原位合成甲基丙烯酸锌增强氢化丁腈橡胶

用ZnO和甲基丙烯酸(MAA)经原位反应合成了甲基丙烯酸锌(ZDMA),将其作为增强剂用以增强氢化丁腈橡胶(HNBR),研究了ZnO／MAA(摩尔比,下同)、过氧化二异丙苯(DCP)用量和ZDMA用量对硫化胶力学性能的影响。结果表明,当ZnO／MAA为0．8,DCP用量为4份(质量,下同)时,原位合成ZDMA能够显著地提高HNBR的力学性能。随着ZDMA理论生成量的增加,硫化胶的拉伸强度先增加后减少,当ZDMA理论生成量为30份时,硫化胶的最大拉伸强度为47.2MPa．而扯断伸长率保持在393％以上;100％定伸应力随ZDMA理论生成量的增加而增加。经傅里叶变换红外光谱法和广角X光衍射法分析表明,在HNBR混炼过程中,ZnO和MAA可以原位生成ZDMA。     

Study on wear,cutting and chipping behaviors of hydrogenated nitrile butadiene rubber reinforced by carbon black and in‐situ prepared zinc dimethacrylate

In this study, the wear (Akron and DIN) and the cutting and chipping (C&C) behaviors of hydrogenated nitrile butadiene rubber (HNBR) reinforced by carbon black (N115) and in‐situ prepared zinc dimethacrylate (ZDMA) were investigated. It was validated that ZDMA was more effective than N115 to enhance the wear and C&C resistance of HNBR composites. The Akron wear resistance of the HNBR/N115 composites increased with the content of ZDMA, and the Schallamach ridges observed on the abraded surfaces became less and less clear. With increasing content of ZDMA, the failure mode of the DIN abraded surface underwent the transition from craters to Schallamach ridges, and finally to scratches. The HNBR/N115 composite reinforced by 10 phr ZDMA had the best DIN wear resistance when Schallamach ridges were the dominant failure mode. The use of 30 phr ZDMA can dramatically enhance the C&C resistance of the HNBR/N115 composites. The C&C resistance was suggested to be related to both the variation of the morphology of the C&C ridges and the direction of crack propagation as a function of the content of ZDMA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

In situ reactive compatibilized polypropylene/nitrile butadiene rubber blends by zinc dimethacrylate: Preparation,structure, and properties

This study demonstrated an approach of compatibilization between polypropylene (PP) and nitrile butadiene rubber (NBR) by using zinc dimethacrylate (ZDMA) as a reactive compatibilizer in the presence of peroxides. The PP/NBR/ZDMA ternary blends with improved mechanical properties were successfully prepared via peroxide dynamic vulcanization. The resultant blends exhibited a significant increase in mixing torque and complex viscosity after incorporation of ZDMA. Morphology studies showed that the addition of ZDMA reduced the size of the crosslinked NBR phase. Transmission electron microscopy (TEM) combined with scanning electron microscopy (SEM) verified that the possible reactions between ZDMA, NBR, and PP increased the interfacial thickness and improved the compatibility between NBR and PP phase. Crystallization behavior analysis indicated that incorporation of ZDMA promoted the nucleation process of PP. Thermal gravimetric analysis (TGA) showed that the maximum degradation temperature was increased by ZDMA. POLYM. ENG. SCI., 54:2321–2331, 2014. © 2013 Society of Plastics Engineers     

原位生成甲基丙烯酸锌增强天然橡胶的结构和性能

用ZnO与甲基丙烯酸(MAA)在天然橡胶(NR)基体中原位生成甲基丙烯酸锌(ZDMA),并在硫化剂过氧化二异丙苯(DCP)作用下制备了NR／ZnO／MAA纳米复合材料。用傅里叶变换红外光谱法、X射线衍射法、能量色散X射线法和扫描电子显微镜法分析了NR在混炼和硫化过程中的结构和形态变化,并研究了硫化胶的力学性能。结果表明,在NR混炼过程中加入摩尔比为0．5的ZnO／MAA。可以原位生成ZDMA;在硫化过程中,ZDMA在DCP作用下发生复杂化学反应,形成界面紧密结合的纳米复合材料,导致硫化胶的力学性能显著提高。当ZnO／MAA为加份时,硫化胶的拉伸强度、撕裂强度、扯断伸长率分别为30．6MPa,54．7kN／m,410％,其增强效果优于直接添加ZDMA。     

Cure kinetics and morphology of natural rubber reinforced by the in situ polymerization of zinc dimethacrylate

Peroxide‐cured natural rubber (NR) reinforced by zinc dimethacrylate (ZDMA) was prepared. The cocrosslinking action of ZDMA and the formation and evolution of the phase morphology induced by ZDMA during the curing process were systematically investigated. A curemeter and a differential scanning calorimeter were used to investigate the cure kinetics, and the kinetic parameters and the apparent activation energy were obtained. The phase morphology of the composites obtained from transmission electron microscopy revealed that separated nanophases of poly(zinc dimethacrylate) (PZDMA) existed in the rubber matrix. Covalent crosslinking, physical adsorption, and ionic crosslinking simultaneously existed in the composites, and they were determined with an equilibrium swelling method. On the basis of this, new microstructure models of NR/ZDMA composites and ionic crosslinking were put forward. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

甲基丙烯酸锌增强EPDM的力学性能和交联密度

在低用量的过氧化物硫化体系下,甲基丙烯酸锌对三元乙丙橡胶具有良好的增强效果,锌盐用量的增加会显著提高硫化胶的硬度和强度,且保持了较高的伸长率。交联结构数据表明增强作用与离子交联键密度相关。     

原位生成甲基丙烯酸锌对天然橡胶补强的研究

在天然橡胶(NR)混炼过程中加入氧化锌与甲基丙烯酸(MAA),在橡胶基体中原位生成甲基丙烯酸锌(ZDMA),并在硫化剂过氧化二异丙苯作用下制备NR/ZnO/MAA硫化胶。用扫描电镜、透射电镜研究了硫化胶的形态,并研究了制备条件对硫化胶力学性能的影响,结果表明,在155℃硫化温度,DCP用量为1.5～2 0质量份(phr)条件下,NR硫化胶具有较佳的力学性能。随着ZnO/MAA用量的增加,硫化胶定伸应力、拉伸强度和撕裂强度显著增加,表现出显著的补强作用。     

Stress softening of NR reinforced by in situ prepared zinc dimethacrylate

The stress softening effect of nature rubber (NR) reinforced by in situ prepared zinc dimethacrylate (ZDMA) was studied. Degree of stress softening effect (Ds) in the 4th stress–strain cycle of the NR with 10 phr (parts per hundreds of rubber) ZDMA was only 2.23 (strain = 100%), whereas it reached to 59.98 at 50 phr ZDMA (strain = 200%). The stress softening effects of carbon black filled into NR, and compared with the ZDMA effect, was also studied here. Mooney–Rivlin semiempirical equation was introduced here to analysis the stress–strain behavior of the NR vulcanize filled with in situ prepared ZDMA, and the results showed that the ZDMA/NR system has an obvious Payne effect which is in good agreement with the stress softening effect. Crosslink density analysis indicated a high ionic crosslink density in the NR filled with high content ZDMA, which contributed to the low elastic recovery of the stress softening. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

甲基丙烯酸锌与炭黑共同补强天然橡胶的研究

在开放式炼胶机上,分别以直接添加和原位生成2种方法向天然橡胶(NR)基体中添加甲基丙烯酸锌(ZDMA),制备了2种类型的ZDMA与炭黑共同补强的NR硫化胶,X射线衍射(XRD)分析证实,成功制备了ZDMA。扫描电镜(SEM)研究表明,原位生成ZDMA硫化胶的断面比直接添加ZD-MA硫化胶的粗糙很多,表现出更强的界面结合力。力学性能研究表明,用ZDMA部分替代炭黑,可以有效提高硫化胶的力学性能。在相同添加量下,原位生成ZDMA硫化胶的力学性能优于直接填充ZD-MA硫化胶的。     

Improved mechanical properties and special reinforcement mechanism of natural rubber reinforced by in situ polymerization of zinc dimethacrylate

The peroxide‐cured natural rubber (NR) was reinforced by in situ polymerization of zinc dimethacrylate (ZDMA). The experimental results showed NR could be greatly reinforced by ZDMA. The tensile strength and the hardness of NR/ZDMA composites increased with the content of ZDMA. The reinforcement mechanism was studied further. Both high crosslinking density provided by ionic crosslinking and strain‐induced crystallization improved the mechanical properties. The crosslinking density was determined by an equilibrium swelling method and the crystallization index was measured by Wide‐angle X‐ray diffraction (WXRD). When the amount of ZDMA was high, the ability of strain‐induced crystallization decreased, due to the strong interactions between the rubber phase and the hard poly‐ZDMA (PZDMA) nanodispersions. At the moment, the increasing ionic crosslinking density made up for the effect of the drop of the strain‐induced crystallization, and played a more important role in the reinforcement. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Crosslink network evolution of nature rubber/zinc dimethacrylate composite during peroxide vulcanization

In this article, we investigated the evolution of the crosslink networks in nature rubber (NR) which is filled with in situ zinc dimethacrylate (ZDMA) during vulcanization. The results revealed that a primary network dominated by the ionic bond could be formed in the first 1 min, while the backbone of the covalent crosslink network was not formed. The ionic crosslinks, cooperating with some other physical crosslinks and some primary covalent crosslink points, play an important role in supporting the crosslink backbone of the composite in this period. This primary network was strong enough to bear the force exerted by the moving die of the Rheometer and to enable the composite that do not dissolve in toluene. After that, both the covalent crosslinking of NR molecules and polymerization of ZDMA react rapidly to give a birth to the fundamental network of the composites. Fourier transform infrared spectroscopy and differential scanning calorimeter were also used to investigate the curing reaction of the NR/ZDMA compounds. After ZDMA reaching a considerable conversion, the substantial covalent crosslinking reaction starts to be initiated. These results support the primary network dominated by the ionic bond formed in the first 1 min. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

甲基丙烯酸锌增强氢化丁腈橡胶复合材料的性能

采用甲基丙烯酸锌(ZMMA)为增强剂填充氢化丁腈橡胶(HNBR),研究了ZMMA用量对ZMMA/HNBR复合材料硫化特性、力学性能、热稳定性以及玻璃化转变温度(Tg)的影响。结果表明,随着ZMMA用量的增加,复合材料的焦烧时间和正硫化时间缩短,最大转矩和交联密度提高;复合材料的拉伸强度先升高后下降,撕裂强度和100%定伸应力增大,而扯断伸长率降低。复合材料的Tg随着ZMMA用量的增加逐渐升高;ZMMA的加入提高了复合材料的热稳定性。     

Devulcanization of nitrile butadiene rubber in nitrobenzene

Sulfur‐crosslinked nitrile butadiene rubber (s‐NBR) was found to be devulcanized when it was heated with nitrobenzene at 200°C for 3 h. The tetrahydrofuran (THF)‐soluble fraction from s‐NBR heated with nitrobenzene was purified by reprecipitation with THF/n‐hexane, chloroform/n‐hexane, and THF/n‐hexane systems and was then characterized by means of Fourier transform infrared (FTIR) spectroscopy, ¹H‐NMR, gel permeation chromatography, dynamic thermogravimetry/differential thermal analysis (DTA), and differential scanning calorimetry (DSC). FTIR and ¹H‐NMR results revealed that the THF‐soluble fraction contained aromatic rings derived from nitrobenzene. Furthermore, the molecular weight of the THF‐soluble fraction was much lower than that of the parent noncrosslinked poly(acrylonitrile‐co‐butadiene). Although the weight loss of THF‐soluble fraction began at a lower temperature than that of the nonheated original nitrile butadiene rubber, the residual weight at 700°C tended to be higher for the former. This tendency became more marked with increasing time of heat treatment with nitrobenzene. The DSC‐determined glass‐transition temperature of the THF‐soluble fraction was higher than that of the original s‐NBR. To elucidate the devulcanization mechanism, we investigated two types of model reactions; one was the reaction of diphenyl disulfide with nitrobenzene, and the other was the reaction of polybutadiene with nitrobenzene. The former reaction, carried out at 250°C in diphenyl ether, yielded diphenyl sulfide with a loss of diphenyl disulfide and nitrobenzene. The use of a higher molar ratio of nitrobenzene to diphenyl disulfide resulted in a depression of diphenyl sulfide formation. The reaction of p‐chloronitrobenzene with diphenyl disulfide also gave diphenyl sulfide. The reaction of polybutadiene with nitrobenzene at 200°C resulted in the backbone scission of the polymer. The THF‐soluble solid product of the latter model reaction was found by FTIR and ¹H‐NMR to contain aromatic rings derived from nitrobenzene. The devulcanization mechanism is discussed on the basis of a comparison of the results of the model reactions with those of the s‐NBR devulcanization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3342–3353, 2004     

原位生成甲基丙烯酸镁对天然橡胶的补强研究

在天然橡胶混炼过程中加入氢氧化镁[Mg(OH)2]与甲基丙烯酸(MAA)，在橡胶基体中原位生成甲基丙烯酸镁(MDMA)，并在硫化剂DCP作用下制备NR／Mg(OH)2／MAA硫化胶。用FTIR、XRD研究了胶料在混炼和硫化过程中的结构变化，并研究了硫化胶的力学性能，结果表明，在NR混炼过程中加入摩尔比为0．5的Mg(OH)2／MAA，可以原位生成MDMA；在硫化过程中，MDMA在DCP作用下，一方面自聚生成PMDMA，另一方面与橡胶发生化学结合，从而形成紧密结合的复合材料，导致硫化胶的力学性能显著提高。     

Effect of vulcanizing system on the crosslink density of nitrile rubber compounds

The synergistic activity of binary accelerator systems in rubber vulcanization is well known. Binary accelerator systems are being widely used in industry and are becoming increasingly popular because of the fact that such mixed systems can produce a vulcanizate with superior mechanical properties compared to those of stock cured with a single accelerator. The authors have studied the performance of a binary accelerator system based on cyclohexyl benzothiazole sulfenamide (CBS), tetramethyl thiuram disulphide (TMTD) in the sulfur vulcanization of nitrile rubber. The amount of sulfur and accelerator was varied to change the network crosslink density of vulcanizates. The observed mutual activity has been discussed based on the mechanical properties and crosslink density. The physical crosslink density of the various nitrile rubber mixes was estimated using the Kinetic Theory of Elasticity. The mechanical properties of the various rubber compounds were related to the corresponding crosslink density estimated for each compound. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2440–2445, 2005     

Reinforcement of EPDM by in situ prepared zinc dimethacrylate

The mechanical properties and crosslink density of peroxide‐cured ethylene‐propylene‐diene rubber (EPDM) reinforced with zinc dimethacrylate (ZDMA) were studied. ZDMA was in situ prepared in EPDM matrix through the neutralization reaction of zinc oxide (ZnO) and methacrylate acid (MAA). The effect of ZnO/MAA amount and molar ratio of ZnO/MAA on the properties of the EPDM vulcanizate were investigated in detail. The experimental results showed that EPDM can be greatly reinforced by ZDMA. The excess amount of ZnO considerably increases the tensile strength of the EPDM vulcanizate to reach as high as 37 MPa, whereas its elongation at break keeps over 350%. The process of in situ formation of ZDMA in the EPDM compound was verified by WAXD. Such vulcanizate contains both covalent crosslinks and ionic crosslinks. Crosslink density was determined by an equilibrium swelling method. Dependence of crosslink density on the amount and molar ratio of ZnO/MAA was studied and the extraordinary high tensile strength of the EPDM/ZDMA vulcanizate was related to ionic crosslink density. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1339–1345, 2002; DOI 10.1002/app.10112     

Molecular simulations of gas transport in nitrile rubber and styrene butadiene rubber

Nitrile rubber (NBR, 39:61 wt% of acrylonitrile:butadiene) and styrene butadiene rubber (SBR, 50:50 wt% of styrene:butadiene) matrices have been equilibrated by molecular dynamics (MD) simulations. Transition-state approach is used to calculate the diffusion and solubility coefficients of small penetrants in these matrices, indicating quite low values in NBR and reasonable agreement with experimental results. MD simulations have been performed to analyze water diffusion in these matrices. Aggregation of water molecules is observed in the hydrophobic matrix SBR. MD simulations with fictitious nonpolar water molecules inhibit aggregation and lead to enhanced diffusion in SBR. In NBR there is a slight increase in diffusion for fictitious water molecules. The lower diffusion constants in NBR result from slower local relaxation of the matrix due to tighter intermolecular packing and higher cohesive energy density. The free volume distribution that affects solubility coefficients is not a major determining factor for the diffusion coefficients in these matrices.     

Investigation on the mechanical properties and oil resistance of sulfur cured nitrile rubber/hydrogenated nitrile butadiene rubber blends

Nitrile rubber (NBR)/hydrogenated nitrile butadiene rubber (HNBR) blends with various ratios were compounded with internal mixer and two-roll open mill. Mechanical properties and low-temperature performance (TR10) of the NBR/HNBR blends after aging under different conditions were investigated. Furthermore, equilibrium swelling test and moving die rheometer (MDR) test were used to systematically investigate the effects of HNBR dosage on the crosslink densities and curing behaviors. Vulcanization torque and crosslink densities decreased with an increase in HNBR content. The crosslink density of pure HNBR is higher than that of pure NBR, which is related to the macromolecular structures of the rubber. Compression sets of the NBR/HNBR vulcanizates were correlated with HNBR dosage indicating a linear relationship. Low-temperature performance of the NBR/HNBR blends was improved after being aged in the synthetic hydrocarbon hydraulic oils (SH-1 and SH-2). This work shows that the low-temperature performance and oil resistance could be better balanced by blending NBR with HNBR, while the mechanical properties maintain relatively high level.     

丁腈橡胶非均相催化加氢研究进展

丁腈橡胶（NBR）选择性催化加氢是制备高附加值、高性能氢化丁腈橡胶（HNBR）的一个重要过程。将链段中C==C双键加氢饱和而保留氰基基团,不仅可保持其原有的耐油性和耐磨性,而且可极大地改善其耐侯性、耐臭氧性等。本文介绍了NBR加氢的几种工艺,着重综述了NBR非均相催化加氢的研究进展及发展方向,探讨了负载型催化剂的载体孔道结构和表面性质及活性组分组成对NBR加氢性能的影响。本文还对非均相催化加氢过程中的溶剂效应、催化剂的回收和循环再生进行了阐述,提出溶剂对催化加氢速率和加氢度都有重要影响,溶剂的受氢能力（β值）是影响加氢过程的关键参数。催化剂失活的主要原因是表面活性位点被聚合物覆盖,而利用有效的溶剂洗涤或者采用催化剂表面功能化的方式,可促使活性位再次暴露,恢复其加氢活性。最后,对非均相加氢制备高附加值HNBR体系中的催化剂设计、溶剂效应和催化剂再生等发展方向进行了展望。