Phase morphology and thermomechanical analysis of poly(styrene‐co‐acrylonitrile)/ethylene–propylene–diene monomer blends: Uncompatibilized and reactively compatibilized blends with two mixing sequences

The phase morphology developing in immiscible poly(styrene‐co‐acrylonitrile) (SAN)/ethylene–propylene–diene monomer (EPDM) blends was studied with an in situ reactively generated SAN‐g‐EPDM compatibilizer through the introduction of a suitably chosen polymer additive (maleic anhydride) and 2,5‐dimethyl‐2,5‐di‐(t‐butyl peroxy) hexane (Luperox) and dicumyl peroxide as initiators during melt blending. Special attention was paid to the experimental conditions required for changing the droplet morphology for the dispersed phase. Two different mixing sequences (simple and two‐step) were used. The product of two‐step blending was a major phase surrounded by rubber particles; these rubber particles contained the occluded matrix phase. Depending on the mixing sequence, this particular phase morphology could be forced or could occur spontaneously. The composition was stabilized by the formation of the SAN‐g‐EPDM copolymer between the elastomer and addition polymer, which was characterized with Fourier transform infrared. As for the two initiators, the blends with Luperox showed better mechanical properties. Scanning electron microscopy studies revealed good compatibility for the SAN/EPDM blends produced by two‐step blending with this initiator. Dynamic mechanical thermal analysis studies showed that the two‐step‐prepared blend with Luperox had the best compatibility. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Dynamic vulcanization of polyethylene‐based thermoplastic elastomer blends

In this investigation, the effects of blending with ethylene–propylene–diene terpolymer and subsequent dynamic curing with sulfur on the macromolecular structure and properties of pure low‐density polyethylene and high‐density polyethylene were studied. The crosslinking efficiency of polyethylene‐based ethylene–propylene–diene terpolymer blends upon dynamic curing was assessed with torque and gel content measurements. The curing of dispersed ethylene–propylene–diene terpolymer in a polyethylene matrix improved both the mechanical and thermomechanical properties as a result of the formation of a crosslink structure in the rubber phase. In view of the electrical applications of this cured blend material, the volume resistivity was measured. The thermal stability of vulcanized polyethylene/ethylene–propylene–diene terpolymer blends was found to be superior to that of unvulcanized blends. In scanning electron microscopy analysis, good interface bonding between the polyethylene matrix and dispersed ethylene–propylene–diene terpolymer was observed for the cured blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Design and properties of a series of high‐temperature thermoplastic elastomeric blends from polyamides and functionalized rubbers

A series of high‐temperature thermoplastic elastomers (TPEs) and thermoplastic vulcanisates (TPVs) were successfully developed based on two different types of heat resistant polyamide (PA) (25 parts by weight)—PA‐12 and PA‐6, in combination with three different functionalized rubbers (75 parts by weight) of varying polarity, e.g., maleic anhydride grafted ethylene propylene diene terpolymer (MA‐g‐EPDM), sulphonated ethylene propylene diene terpolymer, and carboxylated acrylonitrile butadiene rubber, by melt mixing method. These rubbers have low level of unsaturation in its backbone, and the plastics showed high melting range. Thus, the developed TPEs and TPVs were expected to be high temperature resistant. Resol type resin was used for dynamic vulcanization to further increase the high temperature properties of these blends. Interestingly, initial degradation temperature of the prepared blends was much higher (421 °C for MA‐g‐EPDM/PA‐12) than the other reported conventional TPEs and TPVs. Fourier transform infrared analysis described the interactive nature of the TPEs and TPVs, which is responsible for their superior properties. The maximum tensile strength with lowest tension set was observed for the carboxylated acrylonitrile butadiene rubber/PA‐12 TPV. Mild increase in mechanical properties without any degradation was observed after recycling. Dynamic mechanical analysis results showed two distinct glass transition temperatures and indicated the biphasic morphology of the blends, as evident from the scanning electron microscopy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45353.     

Rheology and properties of EPDM/BR blends with or without a homogenizing agent or a coupling agent

Rheology, dynamic mechanical properties, mechanical properties, and morphology of ethylene–propylene–diene rubber/butadiene rubber (EPDM/BR) blends with or without a homogenizing agent or a coupling agent were investigated. AAHR (a mixture of aliphatic and aromatic hydrocarbon resins) was used as a coupling agent. The dynamic mechanical analysis and the morphological studies revealed that EPDM and BR were incompatible and the addition of AAHR was very effective to plasticize the EPDM/BR blend and enhance the compatibility between EPDM and BR. It was found that the addition of an AAHR increased the amounts of bound rubbers and, hence, the vulcanizate properties such as tear strength and fatigue resistance of the EPDM/BR blends were improved. The blends of maleic anhydride-grafted EPDM and BR were also prepared and the properties were compared. The dynamic mechanical analysis and the morphological studies revealed that the addition of TESPT increased the weight of bound rubbers and provided better dispersion of carbon black, resulting in good mechanical properties such as tear strength and fatigue resistance of the vulcanized EPDM/BR blends. © 1996 John Wiley & Sons, Inc.     

Effect of butyl rubber type on properties of polyamide and butyl rubber blends

Polyamide‐12 was blended with butyl rubber, bromobutyl rubber, and chlorobutyl rubber with and without a sulfur curing system. Mechanical properties for dynamically vulcanized blends generally exceed those made with no vulcanization. Chlorobutyl‐containing blends prepared by dynamic vulcanization have higher tensile strength and elongation at break values in comparison to those made from other butyl rubbers. For a variety of polyamide/rubber blends made by dynamic vulcanization, there is very little effect of rubber percentage unsaturation and Mooney viscosity on the mechanical properties of the blends. In chlorobutyl‐containing blends prepared by dynamic vulcanization, the swelling index values attributed to the rubber portion decrease as rubber content decreases, and it is likely that the polyamide phase completely surrounds the rubber particles at compositions exceeding approximately 25% polyamide. Swelling index results can be correlated with elongation at break values for similar blends. The results of differential scanning calorimetry suggest that the polyamide phase is not a neutral component in high shear mixing with butyl rubbers with or without curing agents. Rheological studies indicate strong non‐Newtonian behavior for all blends of polyamide‐12 with butyl rubbers. Scanning electron microscopy on polyamide‐12/butyl rubber blends indicates compatibility for butyl rubbers in the order of chlorobutyl > bromobutyl > butyl rubber. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1423–1435, 2004     

Compatibility studies on some polymer blend systems by electrical and mechanical techniques

Systematic electrical and mechanical studies were carried out on natural rubber (NR) blended with different types of synthetic rubber such as styrene‐butadiene rubber (SBR), polybutadiene rubber (BR), and ethylene‐propylene‐diene monomer (EPDM) as nonpolar rubbers and nitrile‐butadiene rubber (NBR) and chloroprene rubber (CR) as polar rubbers. The NR/SBR, NR/BR, NR/EPDM, NR/NBR, and NR/CR blends were prepared with different ratios (100/0, 75/25, 50/50, 25/75, and 0/100). The permittivity (ε′) and dielectric loss (ε″) of these blends were measured over a wide range of frequencies (100 Hz–100 kHz) and at room temperature (∼ 27°C). The compatibility results obtained from the dielectric measurements were comparable with those obtained from the calculation of the heat of mixing. These results were confirmed by scanning electron microscopy and showed that NR/SBR and NR/BR blends were compatible while NR/EPDM, NR/NBR, and NR/CR blends were incompatible. To overcome the problem of phase separation (incompatibility) between NR and EPDM, NBR, or CR, a third component such as SBR or poly(vinyl chloride) (PVC) was added as a compatibilizing agent to these blends. The experimental data of dielectric and mechanical measurements showed that the addition of either SBR or PVC could improve the compatibility of such blends to some extent. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 60–71, 2001     

Preparation and characterization of acrylonitrile–styrene–methylmethacrylate terpolymer as a compatibilizer for rubber blends

Acrylonitrile‐co‐styrene‐co‐methylmethacrylate (AN‐S‐MMA) terpolymer was prepared by bulk and emulsifier‐free emulsion polymerization techniques. The bulk and emulsion terpolymers were characterized by means of Fourierr transform infrared spectroscopy, ¹³C nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography, thermal gravimetric analysis, and elemental analysis. The kinetics of the terpolymerization were studied. The terpolymers were then incorporated into butadiene—acrylonitrile rubber (NBR)/ethylene propylene diene monomer rubber (EPDM) blends and into chloroprene rubber (CR)/EPDM blend. The terpolymers were then tested for potential as compatibilizers by using scanning electron microscopy and differential scanning calorimetry. The terpolymers improved the compatibility of CR/EPDM and NBR/EPDM blends. The physicomechanical properties of CR/EPDM and NBR/EPDM blend vulcanizates revealed that the incorporation of terpolymers was advantageous, since they resulted in blend vulcanizates with higher 100% moduli and with more thermally stable mechanical properties than the individual rubbers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3143–3153, 2003     

硅橡胶并用改性研究进展

介绍了国内外硅橡胶与三元乙丙橡胶、丙烯酸酯橡胶、氟橡胶、聚氨酯橡胶、二烯类橡胶、丁基橡胶等并用的研究情况和各种并用胶的优缺点。指出硅橡胶与其他橡胶并用的关键问题是相容性和共硫化特性。     

Characterization of elastomer blend and compatibility

Binary blends of acrylonitrile‐co‐butadiene rubber and ethylene propylene diene monomer rubber are immiscible. However, they can be made compatible by addition of a third elastomer viz., chlorinated polyethylene or chlorosulphonated polyethylene in small concentrations. Various sophisticated analytical techniques, e.g., ultrasonic velocity measurements in solutions, infrared spectroscopy of solution cast films, thermo‐mechanical analysis, processing characteristics through rubber process analyzer (RPA‐2000), determination of the vulcanizate properties, and also phase morphology studies by atomic force microscopy have been made to elucidate compatibility and its effect on end‐use properties of the evolved blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 480–489, 1999     

Optimization of accelerators on curing characteristics,tensile, and dynamic mechanical properties of (natural rubber)/(recycled ethylene‐propylene‐diene‐monomer) blends

The migration of sulfur from natural rubber (NR) compound to the ground waste ethylene‐propylene‐diene monomer (EPDM) rubber phase may have caused the cure incompatibility between these two rubbers. Optimization of accelerators had been adopted to overcome the cure incompatibility in NR/(R‐EPDM) blends as well as to get increased curative distribution. In this study, blends of NR and R‐EPDM were prepared. The effect of accelerator type on curing characteristics, tensile properties, and dynamic mechanical properties of 70/30/NR/(R‐EPDM) blend was investigated. Four types of commercial accelerators were selected [ie, N‐tert‐butyl‐2‐benzothiazyl‐sulphonamide , N‐cyclohexyl‐benzothiazyl‐sulfenamide (CBS), tetramethylthiuram disulfide, and 2‐mercaptobenzothiazol]. It was found that the tensile strength of the blends cured in the presence of CBS was relatively higher than the other three accelerators. Scanning electron micrographs of CBS‐cured NR/(R‐EPDM) blends exhibited more roughness and cracking path, indicating that higher energy was required toward the fractured surface. The high crosslinking density observed from the swelling method could be verified from the storage modulus (E′) and damping factor (tan δ) where (tetramethylthiuram disulfide)‐cured NR/(R‐EPDM) blends provided a predominant degree of crosslinking followed by N‐tert‐butyl‐2‐benzothiazyl‐sulphonamide , CBS, and 2‐mercaptobenzothiazol, respectively. J. VINYL ADDIT. TECHNOL., 21:79–88, 2015. © 2014 Society of Plastics Engineers     

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     

Comparison of the performance of vulcanized rubbers and elastomer/TPE/iron composites for less lethal ammunition applications

One of the exciting novel potential applications of thermoplastic elastomers (TPEs) is less‐lethal ammunition (LLA). The importance of LLA in crowd control and law enforcement has been acknowledged, and became evident for air marshals after the September 11, 2001 crisis. This article will compare the dynamic mechanical behavior of various elastomer/TPE/iron composites and commercially available LLA based on conventional cured rubbers (ethylene‐propylene‐diene rubber [EPDM], styrene‐butadiene rubber [SBR], and natural rubber [NR]). Optimum combination of properties for LLA application was shown by the poly(styrene‐b‐isobutylene‐b‐styrene) (SIBS)/butyl elastomer (IIR)/iron 50/50/233 composite. POLYM. ENG. SCI., 45:966–975, 2005. © 2005 Society of Plastics Engineers     

Microstructure and miscibility of acrylonitrile–butadiene rubber/ethylene–propylene–diene monomer blends studied by positron annihilation spectroscopy

The free‐volume properties and miscibility of ethylene–propylene–diene monomer/acrylonitrile–butadiene rubber blends with poly(vinyl chloride) used for compatibilization were investigated with positron annihilation lifetime spectroscopy and Doppler broadening of annihilation radiation. The results showed that the ortho‐positronium annihilation lifetimes and intensities as well as the S parameter had a linear relationship with a negative slope as a function of the weight percentage of acrylonitrile–butadiene rubber, which indicated the miscibility of the blend. The filling effect of silica on the free‐volume properties of an ethylene–propylene–diene monomer/acrylonitrile–butadiene rubber (75/25) blend was also examined. On the other hand, a correlation between the size and concentration of the free‐volume holes and the electrical and mechanical properties of the aforementioned blends was established. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

The effect of montmorillonite and compatibilizer quantities on stiffness and toughness of polyamide nanoblends

Although polymer blend nanocomposites are widely studied, the balance between stiffness and toughness has not yet been investigated in detail. Some materials producers as well as some sectors in the automotive industry try to improve the toughness of materials without an important loss in stiffness. With this in mind, the aim of the study reported here was to obtain a good balance between toughness and stiffness of polymer blends with different amounts of clay and compatibilizer. In this context, the microstructure of polyamide 6/ethylene–propylene–diene metallocene terpolymer/(ethylene–propylene–diene copolymer)‐graft‐(maleic anhydride) blends with various amounts of clay (2, 3, 4 and 5 wt%) and compatibilizer (10 and 20 wt%) was studied to analyse the achieved morphology to understand the macroscopic properties. The morphology of the rubber phase and the dispersion of the montmorillonite (MMT) are the main factors that influence the mechanical properties. In this sense, the highest Young's modulus is achieved for nanoblends with 5 wt% of MMT, although this nanoblend has the lowest value of notched Izod impact strength. The results obtained suggest that there is a clear trade‐off between stiffness, toughness and temperature behaviour when the ratio of (ethylene–propylene–diene copolymer)‐graft‐(maleic anhydride) to MMT is 5:1. Copyright © 2009 Society of Chemical Industry     

Thermal stability and aging characteristics of (natural rubber)/(waste ethylene‐propylene‐diene monomer terpolymer) blends

Comparative studies of the thermogravimetric analysis and thermo‐oxidative aging of (natural rubber)/(waste ethylene‐propylene‐diene monomer terpolymer) (NR/W‐EPDM) and (natural rubber)/(ethylene‐propylene‐diene monomer terpolymer) (NR/EPDM) blends were carried out. The blends were prepared at five different blend ratios (90/10, 80/20, 70/30, 60/40, and 50/50) on a two‐roll mill. As the pure EPDM or W‐EPDM content in the blends increased, their thermal stability also increased. The thermo‐oxidative aging of these blends was done at 100°C for 48 h. Afterwards, the NR/EPDM blends exhibited better retention of properties than the NR/W‐EPDM blends. Crosslink density measurements of the blends after thermal aging indicated that higher crosslink density was obtained from a higher content of EPDM or W‐EPDM, a result which might be due to the high rate of radical termination leading to crosslinks in the bulk of the polymer. J. VINYL ADDIT. TECHNOL., 20:99–107, 2014. © 2014 Society of Plastics Engineers     

Improved mechanical properties of NR/EPDM blends by controlling the migration of curative and filler via reactive processing technique

Simple blending of natural rubber/ethylene–propylene–diene rubber (NR/EPDM) generally results in inferior mechanical properties because of curative migration and their differences for filler affinity. In this work, the 70/30 and 50/50 NR/EPDM blends prepared by reactive processing techniques were investigated and compared with the simple, nonreactive blends. The reactive blend compounds were prepared by preheating EPDM, containing all curatives to a predetermined time related to their scorch time prior to blending with NR. For the 70/30 gum blends, four types of accelerators were studied: 2,2‐mercaptobenzothiazole (MBT), 2,2‐dithiobis‐ (benzothiazole) (MBTS), N‐cyclohexyl‐2‐benzothiazolesulfenamide (CBS), and N‐tert‐butyl‐2‐benzothiazolesulfenamide (TBBS). When compared with the simple blends, the reactive blends cured with CBS and MBTS showed a clearly improved tensile strength whereas the increase of tensile strength in the blends cured with TBBS and MBT was marginal. However, a dramatic improvement of ultimate tensile properties in the reactive 50/50 NR/EPDM blends cured with TBBS was observed when compared with the simple blend. For the N‐550‐filled blends at the blend ratios of 70/30 and 50/50, the reactive‐filled blends prepared under the optimized preheating times demonstrated superior tensile strength and elongation at break over the simple blends. The improved crosslink and/or filler distribution between the two rubber phases in the reactive blends accounts for such improvement in their mechanical properties. This is shown in the scanning electron micrographs of the tensile fractured surfaces of the reactive blends, which indicate a more homogeneous blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

高岭土填充橡胶共混物的性能及表征

以一种高岭土为增强相,分别填充天然橡胶、丁苯橡胶、顺丁橡胶、丁腈橡胶、三元乙丙橡胶、氯丁橡胶和硅橡胶,制备高岭土/橡胶复合材料,通过力学和热老化性能测试、红外光谱和偏光显微镜测试分析,确定了高岭土在各种橡胶中填充的最佳配比,研究高岭土的用量对橡胶力学性能、热老化性能和相容性上的影响,并与白炭黑填充橡胶进行比较。实验表明,除扯断伸长率外,高岭土/橡胶具有优异的力学和耐热性能,高岭土与橡胶有较好的相容性,且适合刚性橡胶的补强。     

Study on the damping of EVM based blends

The mechanical and damping properties of blends of ethylene‐vinyl acetate rubber(VA content >40 wt %) (EVM)/nitrile butadiene rubber (NBR) and EVM/ethylene‐propylene‐diene copolymer (EPDM), both with 1.4 phr BIPB (bis (tert‐butyl peroxy isopropyl) benzene) as curing agent, were investigated by DMA. The effect of polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), and dicumyl peroxide (DCP) on the damping and mechanical properties of both rubber blends were studied. The results showed that in EVM/EPDM/PVC blends, EPDM was immiscible with EVM and could not expand the damping range of EVM at low temperature. PVC was miscible with EVM and dramatically improved the damping property of EVM at high temperature while keeping good mechanical performance. In EVM/NBR/PVC blends, PVC was partially miscible with EVM/NBR blends and remarkably widened the effective damping temperature range from 41.1°C for EVM/NBR to 62.4°C, while CPVC mixed EVM/NBR blends had an expanded effective damping temperature range of 63.5°C with only one damping peak. Curing agents BIPB and DCP had a similar influence on EVM/EPDM blends. DCP, however, dramatically raised the height of tan δ peak of EVM/NBR = 80/20 and expanded its effective damping temperature range to 64.9°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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     

Study on Blends of Ethylene Propylene Diene Rubber and Thermoplastic Polyurethanes

Blends of ethylene propylene diene rubber (EPDM) and thermoplastic polyurethane (TPU) have been studied to understand the compatibility and morphology. The study was initially done with unmodified EPDM and subsequently with modified EPDM through maleation process. Mechanical properties of unmodified EPDM blends are improved with the addition of TPU. However, the appearance of two T _gs even at lower concentrations of PU in the blends indicates that the blends are incompatible. Blends of maleated EPDM with TPU showed a single T _g and further improvement in mechanical properties which is attributed to the improvement in compatibility as also confirmed by SEM analysis.