Effect of dicumyl peroxide and phenolic resin as a mixed curing system on the mechanical properties and morphology of TPVs based on HDPE/ground tire rubber

Thermoplastic vulcanizates (TPVs) are a special group of thermoplastic elastomer with the characteristic that consists of rubber elasticity and the processability of thermoplastic polymers. TPVs based on high density polyethylene (HDPE)/ground tire rubber (GTR) with phenolic resin (HY‐2045) and dicumyl peroxide (DCP) as vulcanizing agents are prepared through dynamic vulcanization in this article. The blends consisting of 40/60 HDPE/GTR are melt‐mixed in an internal mixer and then pressed with a compression molding machine. The aim of this experiment is to study the influence of a compound curing agent system on the mechanical properties of the HDPE/GTR composites. The results indicate that the mechanical properties of the HDPE/GTR blends are improved significantly by adding 4 phr HY‐2045 and 0.3 phr DCP than those of TPVs without any vulcanizing agents after dynamic vulcanization. The X‐ray photoelectron spectroscopy study and the FTIR‐ATR analysis confirmed that the crosslinking phenomenon occurred in the preparation of TPVs; and the gel fraction analysis indicates that the GTR components and the HDPE components of the HDPE/GTR blends are all moderately crosslinked. In addition, the morphology of the HDPE/GTR blends has been investigated by scanning electron microscopy. POLYM. COMPOS., 36:1907–1916, 2015. © 2014 Society of Plastics Engineers     

Mechanical properties of high‐density polyethylene/scrap rubber powder composites modified with ethylene–propylene–diene terpolymer,dicumyl peroxide,and silicone oil

The effect of ethylene–propylene–diene terpolymer (EPDM), dicumyl peroxide (DCP), and dimethyl silicone oil on the mechanical properties of high‐density polyethylene (HDPE) composites filled with 60 mesh cryogenically scrap rubber powder (SRP) was studied. The addition of 10 wt % EPDM, 0.2 wt % DCP, and 4 wt % dimethyl silicone oil significantly increased both the impact strength and elongation at break of the HDPE/SRP composites. After the modification, the impact strength increased by 160%, and the elongation at break increased by 150% for the composites containing 40 wt % SRP. The impact load–time curves showed that the increase of impact energy for the modified composites was attributed to the increase of the maximum force at yield point and the ductile deformation after yielding. The rheological behavior, dynamic mechanical properties, and morphology observation suggested that an enhanced adhesion between SRP and polymer matrix formed in the modified HDPE/SRP composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2020–2027, 2003     

Preparation and characterization of PPRC/EPDM thermoplastic vulcanizates: A comparative study

Thermoplastic vulcanizates (TPVs) of polypropylene random copolymer (PPRC) with ethylene–propylene diene monomer rubber (EPDM) were prepared through in situ and ex situ compatibilization techniques. Silanized silica as nanofiller was incorporated in the ex situ compatibilized TPVs. Mechanical properties were measured for different formulated TPVs with increasing loading of EPDM from 10 to 30 phr. A comparative data is generated to discuss the effect of two compatibilization techniques and addition of silica filler in the TPVs. The degradation studies were also carried out to check the stability of the blends under harsh ultraviolet environment. The in situ compatibilized TPVs provided better overall mechanical properties. Moreover, it is worth mentioning that the properties of ex situ compatiblized TPVs were enhanced by incorporation of silanized silica filler. Silanized silica filler helped in reducing the die swell significantly. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46726.     

Reinforcement of peroxide‐cured styrene–butadiene rubber vulcanizates by mathacrylic acid and magnesium oxide

Through the neutralization of magnesium oxide (MgO) and methacrylic acid (MAA), magnesium methacrylate [Mg(MAA)₂] was in situ prepared in styrene–butadiene rubber (SBR) and used to reinforce the SBR vulcanizates cured by dicumyl peroxide (DCP). The experimental results show that the mechanical properties, dynamic mechanical properties, optical properties, and crosslink structure of the Mg(MAA)₂‐reinforced SBR vulcanizates depend on the DCP content, Mg(MAA)₂ content, and the mole ratio of MgO/MAA. The formulation containing DCP 0.6–0.9 phr, Mg(MAA)₂ 30–40 phr, and MgO/MAA mole ratio 0.50–0.75 is recommended for good mechanical properties of the SBR vulcanizates. The tensile strength of the SBR vulcanizates is up to 31.4 MPa when the DCP content is 0.6 phr and the Mg(MAA)₂ content is 30 phr. The SBR vulcanizate have good aging resistance and limited retention of tensile strength at 100°C. The SBR vulcanizates are semitransparent, and have a good combination of high hardness, high tensile strength, and elongation at break. The T_g values of the SBR vulcanizates depend largely on the DCP content, but depend less on the Mg(MAA)₂ content and the MgO/MAA mole ratio. The contents of DCP, Mg(MAA)₂, and the MgO/MAA mole ratio have also great effects on the E′ values of the vulcanizates. The salt crosslink density is greatly affected by the Mg(MAA)₂ content and MgO/MAA mole ratio, but less affected by the DCP content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2667–2676, 2002     

Thermal and mechanical properties of silicon rubber/cis‐polybutadiene rubber/ethylene–propylene–diene monomer blends

Considering the properties of silicon rubber, ethylene–propylene–diene monomer (EPDM), and cis‐polybutadiene rubber (BR), a blend made by a new method was proposed in this article; this blend had thermal resistance and good mechanical properties. The morphology of the blend was studied by SEM, and it was found that the adhesion between the phases of BR, EPDM, and polysiloxanes (silicon rubber) could be enhanced, and the compatibility and covulcanization were good. The influence of the mass ratio of peroxide and silica on the mechanical properties and thermal resistance of the blend was studied. The results showed that the mechanical properties and thermal resistance of the blend were improved when silicon rubber/BR/EPDM was 20/30/50, dicumyl peroxide/sulfur was 2.5/2.5, and the amount of silica was 80 phr. The integral properties of rubber blend had more advantages than did the three rubbers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4462–4467, 2006     

Effects of shear stress and subcritical water on devulcanization of styrene–butadiene rubber based ground tire rubber in a twin‐screw extruder

The devulcanization reaction of styrene–butadiene rubber (SBR) based ground tire rubber (GTR) in GTR/ethylene–propylene–diene monomer rubber (EPDM) blend was investigated through a compound‐induced reaction by increasing screw rotation speed and being in the presence of subcritical water. The effects of temperature, pressure, screw rotation speed, or promoting agents on the gel content, Mooney viscosity, and Fourier transform infrared spectra of the sol of the devulcanized blends (devulcanized ground tire rubber (DGTR)/EPDM) were measured, and the mechanical properties and microstructures of the revulcanized blend ((DGTR/EPDM)/SBR) were characterized. The results show that subcritical water as a swelling agent and reaction medium promotes the devulcanization reaction, increases the selectivity of the crosslink breakage, keeps the extrusion material from oxidative degradation, reduces the gel particle size of the devulcanized blends, and significantly improves the mechanical properties of the revulcanized SBR/(DGTR/EPDM) blends. In subcritical water, the suitable promoting agents (alkylphenol polysulfide 450, hydrogen peroxide H₂O₂, or 450/H₂O₂) accelerate the devulcanization reaction, keep the double bond content, and lead to further decrease of the gel content and Mooney viscosity of the devulcanized blends and further increase of the mechanical properties of the revulcanized SBR/(DGTR/EPDM) blends. Especially the compound promoting agent (450/H₂O₂) improves the selectivity of the crosslink breakage in devulcanization of SBR‐based GTR. When 450/H₂O₂ is added as a compound promoting agent at the best reaction condition in subcritical water (200°C, 1.6 MPa and 1000 rpm), the tensile strength and elongation at break of the revulcanized SBR/(DGTR/EPDM) blends reach to 85.4% and 201% of vulcanized SBR (24.0 MPa, 356%), respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1845–1854, 2013     

Thermoplastic elastomers based on recycled high‐density polyethylene,ethylene–propylene–diene monomer rubber,and ground tire rubber

High‐performance thermoplastic elastomers (TPEs), based on recycled high‐density polyethylene (HDPE^R), olefinic type ethylene–propylene–diene monomer rubber (EPDM), and ground tire rubber (GTR) treated with bitumen, were prepared by using dynamic vulcanization technology, and their structure–property relationships were investigated. It was established that special pretreatment of GTR by bitumen confers outstanding mechanical properties on the resulting TPEs. TPEs, containing GTR pretreated by bitumen, exhibit thermal behavior similar to that of the HDPE^R/EPDM basic blend in the temperature region up to about 340°C. Rheological measurements showed that bitumen acts as an effective plasticizer for the GTR‐containing TPEs. SEM, DSC, and DMTA results revealed improved adhesion between the particles of GTR treated by bitumen and the surrounding thermoplastic matrix, compared to that of the untreated GTR particles. It was concluded that bitumen acts as an effective devulcanizing agent in the GTR treatment stage. In the following steps of TPE production, bitumen acts simultaneously as a curing agent for the rubber components (EPDM/GTR) and as a compatibilizer for the blend components. GTR‐containing TPEs, prepared by extrusion technology, were reprocessed (by passing through the extruder six times) without any observable changes in their tensile properties, thermal stability, and melt viscosity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 659–671, 2005     

Curing characteristics,mechanical properties and morphology of butyl rubber filled with ground tire rubber (GTR)

The results on testing application of ground tire rubber (GTR), as potential filler for butyl rubber, are presented. The GTR content variation, within the range of 10–90 phr, was studied with respect to the vulcanization process, static mechanical properties (tensile strength, elongation-at-break, hardness and resilience), dynamic mechanical properties and the morphology of the obtained vulcanizates. Butyl rubber was characterized by its low compatibility to other elastomers [i.e., natural rubber and styrene–butadiene rubber (SBR)—the main ingredients of tires] and low degree of unsaturation. To evaluate the impact of these factors on curing characteristics and mechanical properties of butyl rubber vulcanizates filled with GTR, the same compositions of SBR compounds, cured under identical conditions, were used as reference samples. Based on the obtained data, it can be stated that butyl rubber vulcanizates containing 30 phr of GTR as filler revealed the highest tensile strength and elongation-at-break. The microstructural analysis of a sample containing 30 phr of GTR revealed strong interactions between the butyl rubber matrix and GTR. This phenomenon resulted mainly from two factors. First, the cross-link density of the butyl rubber matrix was affected by its competition against GTR for cross-linking agents. Secondly, the migration of carbon black particles from GTR into the butyl rubber matrix had a significant impact on properties of the obtained vulcanizates.     

Investigation of crystallization behavior in dynamically vulcanized EPDM–nylon copolymer blends

A thermoplastic vulcanizate (TPV) of a ethylene–propylene–diene terpolymer (EPDM) and nylon copolymer (PA) was prepared by dynamic vulcanization. Maleic anhydride (MAH)–grafted EPDM (EPDM–g–MAH), MAH‐grafted EPR (EPR–g–MAH), and chlorinated polyethylene (CPE) were used as compatibilizers. The effect of dynamic vulcanization and compatibilizer on the crystallization behavior of PA was investigated. Differential scanning calorimeter measurement results showed no pronounced shift in the crystallization temperature for PA in EPDM–PA TPV compared to that for PA in the neat state, whereas the crystallization temperature increased after adding compatibilizer. The decrease in the crystallinity of TPVs was a result of the crystallization occurring in confined spaces between rubber particles. The equilibrium melting temperature (Tm⁰) of the PA copolymer was measured and was determined to be 157°C. The isothermal crystallization kinetics of PA in the neat and TPV states also was investigated. The crystallization rate was highest in the compatibilized TPV and lowest in the neat PA, whereas it was intermediate in the uncompatibilized TPV unvulcanized blends. Compared with unvulcanized EPDM–PA blends, the dynamic vulcanization process seemed to cause an obvious increase in the crystallization rate of the PA copolymer, especially when a suitable compatibilizer was used. This occurred because the dynamic vulcanization introduced fine crosslinked rubber particles that could act as heterogeneous nucleating centers. In addition, the use of a suitable compatibilizer permitted the formation of finely dispersed vulcanized rubber particles and therefore increased the density of the nucleating centers. The complex morphology of the blends was investigated by atomic force microscopy to evaluate the effect of compatibilizer on the size of the dispersed rubber particles. Compared with the morphology of TPVs with the same dosage of EPDM–g–MAH compatibilizer, the morphology of TPVs using EPR–g–MAH as compatibilizer showed much smaller dispersed rubber particles, which may have contributed to the higher crystallization rate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 824–829, 2003     

Tensile properties and morphology of the dynamically cured EPDM and PP/HDPE ternary blends

The tensile properties and morphology of the polyolefin ternary blends of ethylenepropylene–diene terpolymer (EPDM), polypropylene and high density polyethylene were studied. Blends were prepared in a laboratory internal mixer where EPDM was cured in the presence of PP and HDPE under shear with dicumyl peroxide (DCP). For comparison, blends were also prepared from EPDM which was dynamically cured alone and blended with PP and HDPE later (cure–blend). The effect of DCP concentration, intensity of the shear mixing, and rubber/plastics composition was studied. The tensile strength and modulus increased with increasing DCP concentration in the blends of EPDM-rich compositions but decreased with increasing DCP concentration in blends of PP-rich compositions. In the morphological analysis by scanning electron microscopy (SEM), the small amount of EPDM acted as a compatibilizer to HDPE and PP. It was also revealed that the dynamic curing process could reduce the domain size of the crosslinked EPDM phase. When the EPDM forms the matrix, the phase separation effect becomes dominant between the EPDM matrix and PP or HDPE domain due to the crosslinking in the matrix.     

Effects of epoxidized natural rubber (ENR‐50) and processing parameters on the properties of NR/EPDM blends using response surface methodology

The effects of epoxidized natural rubber (ENR‐50) and processing parameters on the properties of natural rubber/ethylene–propylene–diene rubber (NR/EPDM; 70 : 30 phr) blends were studied. The compounds were prepared by melt compounding method. Using response surface methodology of two‐level full factorial, the effects of ENR‐50 contents (?1 : 5 phr; +1 : 10 phr), mixing temperature (?1 : 50°C; +1 : 110°C), rotor speed (?1 : 40 rpm; +1 : 80 rpm), and mixing time (?1 : 5 min; +1 : 9 min) in NR/EPDM blends were evaluated. Cure characteristics and tensile properties were selected as the responses. The significance of factors and its interaction was analyzed using ANOVA and the model's ability to represent the system was confirmed using the constant of determination, R² with values above 0.90. It was found that the presence of ENR‐50 has the predominant role on the properties of NR/EPDM blends. The addition of ENR‐50 significantly improved cure characteristics and tensile strength up to 5.12% and 6.48% compared to neat NR/EPDM blends, respectively. These findings were further supported by swell measurement, differential scanning calorimetry, and scanning electron microscopy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40713.     

Facile fabrication of shape memory composites from natural Eucommia rubber and high density polyethylene

Shape memory materials are a type of smart material with potential applications in sensors, textiles, aerospace engineering and medical devices. In this study, we prepared Eucommia rubber and high density polyethylene (HDPE) composites with co‐continuous architecture by a simple physical blending method. The shape memory composites memorized two temporary shapes using different melting points of natural Eucommia rubber and HDPE with the addition of dicumyl peroxide (DCP). The architecture of Eucommia rubber/HDPE composites is critical to the materials' properties: each component forms a three‐dimensional percolating network and good properties of the two components may be synergically combined. Our results showed that the memory behavior of the composites was dependent on the degree of crystallinity in the composites. When the DCP was 1 phr, the physical and mechanical properties of the Eucommia rubber/HDPE composites improved and exhibited excellent shape memory behavior, with better values of the shape fixity ratio than of the shape recovery ratio. When DCP was 6 phr, the crystalline phase of Eucommia rubber in the composites was almost completely destroyed, which resulted in one temporary shape memory behavior of the composites. © 2016 Society of Chemical Industry     

Adhesion between ethylene-propylene-diene monomer and thermoplastics in two-component injection molding: Effect of dicumylperoxide as curing agent

Strong adhesion at the interface is an important aspect in two-component (2K) injection molding. It was therefore investigated whether dicumylperoxide (DCP) as curing agent in ethylene-propylene-diene monomer (EPDM) could stimulate interdiffusion and/or induce chemical bonding with thermoplastics. EPDM mixtures containing DCP concentrations between 2 to 8 parts per hundred rubber (phr) were combined with polar and non-polar thermoplastics. Changes in EPDM physico-mechanical bulk properties were analyzed, and the adhesion was evaluated by high temperature contact angle measurements and tensile testing. Results showed that DCP concentration did not influence EPDM-thermoplastic compatibility. However, EPDM adhesion with polyethylene (PE) did improve when using up to 6 phr DCP (57% adhesion) as crosslinking is promoted. While with polypropylene (PP), adhesion linearly decreased (from 55% to 35% adhesion) with higher DCP concentrations due to prevailing scission reactions. Adhesion through chemical bonding with acrylonitrile-butadiene-styrene (ABS) caused better adhesion at 4 phr (43% adhesion) compared to polycarbonate (PC) at 4 phr (13% adhesion) where only limited interdiffusion occurs. Thus, selecting the optimal DCP concentration is highly important to boost adhesion between EPDM and thermoplastics. Furthermore, at these optimal DCP concentrations, physico-mechanical properties require consideration as these properties were significantly affected.     

EPDM／HDPE热塑性硫化胶的结构与性能研究

采用动态硫化法制备了三元乙丙橡胶（EPDM）／高密度聚乙烯（HDPE）热塑性硫化胶（TPV）,并对其力学性能和微观相结构进行了研究。结果表明。EPDM/HDPE TPV的力学性能随HDPE含量的增加而提高,其应力-应变曲线呈现出典型的弹性体特征;当EPDM／HDPE共混比为60／40时,所制备的TPV表现出了良好的综合性能;EPDM分散相的粒径在1～20μm之间且较均匀地分散于基体中;HDPE连续相在拉伸断裂过程中于断面处形成了成簇的纳米级微纤维;TPV两相结合良好。     

管材用回收高密度聚乙烯/胶粉复合材料的研究

采用一步法活化增容制备了回收高密度聚乙(烯RHDPE/)胶粉管材专用料,并研究了引发剂过氧化二异丙苯强度从37.5 kJ/m2提高到48 kJ/m2;弯曲强度从10.5 MPa提高到12.9 MPa;弯曲模量从356 MPa提高到405(DCP)、接枝单体马来酸酐(MAH用)量对体系力学性能的影响。结果表明:当DCP、MAH用量分别为0.1份、1.0份时,RHDPE/胶粉体系获得最佳的力学性能,与简单共混物比较,拉伸强度从18.8 MPa提高到23.8 MPa;缺口冲击MPa。通过流变性能测试结果和扫描电(镜SEM)照片分析活,化增容对RHDPE/胶粉体系有效。     

Effect of borax on the thermal and mechanical properties of ethylene‐propylene‐diene terpolymer rubber‐based heat insulator

The effect of Borax on the mechanical and ablation properties of three different ethylene‐propylene‐diene terpolymer (EPDM) compounds containing 20 phr carbon fiber, 20 phr Kevlar or 10 phr/ 10 phr carbon fiber/ Kevlar was investigated. All formulations contained 30 phr fumed silica powder and 10 phr paraffinic oil. It was found that adding Borax to the composite samples containing carbon fiber or Kevlar fiber or their mixture with an equal ratio can increase the tensile strength, elastic modulus and hardness with a slightly decrease in the elongation at break of the rubber samples. The results of thermogravimetry analysis (TGA) on the various samples showed significant increase in the char yield at 670°C by adding Borax to the rubber compounds. Moreover, ablation resistance of samples was also improved by increasing Borax content. Meanwhile, density and thermal conductivity of the insulator were also reduced up to about 10% when the carbon fiber was replaced with the Borax. The results indicated that composites containing Kevlar have high storage modulus and produce compact and stable char. EPDM rubber composite containing Borax (20 phr), carbon fiber (10 phr), and Kevlar (10 phr) showed thermal and ablative properties comparable with those of the asbestos‐ filled EPDM. The thermal conductivity and ablation rate of the above‐ mentioned sample were 0.287 W/m/K and 0.13 mm/s respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41936.     

Structure and mechanical properties of nanodispersed fibrous silicate‐reinforced ethylene–propylene–diene monomer nanocomposites

In this study, ethylene–propylene–diene monomer (EPDM)/fibrillar silicate (FS) nanocomposites were successfully prepared by mechanically blending EPDM with FS, which was modified by silane coupling agent KH570 containing methacryloxy group. The effects of silane content and modified FS on the dispersion of FS and mechanical properties of the composites were investigated. The impact of water in FS on mechanical properties of the composites was also evaluated. The results showed that modified FS could be dissociated into nanofibers dispersing evenly in the EPDM matrix by increasing substantially the loading of silane through the mechanical blending. The optimum loading level of silane coupling agent was up to 24 phr/100 phr FS. Silane KH570 could improve the dispersion of FS and strengthen nanofibers–rubber interfacial adhesion even at the loading of as high as 50 phr FS, making FS to exhibit excellent reinforcement to EPDM. Too much FS could not be completely dissociated into nanofibers, slowing down further improvement. The EPDM/FS composites exhibited the similar stress–strain behavior and obvious mechanical anisotropy with short microfiber‐reinforced rubber composites. With the increase in silane coupling agent and modified FS, the number of nanofibers increased because of the exfoliation of FS microparticles; thus, the mechanical behaviors would become more obvious. It was suggested that the free water in FS should be removed before mechanically blending EPDM with FS because it obviously affected the tensile properties of the composites. Regardless of whether FS was dried or modified, the EPDM/FS composites changed little in tensile strength after soaked in hot water. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of adhesive‐coated glass fiber in natural rubber (NR), acrylonitrile rubber (NBR), and ethylene–propylene–diene rubber (EPDM) formulations. I. Effect of adhesive‐coated glass fiber on the curing and tensile properties of NR,NBR, and EPDM formulations

Adhesive‐coated glass fibers (3 and 6 mm in length) were added at loadings of 10, 20, and 30 phr in natural rubber (NR), nitrile rubber (NBR), and ethylene–propylene–diene comonomer (EPDM) formulations in both plain and carbon black mixes. The compounds were mixed in a two‐roll mill and were characterized for their cure properties, tensile, tear, and Mullin's effect. In NR mixes, all of the formulations showed reversion in cure behavior, suggesting that NR remained unaffected. In NBR and EPDM mixes, almost all of the mechanical properties of the fiber improved. The result was more significant in EPDM than in NBR. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1111–1123, 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     

The Effects of Dynamic Vulcanization by Dicumyl Peroxide (DCP) and N,N-m-Phenylene Bismaleimide (HVA-2) on the Properties of Polypropylene (PP)/Ethylene-Propylene Diene Terpolymer (EPDM)/Natural Rubber (NR) Blends

ABSTRACT

This paper discusses some properties of the polypropylene (PP)/ethylene-propylene diene terpolymer (EPDM)/natural rubber (NR) blends, such as tensile properties, heat resistance, gel content, and morphology. Dicumyl peroxide (DCP) and N,N-m-phenylene bismaleimide (HVA-2) and their combination were applied in PP/EPDM/NR blends as cross-link agents. In terms of tensile properties, the combination of DCP with HVA-2 shows the highest tensile strength and elongation at break in all PP/EPDM/NR blend ratios compared to similar blends, except with DCP or HVA-2 alone. The addition of HVA-2 produced blends with good heat resistance, while the combination of DCP with HVA-2 shows the highest gel content dealing with the cross-links formation. SEM micrographs from the surfaces extraction of the blends support that the cross-links have occurred during dynamic vulcanization process.