Mechanical properties of PVC/SBR blends compatibilized by acrylonitrile-butadiene rubber and covulcanization

The mechanical properties of poly(vinyl chloride) (PVC)/styrene-butadiene rubber (SBR) blends compatibilized by acrylonitrile-butadiene rubber (NBR) were studied. A sulfur curing system was employed to crosslink the rubber of the blends. In the case of the blends without any curing agents, an increase in NBR content did not improve the tensile strength and elongation-at-break. However, a significant improvement in the mechanical properties was observed when NBR was added as a compatibilizer and the blend was vulcanized. In the PVC/NBR/SBR (50/10/40) blends, the tensile strength and elongation-at-break increased with an increase in sulfur concentration. This improvement was attributed to covulcanization between NBR and SBR. The fracture toughness of PVC/NBR/SBR (50/10/40) blends was characterized by the critical strain energy release rate, G_c. In the case of the PVC/NBR-29/SBR (50/10/40) blends, an increase in sulfur concentration resulted in a dramatic increase in G_c. However, the G_c value of PVC/NBR-40/SBR (50/10/40) blends decreased with an increase in sulfur concentration owing to the brittle behavior of one of the blend components—the PVC/NBR-40 (50/10) phase.     

丁腈橡胶/聚氯乙烯共混胶

探讨了丁腈橡胶(NBR)中的结合丙烯腈质量分数、NBR／聚氯乙烯(PVC)(质量比,下同)、增塑剂邻苯二甲酸二辛酯(DOP)用量、PVC聚合度对NBR／PVC共混胶性能的影响,研究了NBR／低聚合度PVC共混胶的力学性能及加工流动性能。结果表明,随着NBR中结合丙烯腈质量分数的增加,NBR／PVC共混胶的耐油性能明显增强,力学性能也相应有所改善;NBR／PVC为80／20～60／40时．NBR／PVC共混胶的综合性能较好;DOP用量对NBR／PVC共混胶性能的影响不大;聚合度为700的PVC更适合于生产NBR／PVC共混胶,其力学性能、加工流动性能、耐老化性能与德国Bayer公司生产的牌号为Perbunan NT／VC3470B的NBR／PVC共混胶相当。     

Morphology evolution of immiscible LDPE/PVC blends in the presence of compatibilizer and phase dispersant

Phase dispersion and coalescence in low‐density polyethylene (LDPE)/polyvinyl chloride (PVC) (70/30) blends influenced by compatibilizer and phase dispersant was studied. It was found that the morphology evolution of blends is sensitive to not only processing conditions (shear strength and mixing time) but also the added compatibilizer or phase dispersant. In our conditions, the stable phase morphology of each blend is obtained after mixing 15–25 min. In addition, the dispersed PVC phase in blends is easy to aggregate when the mixing rotor speed changed from high to low for the binary blends. As a compatibilizer, chlorided polyethylene (CPE) or nitrile rubber (NBR) can stabilize the morphology and hinder the coalescence of the dispersed PVC phase when added to the blends. However, the phase dispersant butadiene rubber (BR) or styrene butadiene rubber (SBR) could not stabilize the phase structure, although it could accelerate phase dispersion. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 763–772, 2004     

Compatibilization of SBR/NBR Blends Using Poly Acrylonitrile as Compatibilizer

Blends of styrene-co-butadiene rubber (SBR) and acrylonitrile-co-butadiene rubber (NBR) were prepared and their rheological and mechanical properties were examined. The effect of the addition of 5 phr of poly acrylonitrile as compatibilizer on the compatibility of the rubber blend was studied. Ultrasonic and scanning electron microscopy (SEM) techniques were used to assess the degree of compatibility of the blend. The results revealed that the use of the prepared compatibilizer has significantly resulted in the clear stability of the cure rate index (CRI) of the blends and that the tensile strength was improved at (50/50) SBR/NBR blend. The degree of compatibility was enhanced to a great extent.     

Poly(vinyl chloride)/styrene-butadiene rubber blends prepared by dynamic vulcanization with nitrile rubber as the compatibilizer

A new kind of thermoplastic elastomer is obtained by dynamic curing of PVC/SBR blends. A compatibilizer is necessary, and of three tested—NBR and two ABSs—NBR-18 is the best. Sulfur and Dicumyl peroxide were chosen as the two different curing agents for the blends. The curing agent and its concentration have a dramatic effect on the mechanical properties. Di(2-ethyl hexyl)phthalate was used as the plasticizer for PVC. Variations in the PVC and di(2-ethyl hexyl)phthalate concentrations can produce materials having a wide range of hardness and strength to meet the needs of different applications. The effects of processing parameters such as blending time and processing temperature and the effect of filler in the blend on the mechanical properties were also investigated. The material, after processing five times, showed no significant changes in physical properties. © 1995 John Wiley & Sons, Inc.     

Micromechanical properties on the surface of PVC/SBR blends spatially resolved by a nanoindentation technique

The microhardness and micromodulus on the surface of poly(vinyl chloride) (PVC)/styrene‐butadiene rubber (SBR) blends were determined using a nanoindenter. A flat surface was obtained by microtoming the sample at ?100°C in liquid nitrogen. Dozens of indents along a line with a spatial interval of 0.5 μm were performed. From the loading and unloading curves of each indentation, the stiffnesses of the unloading curve and the contact area between the sample and the indenter were evaluated, and the local modulus and hardness were calculated. Profiles of the local hardness and modulus were obtained from the lines of indents. Pure PVC and a miscible PVC/acrylonitrile‐butadiene rubber (NBR) (40/10) blend showed constant modulus and hardness values. In the case of an immiscible PVC/SBR (50/50) blend, which has a morphology of elongated PVC droplets in the SBR matrix, the hardness and modulus profiles showed regions of the different phases. At the interface between the SBR and PVC phases, a step change in the modulus and hardness profiles was observed. The force required to deform the material at the same displacement increased systematically across the interface from the SBR to the PVC phase because of the increasing contribution of the PVC phase. Polym. Eng. Sci. 44:609–614, 2004. © 2004 Society of Plastics Engineers.     

A Study of FTIR,Thermal Properties and Natural Weathering Test on NBRVirgin/Recycled with SBR Blends

The effects of styrene butadiene rubber/virgin acrylonitrile butadiene rubber (SBR/NBRv) blends and styrene butadiene rubber/recycled acrylonitrile butadiene rubber (SBR/NBRr) blends on properties such Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were carried out. Results indicated that, based on intensity of amine peak from FTIR at 85/15 blend ratio (R15) revealed optimum formation of crosslink between SBR and NBR either using virgin or NBRr. TG thermograms of SBR/NBRv blends of all ratios showed better onset thermal stability than SBR/NBRr blends. The change in the horizontal baseline from high to low energy level occurred in virgin NBR blends because the amount of reactive sites available in virgin NBR is higher compared to NBRr. Meanwhile NBRr blends showed T_c because the amount of crosslink occurred in these blends were slightly lower than NBRv blends. Up to 25 phr of NBRr, the tensile strength and elongation at break (E_b) retention of SBR/NBRv blends was better than SBR/NBRr blends after 6 months' weathering test except for M100. The scanning electron microscopy on the surface of both blends after 6 months exposure indicated that the severity of the crack was minimal for SBR/NBRr blends compared to SBR/NBRv particularly at 50/50 blend ratio designated the SBR/NBRr blends that contained more NBRr particles could reduce the degradation towards natural weathering.     

Homogeneous Styrene Butadiene/Acrylonitrile Butadiene Rubber Blends

The graft copolymerization of acrylonitrile (AN) onto butadiene rubber (BR) was carried out in toluene at 80°C, using dibenzoyl-peroxide (BPO) as initiator. The synthesized poly acrylonitrile-grafted-butadiene rubber (AN-g-BR) was characterized by N% elemental analysis and Fourier-transform infrared (FT-IR) spectroscopy. Styrene butadiene rubber/acrylonitrile butadiene rubber (SBR/NBR) blends were prepared with different blend ratios in presence and absence of AN-g-BR, where the homogeneity of such blends were examined with intrinsic viscosity (η) measurements, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The scanning electron micrographs illustrate disappearance of the macro-scale phase separation of SBR/NBR rubber blend as a result of the incorporation of AN-g-BR into that blend. Viscosity measurements confirm homogeneity of that blend. Differential Scanning Calorimetry traces exhibit shifts in glass transition temperatures (T _g's) of SBR and NBR in their blend, indicating some degree of homogeneity. Physico-mechanical properties of the rubber blend vulcanizates with different blend ratios, in presence and absence of AN-g-BR, were investigated before and after accelerated thermal aging. The SBR/NBR (25/75) homogeneous blend possessed the best physico-mechanical properties after thermal aging, together with the best swelling behavior in motor oil. The physico-mechanical properties of SBR/NBR (25/75) filled blend with different types of inorganic fillers during thermal aging were studied.     

Effect of NBR partitioning agent on the mechanical properties of PVC/NBR blends and investigation of phase morphology by atomic force microscopy

Poly(vinyl chloride) (PVC)/acrylonitrile–butadiene rubber (NBR) blends with different types of partitioning agent were obtained through melt blending. The samples were characterized according to the viscosities properties, torque rheometry and mechanical resistance as tensile testing, tear strength, and hardness. The morphology and phase imaging were studied using an atomic force microscopy operating in tapping mode (TMAFM). It was observed that the PVC/NBR blends with PVC as partitioning agent showed an increase in the tensile stress and Young’s modulus compared to the PVC/NBR blends with calcium carbonate as partitioning agent. The morphology of the blends examined by TMAFM evidenced the effect of the partitioning agent as obtained with other techniques.     

高岭土增强PVC/橡胶非硫化复合体系的研究

研究了橡胶种类及用量、增塑剂用量、表面处理剂种类及用量对聚氯乙烯／橡胶非硫化复合体系力学性能的影响,并用扫描电镜分析了有机胺类表面处理剂改性高岭土／聚氯乙烯／丁腈橡胶的界面结合状况。结果表明,当丁腈橡胶（NBR）用量为30份,增塑剂DOP用量为60份,表面处理剂1质量分数为3％,并且填有60份的高岭土时,可得到力学性能较佳的高岭土／聚氯乙烯／丁腈橡胶共混物。     

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     

Effects of rubber curing ingredients and phenolic-resin on mechanical,thermal, and morphological characteristics of rubber/phenolic-resin blends

This article examines the physical and mechanical characteristics of mixtures of two different synthetic rubbers, namely styrene-butadiene rubber (SBR) and nitril-butadiene rubber (NBR), with novolac type phenolic-resin (PH). According to Taguchi experimental design method, it is shown that the addition of PH increases the crosslinking density of rubber phase probably due to its curative effects. Thermal analysis of the blends indicates that, contrary to NBR/PH blend, thermal stability of SBR/PH blend is dependent on sulfur content due to predominant polysulfidic crosslinks formed in SBR. Slight shift in glass-transition temperature (T_g) of pure SBR and NBR vulcanizates by the addition of PH suggests that both SBR/PH and NBR/PH are incompatible blends with a partially soluble PH in the rubber phase. Two-phase morphology of the mixtures is also evidenced by scanning electron microscopy. Correlation of the rubber/PH modulus versus PH concentration by Halpin-Tsai model shows a deviation from the model. Presence of PH in the rubber phase is thought to vary the mechanical properties of the rubber phase by changing both the crosslinking density and rigidity of the molecular network of the rubber, leading to misuse of modulus of pure rubber in Halpin-Tsai equation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Compatibilization of SBR/NBR blends using chemically modified styrene‐co‐butadiene rubber Part 2. Effect of compatibilizer loading

The present work focuses on the compatibization of styrene‐co‐butadiene rubber (SBR)/acrylonitrile‐co‐butadiene rubber (NBR) blends with dichlorocarbene modified styrene‐co‐butadiene rubber (DCSBR) as a function of concentration of compatibilizer and composition of the blend. FTIR studies, differential scanning calorimetry and dynamic mechanical analysis reveal molecular level miscibility in the blends in the presence of compatibilizer. The formation of interfacial bonding is assessed by analysis of swelling behaviour, cure characteristics, stress–strain data and mechanical properties. These studies show that the compatibilizing action of DCSBR becomes more prominent as the proportion of NBR in the blend increases. The resistance of the vulcanizate towards thermal and oil ageing improved with compatibilization. The change in technological properties is correlated with the crosslink density of the blends assessed from swelling and stress–strain data. © 2001 Society of Chemical Industry     

Effect of epoxidized natural rubber on thermal properties,fatigue life,and natural weathering test of styrene butadiene rubber/recycled acrylonitrile‐butadiene rubber (SBR/NBRr) blends

The utilization of waste rubber powder in polymer matrices provides an attractive strategy for polymer waste disposal. Addition of recycled acrylonitrile‐butadiene rubber (NBRr) in rubber compounds gives economic (lowering the cost of rubber compounds) as well as processing advantages. In this study, the properties of styrene butadiene rubber (SBR)/NBRr blends with and without epoxidized natural rubber (ENR‐50) as a compatibilizer were determined. The results such as thermal gravimetric analysis (TGA), fatigue life, and natural weathering test of SBR/NBRr blends with and without ENR‐50 were carried out. Results showed that TG thermograms of SBR/NBRr blends with ENR‐50 show lower thermal stability compared blends without ENR‐50. The incorporation of ENR‐50 into SBR/NBRr blends has reduced char residue compared SBR/NBRr blends without ENR‐50. The incorporation of ENR‐50 in SBR/NBRr blends has increased the rigidity of the blends thus lowering the fatigue life. The increment in tensile properties retention of SBR/NBRr blends with ENR‐50 indicated the enhancement on weathering resistant. The surfaces of SBR/NBRr blends with ENR‐50 after 6 months exposure showed a minimal severity of crack compared with SBR/NBRr blends without ENR‐50. It revealed that the scale of cracks has reduced indicating well‐retaining interfacial adhesion between SBR and NBRr with the presence of ENR‐50 as a compatibilizer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The effect of glycidyl methacrylate and styrene comonomers on compatibility,physical-mechanical properties,and swelling behavior of SBR/NBR blends

The effect of functionalized styrene-butadiene rubber (SBR) with glycidyl methacrylate (GMA) monomers, in the presence of styrene comonomers (SBR-g-GMA-co-St) as a compatibilizer on physical-mechanical, morphological, and swelling behavior of SBR/nitrile butadiene rubber (NBR) blends were studied. It was proved that the compatibilizer made through dicumyl peroxide-induced reaction which possessed 1.5 phr GMA in addition to 1.5 phr styrene comonomers showed higher efficiency of grafting. Possible in situ reactions between SBR-g-GMA-co-St and NBR component also were evaluated with an attenuated total reflectance mode of Fourier-transform infrared spectroscopy. SBR/NBR blend containing compatibilizer with a middle value of grafting demonstrated the most reactions between components. Dynamic mechanical thermal analysis results illustrated that the presence of SBR-g-GMA-co-St caused a significant improvement in compatibility of two components. This was verified with the scanning electron microscope pictures in which a smoother surface of the sample was clear. The enhancement in microstructure led to an increase in tensile strength, elongation at break, and storage modulus. Moreover, the increase in the intermolecular cross-links and made interactions considerably affected blends' swelling behavior in both hydrocarbon solvents (carbon tetrachloride and chloroform).     

Morphology and dynamic mechanical properties of natural rubber/nitrile rubber blends containing trans‐polyoctylene rubber as a compatibilizer

The use of trans‐polyoctylene rubber (TOR) as a compatibilizer for blends of natural rubber (NR) and acrylonitrile‐butadiene rubber (NBR) was investigated using atomic force microscopy (AFM) and dynamic mechanical analysis (DMA). The NR/NBR blends containing varying proportions of TOR were prepared in an internal mixer. AFM micrographs of NR/NBR blend at 50/50 (w/w) composition showed heterogeneous phase morphology with NR as a matrix and NBR as a dispersed phase. Inclusion of TOR in the NR/NBR blend altered the phase morphology by reducing the size of the NBR phase. DMA of NR/NBR/TOR showed reduction in tan δ peak height of NBR and an increase in storage modulus E′ in the rubbery region for the NR/NBR blends. A comparison of the E′ obtained from experimental data with that from theoretical models was made to deduce the location of TOR in the blend. Based on the fittings of calculated and experimental values of E′, it was inferred that TOR was incorporated into the NR phase at lower proportion as well as at the interfacial region at higher proportion. The Cole–Cole plot illustrated the compatibilizing effect of TOR. Copyright © 2004 Society of Chemical Industry     

动态硫化PVC/SBR共混体系的研究

采用动态硫化法制备了ＰＶＣ／ＳＢＲ共混物，考察了橡塑比、硫化体系、相容剂及ＰＶＣ交联对共混物性能的影响。结果表明，当ＰＶＣ／ＳＢＲ并用比为７５／２５，相容剂ＮＢＲ／氯化聚乙烯并用比为２．５／２．５，采用半有效或半有效加２份交联剂ＤＣＰ的硫化体系时，共混物综合性能较好。在ＰＶＣ中加入０．４份促进剂ＮＡ－２２可明显改善共混物的压缩永久变形。