Effects of trans-polyoctylene rubber (TOR) on the properties of NR/EPDM blends

trans-Polyoctylene rubber (TOR) was melt blended with an incompatible NR/EPDM (70/30) blend. Mixing torque and temperature were reduced as TOR was added to NR/EPDM blend. The curing characteristics of the blend were affected as TOR participated in vulcanization and became a part of network. A scanning electron micrograph demonstrated that addition of TOR improved the compatibility of the blend and thereby led to a finer phase morphology. The ozone resistance of the blends was determined in terms of a critical stress–strain parameter. The critical stored energy density for ozone cracking was significantly enhanced for the TOR containing rubber blend. It was believed that the improvement in ozone resistance arised from finely dispersed ozone-resistant EPDM particles in the blend. TOR caused an improvement in dynamic properties and an increase in tensile modulus, but a decrease in tensile stress and elongation at break of the rubber blend. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 749–756, 1999     

Ozone cracking and flex cracking of crosslinked polymer blend compounds

Ozone cracking and flex cracking of crosslinked elastomer blends of brominated isobutylene/para‐methylstyrene copolymer (BIMSM) and unsaturated elastomers, such as polybutadiene rubber (BR) and natural rubber (NR), are studied. This saturated BIMSM elastomer, which is a terpolymer of isobutylene, para‐bromomethylstyrene, and para‐methylstyrene, functions as the ozone‐inert phase of the blend. Ozone cracking is measured by the failure time of a tapered specimen under a fixed load in a high severity ozone oven, whereas flex cracking is ranked by the De Mattia cut growth. The ozone resistance of BIMSM/BR/NR blends is compared to that of a BR/NR blend (with or without antiozonant) at constant strain energy densities. The effects of the BIMSM content in the blend, the structural variations of BIMSM, and the network chain length between crosslinks on these two failure properties, which are important in crosslinked compounds for applications in tire sidewalls, are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2183–2196, 2007     

Hydrogenated natural rubber blends: Aspect on thermal stability and oxidative behavior

Hydrogenated natural rubber (HNR) prepared from natural rubber (NR) is a new sustainable elastomer with excellent thermal properties. This study reports on the effect of vulcanization system and blend ratio on the thermal and oxidative resistance of HNR/NR vulcanizates. The various HNR/NR ratios vulcanized by peroxide and sulfur donor system exhibited the highest retention of tensile strength after thermal aging due to the formation of zinc‐dimethyldithiocarbamate (ZDMDC) which is an efficient antioxidant. The results from thermogravimetric analysis (TGA) indicated that the saturated structure of HNR had higher decomposition temperature and activation energy to enhance the thermal stability of HNR/NR vulcanizates. The initial and maximum decomposition temperatures of NR and HNR phases in vulcanizates were not affected by rubber blend ratio. This suggests that the decomposition pattern of HNR has no influence on another constituent. The increase in HNR content in the blends could retard the ozonolysis resulting in the surface cracking attacked by ozone. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

溴化丁基橡胶/丁腈橡胶并用胶微观结构及性能研究

用改性沥青作相容剂,研究溴化丁基橡胶(BIIR)/丁腈橡胶(NBR)并用胶的微观结构和性能。结果表明:与未添加改性沥青CJ-100的BIIR/NBR并用胶相比,添加改性沥青CJ-100的BIIR/NBR并用胶的相容性较好,加工性能改善,气密性、耐屈挠和耐臭氧性能提高;添加5份改性沥青CJ-100的BIIR/NBR(并用比为80/20)并用胶物理性能、气密性、耐屈挠和耐臭氧性能较好,气密性接近全BIIR胶料,有望用于全钢载重子午线轮胎气密层。     

Development of novel elastomeric blends containing natural rubber and ultra-low-density polyethylene

This study sought to develop novel elastomeric compounds using natural rubber (NR) and ultra-low-density polyethylene (ULDPE). Blends were prepared by means of a two-roll mill for three ratios (70/30, 60/40, and 50/50 NR/ULDPE). Conventional vulcanization was performed in a compression mold. The physical and mechanical properties of the blend were determined according to ASTM standards. The results were compared with those obtained from NR blended with styrene-butadiene rubber (SBR). The morphological examinations with scanning electron microscopy indicated that ULDPE was compatible with NR; thus, the addition of a compatibilizer was not necessary. The cocontinuous phase was dominant in the NR/ULDPE blend containing 50 and 60 wt % NR. The tensile properties, tear resistance, and aging resistance of the NR/ULDPE blends were found to be superior to those of NR/SBR blends. On the other hand, the abrasion and flex cracking resistances of the NR/ULDPE blend were inferior to those exhibited by SBR blends but the Mooney viscosity and resilience of both blends fell in the same range. However, the addition of dicumyl peroxide appeared to have caused crosslinking of the ULDPE phase in the blend, which in turn increased the tensile properties and abrasion and aging resistance. The properties of the tertiary NR/SBR/ULDPE blend were investigated as well. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 650–660, 2001     

Studies on oil distribution in polymer blends

Oils and resins are widely used in rubber industries to improve or control the mechanical properties, viscoelastic behavior, processability, and tackiness of a rubber compound. Very few fundamental studies have been reported on the function and the mechanism of oils and resins in a rubber mixture. In this article oil or resin distribution to each phase in an immiscible binary elastomer blend was studied by measuring the change of thermodynamical parameters, such as glass transition temperature, melting point of crystallines, and heat at melt of each polymer component. Several independent approaches give consistent results. It was found that aromatic oil was favorably distributed to the polystyrene-butadiene (SBR) phase of an SBR/natural rubber (NR) blend. Similarly, unequal distribution of resin in a blend was observed for a natural resin (rosin) and a petroleum resin. © 1996 John Wiley & Sons, Inc.     

Natural rubber/ethylene propylene diene blends for high insulation iron crossarms

This research studied the composition and behavior of natural rubber (NR) and ethylene propylene diene monomer (EPDM) blends at various carbon black concentrations (0–30 phr) in terms of electrical resistivity, dielectric breakdown voltage testing, and physical properties. The blends having electrical properties suitable for application in high‐insulation iron crossarms were selected for investigation of compatibility and increased physical properties. The effect of the homogenizing agent concentration on improvement of compatibility of blends was studied by scanning electron microscopy, pulsed nuclear magnetic resonance spectroscopy, and rheology techniques. We also examined mechanical properties such as tensile strength, tear strength, elongation at break, and hardness. The NR/EPDM blends filled with a fixed concentration of silica were investigated for ozone resistance. A carbon black content as high as 10 phr is still suitable for the insulation coating material, which can withstand electrical voltage at 10 kVac. Addition of the homogenizing agent at 5 phr can improve the mechanical compatibility of blends, as evidenced by the positive deviation of shear viscosity of the rubber blend, that is, the calculated shear viscosity being higher than that of experimental data. Moreover, the pulsed NMR results indicated that the spin‐spin relaxation (T₂) of all three components of the rubber blend was compressed upon the addition of the homogenizing agent. The ratio of NR/EPDM in the blend to best resist the ozone gas is 80/20 with the addition of silica of 30 phr into the blend. Also, the NR/EPDM filled with silica had a decreased change in thermal and mechanical properties of blends after thermal aging. The synergistic effect of silica content and high NR content (80) in 20 phr EPDM could improve antioxidation by ozone in the absence of a normal antioxidant for natural rubber. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3401–3416, 2004     

Toughening of poly(L‐lactide) by melt blending with rubbers

Poly(L ‐lactide) (PLA) was melt‐blended with four rubber components—ethylene–propylene copolymer, ethylene–acrylic rubber, acrylonitrile–butadiene rubber (NBR), and isoprene rubber (IR)—in an effort to toughen PLA. All the blend samples exhibited distinct phase separation. Amorphous PLA constituted a topologically continuous matrix in which the rubber particles were dispersed. According to Izod impact testing, toughening was achieved only when PLA was blended with NBR, which showed the smallest particle size in its blend samples. In agreement with the morphological analysis, the value of the interfacial tension between the PLA phase and the NBR phase was the lowest, and this suggested that rubber with a high polarity was more suitable for toughening PLA. Under the tensile stress conditions for NBR and IR blend samples, these rubbers displayed no crosslinking and showed a high ability to induce plastic deformation before the break as well as high elongation properties; this suggested that the intrinsic mobility of the rubber was important for the dissipation of the breaking energy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

天然橡胶硫化胶耐臭氧老化性能的快速评价方法

考察了伸长率、臭氧体积分数、相对湿度等试验条件对天然橡胶（NR）硫化胶耐静态臭氧老化性能的影响,建立了NR硫化胶耐臭氧老化的快速评价方法,并用该方法优选出了适宜NR胶料的防护蜡及其适宜用量。结果表明,提高伸长率,增加臭氧体积浓度和相对湿度,试样表面开始出现臭氧龟裂且龟裂程度逐渐增大。炭黑填充的NR硫化胶耐臭氧老化性能适宜的快速评价条件为:温度为40 ℃、伸长率为50%、臭氧体积分数为1.00×10-4%、相对湿度为50%。提高防护蜡中异构烷烃含量和中间碳数烷烃含量以及防护蜡用量,有利于改善NR硫化胶耐臭氧老化性能。运用该快速评价方法筛选出NR硫化胶耐臭氧老化性能较好的为防护蜡A,其最佳用量为3份。     

Co-compatibilising effect of carbon nanotubes and liquid isoprene rubber on carbon black filled natural rubber/polybutadiene rubber blend

Abstract

Bis-(triethoxysilylpropyl)-tetrasulfane functionalised carbon nanotubes (t-CNTs) were used as compatibiliser along with liquid isoprene rubber (LIR) in the natural rubber (NR)/polybutadiene rubber (BR) blend. Their reinforcing and compatibilising effects were evaluated by mechanical, fatigue crack growth resistance properties and blend homogeneity. Scanning electron microscope and transmission electron microscope showed enhanced interfacial adhesion between the binary rubber phases and improved dispersion of the minor phase in the rubber blend respectively with the co-existence of LIR and carbon nanotubes. The tensile strength of the carbon black (CB) filled NR/BR blend reached its optimum when 3 phr CB was replaced with an equal amount of t-CNTs in the presence of 7 phr LIR, while the fatigue crack growth resistance property achieved its maximum in the presence of 3 phr LIR. This interesting co-compatibilisation behaviour of t-CNTs and LIR suggests that t-CNTs have a better effect than CB with the assistance of LIR, which is an effective plasticiser in the NR/BR blend.     

Dynamics of migration and phase selective localization of nanoclay in HNBR/ENR blends

The phase specific selective localization and dynamics of migration of nanoclay in hydrogenated acrylonitrile butadiene rubber (HNBR)/epoxidized natural rubber (ENR) blend systems is investigated. The phase specific dispersion of clay particles is monitored through measuring the online measured electrical conductance (OMEC) during mixing by means of a sensor system installed inside the chamber of an internal mixer. The results of different characterization techniques, such as atomic force microscopy, transmission electron microscopy, and small angle X‐ray scattering have been used to understand and interpret the OMEC behaviors of nanoclay‐filled rubber compounds individually (HNBR and ENR) and their blend systems. The observed online conductance is ionic in nature that arises due to the release of surfactant molecules from the clay galleries. It is observed that the OMEC behavior depends mainly on two factors: the localization of nanoclay in specific phase of the blend system and on the gradual development of blend morphology. The OMEC behavior and the supported data from the microscopic methods, clearly reveal the migration of organoclay from the ENR to HNBR phase during the mixing process, particularly localizing near the interface of the blend. Further, the localization of organoclay is also evaluated by applying the surface tension measurements based model, which also predicts the favorable localization of organoclay in HNBR phase of the blend. The work clearly suggests the OMEC method to be a powerful online tool to monitor and control the nanoclay dispersion and localization in rubber based nanocomposites during the melt mixing process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44074.     

动态硫化EPDM／PP热塑性弹性体相态结构及其力学行为

研究动态硫化ＥＰＤＭ／ＰＰ热塑性弹性体相态结构及其力学行为。结果表明：动态硫化ＥＰＤＭ／ＰＰ共混物相态是ＥＰＤＭ橡胶以颗粒状分布在ＰＰ连续相中,这种相态结构一般不随橡塑比的变化而改变,但ＥＰＤＭ橡胶颗粒的形态变化显著。动态硫化ＥＰＤＭ／ＰＰ共混物,在橡塑比小于２５／７５,共混物具有类似橡胶应力－应变特征。     

Silicone Rubber Compatibilized Syndiotactic Polystyrene and Thermotropic Liquid Crystalline Polymer (Vectra A950) Blend

Blends of syndiotactic polystyrene (s-PS), thermotropic liquid crystalline polymer (Vectra A-950), and silicone rubber with two different loading levels, have been prepared through melt processing in internal mixer at 285°C. Silicone rubber was used as a compatibilizer for this blend system. The effect of silicon rubber on crystalline, dynamic mechanical, rhelogical, thermal properties, and phase morphology of the (s-PS/TLCP) blend has been investigated in details. With the addition of compatibilizer the viscosity of the blend system increased to an order of magnitude. Dynamic mechanical analysis (DMTA) and differential scanning calorimetry (DSC) results showed that the glass transition temperature (T_g) of the blend, in presence of silicone rubber, shifted towards lower temperature region. From FTIR analysis it is evident that the ‘C=O’ stretching frequency has shifted towards lower side. SEM analysis suggested that, the TLCP domain size is reduced in ternary blend in comparison to binary blend system.     

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。     

Mechanical properties and blend compatibility of natural rubber –chlorosulfonated polyethylene blends

Natural rubber (NR) was blended with chlorosulfonated polyethylene (CSM) with various formulation and blend ratios (NR/CSM: 80/20 –20/80, wt/wt). Rubber blends were prepared by using a two‐roll mill and vulcanized in a compression mold to obtain the 2 mm‐thick sheets. Tensile properties, tear resistance, thermal aging resistance, ozone resistance, and oil resistance were determined according to ASTM. Compatible NR/CSM blends are derived from certain blends containing 20–30% CSM without adding any compatibilizing agent. Tensile and tear strength of NR‐rich blends for certain formulations show positive deviation from the rule of mixture. Thermal aging resistance depends on formulation and blend ratio, while ozone and oil resistance of the blends increase with CSM content. Homogenizing agents used were Stuktol®60NS and Epoxyprene®25. Stuktol®60NS tends to decrease the mechanical properties of the blends and shows no significant effect on blend morphology. Addition of 5–10 phr of epoxidized natural rubber (ENR, Epoxyprene® 25) increases tensile strength, thermal aging resistance, and ozone resistance of the blends. It is found that ENR acts as a compatibilizer of the NR/CSM blends by decreasing both CSM particle size diameter and α transition temperature of CSM. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 127–140, 2006     

CPE在钢丝增强橡胶软管中的应用

介绍了氯化聚乙烯(CPE)与氯丁橡胶、丁苯橡胶并用,制备钢丝增强橡胶软管外胶胶料。产品具有良好的耐候性、抗臭氧性、抗冲击性、耐化学药品性和耐油性等特点,达到GB3683-92要求。而且生产成本低、易于微机控制、减轻了劳动强度。     

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.     

Mechanical and aging properties of cross‐linked ethylene propylene diene rubber / styrene butadiene rubber blends

The mechanical properties and aging characteristics of blends of ethylene propylene diene monomer (EPDM) rubber and styrene butadiene rubber (SBR) were investigated with special reference to the effect of blend ratio and cross‐linking systems. Among the blends, the one with 80/20 EPDM/SBR has been found to exhibit the highest tensile, tear, and abrasion properties at ambient temperature. The observed changes in the mechanical properties of the blends have been correlated with the phase morphology, as attested by scanning electron micrographs (SEMs). The effects of three different cure systems, namely, sulfur (S), dicumyl peroxide (DCP), and a mixed system consisting of sulfur and peroxide (mixed) on the blend properties also were studied. The stress‐strain behavior, tensile strength, elongation at break, and tear strength of the blends were found to be better for the mixed system. The influence of fillers such as high‐abrasion furnace (HAF) black, general‐purpose furnace (GPF) black, silica, and clay on the mechanical properties of 90/10 EPDM/SBR blend was examined. The ozone and water aging studies also were conducted on the sulfur cured blends, to supplement the results from the mechanical properties investigation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2606–2621, 2004     

TPU/硅橡胶弹性体动态硫化过程相态结构控制研究

将硅橡胶加氢硫化,采用动态硫化方法制备了聚氨酯/硅橡胶热塑性弹性体,并与简单二元共混体系进行了比较.在简单共混体系中,硅橡胶用量为55%和60%时,体系分别形成两相连续和聚氨酯分散相结构,而在动态硫化后均实现了硫化硅橡胶均匀分散在聚氨酯基体中的相态结构.在动态硫化过程中,催化剂加入1 min内已经实现了相反转,但此时分散相分散不均匀;动态硫化5 min产物相比简单二元共混体系,拉伸强度提高了1 277%,断裂伸长率提高了546%.     

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.