丁腈橡胶/聚酰胺热塑性硫化胶的制备

用橡塑预混法、二步法和母炼胶法制备了丁腈橡胶／聚酰胺热塑性硫化胶(NBR／PATPV),研究了3种工艺对NBR／PATPV相态结构、流变性能、物理机械性能和耐溶剂性能的影响。结果表明,NBR与PA在高温、高剪切作用下,两相界面之间可发生微化学反应,但并不影响动态硫化时两相之间的相态反转过程。用橡塑预混法可制得分散相粒径小且分布均匀的TPV,该TPV的100％定伸应力大,压缩永久变形小,耐溶剂性能不佳,表观黏度略大,但挤出物外观光滑。     

硫化体系对氯化丁基橡胶/尼龙12动态硫化胶性能的影响

研究了氧化锌、N,N’-间苯撑双马来酰亚胺(HVA-2)/氧化锌和1,3-双柠糠酰亚胺甲基苯(PK 900)/氧化锌3种硫化体系下氯化丁基橡胶(CIIR)/尼龙(PA)12混炼胶的硫化特性及CIIR/PA 12动态硫化胶(TPV)的物理机械性能和微观相结构,并考察了PK 900与氧化锌不同配比对CIIR/PA 12TPV物理机械性能、流变性能及微观相结构的影响。结果表明,PK 900/氧化锌的硫化速率介于氧化锌和HVA-2/氧化锌两者之间,由其制备的TPV橡胶相粒径为1～2μm,均匀分布在树脂相中,物理机械性能最优;固定PK 900用量为3份时,随着氧化锌用量的减少,CIIR/PA 12 TPV的拉伸强度、扯断伸长率和100%定伸应力均呈现先增大后减小的趋势;当PK 900/氧化锌(质量比)为3/5时,CIIR/PA 12TPV的物理机械性能最佳,且呈现低剪切速率高黏度、高剪切速率低黏度的特性。     

特种共混型热塑性弹性体——Ⅱ.CPE及CSM与PA共混体系的组成对性能的影响

以CPE、CSM 及PA为原料,采用动态硫化法制备了具有特殊性能的共混型热塑性弹性体,考察了各种因素对共混物性能的影响,比较了 CPE/PA 和 CSM/PA 的综合性能。结果表明,橡胶相的交联程度对共混物的综合性能有较大影响;在 CPE/PA 共混体系中,DCP 交联体系较促进剂 NA-22 为优;助交联剂 TAIC 在本体系中起改性作用;白炭黑在共混体系中无明显补强效果,但经表面处理后,可提高橡胶相的交联程度;从共混物的返炼特性判断,当 CPE/PA(质量份)为 90/10—80/20时发生相转变;CPE/PA 的综合性能较 CSM/PA 为优。     

Morphology development by reactive compatibilisation and dynamic vulcanisation of nylon6/EPDM blends with a high rubber fraction

Binary nylon6/rubber blends with 50 or 60 weight percent of an EPDM rubber exhibit co-continuous morphologies and thereby relatively poor mechanical properties. This paper describes methods to develop nylon6/EPDM blends with a high amount of finely dispersed rubber particles embedded in a nylon matrix. Using a suitable compatibiliser and by slightly crosslinking the rubber phase during melt-mixing, it was possible to disperse up to 60 wt% rubber in the nylon matrix and to improve the mechanical properties markedly. These materials are called thermoplastic vulcanisates and exhibit good elastic properties with a thermoplastic processability. The influence of the compatibiliser, the crosslinking agent and the viscosity ratio rubber/thermoplastic on the blend phase morphology is investigated using transmission electron microscopy. It was found that the viscosity ratio rubber/nylon plays a crucial role in order to achieve a nylon6/rubber TPV with a fine rubber dispersion. The viscosity of the nylon phase should be low enough to shift the phase inversion towards higher rubber content. On the other hand, if the viscosity of the nylon is too low, a coarse blend morphology was achieved resulting in poor mechanical properties.     

增容剂对动态硫化氯化丁基橡胶/尼龙12热塑性弹性体性能的影响

分别以聚丙烯接枝马来酸酐( PP -g - MAH)、苯乙烯-乙烯-丁二烯-苯乙烯共聚物接枝马来酸酐(SEBS-g- MAH)以及新型改性剂苯乙烯-共轭二烯烃嵌段共聚物选择加氢物(SEPS)作为增容剂,考察了不同增容剂对动态硫化氯化丁基橡胶/尼龙12热塑性弹性体(PA 12/CIIR TPV)物理机械性能的影响,并研...     

Influence of a crosslinked system on the morphology and properties of TPVs based on PA/NBR

The mechanical properties of thermoplastic vulcanizates (TPVs), depend strongly on their morphologies, which themselves depend on the properties of the primary polymers, the composition of the TPV, and the crosslink system and crosslink process. The morphology is defined during the dynamic vulcanization. This work deals with the study of the influence of crosslink systems on TPVs based on PA/NBR (copolyamide PA6/6‐6 and nitrile rubber) in a 40/60 composition. Dicumyl peroxide, bismaleimide, phenolic resin, a sulfur‐accelerated system, and dicumyl peroxide with two coagents were used as crosslinkers. TPVs were characterized by taking into account their mechanical strength, solvent resistance, compression set, and morphology. The curing system constituted by dicumyl peroxide and sulfur/bismaleimide as coagents resulted in a more defined morphology, and therefore the TPV exhibited the best properties. For these TPVs, a morphology consisting of spherical domains of rubber distributed homogeneously on the polyamide matrix could be observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

羧基丁腈橡胶/PA12热塑性弹性体的制备及性能研究

通过动态硫化法制备了羧基丁腈橡胶/聚酰胺12(XNBR/PA12)热塑性硫化橡胶(TPV),考察了XNBR羧基含量和XNBR/PA12橡塑比(质量比,下同)对TPV力学性能、流变性能、耐油性能和耐热空气老化性能的影响.结果表明,随着橡塑比的增大,TPV力学性能先上升后下降;当XNBR羧基含量为7％(质量分数,下同)、橡...     

增塑体系对CIIR/PA12 TPV性能的影响

采用动态硫化方法制备CIIR/聚十二内酰胺(PA12)热塑性硫化胶(TPV),研究增塑剂环烷油、聚异丁烯和N-丁基苯磺酰胺对CIIR/PA12 TPV物理性能、流变性能、结晶性能、动态力学性能和气密性的影响.结果表明:N-丁基苯磺酰胺对CIIR/PA12 TPV有一定的增塑效果;与环烷油和聚异丁烯相比,N-丁基苯磺酰胺...     

动态硫化丁腈橡胶/尼龙6热塑性弹性体的制备及性能

采用动态硫化法制备了丁腈橡胶/尼龙6热塑性弹性体(NBR/PA 6 TPV),考察了硫化体系、羧基丁腈橡胶(XNBR)以及增塑剂高密度氧化聚乙烯蜡(AC-316 A)和正丁基苯磺酰胺(BBSA)对TPV硫化特性、力学性能和微观形貌的影响。结果表明,以促进剂HVA-2/促进剂DM为硫化体系,动态硫化过程体系黏度的变化比以酚醛树脂/SnCl2为硫化体系时更平稳;但用后者制备TPV,其撕裂强度和扯断伸长率等力学性能更优,PA 6的结晶度更低。XNBR能对NBR和PA 6起到增容作用,当XNBR与NBR的质量比为10/90时,TPV的力学性能最好,NBR在PA 6中分散得最均匀。AC-316 A和BBSA都能对TPV起到增塑作用,随其用量的增加,体系黏度降低。     

氯化丁基橡胶/聚丙烯酸酯阻尼橡胶的力学性能

采用聚丙烯酸酯(PA)为第二组分,与氯化丁基橡胶（CIIR)制备了CIIR／PA阻尼橡胶,分析了CIIR／PA共混物的结构,讨论了原料组成、交联剂用量和填料种类对其力学性能的影响、结果表明,CIIR／聚(丙烯酸乙酯-甲基丙烯酸丁酯)[P(EA-BMA)]共混物的正硫化时间为10min．CIIR／聚丙烯酸乙酯(PEA)硫化共混物中存在共交联结构;共交联CIIR／PEA共混物形成了双相连续的微观相态结构;当P(EA-BMA)中PBMA链段的质量分数增加到20%时,共交联CIIR／P(EA-BMA)共混物的拉伸强度和100％定伸应力下降,当P(EA-BMA)中PBMA链段的质量分数继续增加,共混物的拉伸强度和100％定伸应力又逐渐上升,当酚醛树脂(PR)用量不大于20份时,随着PR用量的增加,共交联CIIR／PEA共混物的100％定伸应力和邵尔A型硬度增大,拉伸强度和扯断伸长率减小;当PR用量为30份时,共混物的100％定伸应力减小,拉伸强度增大;填料中以炭黑的增强效果最好,玻璃微球增强效果最差。     

Evolution of rheological properties and morphology development during crosslinking of polyolefin elastomers and their TPV blends with polypropylene

This work investigates the evolution of the rheological properties of elastomeric dynamically vulcanized ethylene‐α‐olefin copolymers (ECs) and their blends with polypropylene (PP), during peroxide initiated crosslinking. Rheological techniques are used in conjunction with gel content measurements to determine the onset of gelation during static crosslinking. The complex viscosity and moduli follow power‐law dependence with respect to frequency at the gel point. The relaxation exponent and corresponding values of tan δ at the gel point are determined from the complex viscosity versus frequency curves and used as criteria for the determination of the instance of gelation. The evolution of morphology of thermoplastic vulcanizate (TPV) blends consisting of EC and PP during dynamic crosslinking is discussed in the context of the evolving rheological properties of the matrix and the dispersed phase that take place upon peroxide modification. TPVs having the crosslinked EC as the matrix present a very fine morphology, whereas the blends containing crosslinked EC particles, present a coarser morphology. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

三元乙丙橡胶/聚丙烯动态硫化热塑性弹性体的相态结构

用扫描电镜研究了三元乙丙橡胶(EPDM)聚/丙烯(PP)动态硫化热塑性弹性体(TPV)相态结构的形成过程,探讨了交联密度、制备工艺、螺杆转速对EPDM/PP TPV相态结构的影响。结果表明,采用以酚醛树脂为硫化剂的动态硫化工艺制备的EPDM/PP TPV,其相态结构实现了由EPDM和PP组成的双连续相到以EPDM为分散相、PP为连续相的转变;当硫化剂用量为7份时,橡胶相硫化速率和交联密度最大;当螺杆转速为180 r/m in时,反应性挤出工艺较之密炼机工艺制备的EPDM/PP TPV的橡胶粒子更细小、分散更均匀。     

Relationship between the rheology and morphology of dynamically vulcanized thermoplastic elastomers based on EPDM/PP

Relationship between the rheological properties and morphology of dynamically vulcanized thermoplastic elastomers (TPVs) based on Ethylene Propylene Diene Monomer (EPDM) and Polypropylene (PP) blends containing 20, 40 and 60% of EPDM were studied. The samples were prepared in a laboratory internal mixer at a rotor speed of 60 rpm. We performed morphological studies on the cryogenically fractured samples using scanning electron microscopy (SEM). The rheological behavior and melt viscoelastic properties of the samples were studied by rheometric mechanical spectrometry (RMS) at a temperature of 220°C. The TPV samples showed a significant viscosity upturn and a strong storage modulus that tended to plateau at low shear rates, with the highest extent for the sample containing 60% of EPDM. These results were attributed to a network structure resulting from agglomerates formed between the cured rubber particles, as evidenced by the morphological features of the samples. The multiple elastic response, expressed in terms of relaxation time distribution, H(λ), exhibited by the molten TPV sample containing 60% of EPDM suggests that apart from the contribution of flow‐induced molecular orientation of the PP matrix, there may also exist some elastic response induced by agglomerates formed between the cured rubber particles. The results predicted from the linear viscoelastic model proposed in the present work were found to be in good agreement with the experimental results. POLYM. ENG. SCI. 45:84–94, 2005. © 2004 Society of Plastics Engineers.     

混炼型聚氨酯橡胶/聚十二内酰胺热塑性硫化胶动态硫化历程与性能

采用动态硫化方法制备了混炼型聚氨酯橡胶（MPU）/聚十二内酰胺（PA 12）热塑性硫化胶（TPV）,通过控制动态硫化时间探究了该TPV的动态硫化历程,同时研究了不同动态硫化阶段共混物的物理机械性能和动态力学性能。结果表明,随着动态硫化时间的延长,MPU/PA 12 TPV逐步完成相转变,在温度和剪切作用下,MPU相由连续相转变为分散相,而PA 12则由分散相转变为连续相;随着动态硫化时间的延长,MPU/PA 12共混物的储能模量升高,损耗模量降低,损耗因子减小。此外,随着动态硫化时间的延长,MPU/PA 12共混物的综合力学性能提高。     

POE/硅橡胶热塑性弹性体的力学性能及加工性能研究

采用动态硫化方法制备了乙烯-丙烯共聚物(POE)/硅橡胶热塑性弹性体。考察了共混比和交联剂含量对POE/硅橡胶热塑性弹性体的力学性能以及流变加工特性的影响。结果表明,m(硅橡胶)/m(POE)为60/40,交联剂质量分数为2.5%时表现出优越的力学性能,拉伸强度达到9.8MPa,断裂伸长率达到740%。制备出的POE/硅橡胶在流变测试中表现出优越的流变性能,具有高剪切粘度低,低剪切粘度高的特点。     

Dynamically vulcanized blends of polypropylene and ethylene octene copolymer: Influence of various coagents on thermal and rheological characteristics

The present study focuses on the influence of the three structurally different coagents, namely triallyl cyanurate (TAC), trimethylol propane triacrylate (TMPTA) and N,N′‐m‐phenylene dimaleimide (MPDM) on the thermal and rheological properties of thermoplastic vulcanizates (TPVs) based on the polypropylene (PP) and ethylene octene copolymer (EOC). Depending on the structure and reactivity, different coagents show different behaviors. All the TPV compositions were made by melt mixing method in a Haake Rheomix at 180°C. Rheological properties have also been evaluated at the same temperature. Viscoelastic properties of the TPVs were analyzed by a dynamic oscillatory rheometer in the melt state in a Rubber Process Analyzer (RPA 2000). Morphologically, TPVs consist of dense crosslinked rubber domains dispersed in a continuous thermoplastic matrix. The crosslinked rubber particles have a tendency to form agglomerates and build local clusters which undergo disintegration by shearing. A variety of rheological characteristics such as Payne effect, shear rate sensitivity, modulus recovery and dynamics of relaxation were studied by performing strain sweep, frequency sweep and stress relaxation tests. Among the various coagents taken for investigation, MPDM‐based TPVs show improved dynamic functions (complex modulus and complex viscosity) and lower rate of stress relaxation over TAC, TMPTA and the control sample without any coagent. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Covulcanisation of natural rubber and chlorobutyl rubber. Effect of curative diffusion between phases and ZnCl2 addition

Abstract

Natural rubber (NR) and chlorobutyl rubber (CIIR) were compounded with various formulations containing tetramethylthiuram disulphide (TMTD), sulphur, and ZnO, and masterbatches of these compounds were blended in a 70 : 30 NR/CIIR ratio and vulcanised in a press at 150°C. Crosslink densities of vulcanisates were determined by swelling and tensile properties measured. In formulations in which the concentration gradient permitted the diffusion of TMTD and sulphur to a CIIR phase containing ZnO, tensile strengths were slightly better than 70% of the values of NR compounds of similar crosslink densities. In formulations in which TMTD and sulphur diffused to the faster curing NR phase, blend properties were also better than 70% of those of NR compounds, but at higher crosslink densities, tensile strengths and elongation at break decreased in parallel. This was attributed to failure in a layer of more highly crosslinked material formed within the NR phase close to the interface. Although ZnCl₂ can crosslink CIIR to NR, thus ensuring good interfacial bonding, the addition of ZnCl₂ to the CIIR masterbatch led to attack on the TMTD accelerator and a significant reduction in crosslink density and tensile properties of blends.     

The effect of selective location of carbon nanotubes on electrical properties of thermoplastic vulcanizates

Three types of conductive thermoplastic vulcanizates (TPVs) were prepared by blending polypropylene (PP), carbon nanotubes (CNT), and carboxylic acrylonitrile butadiene ultrafine full‐vulcanized powdered rubber (xNBR‐UFPR). The CNT locations were different in these three types of TPVs, i.e., CNTs were localized in PP matrix, in the xNBR‐UFPR phase, or mainly in the interface. It had been found that TPV with CNTs localized mainly in the interface had the lowest conductive percolation threshold among these three types of TPVs. The volume resistivity of the TPV with 2 phr CNTs was as small as 220 Ω?cm. Moreover, the conductive TPV possessed good mechanical properties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Studies on the melt flow behavior of thermoplastic elastomers from polypropylene—Natural rubber blends

The melt flow behavior of thermoplastic polypropylenenatural rubber blends has been evaluated with specific reference to the effects of blend ratio, extent of dynamic crosslinking of the rubber phase and temperature, on viscosity, flow behavior index, and deformation of the extrudate. The proportion of rubber in the blend and the extent of dynamic crosslinking of the rubber phase were found to have profound influence on the viscosity of the blends at lower shear stresses. But at higher shear stresses, the effect of blend ratio on viscosity was comparatively less for the uncrosslinked blends than that for the crosslinked blends. At lower shear stress, the viscosity of the blend increased with increase in degree of crosslinking but at higher shear stress, the effect of crosslinking on viscosity was found to vary depending on the ratio of the plastic and rubber components in the blend. The deformation of the extrudates was also very much dependent on both blend ratio and degree of crosslinking.     

Preparation of dynamically vulcanized thermoplastic elastomer nanocomposites based on LLDPE/reclaimed rubber

Dynamically vulcanized thermoplastic elastomers nanocomposites (TPV nanocomposites) based on linear low density polyethylene (LLDPE)/reclaimed rubber/organoclay were prepared via one‐step melt blending process. Maleic anhydride grafted polyethylene (PE‐g‐MA) was used as a compatibilizing agent. The effects of reclaimed rubber content (10, 30, and 50 wt %), nanoclay content (3, 5, and 7 wt %), and PE‐g‐MA on the microstructure, thermal behavior, mechanical properties, and rheological behavior of the nanocomposites were studied. The TPV nanocomposites were characterized by X‐ray diffraction, transmission electron microscopy, scanning electron microscopy (SEM), differential scanning calorimeter, mechanical properties, and rheometry in small amplitude oscillatory shear. SEM photomicrographs of the etched samples showed that the elastomer particles were dispersed homogeneously throughout the polyethylene matrix and the size of rubber particles was reduced with introduction of the organoclay particles and compatibilizer. The effects of different nanoclay contents, different rubber contents, and compatibilizer on mechanical properties were investigated. Increasing the amount of nanoclay content and adding the compatibilizer result in an improvement of the tensile modulus of the TPV nanocomposite samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011