Effect of the vulcanizing system on the mechanical properties of butyl rubber/ethylene propylene diene monomer–carbon black blends

The effect of the vulcanizing system on the mechanical properties of butyl rubber/ethylene propylene diene monomer–general purpose furnace black–(GPF) blends was studied with static and dynamic mechanical measurements for these blends. The classical theory of elasticity was applied to show the mechanical behavior of the rubber–polymer blend and to calculate the degree of crosslinking. From the dynamic mechanical measurements, the elastic modulus, internal friction, and thermal diffusivity were calculated. The observed variations were explained in view of the role played by both the vulcanizing system and the reinforcing carbon black. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1539–1544, 2003     

Ageing studies of ethylene propylene diene monomer rubber/styrene butadiene rubber blends: Effects of heat,ozone, gamma radiation,and water

The ageing behavior due to the effects of heat, ozone, γ‐ radiation, and water on ethylene propylene diene monomer rubber/styrene butadiene rubber (EPDM/SBR) blends was studied. The tensile strength, crack initiation, ozone ageing, gamma radiation, and water resistance of the blends were measured and used to determine the extent of ageing. Tensile strength of blends of different compositions increased after thermal ageing for 96 h at 100°C probably due to the continued cross‐linking. It has been observed that an increase in EPDM in the blends improves the ozone resistance of the blends. Crack initiation was noted only in blends with lesser amount of EPDM and the cracks in such blends were found deeper, wider and continuous. With 15 kGy irradiation dose, the tensile strength of the blends found to be decreased while it increased with 80 kGy dosage of γ‐radiation. The elongation at break showed a decreasing trend with increased dosage of γ‐radiation. It has also been observed that the EPDM rich blends showed negligible water uptake. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Morphologies of polyethylene–ethylene/propylene/diene monomer particles in polypropylene‐rich polyolefin blends: Flake structure

Morphologies of polyethylene–ethylene/propylene/diene monomer (PE/EPDM) particles in 93/7 polypropylene (PP)/PE blends were investigated. SEM micrographs of KMnO₄‐etched cut surfaces and fracture surfaces of the blends revealed the existence of the “flake” structure. In the particles, crystalline PE formations with flake shape, which remain after etching, are called flakes. In addition to the PE‐crystalline flakes, amorphous PE, located between PE crystalline lamellae and EPDM rubber, complement the flake structure. The flakes are usually linked with the PP matrix, as seen in the heptane‐treated cut surfaces. These links, although observed with compatibilized samples, originate from the crystalline nature of PE particles, if no compatibilizer is added. Separately, the morphology of Royalene (consisting of high‐density PE and EPDM rubber, used as a PP/PE compatibilizer) was investigated by low‐voltage scanning TEM. The interaction of the components in the PE/EPDM blends can explain the formation of the flakes and toughening of the PP/PE blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3087–3092, 2003     

Effect of talc on the properties of polypropylene/ethylene/propylene/diene terpolymer blends

In the present study, the effect of talc content on the mechanical, thermal, and microstructural properties of the isotactic polypropylene (i‐PP) and elastomeric ethylene/propylene/diene terpolymer (EPDM) blends were investigated. In the experimental study, five different talc concentrations, 3, 6, 9, 12, and 15 wt %, were added to i‐PP/EPDM (88/12) blends to produce ternary composites. The mechanical properties such as yield and tensile strengths, elongation at break, elasticity modulus, izod impact strength for notch tip radius of 1 mm, and hardness with and without heat treatments and thermal properties, such as melt flow index (MFI), of the ternary composites have been investigated. The annealing heat treatment was carried out at 100°C for holding time of 75 h. From the tensile test results, an increased trend for the yield and tensile strengths and elasticity modulus was seen for lower talc contents, while elongation at break showed a sharp decrease with the addition of talc. In the case of MFI, talc addition decreased the MFI of i‐PP/EPDM blends. It was concluded that, taking into consideration, mechanical properties and annealing heat treatment, heat treatment has much more effect on higher yield and tensile strengths, elongation at break, elasticity modulus, impact strength, and hardness. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3033–3039, 2006     

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     

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     

Studies on dynamic and static crosslinking of ethylene vinyl acetate and ethylene propylene diene tercopolymer blends

The effect of blend ratio on the crosslinking characteristics of ethylene vinyl acetate and ethylene propylene diene tercopolymer (EVA‐EPDM) blends was studied by differential scanning calorimetry and a torque rheometer (Rheocord‐90). The activation energy decreases with an increase in EVA content in the blend. The cure rate increases whereas the optimum cure time and energy consumption for curing decrease with an increase in the EVA/EPDM ratio. The dynamic curing obtained by the torque rheometer is very fast compared to the static curing obtained by differential scanning calorimetry. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2756–2763, 1999     

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     

Development of hydroxyapatite nanoparticles reinforced chlorinated acrylonitrile butadiene rubber/chlorinated ethylene propylene diene monomer rubber blends

Hydroxyapatite nanoparticles (HA) reinforced polymer blend based on chlorinated nitrile rubber (Cl-NBR) and chlorinated ethylene propylene diene monomer rubber (Cl-EPDM) were prepared. Resulting blend composites were analyzed with regard to their rheometric processing, crystallinity, glass transition temperature (T_g), mechanical properties, oil resistance, AC conductivity, and transport behavior. The decrease in optimum cure time with the addition of HA is more advantageous for the development of products from these blend nanocomposites. The XRD, FTIR, and SEM confirmed the attachment and uniform dispersion of HA nanoparticles in the Cl-NBR/Cl-EPDM blend. The good compatibility between polymer blend and nanoparticles was also deduced by the formation of spherically shaped HA particles in the blend matrix determined by TEM analysis. DSC analysis showed an increase in T_g of the blend with the filler loading. The addition of HA particles to the blend produced a remarkable increase in tensile and tear strength, hardness, AC conductivity, abrasion, and oil resistance. The diffusion of blend composites was decreased with an increase in penetrant size. The diffusion mechanism was found to follow an anomalous trend. Among the blend composites, the sample with 7 phr of HA not only showed good oil and solvent resistance but also a remarkable increase in AC conductivity and mechanical properties.     

氯化聚乙烯用量对三元乙丙橡胶/尼龙共混胶性能的影响

研究了增容剂氯化聚乙烯（CPE）的用量对三元乙丙橡胶/尼龙（EPDM/PA）硫化胶热空气老化前后和用非极性油处理后力学性能及耐磨性能、耐油性能的影响。结果表明,随着CPE用量的增大,EPDM/PA硫化胶热空气老化后拉伸强度和100%定伸应力呈上升趋势,扯断伸长率和永久变形均缓慢下降,邵尔A硬度保持不变。用非极性油处理后EPDM/PA硫化胶的拉伸强度和扯断伸长率随CPE用量的增大呈上升趋势,100%定伸应力基本不变。CPE的加入对硫化胶的拉伸强度、撕裂强度、扯断伸长率等性能有一定的提高,说明EPDM和PA两相的相容性改善,在用量为6份时硫化胶的力学性能较佳。随着CPE用量的增大,DIN磨耗呈下降趋势,耐磨性能提高;质量变化率和体积变化率略有降低,耐油性能有所提高。     

Effects of fillers,maleated ethylene propylene diene diene rubber,and maleated ethylene octene copolymer on phase morphology and oil resistance in natural rubber/nitrile rubber blends

The phase morphology and oil resistance of 20/80 NR/NBR blends filled with different types of fillers and copolymers were investigated. In the case of filler effect, N220, N330, and N660 carbon blacks with different particle sizes were used. Additionally, the blends filled with nonblack‐reinforcing fillers, that is, precipitated and silane‐treated silica, were investigated. To study the compatibilization effect, maleated ethylene propylene diene rubber (EPDM‐g‐MA) and maleated ethylene octene copolymer (EOR‐g‐MA) were added to the blends. The results revealed that the addition of filler, either carbon black or silica, to the blend caused a drastic decrease in NR dispersed phase size. Carbon blacks with different particle sizes did not produce any significant difference in NR dispersed phase size under the optical microscope. Silica‐filled blends showed lower resistance to oil than did the carbon black–filled blends. In addition, it was determined that neither EOR‐g‐MA nor EPDM‐g‐MA could act as a compatibilizer for the blend system studied. The oil resistance of the blends with EPDM‐g‐MA is strongly affected by the overall polarity of the blend. In the case of EOR‐g‐MA, the oil resistance of the blends is significantly governed by both overall polarity of the blend and phase morphology. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1156–1162, 2003     

用于变压器的丁腈橡胶/三元乙丙橡胶并用胶

为了实现丁腈橡胶(NBR)与三元乙丙橡胶(EPDM)并用作为变压器密封材料,研究了并用比、增容剂及硫化体系种类对NBR/EPDM并用胶的影响。结果表明,NBR/EPDM(质量比)为70/30时并用胶具有良好的耐臭氧性能与最佳的综合物理机械性能;在并用胶中加入增容剂乙华平8784可以改善其物理机械性能;使用过氧化物硫化体系硫化并用胶的物理机械性能比使用硫黄/促进剂硫化体系者更好。     

Study on isotactic polypropylene/zinc‐neutralized sulfonated ethylene propylene diene monomer rubber/CaCO3 ternary blends

The morphological structure and mechanical properties of isotactic polypropylene (PP)/zinc‐neutralized sulfonated ethylene propylene diene monomer rubber (Zn? SEPDM)/CaCO₃ blends were studied. PP/Zn? SEPDM/CaCO₃ blends were prepared through two different sequences. A: Blending PP with Zn? SEPDM, then adding CaCO₃; B: Blending Zn? SEPDM with CaCO₃, then adding PP. The blending sequence has substantial influence on the mechanical properties. SEM micrographs and X‐ray photoelectron spectrometry indicate that the CaCO₃ filler is encapsulated by Zn? SEPDM in those blends prepared through sequence B, which caused an extra increase of impact strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1635–1640, 2004     

Effect of ethylene ionomers on the properties of crosslinked polyethylene

Most premature failure of underground crosslinked polyethylene (XLPE) cables in service, a matter of great concern, is due to aging induced by water treeing. To improve the water‐tree resistance, sodium‐neutralized poly (ethylene‐co‐acrylic acid) (EAA–Na) ionomers were blended with XLPE; the EAA–Na ionomers were prepared through the neutralization of sodium hydroxide and poly(ethylene‐co‐acrylic acid). A series of XLPE/EAA–Na ionomer blends were investigated through the measurement of the water absorption ratio, water treeing, and mechanical and dielectric testing; the results strongly suggested that EAA–Na ionomers could improve the water‐tree resistance of XLPE, and the XLPE/EAA–Na blends retained excellent mechanical properties and dielectric properties. Moreover, through the characterization of XLPE/EAA–Na blends with Fourier transform infrared spectrometry, dynamic mechanical analysis, and scanning electron microscopy, it was found that the neutralization reaction could be achieved completely; the XLPE and EAA–Na ionomers were partially compatible, so the EAA–Na ionomers could be dispersed well in the matrix with the process examined in this study. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3483–3490, 2007     

Study on the ablative properties of ethylene propylene diene terpolymer/silsesquioxane insulation materials

Octaphenylsilsesquioxane (OPS), polyphenylsilsesquioxane (PPSQ), and octavinylsilsesquioxane (OVP) have been incorporated into ethylene propylene diene terpolymer (EPDM) in order to study their effects on the ablative properties of the respective EPDM composites. The results show that PPSQ and OVP serve as effective ablative additives for EPDM composites. The linear ablation rates of EPDM composites with 4.4 wt % OVP or PPSQ were reduced by 21 or 16.5%, respectively, compared with the control sample. Moreover, OVP and PPSQ also improved the flame retardancy and suppressed smoke emission. The heat release rate of EPDM composite with 4.4 wt % OVP was measured as 90.6 kW m⁻², 17% lower than that of the control sample, and the same amount of PPSQ reduced the total smoke release from 1946 to 1497 m² s⁻¹. Thermogravimetric analysis results showed EPDM/OVP composite to leave a higher residual mass than the calculated value. Besides, scanning electron microscopy, cone calorimetry (CONE), and BET tests showed that the chars formed during the ablation of EPDM composites containing OVP and PPSQ had better structural stability and thermal stability owing to the fact that they were denser and more homogeneous. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48365.     

Thermomechanical devulcanization of ethylene propylene diene monomer rubber and its application in blends with high-density polyethylene

The recycling of ethylene propylene diene monomer (EPDM) rubber remains a challenge, as its cross-linked structure cannot be broken down reversibly. Devulcanization may offer a breakthrough; however, a 100% decrease in cross-link density (CLD) with no chain degradation has never been reported. In this research, sulfur- and peroxide-cured EPDM rubbers of known compositions were devulcanized on a two-roll mill and in an internal mixer. The CLD of both rubber samples decreased by around 85%, while the sol content of the peroxidic devulcanizate was considerably higher than that of the sulfuric devulcanizate (23% vs. 3%). Horikx's theory revealed that sulfur-cured samples showed excellent selectivity for cross-link scission, while peroxide-cured samples suffered degradation. Uncured, cured, and devulcanized rubber samples were mixed into high-density polyethylene at various compositions. Large EPDM rubber contents impaired the mechanical properties of the blends, indicating insufficient adhesion between the two phases. Compounds containing originally uncured rubber mixtures had the most beneficial mechanical properties.     

超细全硫化粉末丁苯橡胶/三元乙丙橡胶共混物的结构与性能

制备了超细全硫化粉末丁苯橡胶(UFPSBR)/三元乙丙橡胶(EPDM)共混物,研究了其硫化特性、相态结构、动态力学性能及物理机械性能。透射电镜观察表明,无论UFPSBR与EPDM共混比如何,UFPSBR粒子始终保持为分散相。当UFPSBR用量为10份(质量)时,它在EPDM中的分散相尺寸为200 nm左右;用量较高时其分散相尺寸较大,存在大量的聚集体。动态力学分析结果显示共混物存在2个玻璃化转变温度,说明共混物存在两相结构。加工性能分析结果表明,UFPSBR粒子在EPDM基质中形成了网络结构,对EPDM基质起到了较好的增强作用,当UFPSBR与EPDM的质量共混比为50/50时,共混物的拉伸强度可达13.4 MPa。UFPSBR对EPDM的硫化特性有明显影响。     

Effect of swelling process on the thermoelastic temperature change of ethylene propylene diene rubber filled with carbon black

The effects of both dynamic cyclic extension and swelling on the thermoelastic behavior of ethylene propylene diene rubber loaded with different concentrations of carbon black have been studied. As the strain amplitude increases, the concentration of the ruptured bonds increases, leading to more enhanced friction between particles and consequently to the observed rise in temperature. Temperature change was found to be highly dependent on the swelling and also on carbon black concentration. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1890–1897, 1999     

Studies on electrically conductive composites of ethylene propylene diene monomer rubber and steel fibers

Electrically conductive composites comprised of ethylene propylene diene monomer (EPDM) rubber and steel fibers were prepared by an open mill mixing method. Fibers of two distinctly different lengths (5 mm and several meters) were used and the influence of these fibers on electrical conductivity, mechanical, thermal, and physical properties of the composites was investigated. Composites with different compositions were prepared by varying the loading levels of fibers from 20–100 phr (parts per hundred parts of rubber). Homogeneity of the composites was determined using scanning electron microscopy. Further analysis included the measurement of resistance, hardness, tensile strength, tear strength, rebound resilience, etc. The results of the analysis revealed that the addition of steel fibers rendered conductivity to the otherwise insulating EPDM rubber even at small loading levels, however, the length appears to have negligible effect on conductivity. In case of short fibers, the resistance of composites was observed to decrease from > 40 MΩ (Initial value of EPDM rubber) to 25 KΩ at a loading level of 20 phr with a further significant decrease of the order of 10³, that is around 18 Ω at 100 phr. Composites with long fibers exhibited resistance in the range of 15 kΩ–70 Ω at loading levels between 30 and 100 phr. The conductivity of the sample is observed to be altered negligibly on ageing. Mechanical properties such as hardness, tensile, and tear strength were observed to be enhanced in case of composites except resilience which decreased by 29 % in comparison to EPDM rubber. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

环氧化天然橡胶共交联改性EPDM/NR共混物的性能

将三元乙丙橡胶(EPDM)与环氧化天然橡胶(ENR)共交联改性后,再与天然橡胶(NR)共混,考察了ENR共交联改性EPDM/NR共混胶的硫化特性、硫化胶的物理机械性能、溶胀指数和耐热空气老化性能,并对该硫化胶进行了差示扫描量热分析。结果表明,EPDM经过ENR共交联改性后与NR共混,ENR共交联改性EPDM/NR共混胶的交联程度明显提高,各相达到了同步交联,硫化胶的综合性能得到了显著改善。