NBR Phase Research Articles

Properties of Recycled Poly(vinylchloride)/ Acrylonitrile-Butadiene Rubber Blends: The Effect of Maleic Acid

Maleic acid (MAc) was used to improve the compatibility of recycled poly(vi nylchloride)(PVCr)/acrylonitrile-butadiene rubber (NBR) blends. Virgin PVC (PVCv) blends with NBR were also prepared for comparison. The blends were melt mixed using a Haake Rheomix Polydrive R 600/610 at 150 °C and a rotor speed of 50 rpm. It was found that the maleic acid significantly improved the PVCr/NBR blends properties. At a similar blend composition, the PVCr/NBR + MAc blends exhibited a higher peak stress and a higher stress at 100% elongation (M100) but a lower elongation at break and a lower swelling index than ordinary PVCr/NBR blends. Scanning electron microscopy (SEM) of the tensile fracture surfaces of the blends indicated that the maleic acid increased the interfacial interaction between the PVCr and NBR phases, thus improving their compatibility. Differential scanning calorimetry (DSC) indicated that the PVCr/NBR with MAc incorporated had a higher Tg than the PVCr/NBR and PVCv/NBR blends.

Effect of acrylic acid on the properties of recycled poly(vinyl chloride)/acrylonitrile–butadiene rubber blends

AbstractThe effect of acrylic acid (AAc) on the torque, stabilization torque, mechanical energy, swelling behavior, mechanical properties, thermal stability, and morphological characteristics of recycled poly(vinyl chloride)/acrylonitrile–butadiene rubber (PVCr/NBR) blends was studied. The blends were melt mixed at a temperature of 150°C and rotor speed of 50 rpm. AAc was used to improve the compatibility of PVCr/NBR blends. Virgin PVCv/NBR blends were prepared to provide a comparison. It was found that PVCr/NBR + AAc blends exhibit higher stabilization torque, mechanical energy, stress at peak, and stress at 100% elongation, but lower elongation at break and swelling index than those of PVCr/NBR and PVCv/NBR blends. SEM study of the tensile fracture surfaces of the blends indicated that the presence of AAc increased the interfacial interaction between PVCr and NBR phases, thus improving the compatibility between PVCr and NBR phases. However, thermal gravimetry analysis of the blends showed that the presence of AAc decreased the thermal stability of PVCr/NBR blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2181–2191, 2005

Blend of waste poly(vinylchloride) (PVCw)/acrylonitrile butadiene-rubber (NBR): the effect of maleic anhydride (MAH)

Waste poly(vinylchloride) (PVCw) was blended with acrylonitrile butadiene-rubber (NBR) in different proportions. The blends were melt mixed using a Haake Rheomix Polydrive R 600/610 at 150 °C and rotor speed of 50 rpm. Maleic anhydride (MAH) was used to improve the compatibility of PVCw/NBR blends. Virgin PVC/NBR blends were also prepared as comparison. It was found that PVCw/NBR+MAH blends exhibit higher stabilization torque, mechanical energy, stress at peak and stress at 100% elongation (M 100) but lower elongation at break, E b and swelling index than PVCw/NBR and PVCv/NBR blends. The scanning electron microscopy (SEM) study of tensile fracture surfaces of the blends indicates that the presence of MAH increased the interfacial interaction between PVCw and NBR phases and, thus, improved compatibility between PVCw and NBR blends.

Influences of trans‐polyoctylene rubber on the physical properties and phase morphology of natural rubber/acrylonitrile–butadiene rubber blends

AbstractThe influence of trans‐polyoctylene rubber (TOR) on the mechanical properties, glass‐transition behavior, and phase morphology of natural rubber (NR)/acrylonitrile–butadiene rubber (NBR) blends was investigated. With an increased TOR level, hardness, tensile modulus, and resilience increased, whereas tensile strength and elongation at break tremendously decreased. According to differential scanning calorimetry and dynamic mechanical analysis, there were two distinct glass‐transition temperatures for a 50/50 NR/NBR blend, indicating the strongly incompatible nature of the blend. When the TOR level was increased, the glass transition of NBR was strongly suppressed. NBR droplets of a few micrometers were uniformly dispersed in the continuous NR phases in the NR/NBR blends. When TOR was added to a 50/50 NR/NBR blend, TOR tended to be located in the NR phase and in some cases was positioned at the interfaces between the NBR and NR phases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 125–134, 2002

The effect of mercapto‐modified EVA on rheological and dynamic mechanical properties of NBR/EVA blends

AbstractThe effect of mercapto‐modified ethylene vinyl acetate copolymer (EVALSH) on the rheological and dynamic mechanical properties of acrylonitrile butadiene rubber (NBR) and ethylene vinyl acetate copolymer (EVA) blends was evaluated at different blend compositions. The addition of 5 phr of EVALSH in the blends resulted in an increase of the melt viscosity and a substantial decrease of the extrudate swell ratio. These results can be attributed to the interactions occurring between the double bond of the NBR phase and the mercapto groups along the EVALSH backbone. The power–law index also presents a slight increase in the presence of EVALSH, indicating a decrease in the pseudoplastic nature of the compatibilized blends. The reactive compatibilization of NBR/EVA blends with EVALSH was also confirmed by the decrease of damping values and an increase of glass transition temperature, in dynamic mechanical analysis. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2335–2344, 2002

Study of carbon black distribution in BR/NBR blends based on damping properties: Influences of carbon black particle size, filler, and rubber polarity

AbstractEffects of filler and rubber polarity on the distribution of filler in butadiene/nitrile rubber (BR/NBR) blends were investigated, using the dynamic mechanical thermal analysis technique. As 30‐phr filler is added, the reduction in heights of damping peaks (tan δmax), attributed to the dilution effect, was observed. It was also found that the BR phase in the blends, compared to the NBR phase, is more preferential for small‐ and large‐particle size carbon blacks to reside, probably because of the lower viscosity and lower polarity of the BR phase. The addition of silica instead of carbon black leads to an increase in filler migration to the NBR in the 20/80 BR/NBR blend, which is attributed to the strong silica–NBR interaction. In addition, an increase in NBR polarity promotes carbon black migration to the BR phase. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3198–3203, 2001

Effect of the size of the dispersed NBR phase in PVC/NBR blends on the stability of PVC to electron irradiation

Acrylonitrile–butadiene copolymers (NBR) with different acrylonitrile contents were melt-mixed with poly(vinyl chloride) (PVC). The morphology of the blends was examined with transmission electron microscopy (TEM). The samples were also exposed to an electron beam and the chlorine-loss upon electron irradiation was monitored with electron dispersion X-ray analyzer (EDX). TEM results indicated that all samples blended with different NBR, including NBR-33 and NBR-41, were heterogeneous, but the dispersion of NBR-33 was the finest. The results of the chlorine-loss study showed that the radiation sensitivity of PVC was improved by the addition of NBR and the extent of improvement was strongly related to the miscibility. Analysis of experimental data demonstrated that chlorine loss of PVC/NBR blends followed the Vesely's double exponential equation but the coefficient and rate constants varied with different NBR. For polymer blends containing a component that is radiation insensitive and another component that is unstable under irradiation, such as a fluoropolymer and chloropolymer, the loss of fluorine or chlorine as a function of radiation dose can be used to compare the size of the dispersed phase of the polymer blends.

Properties influenced by addition of copoly (ethylene/octene) in BR–NBR blends

The effects of copoly (ethylene/octene) (EOM) on rheological, mechanical, and cure properties and on carbon black distribution in each phase of butadiene rubber–nitrile/butadiene rubber (BR–NBR) blends have been investigated. It was found that EOM added to the blends is able to function as a plasticising agent for BR and NBR, and the plasticising efficiency of EOM is more significant in NBR than BR. With increasing EOM content, the deviation of Mooney viscosity from the additive line (interpolated values) reduces markedly. In pure components (i.e. 100 : 0 and 0 : 100), cure rate reduces and cure time increases with addition of EOM. In contrast in the blend systems, cure rate increases and cure time decreases when EOM is added. The distribution of carbon black in each phase of the blends is strongly controlled by the viscosity of each phase in the blend. The lower the phase viscosity, the greater the residual carbon black. Accordingly, dynamic mechanical thermal analysis reveals a slight shift in the glass transition temperature of the BR phase to higher temperature, compared with the NBR phase, as EOM is added. From the results obtained, it is proposed that EOM exists in the interfacial area between the two phases. However, at higher amounts of EOM, saturation of EOM at the interfacial area occurs and the excess EOM starts to migrate to the BR phase. Further increase in EOM concentration leads to saturation of EOM in the BR phase and EOM then migrates to the NBR phase.

Morphology and physical properties of SAN/NBR blends: The effect of AN content and melt viscosity of SAN

To study the effect of dispersed poly(butadiene-co-acrylonitrile) (NBR) rubber size on the physical properties of poly(styrene-co-acrylonitrile) (SAN)/NBR blends, SANs with various melt viscosities and acrylonitrile (AN) contents were examined. The dispersed size of NBR, whose AN content is 30 wt %, was reduced as the melt viscosity of the SAN matrix was increased or as the AN content of the SAN matrix was reduced in the range of 19–32 wt %. As the melt viscosity of the SAN matrix was increased, the damping peak of the NBR phase moved to a higher temperature, and as the AN content of SAN was reduced, the damping peak of the SAN phase moved to a lower temperature. Higher values of impact strength and elongation at break and reduced yield behavior at a low shear rate were observed at a finer dispersion of NBR. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 935–941, 1999

Ionic conductivity of new dual‐phase polymer electrolyte composed of poly(epichlorohydrin‐co‐oxirane) and NBR

A new type of dual-phase polymer electrolyte (DPE) film was prepared by mechanical mixing of a poly(epichlorohydrin-co-oxirane) (ECO) and poly(acrylonitrile-co-butadiene) rubber (NBR) binary solution and then by solution casting. Both of the polymers are commercially available. The casting films were swollen with a LiClO4/propylene carbonate (PC) solution to obtain DPE films. The ionic conductivity of the DPE films was calculated on the basis of alternating current impedance measurements. The results showed that the ionic conductivity is dependent on the content of the LiClO4/PC solution and the ECO/NBR blend ratio. High ionic conductivity (>10−3 S/cm at 298 K) was achieved when the ECO content in the matrix is 90% (w/w), the contentration of LiClO4/PC solution is at 3 mol/L, and the weight percent of LiClO4/PC is 40. The impedance spectrum provided evidence that a dual-phase structure was created, in which the ECO phase provided an ion-conductive pathway and the NBR phase acted as a supportive matrix. A new ionic conductivity mechanism was proposed. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 353–357, 1998

Ionic conductivity of new dual-phase polymer electrolyte composed of poly(epichlorohydrin-co-oxirane) and NBR

A new type of dual-phase polymer electrolyte (DPE) film was prepared by mechanical mixing of a poly(epichlorohydrin-co-oxirane) (ECO) and poly(acrylonitrile-co-butadiene) rubber (NBR) binary solution and then by solution casting. Both of the polymers are commercially available. The casting films were swollen with a LiClO 4 / propylene carbonate (PC) solution to obtain DPE films. The ionic conductivity of the DPE films was calculated on the basis of alternating current impedance measurements. The results showed that the ionic conductivity is dependent on the content of the LiClO 4 /PC solution and the ECO/NBR blend ratio. High ionic conductivity (>10 -3 S/cm at 298 K) was achieved when the ECO content in the matrix is 90% (w/w), the contentration of LiClO 4 /PC solution is at 3 mol/L, and the weight percent of LiClO 4 /PC is 40. The impedance spectrum provided evidence that a dual-phase structure was created, in which the ECO phase provided an ion-conductive pathway and the NBR phase acted as a supportive matrix. A new ionic conductivity mechanism was proposed.

Monitoring of Homogenization and Analysis of Nanoscale Structure in a Butadiene−Acrylonitrile Copolymer/Poly(vinyl chloride) Blend

The progress of homogenization in the mechanical blending of a butadiene−acrylonitrile copolymer (NBR) and a poly(vinyl chloride) (PVC) was observed with scanning and transmission electron microscopes. The significant events of the microscopic examinations were as follows: (i) NBR formed a continuous and PVC a dispersed phase. (ii) The skins of PVC grains (100−150 μm) were removed first, and the grains were broken into agglomerates (∼10 μm). (iii) The agglomerates were disintegrated stepwise into primary particles (∼1 μm), domains (∼0.1 μm), and eventually the nodular particles of the size between domains and microdomains (∼10 nm). The electron microscopic visualizations, together with the material behavior expressed in terms of the internal mixer geometry and the viscoelastic properties during mixing action, suggest a schematic model for the homogenization mechanism. The microphase structure of the finished blend was characterized by cross-polarization/magic angle spinning (CP/MAS) 13C NMR spectroscopy. Analyses of T1ρ spin−lattice relaxation for specific carbons permitted a precise identification of the microstructures. Double-component resolution of the magnetization decay confirmed a coexistence of a mixed phase and two microseparated phases, the latter corresponding to an unmixed NBR phase and PVC microcrystallites. From the T1ρ relaxation times, the sizes of the microphases were estimated to be in the nanoscale.

Polymer electrolytes with a dual-phase structure composed of poly(acrylonitrile- co-butadiene)/poly(styrene- co-butadiene) blend films impregnated with lithium salt solution

Dual-phase polymer electrolytes that possess good mechanical strength and high ionic conductivity were prepared by mechanically mixing a poly(acrylonitrile- co-butadiene) rubber (NBR) and poly(styrene- co-butadiene) rubber (SBR) binary solution and casting polymer blend films. The films were swollen with lithium salt solutions (e.g. 1 M LiClO 4 in γ-butyrolactone) to obtain dual-phase polymer electrolyte films. As the mixing rate increases, the average domain size of the NBR and SBR in the film decreased, levelling off at a mixing rate of > 10 000 rev min −1 as it approached the value of 5 μm. A mechanically strong film was obtained by reducing the domain size to less than one-fifth of the film thickness. On the other hand, the ionic conductivity depended on the fraction of NBR in the NBR/SBR matrix rather than on the domain size of the film. Thus high ionic conductivity (> 10 −4 S cm −1) could be achieved with an NBR weight fraction of over 50% (w/w). Additionally, transmission electron microscope observation and differential scanning calorimetric analysis showed evidence that a dual-phase structure was created, in which the NBR phase provided an ion-conductive pathway and the SBR acted as a mechanically supportive matrix. Quantitative analysis of ionic conductivity suggested that a ‘free’ lithium salt solution absorbed in the matrix caused the high ionic conductivity of the polymer electrolyte.

Mechanical properties of dual‐phase polymer electrolytes prepared from poly(styrene‐co‐butadiene) rubber/poly(acrylonitrile‐co‐butadiene) rubber mixed latices

AbstractMechanical properties of two dual‐phase polymer electrolytes (DPEs), prepared from poly(styrene‐co‐butadiene) rubber (SBR) and poly(acrylonitrile‐co‐butadiene) rubber (NBR) latices, are studied. Both DPEs are composed of an SBR supporting phase and an ionconductive phase of NBR/lithium salt solution. The first DPE maintains a tensile strength of 0.5 MPa and elongation of 280% with an ionic conductivity of 10−3 S/cm. Although the glass transition relaxations based on the dual‐phase structure are not resolved in this DPE because of the proximity of the glass transition temperatures of the SBR and NBR, the glass transition shifts to a lower temperature due to the plasticization by the lithium salt solution. In the second DPE, two distinctive glass transition relaxations, corresponding to the SBR and NBR phases, are observed in the viscoelasticity versus temperature measurement, indicating the dual‐phase structure. A simple equivalent mechanical model, which is modified from the Takayanagi model, is introduced to elucidate the mechanical behavior of the dual‐phase structure in the second DPE. According to this model, 8% of DPE is a mechanically continuous SBR phase in the tensile direction, which effectively gives mechanical support to the DPE. © 1995 John Wiley & Sons, Inc.

Polymer Electrolytes with Multiple Conductive Channels Prepared from NBR/SBR Latex Films Impregnated with Lithium Salt and Plasticizer

Polymer electrolytes with high ionic conductivity (>10−3 S/cm) and good tensile strength were prepared by swelling poly(acrylonitrile‐co‐butadiene) (NBR)/poly(styrene‐co‐butadiene) latex films with γ‐butyrolactone (γ‐BL) or plasticizer. Before swelling, the phase is formed at the particle interface. After plasticization, two ion‐conductive channels are present: the phase is present at the interface of the latex particles, and the NBR phase is formed from NBR latex particles. These regions are polar and impregnated selectively with polar γ‐BL solvent or solution, building primary and secondary ion‐conductive channels, respectively. The SBR phase (formed from SBR latex particles) is nonpolar and not impregnated, providing a mechanically supportive matrix. High ionic conductivity on the order of 10−3 S/cm is achieved when latex film was saturated with 0.2 to 0.4M solutions. Various microscopic and macroscopic analyses suggest that two types of ion‐conductive channels exist in the polymer electrolyte film.

Ac impedance analysis on dual-phase polymer electrolytes prepared from SBR/NBR mixed latices

Dual-phase polymer electrolytes (DPE) are analyzed by ac impedance spectroscopy. DPE is prepared from an NBR/SBR latex mixture in the following process: the latex mixture is dried to produce a polymer matrix film, and the polymer matrix is then impregnated with a lithium salt solution as a plasticizer, which selectively permeates into the NBR phase. When a polymer matrix is impregnated with 1M LiClO 4/γ-butyrolactone and its NBR content is small, a distorted complex impedance spectrum, composed of overlapping two semicircles, is observed. The analysis based on an equivalent circuit indicates that isolated fragments of the conductive NBR phase are formulated in addition to the continuous conductive pathways. With increasing content of NBR, the two semicircles get merged. This suggests that the isolated conductive phase comes to be integrated into the continuous ionic pathways. The impregnation process of DPE with a less polar plasticizer was followed by analyzing the complex impedance and modulus spectra. According to this analysis, secondary conductive pathways are formed along the SBR particle boundaries in addition to the NBR conductive phase. Swelling of NBR particles progresses in the secondary conductive pathways, and the NBR particles are finally linked to form continuous ionic pathways between the electrodes.

High density polyethylene/acrylonitrile butadiene rubber blends: Morphology, mechanical properties, and compatibilization

AbstractPolymer blends based on high‐density polyethylene (HDPE) and acrylonitrile butadiene rubber (NBR) were prepared by a melt blending technique. The mixing parameters such as temperature, time, and speed of mixing were varied to obtain a wide range of properties. The mixing parameters were optimized by evaluating the mechanical properties of the blend over a wide range of mixing conditions. The morphology of the blend indicated a two‐phase structure in which NBR phase was dispersed as domains up to 50% of its concentration in the continuous HDPE matrix. However, 70 : 30 NBR/HDPE showed a cocontinuous morphology. The tensile strength, elongation at break, and hardness of the system were measured as a function of blend compostion. As the polymer pair is incompatible, technological compatibilization was sought by the addition of maleic‐modified polyethylene (MAPE) and phenolic‐modified polyethylene (PhPE). The interfacial activity of MAPE and PhPE was studied as a function of compatibilizer concentration by following the morphology of the blend using scanning electron micrographs. Domain size of the dispersed phase showed a sharp decrease by the addition of small amounts of compatibilizers followed by a leveling off at higher concentrations. Also, more uniformity in the distribution of the dispersed phase was observed in compatibilized systems. The tensile strength of the compatibilized systems showed improvement. The mechanical property improvement, and finer and uniform morphology, of compatibilized systems were correlated with the improved interfacial condition of the compatibilized blends. The experimental results were compared with the current theories of Noolandi and Hong. © 1995 John Wiley & Sons, Inc.

Dual‐Phase structure of polymer electrolytes comprised of NBR/SBR latex films swollen with lithium salt solution

AbstractDual‐phase polymer electrolytes (DPE) that have high ionic conductivity (> 10−3 S/cm) and good mechanical strength were prepared by mixing NBR and SBR latices and casting films. The latex films absorbed large quantities of lithium salt solution (e.g., 1M lithium perchlorate in γ‐butyrolactone) to obtain DPE films but did not dissolve with swelling. The NBR phase is polar and was impregnated selectively with the polar lithium salt solution, whereas the SBR phase is nonpolar and formed a mechanically‐supportive matrix. Transmission electron microscopic (TEM), electron energy loss spectral (EELS), and energy‐dispersive x‐ray (EDX) analyses showed microscopically the dual‐phase structure. Evidence for swelling by lithium salt solution was found only in the NBR phase and not in the SBR phase by EDX microanalysis. Ionic conductivity as a function of NBR content or swelling degree showed clearly that a percolation threshold for ionic conductivity exists. © 1994 John Wiley & Sons, Inc.

Ionic Conductivity of Dual‐Phase Polymer Electrolytes Comprised of NBR/SBR Latex Films Swollen with Lithium Salt Solutions

Dual‐phase polymer electrolytes (DPE) with high ionic conductivity and good mechanical strength were prepared by swelling poly(acrylonitrile‐co‐butadiene) rubber (NBR) and poly(styrene‐co‐butadiene) rubber (SBR) mixed latex films with lithium salt solutions (e.g., 1M ). The latex films retain particle morphology in the solid state. The NBR phase (formed from fused NBR latex particles) is polar and is impregnated selectively with polar lithium salt solutions, yielding ion‐conductive channels, whereas the SBR phase (formed from fused SBR latex particles) is nonpolar and is not impregnated, providing a mechanically supportive matrix. The ionic conductivity of the DPE increased dramatically with increasing content of lithium salt solution, and higher amounts of solution were imbibed with increasing content of NBR relative to SBR. Several factors which affect the ionic conductivity of this system were examined, and the highest ionic conductivity (>10−3 S/cm) was obtained when either an NBR/SBR 70/30 (w/w) or a 50/50 (w/w) latex film was saturated with 1M or 1M solution. Ion‐conductive behavior changed critically with increasing lithium salt solution uptake. At low levels of lithium salt solution uptake, evidence suggested that ionic conductivity of the absorbed lithium salt solution was strongly influenced by the presence of the NBR in the ion‐conductive channel, but at higher levels, the effects of the NBR were reduced and “free” lithium salt solution was present.

Pulsed NMR Study of Motional Heterogeneity in Acrylonitrile-Butadiene/Poly(Vinyl Chloride) Blends

Abstract Motional heterogeneity in blends of NBR (AN = 38%) and PVC was studied by 1H pulsed NMR. It was estimated from NMR relaxation measurements that the PVC molecules in the NBR phase form phase domains of the order of less than 10 nm, consistent with the microheterogeneous structure observed by TEM. Furthermore, by spin diffusion experiments using the Goldman-Shen pulse sequence, the size of the PVC phase domains was semiquantitatively evaluated to be 4.2 nm in the case of the cylindrical domains and to be 5.1 nm in the case of the spherical domains. It becomes clear that pulsed NMR complements the results of other analytical methods with more detailed information on the state of the molecular mixing in the blends.