intake of 3.402–3.661 g H₂O/100 g rubber, which agrees reasonably well with the estimated value of 4.108 g H₂O/100 g ENR 50. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1633–1644, 1999     

输油管线用熔结环氧粉末涂料的制备

采用线型酚醛环氧树脂(ENR)、环氧树脂E-12、固化剂JECP-02B制备了输油管线用熔结环氧粉末涂料。考察了线型酚醛环氧树脂与环氧树脂E-12质量比对涂料性能的影响,以及固化剂JECP-02B、流平剂GLP588和固化促进剂2-甲基咪唑对固化行为的影响,用红外光谱分析了固化前后树脂的变化,m(ENR)/m(E-12)=(75/25)~(25/75)、m(固化剂)/m(环氧树脂)=1/4、m(流平剂)/m(环氧树脂)=2/100、m(2-甲基咪唑)/m(环氧树脂)=(0.1~0.15)/100时,涂层性能达到输油管线防腐指标(SY/T 0315-97)。长庆化工有限责任公司用该技术扩大生产约10 t环氧粉末涂料,用于长庆油田输油管线的防腐,产品满足了1.5 m in/230℃快速固化的施工要求。     

Nanoclay distribution and its influence on the mechanical properties of rubber blends

The distribution of modified and unmodified nanoclays inside the rubber phases of immiscible rubber–rubber blends composed of nonpolar–polar natural rubber (NR)/epoxidized natural rubber (ENR) and nonpolar–nonpolar NR/polybutadiene rubber (BR) was investigated for the first time. The distribution of clays at various loadings in the blends was calculated from the viscoelastic properties of the blends. For example, in the 50 : 50 NR/ENR blend, 42% Cloisite 30B migrated to the NR phase, and 58% went to the ENR phase. However, in the same blend, only 7% Cloisite Na⁺ was found in the NR phase, and 93% was found in the ENR phase. Again, in the 50 : 50 NR/BR blends, the NR phase contained 85% Cloisite 30B, whereas 55% Cloisite Na⁺ migrated to the NR phase. All these observations were explained with the help of viscosity, X‐ray diffraction, and morphology analyses. The effect of the distribution of the clay on the mechanical properties was also discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Interaction Between Fumed-Silica and Epoxidized Natural Rubber

Epoxidized natural rubber (ENR)/fumed silica vulcanizates were prepared by mechanical mixing method. Fumed silica content can affect mechanical properties of the composites, and ten parts per hundreds of rubber (phr) fumed silica lead to the best tensile strength. The interaction between ENR and fumed silica was characterized by Kraus equation, crosslink density (tested by NMR), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and scanning electron microscope (SEM). The results showed that the dispersion of silica in ENR was better than in natural rubber (NR), hydrogen bond was produced between ENR and fumed-silica in ENR/silica blends, and glass transition temperature of ENR/silica vulcanizate was higher than pure ENR vulcanizate. TGA and DMA confirmed that there was intense interaction between ENR and silica.     

Effect of carbon black on self‐crosslinking network structure of polychloroprene rubber and epoxidized natural rubber blends

The goal of this research is to improve poor network structure of polychloroprene rubber (CR)/epoxidized natural rubber (ENR) self‐crosslinking blends, which could substitute traditional vulcanizates in some application area. Carbon black (CB)–CR/ENR blends were prepared by reacting CR with ENR in the presence of CB. The structure of CR/ENR blends was characterized by attenuated total‐reflectance Fourier transform infrared spectroscopy (FTIR‐ATR). The effect of CB loading on curing characterization and mechanical properties of CR/ENR blends was investigated, and the interaction among CR, ENR, and CB was studied using differential scanning calorimetry. The effect of CB loading on the Payne effect of CR/ENR was investigated using rubber process analyzer. Scanning electron microscope was used to characterize the morphology of CB–CR/ENR blends. The results showed that CR/ENR blends were obtained by the ring‐opening reaction of epoxy groups in ENR and chlorine groups in CR. Mechanical properties of CR/ENR blends increased with the increase of CB loading. The Payne effect of CR/ENR became more remarkable with increasing CB loading. Morphology study indicated that interfacial compatibility between CR and ENR increased with the increase of CB loading because CB could strengthen the self‐crosslinking network structure of CR/ENR blends. The promoting effect of CB on self‐crosslinking reaction was verified by the assessment of crosslink density. POLYM. COMPOS., 38:463–471, 2017. © 2015 Society of Plastics Engineers