超细全硫化粉末NBR/EPDM共混物的结构与性能

试验研究超细全硫化粉末NBR（UFPNBR）／EPDM共混物的硫化特性、相态结构、动态力学性能，加工性能及物理性能。UFPNBR粒子加入EPDM中明显影响了EPDM的硫化性能，UFPNBR／EPDM共混物采用过氧化物硫化体系硫化效果较好；透射电子显微镜和扫描电子显微镜观察表明，UFPNBR粒子在UFPNBR／EPDM共混物中始终为分散相，但在EPDM基体中没有分散成预期的纳米尺寸；动态力学热分析结果显示，共混物存在两个玻璃化温度，呈两相结构且界面结合较弱；橡胶加工分析仪分析结果表明，UFPNBR粒子在EPDM基体中形成了填料网络结构，使共混物的流动性能变差；UFPNBR对EPDM有一定补强作用，但补强作用不如传统的纳米无机填料。     

团状模塑料/三元乙丙橡胶共混物的表征及其性能的影响因素

用团状模塑料(DMC)与三元乙丙橡胶(EPDM)共混,以EPDM为连续相、DMC为分散相,制备了DMC/EPDM共混物,并对其微观结构进行了表征,研究了DMC与EPDM的质量比、过氧化物硫化荆的种类和用量以及白炭黑的用量对共混物性能的影响.结果表明,DMC和EPDM的界面作用强,相容性好;过氧化苯甲酰(BPO)作硫化荆要好于用过氧化二异丙苯;当DMC与EPDM的质量比为90/100、BPO为5份、白炭黑为50份时,共混物的力学性能和耐热老化性较好.     

三元乙丙橡胶/回收聚苯乙烯增容母料对硫黄硫化三元乙丙橡胶性能的影响

利用Friedel-Crafts烷基化反应,以质量比50/50制备三元乙丙橡胶(EPDM)/回收聚苯乙烯(RPS)增容母料,并将增容母料添加到EPDM中,考察增容母料用量对硫黄硫化EPDM硫化胶性能的影响。结果表明,RPS可以接枝到EPDM上,形成EPDM-g-RPS接枝物;当增容母料用量不高于50份(质量)时,含有增容母料EPDM硫化胶的力学性能明显优于纯EPDM硫化胶,且优于含有相同EPDM/RPS配比的简单共混物。扫描电镜观察结果表明,在含有增容母料的EPDM硫化胶中,RPS分散相更加均匀细小,两相黏结程度明显增强。     

超细全硫化粉末丁腈橡胶/二元共聚氯醚橡胶共混物的结构与性能

采用熔融共混工艺制备了超细全硫化粉末丁腈橡胶(UFPNBR)/二元共聚氯醚橡胶(ECO)共混物,研究了共混物的相态结构、动态力学性能、物理机械性能及老化性能,并与丁腈橡胶(NBR)/ECO共混物进行了对比.透射电镜观察表明,在UFPNBR/ECO体系中,UFPNBR为分散相,ECO为连续相;而在NBR/ECO体系中,ECO为分散相,NBR为连续相.动态力学性能分析结果显示在共混质量比不超过50/50时,UFPNBR/ECO共混物只存在1个玻璃化转变温度;当共混质量比超过50/50时分散相尺寸较大,出现2个玻璃化转变温度,而NBR/ECO始终存在2个玻璃化转变温度.加入适量的UFPNBR(不超过50份,质量)能降低UFPNBR/ECO共混物的压缩永久变形.与NBR/ECO共混物相比,UFPNBR/ECO共混物的脆性温度较低,耐老化性能更好,但物理机械性能稍差.     

乙丙橡胶增韧聚丙烯共混物中橡胶相形态

通过电子扫描电镜(SEM),研究了乙丙橡胶增韧聚丙烯共混物中作为分散相的橡胶粒子的形态。结果表明,在交联剂等助剂的作用下进行过动态硫化的共混物中橡胶相的粒子形状、粒径、粒径分布以及橡胶粒子与连续相聚丙烯所形成的界面形态与单纯的橡塑共混物和PP/EPDM反应器共混物相比有着截然不同的区别。正是由于这些区别,提高了经过动态硫化的共混物的冲击性能。     

动态硫化EPDM/TPX共混型热塑性弹性体的制备

研究了共混工艺和不同硫化体系对动态硫化三元乙丙橡胶(EPDM)/聚-4-甲基戊烯-1热塑性弹性体(TPX TPV)力学性能的影响,并探讨了不同硫化体系共混物的热氧老化性能和微观相态结构。结果表明,EPDM与TPX先混匀再加入硫化剂的共混物力学性能好于先在EPDM中加入硫化剂再混合的共混物力学性能。硫黄最佳用量为0.4份,硫载体最佳用量为1.5份。当硫化剂选用最佳用量时,共混物具有较好力学性能。硫黄硫化共混物和硫载体硫化共混物分别在100℃×72h和180℃×72h热氧老化条件下的力学性能均有所下降,但幅度不太明显,二者均表现出了较好的耐热氧老化性。DMA结果表明,EPDM与TPX有一定的相容性。     

动态硫化对三元乙丙橡胶/聚丙烯共混体系等温结晶行为和形态结构的影响

研究了三元乙丙橡胶/聚丙烯(EPDM/PP)共混物和动态硫化EPDM/PP热塑性弹性体(TPV)的等温结晶行为及形态结构,并用Avrami方程对其进行等温结晶动力学分析。结果表明,EPDM/PP共混物和EPDM/PP TPV的等温结晶行为符合Avrami方程,在相同的结晶温度下,TPV比共混物的Avrami指数小,半结晶时间短,结晶速率常数大;EPDM/PP共混物为双连续相结构,而EPDM/PP TPV是以硫化的细小橡胶颗粒为分散相、PP为连续相的"海-岛"结构,橡胶颗粒尺寸约为0.5μm。     

动态硫化EPDM/EVA热塑性弹性体的制备与性能

采用动态硫化法制备了三元乙丙橡胶(EPDM)/乙烯-醋酸乙烯共聚物(EVA)共混型热塑性弹性体(TPE),并对其力学性能和微观相结构进行了研究。结果表明,动态硫化EPDM/EVA型TPE的拉伸强度及撕裂强度均随EVA含量的增加而提高,当EVA含量低于50wt.%时,其应力-应变曲线呈现出典型的弹性体特征;EPDM/EVA的共混比为60/40时,所制备的TPE表现出了良好的综合性能;EPDM分散相粒径在20μm以下且较均匀地分散EVA基体中。     

动态硫化法制备三元乙丙橡胶/聚酰胺热塑性弹性体

采用动态硫化技术制备了三元乙丙橡胶(EPDM)／聚酰胺(PA)热塑性弹性体,研究了增容剂种类及用量、硫化体系及其用量、加料顺序、PA用量对其性能的影响,用扫描电镜分析了其相态结构。结果表明,用13份(质量份,下同)的氯化聚乙烯作为增容剂时,对该共混体系的增容效果最好;硫黄硫化体系是EPDM／PA热塑性弹性体的最佳硫化剂,当硫黄用量为2份时,既保证了该热塑性弹性体中的橡胶相能充分交联,又可避免过硫化对产品性能造成的负面影响;PA用量为35份的EPDM／PA热塑性弹性体具有良好的力学性能、耐溶剂性能和耐热老化性能;EPDM以平均粒径为2～5μm的粒子形态均匀分布于PA连续相中。     

动态硫化对PET/PTW共混物性能的影响

研究了聚对苯二甲酸乙二醇酯(PET)／乙烯-丙烯酸丁酯-甲基丙烯酸缩水甘油酯三元共聚物(PTW)共混物的动态硫化,讨论了硫化剂2-乙基-4-甲基咪唑(EMI)用量对PET／PTW共混物性能的影响。结果表明,当EMI用量为1．0～2．0份(质量份)时,该共混物具有最佳力学性能。扫描电镜照片表明,该共混物中分散于PET连续相的PTW粒子尺寸较小,且分布均匀。     

The morphology and property of ultra‐fine full‐vulcanized acrylonitrile butadiene rubber particles/EPDM blends

A novel UFNBRP/EPDM blend was prepared by compounding ultra‐fine full‐vulcanized acrylonitrile butadiene rubber particles (UFNBRP) with ethylene–propylene–diene monomer (EPDM) matrix. The morphology, dynamic property, and curing property of the blend were discussed in detail. TEM and SEM observations showed that, no matter how high the blend ratio of UFNBRP to EPDM matrix was, UFNBRP particles always kept being in the dispersion phase because of its extremely high viscosity resulting from self‐crosslinking, but were not dispersed as nanosize units, as expected. Dynamic properties, illustrated by DMTA, further demonstrated that two phases exhibited two separate glass transition temperatures, indicating distinct phase separation and weak phase interaction. Rubber processing analyzer results showed that inorganic filler as well as UFNBRP particles in EPDM matrix formed a network and blocked the flow properties of the compound. At the same time, the introduction of UFNBRP particles evidently affected the vulcanization of EPDM, when sulfur was used as a vulcanizing agent, and improved the mechanical properties of EPDM. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3673–3679, 2006     

基体性质对聚丙烯力学性能的影响

采用过氧化二异丙苯(DCP)作为降解剂,以聚丙烯(PP)为基体,以三元乙丙橡胶(EPDM)为增韧剂,研究了EPDM对降解PP/EPDM共混物力学性能的影响,并利用扫描电子显微镜(SEM)对共混体系微观形貌进行了表征。熔体质量流动速率结果表明:随着EPDM质量分数从10%增加到30%时,对应共混物的熔体质量流动速率明显下降,从14.8 g/10 min下降到10.8 g/10 min。随着EPDM用量的增加,共混物的冲击强度明显增大,从30.06J/m增长到90.26 J/m,拉伸强度有所减小。SEM照片显示,随着EPDM用量的增加,共混物中分散相的尺寸明显增大。因为EPDM含量的增加,导致分散的橡胶粒子产生"聚并",从而分散相的相区尺寸增大。     

Effects of compounding procedure on morphology development,melt rheology,and mechanical properties of nanoclay reinforced dynamically vulcanized EPDM/polypropylene thermoplastic vulcanizates

New nanocomposite thermoplastic vulcanizates (TPVs) comprising dynamically cross‐linked nanoscale EPDM rubber particles dispersed throughout the polypropylene (PP) matrix have been prepared by both batch and continuous melt blending of PP with EPDM in the presence of vulcanizing ingredients, nanoclay and maleated EPDM (EPDM‐g‐MA) as compatibilizer. X‐ray diffraction, linear melt viscoelastic measurement, and tensile mechanical behavior results revealed that the developed microstructure is strongly affected by the type of the melt compounding process as well as the route of material feeding. When EPDM phase was precompounded with a vulcanizing agent, nanoclay, and EPDM‐g‐MA prior to the melt blending with PP, not only nanosize cross‐linked rubber particles appeared uniformly throughout the PP continuous phase, but also the melt blending leads to the significant enhancement of the mechanical properties compared with counterpart samples prepared by one‐step melt mixing process. Also better dispersion of nano layers in the rubber compound before melt blending with PP results in higher mechanical properties of the resulted TPV. POLYM. ENG. SCI., 56:914–921, 2016. © 2016 Society of Plastics Engineers     

Effect of the addition of acrylonitrile/ethylene–propylene–diene monomer (EPDM)/styrene graft copolymer on the morphology–properties relationships in poly(styrene‐co‐acrylonitrile)/EPDM rubber blends

Blends of poly(styrene‐co‐acylonitrile) (SAN) with ethylene–propylene–diene monomer (EPDM) rubber were investigated. An improved toughness–stiffness balance of the SAN/EPDM blend was obtained when an appropriate amount of acrylonitrile–EPDM–styrene (AES) graft copolymer was added, prepared by grafting EPDM with styrene–acrylonitrile copolymer, and mixed thoroughly with both of the two components of the blend. Morphological observations indicated a finer dispersion of the EPDM particles in the SAN/EPDM/AES blends, and particle size distribution became narrower with increasing amounts of AES. Meanwhile, it was found that the SAN/EPDM blend having a ratio of 82.5/17.5 by weight was more effective in increasing the impact strength than that of the 90/10 blend. From dynamic mechanic analysis of the blends, the glass‐transition temperature of the EPDM‐rich phase increased from ?53.9 to ?46.2°C, even ?32.0°C, for the ratio of 82.5/17.5 blend of SAN/EPDM, whereas that of the SAN‐rich phase decreased from 109.2 to 108.6 and 107.5°C with the additions of 6 and 10% AES copolymer contents, respectively. It was confirmed that AES graft copolymer is an efficient compatibilizer for SAN/EPDM blend. The compatibilizer plays an important role in connecting two phases and improving the stress transfer in the blends. Certain morphological features such as thin filament connecting and even networking of the dispersed rubber phase may contribute to the overall ductility of the high impact strength of the studied blends. Moreover, its potential to induce a brittle–ductile transition of the glassy SAN matrix is considered to explain the toughening mechanism. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1685–1697, 2004     

交联剂对动态硫化PP／EPDM中PP晶体及EPDM形态结构的影响

针对ＰＰ／ＥＰＤＭ动态硫化中有机过氧化物交联剂Ａ用量对试样拉伸,弯曲和冲击等性能所产生的较大的影响,采用偏光显微镜研究了不同交联剂Ａ用量下动态硫化ＰＰ／ＥＰＤＭ中连续相ＰＰ的晶体结构和分散相ＥＰＤＭ的形态结构特征。     

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.     

Phase morphology and melt rheological behavior of uncrosslinked and dynamically crosslinked polyolefin blends: role of macromolecular structure

Thermoplastic vulcanizates (TPVs) based on polypropylene (PP) with ethylene–octene copolymer (EOC) and ethylene propylene diene rubber (EPDM) have been prepared by co-agent-assisted peroxide crosslinking system. The study was pursued to explore the influence of two dissimilar polyolefin polymers having different molecular architecture on the state and mode of dispersion of the blend components and their influence on melt rheological properties. The effects of dynamic crosslinking of the PP/EOC and PP/EPDM have been compared with special reference to the concentration of crosslinking agent and ratio of blend components. Morphological analyses show that, irrespective of blend ratio, dynamic vulcanization exhibits a dispersed phase morphology with crosslinked EOC or EPDM particles in the continuous PP matrix. It was found that viscosity ratio plays a crucial role in determining the state and mode of dispersion of blend components in the uncrosslinked system. The lower viscosity and torque values of uncrosslinked and dynamically crosslinked blends of PP/EOC in the melt state indicates that they exhibit better processing characteristics when compared to corresponding PP/EPDM blends.     

Skin-Core morphology and failure of injection-molded specimens of impact-modified polypropylene blends

The structure-property relationship as well as the failure phenomena of injection molded polypropylene (PP) blends modified with ethylene/propylene/diene terpolymer (EPDM) and thermoplastic polyolefinic rubber (TPO) were investigated. Single and double-gated tensile bars were injection molded by different Injection speeds. Microscopic studies on the failure behavior of knit lines were carried out using microtomed sections taken from the doublegated specimens. It was found that during injection molding, a skin-core morphology is formed in both the continuous PP matrix as well as in the modified PP blends containing rubber particles of various deformation. The characteristics of the latter are in agreement with those described by the Tadmor flow model. The skin consists of a thin pure PP layer, whereas the subsurface layer contains more or less elongated rubbery particles due to the elongational flow at the wall. The deformation of the rubbery particles decreases, but their concentration increases with increasing distance from the skin towards the core. The deformed particles are oriented tengentionally to the flow front profile. Failure during tensile and tensile impact loading is initiated in the shear zone along the skin-core boundary. This zone has a transcrystalline character and favors the formation of crazing. Final fracture of the bars depends, however, on how crazing and shear yielding simultaneously interact. Their interaction is a function of the average particle size of the dispersed phase. Above an average particle size of 0.6 μm, crazing is prevented by shear bands. For injection molding of PP/rubber blends a moderate injection speed is recommended, if the melt viscosities of the components are closely matched. In this way a pronounced dispersion gradient of the rubber particles across the plaque thickness is avoided. However, for the blends modified with rubber of high viscosity ratio and greater melt elasticity, use of higher injection speed is advantageous. Here, the higher shear stress field decreases the average particle size taken into the direction perpen dicular to the lead, since the cross section of the stronger deformed particle decreases.     

Mechanical,thermal, and morphological characteristics of compatibilized and dynamically vulcanized polyoxymethylene/ethylene propylene diene terpolymer blends

Dynamically vulcanized blends of polyoxymethylene (POM) and ethylene propylene diene terpolymer (EPDM) with and without compatibilizer were prepared by melt mixing in a twin screw extruder. Maleic anhydride (MAH) grafted EPDM (EPDM‐g‐MAH) has been used as a compatibilizer. Dicumyl peroxide was used for vulcanizing the elastomer phase in the blends. Mechanical, dynamical mechanical, thermal, and morphological properties of the blend systems have been investigated as a function of blend composition and compatibilizer content. The impact strength of both dynamically vulcanized blends and compatibilized/dynamically vulcanized blends increases with increase in elastomer content with decrease in tensile strength. Dynamic mechanical analysis shows decrease in tanδ values as the elastomer and compatibilizer content increased. Thermograms obtained from differential scanning calorimetric studies reveal that compatibilized blends have lower T_m values compared to dynamically vulcanized blends, which confirms strong interaction between the plastic and elastomer phase. Scanning electron microscopic observations on impact fractured surface indicate reduction in particle size of elastomer phase and its high level of dispersion in the POM matrix. In the case of compatibilized blends high degree of interaction between the component polymers has been observed. POLYM. ENG. SCI., 47:934–942, 2007. © 2007 Society of Plastics Engineers     

Novel methods for synthesis of high‐impact polystyrene with bimodal distribution of rubber particle size

By using in situ prepolymerization and radiation curing, high‐impact polystyrene (HIPS) with a bimodal distribution of the size of the rubber particles (bimodal HIPS) was synthesized in the presence of ultrafine full‐vulcanized powdered styrene–butadiene rubber (UFPSBR) and polybutadiene rubber (BR). TEM photographs indicated that UFPSBR was dispersed uniformly as a single particle with a diameter of about 100 nm. On the other hand, bimodal HIPS with different rubber particle size distributions could also be obtained by blending HIPS and UFPSBR grafting styrene (UFPSBR‐g‐St) with different grafting yields. The bimodal HIPS with the smallest rubber particle size, at about 100 nm, could be prepared by blending the monomodal HIPS containing big rubber particles with polystyrene/UFPSBR. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008