Mechanical properties,oil resistance,and thermal aging properties in chlorinated polyethylene/natural rubber blends

The use of natural rubber (NR) for partly substituting elastomeric chlorinated polyethylene (CPE) was determined. Mechanical and thermal aging properties as well as oil resistance of the blends were also investigated. The amount of NR in blends significantly affected the properties of the blends. The blends with NR content up to 50 wt % possessed similar tensile strength to that of pure CPE even after oil immersion or thermal aging. Modulus and hardness of the blends appeared to decrease progressively with increasing NR content. These properties also decreased in blends after thermal aging. After oil immersion, hardness decreased significantly for the blends with high NR content, whereas no change in modulus was observed. The dynamic mechanical properties were determined by dynamic mechanical thermal analysis. NR and CPE showed damping peaks at about ?40 and 4 °c, respectively; these values correlate with the glass‐transition temperatures (T_g) of NR and CPE, respectively. The shift in the T_g values was observed after blending, suggesting an interfacial interaction between the two phases probably caused by the co‐vulcanization in CPE/NR blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 22–28, 2002; DOI 10.1002/app.10171     

Cure characteristics,morphology, mechanical properties,and aging characteristics of silicone rubber/ethylene vinyl acetate blends

Silicone rubber/ethylene vinyl acetate (SR/EVA) rubber mixes with different ratios were prepared by using dicumyl peroxide (DCP) and benzoyl peroxide (BP) as curing agents. The vulcanization characteristics such as cure kinetics, activation energy, and cure rate of the blends were analyzed. The effects of blend ratio and curing agents on the mechanical properties such as stress–strain behavior, tensile strength, elongation at break, tear strength, relative volume loss, hardness, flex crack resistance, and density of the cured blends have been investigated. Almost all the mechanical properties have been found to be increased with increase in EVA content in the blends particularly in DCP‐cured systems. The increment in mechanical properties of the blends with higher EVA content has been explained in terms of the morphology of the blends, attested by scanning electron micrographs. Attempts have been made to compare the experimental results, from the evaluation of mechanical properties, with relevant theoretical models. The aging characteristics of the cured blends were also investigated and found that both the DCP‐ and BP‐cured blends have excellent water and thermal resistance. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1069–1082, 2006     

Effect of filler on the mechanical,dynamic mechanical,and aging properties of binary and ternary blends of acrylic rubber,fluorocarbon rubber,and polyacrylate

We studied the effects of fillers on the mechanical, dynamic mechanical, and aging properties of rubber–plastic binary and ternary blends derived from acrylic rubber, fluorocarbon rubber, and multifunctional acrylates. The addition of fillers, such as carbon black and silica, changed the nature of the stress–deformation behavior with a higher stress level for a given strain. The tensile and tear strengths increased with the addition of the fillers and with loading, but the elongation at break decreased, and the tension set remained unaffected. The aging properties of carbon‐black‐filled blends were better because of the thermal antioxidant nature of carbon black. The swelling resistance of the binary and the ternary blends in methyl ethyl ketone increased with the incorporation of fillers. From dynamic mechanical thermal analysis, we concluded that the filler altered the height and half‐width of the damping peak at the glass‐transition temperatures. There was little change in the loss tangent values at higher temperatures. A higher loading of the filler increased the storage modulus at all of the temperatures measured. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 278–286, 2003     

On the Mechanical Properties of EPDM/CIIR Blends Cured with Reactive Phenolic Resin

Blends of ethylene propylene diene monomer rubber (EPDM) and chlorinated isobutylene isoprene rubber (chlorobutyl, CIIR) with a reactive phenolic resin as the curing agent have been prepared through conventional two-roll mill mixing. The effect of resin curing on the mechanical properties of EPDM/CIIR blends was investigated and compared with conventional curing systems. The morphology of the blends as well as their thermal and steam aging resistance has also been reported. It was found that blends with a phenolic curing system exhibited superior mechanical and thermal aging properties and have potential applications in high-temperature engineered products.     

Phthalonitrile‐epoxy blends: Cure behavior and copolymer properties

Binary blends composed of 4,4′‐bis(3,4‐dicyanophenoxy)biphenyl (biphenyl PN) and diglycidyl ether of bisphenol A (epoxy resin) and oligomeric n = 4 phthalonitrile (n = 4 PN) and epoxy resin were prepared. The cure behavior of the blends was studied under dynamic and isothermal curing conditions using differential scanning calorimetry, simultaneous thermogravimetric/differential thermal analysis, infrared spectroscopy, and rheological analysis. The studies revealed that phthalonitrile‐epoxy blends exhibited good processability and that they copolymerized with or without the addition of curing additive. In the absence of curing additive, the blends required higher temperatures and longer cure times. The thermal and dynamic viscoelastic properties of amine‐cured phthalonitrile‐epoxy copolymers were examined and compared with those of the neat epoxy resin. The properties of the epoxy resin improved with increasing biphenyl PN content and with n = 4 PN addition. Specifically, the copolymers exhibited higher glass transition temperatures, increased thermal and thermo‐oxidative stabililty, and enhanced dynamic mechanical properties relative to the commercially available epoxy resin. The results showed that the phthalonitrile‐epoxy blends and copolymers have an attractive combination of processability and high temperature properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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     

Acrylic rubber‐fluorocarbon rubber miscible blends: Effect of curatives and fillers on cure,mechanical, aging,and swelling properties

The cure characteristics and mechanical properties of gum and filled acrylic rubber (ACM), fluorocarbon rubber (FKM), and their blends of varying compositions were studied both under unaged and aged conditions. The rheometric study showed that optimum cure properties were obtained using a mixed curing system of blocked diamine, hexamethylenediamine carbamate (Diak #1), and ammonium benzoate. From varying the curing agents, the optimum levels of Diak #1 and ammonium benzoate were found to be 1.5 and 2.5 phr, respectively. The addition of different fillers and their loading influenced the cure properties, with increased torque and reduced scorch safety. The gum and filled 50:50 (w/w) ACM‐FKM showed overall performance in strength properties. Postcuring improved the strength of all the systems, especially the systems with a higher proportion of FKM. None of the properties changed significantly during aging of the blends. FKM and the blends containing a higher proportion of FKM were affected least by aging. Swelling of the blends was reduced by the addition of fillers. Dynamic mechanical thermal analysis showed a single tan δ peak corresponding to a single phase transition for both cured and filled blends. The storage modulus of the blend increased from the gum blend to the filled blend, indicating the presence of polymer‐filler interaction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1442–1452, 2003     

Waste ground rubber tire powder/thermoplastic vulcanizate blends: Preparation,characterization, and compatibility

In this article, waste ground rubber tire (WGRT) powder was introduced into thermoplastic vulcanizate (TPV) to prepare the blends of WGRT powder/TPV. The mechanical, rheological, thermal aging, and dynamic properties of the blends were investigated with respect to the particle size and dosage of WGRT powder. The results showed that tensile strength, tear strength, elongation at break, and tensile permanent deformation of the blends increased with the decrease in WGRT particle size and decreased with the dosage of WGRT. The effects of different types and dosages of compatibilizers on mechanical and rheological properties of the blends were studied. The results showed that the compatibilizer PP‐g‐MAH could effectively improve the interfacial compatibility between WGRT and the TPV matrix to enhance the comprehensive properties of blends. The TPV/WGRT/PP‐g‐MAH blends obtained the best overall properties when prepared at the weight ratio 100/30/5. Rheological studies demonstrated that the WGRT/TPV blends represented lower apparent viscosity after PP‐g‐MAH were added, which means that processing performance of the blends was improved by PP‐g‐MAH. Scanning electron microscopy was used to study the morphologies of the blends. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39868.     

Dynamically vulcanized polypropylene/styrene–butadiene rubber blends: The effect of a peroxide/bismaleimide curing system and composition

Polypropylene (PP)/styrene–butadiene rubber blends were studied with special attention given to the effects of the blend ratio and dynamic vulcanization. Dicumyl peroxide (DCP) was used as the curing agent in combination with N,N′‐m‐phenylene bismaleimide (BMI) as the coagent for the curing process. Outstanding mechanical performance, especially with regard to the elongation at break, and better resistance to compression set were achieved with the dynamic vulcanization; this indicated that the DCP/BMI system also acted as a compatibilizing agent. This phenomenon was also confirmed by Fourier transform infrared spectroscopy of the insoluble material, the crystallinity degree of the PP phase (as investigated by X‐ray diffractometry), and scanning electron microscopy. The dynamic mechanical properties of the nonvulcanized and vulcanized blends were also investigated. The aging resistance of the blends was also evaluated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal,morphological, and physicomechanical properties of (chlorinated polyethylene rubber)/(chloroprene rubber) blends

The effect of the blend ratio on the thermal, morphological, and physicomechanical properties of (chlorinated polyethylene rubber)/(chloroprene rubber) (CPE/CR) blends was studied. Two distinct glass transition temperatures (T_g) of all blends were observed in differential scanning calorimetry curves, falling between the T_g of the two pure rubbers. Analysis of the blends by scanning electron microscopy showed both dispersed and continuous phase morphology that depended on the blend composition. Thermogravimetric analysis showed that all the compounds underwent two stages of thermal degradation. The Mooney viscosity and optimum cure times increased with the increase in CPE contents, whereas the scorch times decreased. The tensile strength and elongation at break decreased, whereas the 100% modulus, hardness, and compression set increased with the increase of CPE content; the tear strength had the lowest value for the 50/50 CPE/CR blend because of the poor miscibility. The results from thermal aging and oil resistance tests showed that pure CPE possessed better thermal aging property and oil resistance than those of pure CR. Thus, considerable improvement in oil resistance of the blend compounds was achieved with the increase of CPE content. J. VINYL ADDIT. TECHNOL., 21:18–23, 2015. © 2014 Society of Plastics Engineers     

不同硫化体系对氟橡胶/氯醚橡胶共混物性能的影响

在固定氟橡胶(FKM)硫化体系(双酚AF)的条件下,研究了改变氯醚橡胶(CO)硫化体系对FKM/CO共混物硫化特性以及硫化胶的物理机械性能、耐老化性能、耐油性能及热稳定性的影响。结果表明,采用促进剂NA-22/MgO体系时,FKM/CO共混物具有较好的硫化特性,硫化胶的综合物理机械性能较好,但耐老化性能仍需改善;采用促进剂TCY/MgO/CaCO3体系时需要较长的硫化时间,且焦烧性能较差;并用促进剂TMTD或促进剂DTDM后混炼胶的交联效果变差;FKM/CO共混物具有较好的热稳定性且热失重起始温度高于300℃。     

Influences of the phenolic curative content and blend proportions on the properties of dynamically vulcanized natural rubber/acrylonitrile–butadiene–styrene blends

The vulcanization of natural rubber (NR)‐blended acrylonitrile–butadiene–styrene (ABS) was carried out with a phenolic curing agent by a melt‐mixing process. The NR compound was first prepared before blending with ABS. The effects of the phenolic curative contents (10, 15, and 20 phr) and blend proportions (NR/ABS ratio = 50 : 50, 60 : 40, and 70 : 30) on the mechanical, dynamic, thermal, and morphological properties of the vulcanized NR/ABS blends were investigated. The tensile strength and hardness of the blends increased with increasing ABS content, whereas the elongation at break decreased. The strength property resulting from the thermoplastic component and the vulcanized NR was an essential component for improving the elasticity of the blends. These blends showed a greater elastic response than the neat ABS. The thermal stability of the blends increased with increasing ABS component. Scanning electron micrographs of the blends showed a two‐phase morphology system. The vulcanized 60 : 40 NR/ABS blend with 15‐phr phenolic resin showed a uniform styrene‐co‐acrylonitrile phase dispersed in the vulcanized NR phase; it provided better dispersion between the NR and ABS phases, and this resulted in superior elastic properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42520.     

Thermal aging properties and chemical resistance of blends of natural rubber and epoxidized low molecular weight natural rubber

Studies into solvent resistance and aging properties of blends of natural rubber and epoxidized low molecular weight natural rubber were carried out. Vulcanization of the blends using the semi‐efficient vulcanization (semi‐EV) system was found to have curing advantages over conventional vulcanization (CV) and efficient vulcanization (EV) systems. The rheological properties (cure time, t₉₀, and scorch time, t₂), solvent resistances, and aging properties of the vulcanizates were found to improve as the level of epoxidized low molecular weight natural rubber in the blends increases. The mechanical properties of the blends were also found to be within the accepted level for NR vulcanizates. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1733–1739, 2005     

NBR/HNBR共混胶性能的研究

研究了NBR/HNBR共混比对其共混胶硫化特性、力学性能、耐热空气老化性能及耐臭氧性能的影响。结果表明,随着HNBR用量的增大,共混胶硫化时间先缩短后延长,力学性能先降低后升高,耐热空气老化性能提高,耐臭氧老化性能也提高。     

Preparation and properties of high performance phthalide‐containing bismaleimide reinforced polydicyclopentadiene

A series of phenolphthalein‐containing bismaleimide (PPBMI) reinforced polydicyclopentadiene blends (PPBMI/polyDCPD) were prepared via the ring‐opening metathesis polymerization of DCPD in the presence of PPBMI. The crosslinked networks between PPBMI and polyDCPD backbones resulted in the reinforced structures. The curing behavior, thermal, and mechanical properties were investigated. Differential scanning calorimetry investigations showed the samples exhibit similar singular exothermic peak, and the exothermic peak of the PPBMI/polyDCPD blends slightly shifted to a lower temperature direction compared with the unfilled polyDCPD, meanwhile, the exothermic peak of the PPBMI/polyDCPD blends slightly shifts back to a higher temperature direction with the PPBMI content increased. Both dynamic mechanical analysis and thermo gravimetric analysis measurements revealed the optimal thermal performance of PPBMI/polyDCPD was obtained with 20 wt % loading of PPBMI. In addition, while PPBMI content increased, the weight loss peak at 100–200°C disappeared and the temperature of maximum rate of decomposition (T_d,max) increased. Moreover, bending tests showed the best mechanical performance was achieved at 5 wt % loading of PPBMI in blends. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40474.     

Electron‐beam processing of nylon 6 and HNBR blends. Part II: development of high strength,heat‐ and oil‐resistant thermoplastic elastomers

The effects of electron‐beam irradiation on morphology, mechanical properties and on the heat and hot oil resistance of the thermoplastic elastomeric blend of 30:70 and 70:30, nylon 6 and hydrogenated nitrile rubber (HNBR) were investigated over the dose range 0–8 Mrad. The insoluble content of blends increased with increase in the radiation dose. The morphology of the blend was studied in scanning electron microscopy, with special reference to the effect of radiation prior to processing via injection molding. Irradiated pellets showed better mechanical properties after injection molding compared with irradiated sheets at low radiation dose. The observed differences in mechanical properties are explained on the basis of morphology of the blend. The blend properties were also found to have a strong dependence on nylon content. It was found that the blends rich in nylon had superior mechanical properties, hot oil and solvent resistance, whereas blends with higher HNBR content had better set and heat resistance. The effect of radiation on interaction in these blends was also evaluated and was found to induce possible inter‐chain crosslinking in the blends. Copyright © 2006 Society of Chemical Industry     

Rheological properties,oil, and thermal resistance in sulfur‐cured CPE/NR blends

The use of natural rubber (NR) for partly substituting elastomeric chlorinated polyethylene (CPE) was carried out. Sulfur curing was used to vulcanize NR phase in the blends. Mechanical, rheological, and thermal aging properties as well as oil resistance of the blends were investigated. The amount of NR in blends significantly affects properties of the blends. With NR content in blends up to 20 wt %, tensile properties are similar to those of the pure CPE, even after either oil immersion or thermal aging. Rheological properties of CPE/NR blends determined from the rubber process analyzer (RPA 2000) and parallel‐plate rheometer are controlled strongly by the blend composition. The viscoelastic behavior of pure CPE and the blends with CPE as a major component is governed by the viscous response, which could be seen from the high damping factor, particularly at high strain, the short linear viscoelastic range, and the high degree of pseudoplasticity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1129–1135, 2004     

EPDM–chlorobutyl rubber blends in γ‐radiation and hydrocarbon environment: Mechanical,transport, and ageing behavior

In nuclear applications, ethylene propylene diene monomer (EPDM) rubber is the material of choice as gaskets and O‐rings due to its radiations resistance. In nuclear fuel reprocessing, in addition to radiation, the elastomeric components have to withstand paraffinic hydrocarbons as well. But, EPDM has poor resistance to hydrocarbons. To enhance the durability of EPDM in such environments, EPDM–chlorobutyl rubber (CIIR) blends of varying compositions were developed and characterized for mechanical, thermal, dielectric, and solvent sorption behavior. Spectroscopic and morphological analysis was used to evaluate the compatibility of blends. Due to synergistic effect, the optimal composition of blends with superior mechanical properties and solvent resistance were found to be 60% to 80% EPDM and 20% to 40% CIIR. The optimized blends were irradiated with gamma rays at cumulative doses up to 2 MGy. Based on spectroscopic, morphological, mechanical, thermogravimetric, and sorption properties, blend containing 80% EPDM was found to have superior retention of properties after irradiation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45195.     

Mechanical and thermal properties of novel rubber‐toughened epoxy blend prepared by in situ pre‐crosslinking

A novel method is used for preparing liquid rubber‐toughened epoxy blend, in which an initiator was added to the liquid rubber–epoxy mixture to initiate crosslinking reaction of liquid rubber, and then curing agent was added to form the thermoset. Two epoxy blends with carboxyl‐terminated butadiene‐acrylonitrile copolymers were prepared using traditional and novel methods respectively. Results indicated that the novel rubber‐toughened epoxy blend exhibited much better mechanical properties than its traditional counterpart. The morphologies of the blends were explored by transmission electron microscopy (TEM), it was revealed that the use of the novel method formed a local interpenetrating network structure in the blend, which substantially improved the interfacial adhesion. The impact fracture surfaces of the two blends were observed by scanning electron microscopy (SEM) to explore the toughening mechanism, it was found that crack pinning was the major toughening mechanism for the novel rubber‐toughened epoxy blend. Dynamic mechanical analysis (DMA) was applied to determine the T_g values of the blends, which were found to be close. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41110.     

白炭黑/炭黑混合填料对氟橡胶/硅橡胶共混胶性能的影响

采用沉淀白炭黑和高耐磨炭黑作为氟橡胶/硅橡胶共混胶的填料.研究以不同质量比混合的沉淀白炭黑和高耐磨炭黑对氟橡胶/硅橡胶共混胶的硫化特性、门尼粘度、力学性能、耐热老化性能和耐油性能的影响,并通过RPA分析表征填料-填料的相互作用,采用SEM表征白炭黑/炭黑混合填料在氟橡胶/硅橡胶共混胶中的分散性.结果表明,随着混合填料中白炭黑所占比例的增大,氟橡胶/硅橡胶共混胶的硫化转矩升高,焦烧时间(t10)缩短,正硫化时间(t90)延长,门尼粘度增大.氟橡胶/硅橡胶共混胶的力学性能,耐热老化性能和耐油性能都随着混合填料中白炭黑用量增多而提高.RPA分析表明,全部采用白炭黑补强的共混胶Payne效应最明显,炭黑补强的共混胶Payne效应最弱.SEM分析表明,白炭黑在共混胶中分布比炭黑更加均匀,填料聚集体粒径较小.