Effects of partial replacement of silicone rubber with flurorubber on properties of dynamically cured poly(vinylidene fluoride)/silicone rubber/flurorubber ternary blends

Blends of poly(vinylidene fluoride) (PVDF), silicone rubber (SR) and flurorubber (FKM) were prepared via peroxide dynamic vulcanization. The effect of FKM loading on the morphology, mechanical properties, crystallization behavior, rheology and dynamic mechanical properties of the PVDF/SR/FKM ternary blends was investigated. A “network” was observed in the PVDF/SR binary blends, which disappeared in the ternary blends, but a core-shell-like structure was formed. The mechanical properties were significantly improved. The Izod impact strength of PVDF/SR/FKM blend with 19 wt% FKM was 18.3 kJ/m², which was 3–4 times higher than the PVDF/SR binary blend. The complex viscosity and storage modulus of the PVDF/SR/FKM blends decreased with increasing FKM content, hence the processability was improved. The increase of FKM content seemed to show a favorable effect on the crystallization of the PVDF component. It promoted the nucleation process of PVDF, leading to increased polymer crystallization rate and higher crystallization temperature. The glass-rubber transition temperature of the PVDF phase moved to a lower temperature.     

Preparation and properties of dynamically cured poly(vinylidene fluoride)/silicone rubber blends

Blends of poly(vinylidene fluoride) (PVDF) and silicone rubber (SR) were prepared through dynamic vulcanization. The effects of SR content on crystallization behavior, rheology, dynamic mechanical properties and morphology of the blends were investigated. Morphology characterization shows that the crosslinked spherical SR particles with an average diameter of 2-4 μm form a “network” in the PVDF continuous phase. The dynamic mechanical properties indicate the interface adhesion between PVDF and rubber phase is improved by the dynamic vulcanization. The rheology study shows that with the increase of rubber content the blends pseudoplastic nature is retained, while the viscosity increases, and hence the processability is less good. The incorporation of SR phase promotes the nucleation process of PVDF, leading to increased polymer crystallization rate and crystallization temperature. However, a higher content of SR seems to show a negative effect on the crystallinity of the PVDF component.     

Improving properties of natural rubber/polyamide 12 blends through grafting of diacetone acrylamide functional group

The aim of the present study was to improve the compatibility in blends of natural rubber (NR) and polyamide 12 (PA12) by grafting NR with hydrophilic monomer, diacetone acrylamide (DAAM), via seeded emulsion polymerization. The increase in polarity of NR after grafting modification was confirmed by a considerable increase in the polar component of its surface energy. Blends of graft copolymers of NR and poly(diacetone acrylamide) prepared using 10 wt% of DAAM (NR‐g‐PDAAM10) and PA12 were prepared at a 60/40 blend ratio (wt%) using simple blend and dynamic vulcanization techniques. The mechanical and rheological properties of the resulting blends were subsequently investigated and compared with those of the corresponding blends based on unmodified NR. The results show that dynamic vulcanization led to a significant increase in both mechanical and rheological properties of the blends. It was also observed that the dynamically cured NR‐g‐PDAAM10/PA12 blend had smaller particle size of vulcanized rubber dispersed in the PA12 matrix than observed for the dynamically cured NR/PA12 blend. This is due to the compatibilizing effect of DAAM groups present in NR‐g‐PDAAM10 molecule, which decreases the interfacial tension between the two polymeric phases. Therefore, it can be stated that the interfacial adhesion between NR and PA12 was improved by the presence of DAAM groups in NR molecule. This was reflected in the higher tensile properties observed in the dynamically cured NR‐g‐PDAAM10/PA12 blend. Copyright © 2017 John Wiley & Sons, Ltd.     

The effect of dynamic vulcanization on the properties of polymer-elastomer blends containing crumb rubber

The influence of dynamic vulcanization on the amount of the sol fraction, the crosslink density, the melt flow index, and the mechanical properties of ternary (isotactic polypropylene-rubber-crumb rubber) and binary (rubber-crumb rubber) blends was studied. Two types of ethylene-propylene-diene terpolymer (elastomer) were used as the rubber component, the oil-free elastomer and the elastomer extended with paraffin oil during its synthesis. The blends were vulcanized in the presence of a sulfur accelerating system. It was shown that blends with crumb rubber having a particle size of less than 0.1 mm exhibited the best mechanical and rheological characteristics. The introduction of crumb rubber into thermoplastic elastomers that contain the oil-free ethylene-propylene-diene terpolymer leads, at a certain ratio of the components, to a rise in the melt flow index, regardless of the crumb-rubber particle size and of whether the rubber component was vulcanized.     

Novel fluorosilicone thermoplastic vulcanizates prepared via core‐shell dynamic vulcanization: Effect of fluororubber/silicone rubber ratio on morphology,crystallization behavior,and mechanical properties

Recently, we have reported a novel core‐shell dynamic vulcanization method to prepare poly(vinylidene fluoride) (PVDF)/fluororubber (FKM)/silicone rubber (SR) thermoplastic vulcanizates (TPVs) with cross‐linked rubber core‐shell particles. However, the shell thickness on the properties has not been studied in detail. Herein, these PVDF‐based TPVs different FKM‐shell thickness were prepared by changing FKM/SR ratios. The effect of FKM‐shell/SR‐core ratio on morphology, crystallization, and mechanical properties of the ternary TPVs was studied. The results showed that the FKM shell had more positive effect on interfacial‐induced crystallization behavior than the SR core due to its better compatibility with PVDF. When the FKM/SR ratio was <1, FKM was not enough to encapsulate SR completely, which resulted in the formation of imperfect core‐shell structure. However, when the FKM/SR ratio was >1, perfect core‐shell structure was formed. Therefore, the mechanical properties improved with increasing FKM content; especially, a remarkable improvement was observed when FKM/SR ratio was >1. This study could provide more information for the design of TPVs with core‐shell structure.     

A multiple approach in determination of interfacial tension of biodegradable melt-mixed PBAT/EVOH blends: Correlation of morphology,rheology and mechanical properties

The interfacial tension of biodegradable melt-mixed blends of poly(butylene adipate-co-terephthalate), PBAT, and poly(ethylene-co-vinyl alcohol), (EVOH), was measured by breaking thread (BT), imbedded fiber retraction (IFR), and rheological methods. The PBAT-rich blends were prepared under different melt mixing conditions in order to investigate the effect of mixing conditions and possibility of reactive mixing between the blend components on the blend morphology, rheology, mechanical properties and interfacial tension values. The conditions were varied based on a Taguchi design of experiment using four factors namely EVOH content (0–30 wt%), mixing time (2–15 min), rotor speed (50–90 rpm), and mixing temperature (185–200 °C), each varying at three levels. The average size of EVOH droplets in PBAT matrix was determined for each blend by a field emission-scanning electron microscopy technique. The values of interfacial tension of PBAT/EVOH were found to be 2.57 ± 0.22 and 2.73 ± 0.30 mN m⁻¹ by the BT and IFR methods, respectively. The Palierne, Gramespacher, and Bousmina models were fitted to the rheological data to verify the interfacial tension of the blends. The continuous relaxation spectrum of the blends was determined in order to obtain the relaxation time of the EVOH droplets in the PBAT matrix. The Taguchi analysis revealed that the most effective factor is the EVOH content, and other factors do not play a significant role in the ultimate properties of the blends. Finally, based on the obtained mechanical properties, the possibility of reactive mixing under the applied mixing conditions was ruled out by means of repeated differential scanning calorimetry (DSC) and rheological measurements.     

Compatibilization of immiscible poly(lactic acid)/poly(ε-caprolactone) blend through electron-beam irradiation with the addition of a compatibilizing agent

The aim of this study was to compatibilize immiscible poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) blend by using electron-beam radiation method with the addition of a compatibilizing agent. Glycidyl methacrylate (GMA) was chosen as the compatibilizing agent, in the expectation that the GMA plays a role as a monomeric compatibilizer and a reactive agent at the interface between the PLA and the PCL phases. Compatibilization process has been investigated through the melt mixing of the PLA/PCL and the GMA by using a twin-screw extruder and the exposure of the PLA/PCL/GMA mixture to electron-beam radiation at room temperature. The melt mixing process was performed to locate the GMA at the interface, thereby expecting a finer morphology due to the GMA as the monomeric plasticizer. The exposure process was carried out to induce definite interfacial adhesion at the interface through electron-beam initiated cross-copolymerization by the medium of the GMA as the reactive agent. To investigate the results of this compatibilization strategy, the morphological, mechanical, and rheological properties of the blend were analyzed. The morphological study clearly showed the reduced particle size of dispersed PCL domains and significantly improved interfacial adhesion by the electron-beam irradiation with the addition of the GMA. The stress–strain curves of the blends irradiated at less than 20 kGy showed the typical characteristics of ductile materials. The tensile properties of the blend were strongly affected by the dose of irradiation.     

Reactive compatibilization of PA12/plasticized starch blends: Towards improved mechanical properties

Glycerol-plasticized starch (TPS)/polyamide 12 (PA12) blends were processed by melt mixing using two types of interfacial agent, i.e. diglycidyl ether of bisphenol A and a poly(ethylene-co-butyl acrylate-co-maleic anhydride) copolymer. Morphologies of the blends were tailored from the nature and amount of the interfacial agents. The average size of the dispersed phase was shown to decrease with the incorporation of the reactive agents and was proved to respect models, usually employed for conventional blends, for size predictions of the dispersed phase. By means of rheological experiments, it has been investigated whether the size reduction of the dispersed phase was coming from the compatibilization of the blend or from the viscosity changes due to chain extension in the matrix. The influence of the coupling agents on the viscoelastic behavior of the blend was characterized. Both interfacial agents led to increase the absolute complex viscosity but in the case of diepoxy reactive agent, the Newtonian flow behavior of complex viscosity totally disappeared in the low-frequency region. Mechanical properties of the TPS/PA12 blends were characterized and were proved to be strongly impacted by the use of interfacial agents. Elongation at break was enhanced as a consequence of a better adhesion between the matrix and the dispersed phase, whereas a decrease of the Young’s modulus was observed with increasing DGEBA content. Polyamide 12 crystallization in TPS/PA12 blends was found to be strongly dependent on DGEBA content while the introduction of maleic anhydride-grafted copolymer had no influence.     

Mechanical and Rheological Behavior of Unvulcanized and Dynamically Vulcanized i-PP/EPDM Blends

The mechanical and rheological behavior of dynamically vulcanized PP/EPDM blends is examined and compared with those of unvulcanized blends. The effect of blend ratio and dynamic vulcanization of EPDM rubber on tensile properties and flow are investigated. The mechanical properties of the blends are strongly influenced by the blend ratio. With the increasing of EPDM content the value of yield stress in a solid state decreases with the elastomer volume fractions less than 0.45 for the unvulcanized blends. For the dynamically vulcanized blends the interval of EPDM content, at which the yield peak is seen, is rather limited below 0.25 elastomer volume fractions. It is shown that dynamic vulcanization changes the deformational behavior of PP/EPDM blends. The rheological properties of dynamically vulcanized blends depending on the ratio of the components may be similar to the properties of polymer composites containing the highly disperse structuring filler. The distinction between the rheological behavior of unvulcanized and dynamically vulcanized blends is related to differences of their structures and viscoelastic characteristics of unvulcanized and vulcanized EPDM phase.     

Morphology and properties of biodegradable poly (lactic acid)/poly (butylene adipate-co-terephthalate) blends with different viscosity ratio

Phase morphology exerts a tremendous influence on the properties of polymer blends. The development of the blend morphology depends not only on the intrinsic structure of the component polymers but also on extrinsic factors such as viscosity ratio, shearing force and temperature in the melt processing. In this study, various poly (butylene adipate-co-terephthalate) (PBAT) materials with different melt viscosity were prepared, and then poly (lactic acid) (PLA)/PBAT blends with different viscosity ratio were prepared in a counter-rotating twin-screw extruder under constant processing conditions. The influence of viscosity ratio on the morphology, mechanical, thermal and rheological properties of PLA/PBAT (70/30 w/w) blends was investigated. The experimental results showed that the morphology and properties of PLA/PBAT blends strongly depended on the viscosity ratio. Finer size PBAT phase were observed for viscosity ratio less than 1 (λ < 1) compared to samples with λ > 1. It was found that the interfacial tensions of PLA and PBAT were significantly different when the viscosity ratio was changed, the lowest interfacial tensions (0.12 mN/m) was obtained when the viscosity was 0.77. Additionally, the maximal tensile strength in PLA/PBAT blends were obtained when the viscosity ratio was 0.44, while the maximal impact properties were obtained when the viscosity ratio was 1.95.     

Crystallization behavior,tensile behavior and hydrophilicity of poly(vinylidene fluoride)/polyethylene glycol blends

In this study, polyethylene glycol (PEG) of different molecular weight was added into poly(vinylidene fluoride) (PVDF) through melt blending. The hydrophilicity, processability, mechanical properties of the blends were investigated. Moreover, to understand fully, the crystallization and melting behavior, crystalline structure, molecular interactions of the blends were also studied. Results revealed that the addition of PEG evidently enhances the ductile and reduces the rheological torque of PVDF, what’s more, the contact angle of the blends with water was greatly reduced. The solid surface tension γ_s, chromatic dispersion part γ _s ^d and polar part γ _s ^p suggested the surface tension of the blend gradually increased from 38.31 to 55.65 mJ/m² with the increase of PEG-20000 content.Wherein the dispersion part of the tension changed little, the polar part of the tension increased significantly from 5.74 to 20.41 mJ/m², indicating that the addition of PEG greatly enhanced the polar part of surface tension of the blend, and therefore evidently enlarged the hydrophilic property of the blends. Besides, to elucidate the related effecting mechanism, the crystallization and molecular interaction of the blends were also studied.     

Crystallization behavior and hydrophilicity of poly (vinylidene fluoride) (PVDF)/poly (styrene-<Emphasis Type="Italic">co</Emphasis>-acrylonitrile) (SAN) blends

Poly (styrene-co-acrylonitrile) (SAN) is a hydrophilic non-crystalline copolymer, which is initially used in this paper to improve the hydrophilicity of poly (vinylidene fluoride) (PVDF). Investigation of the crystallization behavior of PVDF/SAN blends showed that the samples presented only α phase regardless of SAN content as cooling from the melt. A double-melting phenomenon was related to the perfection or crystal size of PVDF crystals. As the SAN content is increasing, crystallization of PVDF was limited, leading to a decreased crystallinity and lamellar growth. Besides, the hydrophilicity of PVDF was improved by blending with SAN. The sample containing 70 wt.% SAN performed a similar surface property of the neat SAN owing to the besieging of the PVDF phase by SAN. Observed from the cross section of the blends, PVDF/SAN blends were partially miscible with less than 50 wt.% SAN addition. As the SAN content was more than 50 wt.%, the crystalline PVDF particles clearly dispersed in the amorphous matrix.     

Viscoelastic interfacial properties of compatibilized poly(ε‐caprolactone)/polylactide blend

Poly(ε‐caprolactone)/polylactide blend (PCL/PLA) is an interesting biomaterial because the two component polymers show good complementarity in their physical properties. However, PCL and PLA are incompatible thermodynamically and hence the interfacial properties act as the important roles controlling the final properties of their blends. Thus, in this work, the PCL/PLA blends were prepared by melt mixing using the block copolymers as compatibilizer for the studies of interfacial properties. Several rheological methods and viscoelastic models were used to establish the relations between improved phase morphologies and interfacial properties. The results show that the interfacial behaviors of the PCL/PLA blends highly depend on the interface‐located copolymers. The presence of copolymers reduces the interfacial tension and emulsified the phase interface, leading to stabilization of the interface and retarding both the shape relaxation and the elastic interface relaxation. As a result, besides the relaxation of matrices (τ_m) and the shape relaxation of the dispersed PLA phase (τ_F), a new relaxation behavior (τ_β), which is attribute to the relaxation of Marangoni stresses tangential to the interface between dispersed PLA phase and matrix PCL, is observed on the compatibilized blends. In contrast to that of the diblock copolymers, the triblock copolymers show higher emulsifying level. However, both can improve the overall interfacial properties and enhance the mechanical strength of the PCL/PLA blends as a result. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 756–765, 2010     

Superior heat‐resistant and oil‐resistant blends based on dynamically vulcanized hydrogenated acrylonitrile butadiene rubber and polyamide 12

High‐performance thermoplastic vulcanizates (TPVs) are the new generation of TPVs that provide superior heat and oil aging behavior. TPVs based on hydrogenated acrylonitrile butadiene rubber and polyamide 12 (PA12) have been first developed by the dynamic vulcanization process, in which selective cross‐linking of the elastomer phase during melt mixing with the thermoplastic phase (PA12) was carried out simultaneously. In this present investigation, hydrogenated acrylonitrile butadiene rubber (HNBR)/PA12 and partially hydrogenated carboxylated acrylonitrile butadiene rubber (XHNBR)/PA12 with blend ratio of 50:50, 60:40, and 70:30 wt% were prepared at 185°C at a rotor speed of 80 rpm for 5 min. Di‐(2‐tert‐butyl peroxy isopropyl) benzene was chosen as the suitable cross‐linking peroxide to pursue the dynamic vulcanization. TPV based on 50:50 HNBR/PA12 and XHNBR/PA12 show better physico‐mechanical properties, rheological behavior, thermal stability, dynamic mechanical analysis, and creep behavior among all the TPVs. Morphology study reveals that dispersed phase morphology has been formed with an average dimension of the rubber particles in the range of 0.8–1.5 µm. For aging test, TPVs were exposed to air and ASTM oil 3, respectively. Air aging tests were carried out in hot air oven for 72 hr at 125°C, while the oil aging tests were carried out after immersion of the samples into the oils in an aging oven. After aging, there is only slight deterioration in the physico‐mechanical properties of the TPVs. In case of 50:50 blends of HNBR/PA12 and XHNBR/PA12, the retention of the properties upon after aging was found excellent. These TPVs are designed to find potential application in automotive sector especially for under‐hood‐application, where high‐temperature resistance as well as high oil resistance is of prime importance. Copyright © 2016 John Wiley & Sons, Ltd.     

Reactive compatibilization of polyamide‐6 (PA 6)/polybutylene terephthalate (PBT) blends by a multifunctional epoxy resin

A multifunctional epoxy resin has been demonstrated to be an efficient reactive compatibilizer for the incompatible and immiscible blends of polyamide‐6 (PA 6) and polybutylene terephthalate (PBT). The torque measurements give indirect evidence that the reaction between PA and PBT with epoxy has an opportunity to produce an in situ formed copolymer, which can be as an effective compatibilizer to reduce and suppress the size of the disperse phase, and to greatly enhance mechanical properties of PA/PBT blends. The mechanical property improvement is more pronounced in the PA‐rich blends than that in the PBT‐rich blends. The fracture behavior of the blend with less than 0.3 phr compatibilizer is governed by a particle pullout mechanism, whereas shear yielding is dominant in the fracture behavior of the blend with more than 0.3 phr compatibilizer. As the melt and crystallization temperatures of the base polymers are so close, either PA or PBT can be regarded as a mutual nucleating agent to enhance the crystallization on the other component. The presence of compatibilizer and in situ formed copolymer in the compatibilized blends tends to interfere with the crystallization of the base polymers in various blends. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 23–33, 2000     

Highly toughened poly(lactic acid) (PLA) prepared through melt blending with ethylene-co-vinyl acetate (EVA) copolymer and simultaneous addition of hydrophilic silica nanoparticles and block copolymer compatibilizer

In this study, a highly toughened PLA was prepared through physical melt-blending with EVA at the presence of hydrophilic nanosilica and SEBS-g-MA block copolymer compatibilizer. The effect of nanosilica and compatibilizer on the morphology, mechanical properties, and linear rheology of the PLA/EVA blends was also investigated. According to TEM images, nanosilica was selectively located in the PLA matrix while some were placed on the interface between the two polymers as was also predicted by thermodynamic and kinetic analysis. Upon the addition of nanoparticles, the interfacial adhesion between the phases was enhanced and the average droplet size decreased. Interestingly, incorporation of SEBS-g-MA induced morphological changes as the spherical EVA droplets turned into a cylindrical shape. DSC results indicated that blending with EVA copolymer resulted in the reduction of crystallization of PLA matrix; however, the crystallinity increased at the presence of nanoparticles up to 5 wt%. The addition of compatibilizer considerably hindered the crystallization of the PLA phase. PLA/EVA blend containing optimum levels of nanosilica exhibited considerably enhanced tensile toughness, elongation at break, and impact strength. On the other hand, the simultaneous addition of nanoparticles and SEBS-g-MA led to synergistic toughening effects and the compatibilized blend containing nanosilica exhibited excellent impact toughness. For instance, the elongation at break of the compatibilized PLA/EVA blend containing the optimal content of nanosilica was increased from 7% to 121% (compared to neat sample). The notched Izod impact strength was also increased from 5.1 to 65 kJ/m². Finally, the microstructure of the blends was assessed by rheological measurements.     

Morphology and mechanical and viscoelastic properties of natural rubber and styrene butadiene rubber latex blends

The morphology and mechanical and viscoelastic properties of a series of blends of natural rubber (NR) and styrene butadiene rubber (SBR) latex blends were studied in the uncrosslinked and crosslinked state. The morphology of the NR/SBR blends was analyzed using a scanning electron microscope. The morphology of the blends indicated a two phase structure in which SBR is dispersed as domains in the continuous NR matrix when its content is less than 50%. A cocontinuous morphology was obtained at a 50/50 NR/SBR ratio and phase inversion was seen beyond 50% SBR when NR formed the dispersed phase. The mechanical properties of the blends were studied with special reference to the effect of the blend ratio, surface active agents, vulcanizing system, and time for prevulcanization. As the NR content and time of prevulcanization increased, the mechanical properties such as the tensile strength, modulus, elongation at break, and hardness increased. This was due to the increased degree of crosslinking that leads to the strengthening of the 3‐dimensional network. In most cases the tear strength values increased as the prevulcanization time increased. The mechanical data were compared with theoretical predictions. The effects of the blend ratio and prevulcanization on the dynamic mechanical properties of the blends were investigated at different temperatures and frequencies. All the blends showed two distinct glass‐transition temperatures, indicating that the system is immiscible. It was also found that the glass‐transition temperatures of vulcanized blends are higher than those of unvulcanized blends. The time–temperature superposition and Cole–Cole analysis were made to understand the phase behavior of the blends. The tensile and tear fracture surfaces were examined by a scanning electron microscope to gain an insight into the failure mechanism. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2189–2211, 2000     

Evaluation of the properties of some nitrile–butadiene rubber/polychloroprene mixes and vulcanizates

Nitrile–butadiene rubber (NBR) has been blended with polychloroprene (CR) in a weight ratio of 1:1. The vulcanizing systems in the blend formulations were varied to obtain non crosslinked CR embedded in vulcanized NBR and non crosslinked NBR embedded in vulcanized CR. The effects of these two different phases on the rheological and mechanical characteristics were evaluated. In addition, the dynamic compliance of the blends was measured over wide ranges of frequency and temperature. It has been found that the mechanical and rheological properties of the vulcanized blends depend on the type of vulcanizing system, its concentration and the presence of reinforcing filler. The mechanical properties of the blend containing N‐cyclohexyl‐2‐benzthiazyl sulphenamide/S as vulcanizing system suitable for NBR are higher than those of the blend containing non‐sulfur vulcanizing system (Zno/Mgo and ethylene thiourea) suitable for CR. Both types of rubber (CR and NBR) in the blend are incompatible as two glass transition temperatures have been observed. Copyright © 2000 John Wiley & Sons, Ltd.     

Compatibilization of PA6/rubber blends by using an oxazoline functionalized rubber

The compatibilization of blends of polyamide 6 with a nitrile butadiene rubber has been investigated. The procedure consists of two steps: modification of the nitrile groups of the rubber into oxazoline in the melt through condensation of ethanolamine with formation of a molecule of ammonia, followed by use of the modified rubber as a compatibilizing precursor which is melt mixed with the polyamide to produce the compatibilized blend. The modification reaction has been detected by NMR analysis and a rheological, mechanical and thermomechanical characterization has been carried out on the all the blends. The results indicate that the modification reaction occurs but the conversion of nitrile into oxazoline is relatively low. Use of the modified rubber in the preparation of binary polyamide/rubber blends, leads to an increase in viscosity, which is typical of compatibilized systems, and to enhanced tensile, impact and thermomechanical properties. These phenomena can be explained by the formation of in situ rubber/polyamide copolymers that act as compatibilizers, due to the reaction between oxazoline and the end groups of the polyamide. The presence of residual low molecular compounds, from the modification or from the purification of the rubber worsens all of the properties and inhibits the compatibilizing effect of the modified rubber.     

Development of novel elastomeric blends derived from chlorinated nitrile rubber and chlorinated ethylene propylene diene rubber

Chlorinated nitrile rubber (Cl-NBR) has been blended with chlorinated ethylene propylene diene rubber (Cl-EPDM) in different ratios by a conventional mill mixing method. The effect of the blend ratio on processing characteristics, mechanical properties (such as tensile and tear strength, elongation at break, hardness, abrasion resistance, heat build-up and resilience), structure, morphology, glass transition temperature (Tg), thermal stability, flame retardancy, oil resistance, AC conductivity, dielectric properties and transport behavior of petrol, diesel and kerosene were investigated. The shift in absorption bands of blends studied from FTIR spectra, single Tg from DSC analysis and decrease in amorphous nature from XRD showed the molecular miscibility in Cl-NBR/Cl-EPDM blends. SEM images showed the uniform mixing of both Cl-NBR and Cl-EPDM in a 50/50 blend ratio. The TGA curves indicated the better thermal stability of the polymer blend. The elongation at break, heat build-up, resilience and hardness of the polymer blend decreases with an increase in Cl-NBR content in the blend whereas the flame and oil resistance were increased with increase in Cl-NBR content. Among the polymer blends, the maximum torque, tensile strength, tear and abrasion resistance was obtained for the 50/50 blend ratio because of the effective interfacial interactions between the blend components. AC conductivity and dielectric properties of polymer blend increased with increase in the ratio of Cl-NBR in the blend. Different transport properties such as diffusion, permeation and sorption coefficient were measured with respect to nature of solvent and different blend ratios. Temperature dependence of diffusion was used to estimate the activation parameters and the mechanism of transport found to be anomalous.