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

The 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     

共混比对丁腈橡胶/氯醚橡胶性能的影响

研究了共混比时常规共混及动态硫化共混丁腈橡胶(NBR)／氯醚橡胶(ECO)的力学性能及加工流变性能的影响。结果表明,共混比对NBR／ECO胶料的力学性能及加工流变性能影响显著。NBR经动态硫化后,压缩永久变形及挤出胀大明显减小,拉伸强度提高,表现黏度随ECO用量的增大而减小。共混比对常规共混胶的表观黏度影响不大。动态硫化有利于改善NBR／ECO胶料的加工性能。     

Effect of dynamic vulcanization on properties and morphology of nylon/SAN/NBR blends: A new compatibilization method of nylon/ABS blends

Dynamically vulcanized blends of nylon, styrene–acrylonitrile copolymer (SAN), and nitrile–butadiene rubber (NBR) were examined for mechanical properties, Shore D hardness, Vicat softening temperature, impact process, and phase morphology. The effect of a curing system such as phenolic formaldehyde resins (PF), dicumylperoxide (DCP), and a sulfur system on the mechanical properties of the nylon/SAN/NBR blends was studied, and dynamic vulcanization with a PF system was found to lead to outstanding toughness of the blends. The effect of PF content on the mechanical properties, Shore D hardness, and heat resistance of the nylon/SAN/NBR blends was also investigated. With increasing PF content the notched‐impact strength and Vicat softening temperature (VST) of the nylon/SAN/NBR (50/25/25) blends evidently improved, but tensile strength and Shore D hardness of the blends changed slightly. It can be concluded that the nylon/SAN/NBR (50/25/25) blends dynamically vulcanized by high‐content PF can attain excellent comprehensive mechanical properties, especially supertoughness, at room temperature. SEM was used to investigate the effect of dynamic vulcanization on disperse‐phase particle size, particle size distribution, and phase morphology. It was obvious that disperse‐phase particle size decreased with an increasing PF content. Thermal behavior and miscibility of dynamically vulcanized nylon/SAN/NBR with PF were investigated by DMTA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2057–2062, 2003     

Effect of acrylonitrile content of acrylonitrile butadiene rubber on mechanical and thermal properties of dynamically vulcanized poly(lactic acid) blends

We report here the morphology, thermal and tensile properties of poly(lactic acid) (PLA) blends composed of acrylonitrile butadiene rubber (NBR) with different acrylonitrile contents with/without dynamic vulcanization by dicumyl peroxide (DCP). The interfacial tension of PLA and NBR measured by contact angle measurement decreased as the acrylonitrile content of NBR decreased. Likewise, SEM images showed that the rubber particle size reduced with decreasing acrylonitrile content owing to the stronger interfacial adhesion between the PLA matrix and NBR domains. Incorporation of DCP at 1.0 phr for dynamic vulcanization led to higher crosslink density and, in turn, optimal tensile strength and tensile toughness as a result of the action of PLA‐NBR copolymer as a reactive compatibilizer. The dynamic vulcanization of the blends containing low acrylonitrile NBR gave the most improved tensile properties because the free radicals from DCP decomposition preferentially attacked the allylic hydrogen atoms or double bonds of the butadiene backbone. Accordingly, more NBR macroradicals were generated and probably more PLA‐NBR copolymers were produced. Moreover, further addition of DCP at 2.0 phr provided a large amount of crosslinked NBR gel, which significantly degraded the tensile properties. From the DSC results, dynamic vulcanization lowered the cold crystallization temperature, implying an improvement of cold crystallization. Finally, TGA results showed a higher degradation temperature as a function of DCP content, which suggested that thermal stability increased due to stronger interfacial adhesion as well as higher gel content. © 2019 Society of Chemical Industry     

Dynamically vulcanized acrylonitrile–butadiene–styrene terpolymer/nitrile butadiene rubber blends compatibilized by chlorinated polyethylene

Thermoplastic vulcanizates (TPVs) based on acrylonitrile–butadiene–styrene (ABS)/nitrile butadiene rubber (NBR) blends were prepared by dynamic vulcanization and then compatibilized by chlorinated polyethylene (CM). The effects of CM compatibilizer on the mechanical properties, Mullins effect, and morphological and dynamic mechanical properties of the TPVs were investigated systematically. Experimental results indicated that CM had an excellent compatibilization effect on the dynamically vulcanized ABS/NBR TPVs. Mullins effect results showed that the compatibilized ABS/NBR TPV had relatively lower internal friction loss than the ABS/NBR TPV, indicating the improvement of elasticity. Morphology studies showed that the fracture surfaces of ABS/CM/NBR TPVs were relatively smoother, indicating the improved elastic reversibility. DMA studies showed that the glass to rubber transition temperatures of ABS and NBR phases were slightly shifted toward each other with the incorporation of CM compatibilizer, which indicates the improvement of the compatibility. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40986.     

Properties and morphology of crosslinked butadiene-acrylonitrile rubber and polysulphide rubber (NBR/TM) blends

Blending of thermodynamically immiscible butadiene–acrylonitrile rubber (NBR) and polysulphide rubber (TM) results in superior performance materials as regards solvent resistance, and shows some unusual relations between the composition and properties of the blends obtained. Improved performance after vulcanization is probably because of better interphase bonding, resulting from NBR–TM co-crosslinking. Occurrence of such bonding and its role in amelioration of some of the blends’ properties are discussed in this paper. The effect of TM concentration and crosslinking system on vulcanization state and behaviour is studied by application of chemical, mechanical and thermal methods. © 1998 SCI.     

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     

Investigation of rheological,mechanical, and thermal properties of nanocomposites based on nitrile rubber-phenolic resin reinforced with nanographene

In this study, nanocomposites of acrylonitrile butadiene rubber (NBR)/phenolic resin/graphene nanoparticles (GNPs) were prepared using a two-roll mill. According to the results, the addition of GNPs increased the scorch time, vulcanization time, and viscosity of the blends. By adding phenolic resin and in the presence of a higher percentage of acrylonitrile, the modulus and tensile strength increased and the elongation at break decreased. The mechanical properties of the nanocomposites improved with increasing the amount of nanoparticles. The addition of 1.5 phr GNP to the blends containing NBR with 33% and 45% acrylonitrile increased the tensile modulus by 56% and 49%, respectively. The tensile properties of the nanocomposites were also investigated at 50, 25, and 75°C. It was observed that with increasing the amount of nanoparticles, the deterioration of the mechanical properties at elevated temperatures was reduced. Also, thermal stability increased with increasing the amount of nanoparticles in all the samples.     

Effect of the compatibility on the morphology and properties of acrylonitrile–butadiene rubber/polypropylene thermoplastic vulcanizates

In this study, the morphologies of three types of acrylonitrile–butadiene rubber (NBR)/polypropylene (PP) thermoplastic vulcanizates (TPVs) (with an NBR/PP blend ratio of 70/30) were compared. The TPVs were (1) an ultrafine fully vulcanized acrylonitrile–butadiene rubber (UFNBR)/PP TPV made by the mechanical blending of UFNBR with PP, (2) a dynamically vulcanized NBR/PP TPV without the compatibilization of maleic anhydride grafted polypropylene (MP) and amine‐terminated butadiene–acrylonitrile copolymer (ATBN), and (3) a dynamically vulcanized NBR/PP TPVs with the compatibilization of MP and ATBN. The influence of the compatibility therein on the size of the dispersed vulcanized NBR particles and the crystallization behavior of the PP in the TPVs and the resultant properties are also discussed. As indicated by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, polarizing microscopy, dynamic mechanical thermal analysis, and rheological and mechanical testing, the compatibility was significantly improved by the reactive compatibilization of MP and ATBN, which led to a uniform and fine morphology. The compatibilization increased the crystallization rate and reduced the size of the spherulites of PP. On the other hand, it was found that the dispersed vulcanized NBR particles lowered the degree of crystallinity. The better the compatibility of the blend was, the lower the degree of crystallinity and the storage modulus were, but the higher the loss factor and the processing viscosity were. All TPVs showed almost the same oil resistance, but the TPV prepared with reactive compatibilization had the best mechanical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Swelling and mechanical properties of (acrylonitrile‐butadiene rubber)/(hydrogenated acrylonitrile‐butadiene rubber) blends with precipitated silica filled in gasohol fuels

This work studied the effects of hydrogenated acrylonitrile‐butadiene rubber (HNBR) and precipitated silica (PSi) loadings in acrylonitrile‐butadiene rubber (NBR) filled with 60 parts per hundred of rubber (phr) of carbon black (CB) for oil‐resistant seal applications in contact with gasohol fuel. The cure characteristics, mechanical properties, and swelling behavior of HNBR/NBR blends reinforced with PSi before and after immersion in ethanol‐based oils (E10, E20, and E85) were then monitored. This work studied the effects of PSi loading in rubber compounds on the mechanical properties of the rubber blends. The results suggested that the scorch time of CB‐filled NBR/HNBR was not affected by HNBR loading, but the cure time, Mooney viscosity, and torque difference increased with HNBR content. The swelling of the blends in E85 oil were relatively low compared with those in E10 and E20 oils. The recommended NBR/HNBR blend ratio for oil‐resistant applications was 50/50. Tensile strength and elongation at break before and after immersion in gasohol oils increased with HNBR loading, and the opposite effect was found for tensile modulus and hardness. PSi filler had no effect on scorch time, but decreased the cure time of the blends. The swelling level of the blends slightly decreased with increasing PSi content. The recommended silica content for optimum reinforcement for black‐filled NBR/HNBR blend at 50/50 was 30 phr. The results in this work suggested that NBR/HNBR blends reinforced with 60 phr of CB and 30 phr of silica could be potentially used for rubber seals in contact with gasohol fuels. J. VINYL ADDIT. TECHNOL., 22:239–246, 2016. © 2014 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.     

Mechanical properties and microstructure of acrylonitrile–butadiene rubber vulcanizates reinforced by in situ polymerized phenolic resin

The phenolic resin (PF) was incorporated into acrylonitrile–butadiene rubber (NBR) vulcanizates by in situ polymerization during the vulcanization process. It was found that the tensile strength, tearing strength, and tensile strength (300% elongation) could be considerably enhanced 59.4, 80.2, and 126.4%, respectively, at an optimum PF content of only 15 phr, but the elongation at break and shore A hardness were only slightly affected on the basis of silica‐reinforced NBR vulcanizates. A systematic study of the PF structure formed within the NBR matrix using various experimental schemes and procedures has revealed that the PF resin would form the localized discontinuous three‐dimensional interconnected network structures in the NBR matrix. The substantial reinforcement of PF on the mechanical properties of vulcanized NBR were attributed to the morphology, high flexibility, and moderate stiffness of the PF phases and their excellent bonding with rubbers through “rubber to rubber” and interface layer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Influences of the phenolic curative content and blend proportions on the properties of dynamically vulcanized natural rubber/acrylonitrile–butadiene–styrene blends

The vulcanization of natural rubber (NR)‐blended acrylonitrile–butadiene–styrene (ABS) was carried out with a phenolic curing agent by a melt‐mixing process. The NR compound was first prepared before blending with ABS. The effects of the phenolic curative contents (10, 15, and 20 phr) and blend proportions (NR/ABS ratio = 50 : 50, 60 : 40, and 70 : 30) on the mechanical, dynamic, thermal, and morphological properties of the vulcanized NR/ABS blends were investigated. The tensile strength and hardness of the blends increased with increasing ABS content, whereas the elongation at break decreased. The strength property resulting from the thermoplastic component and the vulcanized NR was an essential component for improving the elasticity of the blends. These blends showed a greater elastic response than the neat ABS. The thermal stability of the blends increased with increasing ABS component. Scanning electron micrographs of the blends showed a two‐phase morphology system. The vulcanized 60 : 40 NR/ABS blend with 15‐phr phenolic resin showed a uniform styrene‐co‐acrylonitrile phase dispersed in the vulcanized NR phase; it provided better dispersion between the NR and ABS phases, and this resulted in superior elastic properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42520.     

Microencapsulation of sulfur in poly(urea–formaldehyde)

Poly(urea–formaldehyde) (PUF) microcapsules loaded with sulfur were prepared by in situ polymerization. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry and thermogravimetric (TG) analysis were used for the characterization of the obtained microcapsules. The chemical structure of the microcapsules was determined by FTIR. SEM analysis showed that the microcapsules were spherical and that the mean diameter of microcapsules was 42 ± 1 μm. Thermal analysis showed that the microcapsules were thermally stable below 247°C. The release properties of sulfur from the PUF microcapsules during the vulcanization of acrylonitrile–butadiene rubber (NBR) were studied by analysis of the vulcanization properties. The results show that at a vulcanizing temperature of 160°C, all of the sulfur entrapped in PUF was released out through the microcracks and pores of the shell, and the curing time of the microcapsule curing system compared with that of the sulfur curing system was longer. The mechanical properties of the NBR vulcanized by sulfur microcapsules were better than those of the NBR vulcanized by sulfur. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical and thermo-oxidative properties of blends of poly(vinyl chloride) with epoxidized natural rubber and acrylonitrile butadiene rubber in the presence of an antioxidant and a base

Being polar and compatible with poly(vinyl chloride), epoxidized natural rubber (ENR) is similar in behaviour to acrylonitrile butadiene rubber (NBR). To assess the extent of this similarity, the mechanical properties of 50/50 blends of PVC with these two rubbers were compared. Their response to thermo-oxidative ageing in the presence of an antioxidant and a base was also investigated by ageing the blends at 100°C for 7 days. Studies involving mechanical properties and FTIR were used to evaluate the extent of thermal degradation. The results revealed that blends of ENR show mechanical properties which are as good as, and in some instances better than, those of the NBR blends. However, the ENR blends with PVC are very prone to oxidative ageing. This might be attributed to the susceptibility of the oxirane group to ring-opening reactions, particularly in the presence of PVC, which yields HCl as it degrades. The amine-type antioxidant 2,24-trimethyl-1,2-dihydroquinoline (TMQ) improved the oxidative stability of both blends. This was more significant in the ENR blend, which in some cases attained stability comparable with that of NBR. The addition of a base, calcium stearate [Ca(St)₂], did not show any influence in the PVC/ENR blend, even though it was expected to curb acid-catalysed degradation. Ca(St)₂, however, improved the oxidative stability of the PVC/NBR blend. The combination of optimum amounts of TMQ and Ca(St)₂ effectively improved the tensile strength of both unaged blends, without appreciable adverse effect on elongation at break. This combination also imparted stability better than that of TMQ alone.     

Effects of methylene diphenyl diisocyanate on the physical,mechanical, and vulcanization properties of nitrile rubber

In this research, methylene diphenyl diisocyanate (MDI) was added to an acrylonitrile–butadiene rubber (NBR) compound as an additive, and its effects on the vulcanization of the rubber investigated. For this purpose, MDI was added at different concentrations (5, 10, and 20 phr) to the rubber compound. The rubber properties, including the rheometry and tensile strength, were investigated. Differential scanning calorimetry and swelling tests were used to assess the vulcanization mechanism and chemical reactions in the presence of MDI. Finally, Fourier transform infrared spectroscopy analysis was used to study the chemical structure of the NBR–MDI cured compounds. We found that MDI played a more important role than the additive in the NBR compound. It acted as a covulcanizing agent along with the sulfur groups. The 10 phr MDI content was found to be the optimum content for achieving the best NBR–MDI properties. This content increased the crosslinking density of the compound and decreased the swelling of NBR in toluene. We also found that MDI adsorbed the accelerator agents and sulfur groups, so it decreased the rate of vulcanization, especially at early ages. Furthermore, it reacted with NBR and produced strong urea (i.e., NH? CO? NH) and thiourethane groups (i.e., S? CO? NH), and this increased NBR's structural strength. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45200.     

Comparison of Properties of Polypropylene (PP)/Virgin Acrylonitrile Butadiene Rubber (NBRv) and Polypropylene (PP)/Recycled Acrylonitrile Butadiene Rubber (NBRr) Blends

The comparison properties of polypropylene (PP)/recycled acrylonitrile butadiene rubber (NBRr) blends and polypropylene/virgin acrylonitrile butadiene rubber (NBRv) blends were investigated. The tensile properties such as tensile strength, tensile modulus and elongation at break of PP/NBRv blends are higher than PP/NBRr blends. However, PP/NBRv blends exhibit lower stabilization torque and higher swelling percentage than PP/NBRr blends. Based on SEM, a finer morphology was observed in PP/NBRv blends in comparison with the PP/NBRr blends. The thermal stability of PP/NBRr is better than that of PP/NBRv blends.     

Compatibilization of nitrile‐butadiene rubber/ethylene‐propylene‐diene monomer blends by mercapto‐modified ethylene‐vinyl acetate copolymers

Mercapto‐modified ethylene‐vinyl acetate (EVASH) has been employed as a reactive compatibilizing agent for nitrile‐butadiene rubber (NBR)/ethylene‐propylene‐diene monomer (EPDM) blends vulcanized with a sulfur/2,2′‐dithiobisbenzothiazole (MBTS) single accelerator system and a (sulfur/MBTS/tetramethylthiuram disulfide (TMTD) binary accelerator system. The addition of 5.0 phr EVASH resulted in a significant improvement in the tensile properties of blends vulcanized with the sulfur/MBTS system. In addition to better mechanical performance, these functionalized copolymers gave rise to a more homogeneous morphology and, in some cases, better aging resistance. The compatibilization was not efficient in blends vulcanized with the S/MBTS/TMTD binary system, probably because of the faster vulcanization process occurring in this system. The good performance of these EVASH samples as compatibilizing agents for NBR/EPDM blends is attributed to the higher polarity of these components that is associated with their lower viscosity. Dynamic mechanical analysis also suggested a good interaction between the phases in the presence of EVASH. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1404–1412, 2004     

Failure properties of thermoplastic elastomers from polyethylene/nitrile rubber blends: Effect of blend ratio,dynamic vulcanization,and filler incorporation

Thermoplastic elastomers from blends of high‐density polyethylene and acrylonitrile butadiene rubber were prepared by a melt‐blending technique. The blends were dynamically vulcanized using sulfur, peroxide, and mixed curing systems. The peroxide concentration was varied to obtain samples of varying degrees of crosslinking. The peroxide system showed better mechanical properties. The crosslink density determination by the equilibrium swelling method revealed that the enhancement in properties can be correlated to the extent of crosslinking. It is observed that the effect of dynamic vulcanization on the property improvement is much more pronounced in rubber‐rich blends. To study the effect of filler incorporation on mechanical properties, fillers such as carbon black, silica, silane‐treated silica, and cork‐filled samples were prepared. All filled systems, except cork filled, exhibited superior mechanical properties. Scanning electron micrographs of selected fractured surfaces were analyzed to study the failure mechanism of the different compositions. Various theoretical models were applied to correlate the observed mechanical behavior with that of theoretically predicted values. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2912–2929, 2006     

Mechanical,Water-Swelling,and Morphological Properties of Water-Swellable Thermoplastic Vulcanizates Based on High Density Polyethylene/Chlorinated Polyethylene/Nitrile Butadiene Rubber/Cross-Linked Sodium Polyacrylate Blends

A novel water-swellable rubber (WSR) had been prepared by dynamically vulcanized high density polyethylene (HDPE)/chlorinated polyethylene (CPE)/nitrile butadiene rubber (NBR) blends where a cross-linked poly(sodium acrylate) (CPNaAA) was used as a super water-absorbent resin. The mechanical, water-swelling and morphological properties of the WSRs were investigated. Increasing CPNaAA dosages, mechanical properties of WSRs decreased while water-swelling ratio were increased significantly; moreover, swelling ratio of WSRs with 70 phr CPNaAA was reached 956.7% at 55 h. Morphological studies showed that CPNaAA were dispersed randomly in the TPVs, and significant gaps could be found in the surface of dried WSRs.