Study on the damping of EVM based blends

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

Rheological and Mechanical Properties of Clay-Thermoplastic Elastomers Derived from PVC and NBR

Based on the character of a clay that could be separated into many 1-nm thickness monolayers, clay poly(vinylchloride)-nitrile butadiene rubber (PVC/NBR) thermoplastic elastomers (TPEs) were acquired using a Brabender Plasticorder at 150°C and 50 rpm rotor speed. Clay concentrations were progressively increased up to 10 phr of PVC/NBR composites. The rheological behavior of the clay PVC/NBR blends was assessed by dynamic mechanical analysis, as well as Brabender torque rheometry. The results revealed that the complex modulus (E?) and elastic modulus (E′) increased with clay loading, indicating that the actual strength of the blends improved. Tensile properties of the PVC/NBR-clay formulations with different filling amounts were studied. The results showed that the mechanical performance of the rubbery samples improved with clay loadings. The observed trend has been attributed to the reinforcing role played by layered clay due to better dispersion as well as improved interactions.     

新型配位交联硫酸铜/丁腈橡胶复合材料的影响因素

研究了金属盐填充的丁腈橡胶(NBR)材料。影响金属盐与NBR二者之间的配位交联反应的因素众多,如金属盐种类、金属盐含量、NBR中丙烯腈的含量、增塑剂、结晶水等等。本文通过对力学性能的分析,逐一考察了这些因素对二者配位交联反应的影响。结果发现,硫酸铜(CuSO4)是比较有效的一种可配位金属盐;当CuSO4含量、NBR中丙烯腈含量逐渐增加时,CuSO4与NBR的配位交联反应均逐渐增强,且随CuSO4含量增加,所得配位交联CuSO4/NBR显示出特殊而优异的力学性能。另外,在CuSO4/NBR体系中加入聚氯乙烯(PVC)或在CuSO4中引入结晶水均可有效提高CuSO4与NBR的配位效率。     

Mechanical Properties and Thermooxidative Aging of a Ternary Blend,Pvc/Enr/Nbr,Compared with the Binary Blends of Pvc

In the quest to improve the thermooxidative aging of the poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blend, nitrile rubber (NBR) was incorporated into the blend to yield a ternary blend of PVC/ENR/NBR. A Brabender Plasticorder with a mixing attachment was used to perform the melt mixing at 150°C and 50 rpm followed by compression molding. The mechanical properties, dynamic mechanical properties, and thermooxidative aging behavior of the ternary blend were compared with those of the binary blends (i.e., PVC/ENR and PVC/NBR). It was found that the ternary blend exhibits mechanical properties which are superior to those of PVC/ENR. A single glass transition temperature (T _g) obtained from dynamic mechanical analysis coupled with synergism in the modulus and some other mechanical properties indicate that PVC, ENR, and NBR form a single phase (miscible system) in the ternary blend. Di-2-ethyl hexylphthalate (DOP) plasti-cizer improves the aging resistance of the blends generally, whereas the presence of CaCO₃ as a filler only imparts minor influences on the properties and aging resistance of the blends.     

Irradiation Modification of PVC/NBR Blend

Electron beam initiated cross-linking on the 50/50 poly(vinyl chloride), PVC/acrylonitrile butadiene rubber, NBR blend was studied in the absence and presence of 4 phr trimethylolpropane triacrylate (TMPTA). The 50/50 NBR/PVC blend was prepared by mixing in a Brabender Plasticoder at 170°C. The blend was then irradiated by using a 3.0 MeV electron beam machine at doses ranging from 0 to 200 kGy in air and room temperature. The changes in gel fraction, tensile strength, hardness, impact strength, scanning electron micrographs and dynamic mechanical properties of the samples were investigated. The gel fraction results indicate that under the irradiation conditions employed, the PVC/NBR blend cross-linked by electron beam irradiation. The addition of TMPTA was found to be effective in the acceleration of the radiation-induced cross-linking. Gradual increases in mechanical properties with irradiation dose were observed before exhibiting a decline due to embrittlement as a consequence of excessive cross-linking at higher irradiation doses. The gradual changeover from ductile to brittle fracture due to the irradiation-induced cross-linking was evident from the SEM examination The increase in the storage modulus and T_g as well as the reduction in the damping peak with the increase in irradiation dose reveal that the enhancement in mechanical properties of NBR/PVC blends upon irradiation is due to the irradiation-induced cross-linking, as well as the improved interaction between NBR and PVC.     

Surface treatment of fluorinated rubber with triazine thiols and their properties

Fluorinated (FKM) vulcanizates were treated by immersing in an aqueous solution of triazine thiols, NaOH, and onium salts for 15–60 min at 50–95°C (W-Method). Treated FKM vulcanizates further were postcured in an air oven for 20 h at 200°C to complete the reaction. The onium salt of triazine thiols were found to be formed by a reaction among the triazine thiols, NaOH, and onium salts and to act as cross-linking agents to the surface of FKM vulcanizates. In the acetone solution of onium salts of triazine thiols, FKM vulcanizates were also treated by immersing for a few minutes at 20°C and then by heating in an air oven for 20 min at 200°C (A-Method). Triazine thiols were introduced as crosslinks onto the FKM backbone. The degree of cross-linking in the surface increased by these treatments and the depth of cross-linking reached up to about 40 μm thickness by control of treating conditions. The coefficient of friction in FKM vulcanizates decreased as a result of the surface treatment up to about 0.5 from 2.6. FKM vulcanizates decreased the tensile strength by these surface treatments because of the generation of cracks on the surface at 50% or 100% elongation. The surface treatment of FKM vulcanizates suppressed markedly the fixing between FKM vulcanizates and stainless steel at 150°C. Especially, the A-Method was very effective treating for retarding the fixing between FKM vulcanizates and metals. © 1994 John Wiley & Sons, Inc.     

Photodegradation of some poly(vinyl chloride) (PVC) blends: PVC/ethylene-vinyl acetate (EVA) copolymers and PVC/butadiene-acrylonitrile (NBR) copolymers

Poly(vinyl chloride) (PVC) and its blends with polybutadiene-acrylonitrile (NBR) (containing 21.7 weight-percent acrylonitrile (AN), a heterogeneous two-phase system; and containing 41.6 weight-percent of AN, a homogeneous one-phase system) and with polyethylene-vinyl acetate (EVA) (containing 45 weight-percent of vinyl acetate (VA), a heterogenous two-phase system; and containing 65 weight-percent VA, a homogeneous one-phase system) were UV-irradiated (at 3500 Å UV-light (solar spectrum)). After UV irradiation the kinetics measurements were made of the formation of hydroperoxy (OOH) and carbonyl (CO) groups and the changes of mechanical properties: tensile strength, elongation to break, and impact energy. As a result of the photooxidative degradation of PVC blends, decreases of mechanical properties were observed. The effects are more severe in PVC/NBR blends, which contain unsaturated bonds (polybutadiene segments) than in the case of PVC/EVA. The phase structure plays an evident role on the UV degradation only of PVC/NBR blends. The photostability of PVC blends can be slightly improved by introducing Tinuvin P or Ni-chelates photostabilizers.     

Compatibility and nonlinear viscoelasticity of polychloroprene/polyvinyl chloride blends with nitrile butadiene rubber as a compatibilizer

Miscible polychloroprene/polyvinyl chloride (CR/PVC) blends with nitrile butadiene rubber (NBR) as a compatibilizer were prepared. The effect of NBR on the compatibility between CR and PVC was mainly analyzed by studying the thermal behavior and the phase structure of CR/PVC blends. An obvious decrement in the T_g of PVC phase successfully provided an explanation for the compatibilization of NBR. Due to the improved compatibility between CR and PVC, the size of PVC particles in CR/PVC blends decreased a lot according to the scanning electronic microscopic images. The significant improvement of mechanical properties of CR/PVC blends was in good agreement with the better compatibility between CR and PVC phases. The softening effect of NBR on the nonlinear viscoelasticity of CR/PVC blends was also studied by RPA 2000. Temperature sweep test by RPA 2000, a less reported characterization method of T_g, was successfully applied to measure T_g of CR/PVC blends and study the compatibilization of NBR. The reason for better thermal stability and the thermal decomposition mechanism of CR/PVC blends were analyzed according to the results of TGA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42448.     

Preparation and characterization of polymethyltrifluoropropylsilicone modified acrylonitrile–butadiene rubber/fluorosilicon rubber blend

The blending of polymethyltrifluoropropylsilicone‐modified acrylonitrile–butadiene rubber (MNBR) and fluorosilicon rubber (FSR) at 70 : 30 ratio was investigated. The grafting of mercapto‐functionalized polymethyltrifluoropropylsilicone onto acrylonitrile‐butadiene rubber (NBR) by thiol‐ene reaction was carried out with 2,2′‐azobisisobutyronitrile as initiator in a Haake torque rheometer. The rheological properties of NBR grafting obtained at varying dosages of polymethyltrifluoropropylsilicone in a Haake torque rheometer were studied using torque curves. Grafting reaction was confirmed by ¹H nuclear magnetic resonance and energy‐dispersive X‐ray spectroscopy. Results of scanning electron microscopy and dynamic mechanical analysis showed better compatibility of MNBR/FSR blend than NBR/FSR reference blend. Meanwhile, the macro‐mechanical properties of the blend significantly improved. The tensile strength and tear strength of MNBR/FSR blend were improved to 14.34 MPa and 44.94 KN/m, respectively, which were 2.92 MPa and 13.03 KN/m higher than those of NBR/FSR reference blend. The low‐temperature brittleness of the blend was improved to ?57°C, an increase of ?6°C compared with that of NBR. These results indicated that MNBR/FSR blend at 70 : 30 ratio had improved compatibility because of the grafting chains that acted as interfacial agents. The low‐temperature resistance of the blend was also enhanced. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42328.     

Wood flour: A new filler for the rubber processing industry. I. Cure characteristics and mechanical properties of wood flour‐filled NBR and NBR/PVC compounds

In this study, conifer wood flour was evaluated as a filler to NBR or NBR/PVC compounds studying it influence on their cure characteristics and mechanical properties. It was shown that the filling by wood flour offers a possibility to obtain high modulus high elastic or less elastic or rigid wood like vulcanizates by varying of both the filling level and NBR/PVC mass ratio.It was established that in contrary to the mineral fillers usually causing significant delay of the vulcanization process, the wood flour shows a tendency to reduce the optimum cure time, τ₉₀. Modulus M₁₀₀ and Shore hardness of the wood flour‐filled vulcanizates of NBR or NBR/PVC compounds in which NBR is predominant, increase in a compliance with the increase of M_max and DM when the filling level increases. The dependence is other when NBR and PVC are in equal amounts or PVC predominates. As a most probable explanation of the effect of the wood flour on the cure characteristics is accepted, the influence of the wood flour polar groups as well as of the presenting as wood flour humidity water molecules, the specific mechanical properties of the wood flour‐filled NBR or NBR/PVC compounds could be connected (to some extend) with a specific interface interaction between the wood flour particles and the polymer matrix. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2734–2739, 2003     

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。     

硫化剂DTDM在NBR中应用的探讨

该文研究了以DTDM为硫化剂的硫化体系配合对NBR性能的影响。结果表明,DTDM硫化的NBR具有与TT硫化NBR相似的性能,拉伸强度、撕裂强度、伸长率较高,耐老化性较好;其硫化配合体系中DTDM用量以3份左右为好,促进剂以NOBS为佳;并用硫黄或TT后能改善胶料的某些性能。     

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.     

Rheological and mechanical properties of dynamically cured poly(vinyl chloride)/nitrile butadiene rubber thermoplastic elastomers

Plasticized poly(vinyl chloride)/nitrile butadiene rubber (PVC/NBR) thermoplastic elastomers (TPEs) were dynamically cured in the melt stage with the incorporation of a semi‐efficient curing system using a Brabender Plasticorder at 150 °C and rotor speed of 50 rev min^?1. Sulfur concentration was progressively increased from zero to 1 part per hundred NBR to study the effect of dynamic curing on mechanical and rheological behaviour of the TPEs. The compounds were characterized in respect of their rheological and mechanical properties. The effectiveness of dynamic curing was studied using Brabender plastograms, a moving disc rheometer and swelling index measurement. The mechanical properties investigated include tensile strength, elongation at break, modulus at 100% elongation, tear strength and hardness. The influence of thermooxidative ageing on the mechanical properties was investigated by incubating the PVC/NBR TPEs in an air oven at 80 °C for 168 h. The torque values obtained from both rheometers increased with increasing sulfur dosage, while the swelling index decreased. The significant increase in the degree of curing evidenced by the steady reduction in the swelling index provided excellent proof of the efficiency of the dynamic curing technique. Thermo‐oxidative ageing resulted in a pronounced enhancement in mechanical properties as a function of sulfur content. This observation seems to indicate that some microstructural changes, such as the formation of new crosslinks, occur in the thermo‐oxidatively aged TPEs. This trend was supported by further reduction in the swelling index of the aged TPEs. © 2003 Society of Chemical Industry     

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     

Self‐crosslinking and cocrosslinking with nitrile rubber of poly(vinyl chloride) with pendent N,N‐diethyldithiocarbamate group

In order to realize the self‐crosslinking and cocrosslinking of poly(vinyl chloride) (PVC) with nitrile‐butadiene rubber (NBR), PVC with pendent N,N‐diethyldithiocarbamate groups (PVC‐SR) was prepared from the reaction of PVC with sodium SR in butanone. The PVC‐SR was self‐crosslinked and the PVC‐SR/NBR blend was cocrosslinked under heating at 170°C. The effect of the degree of functionality of PVC‐SR on the torque, gel content, glass‐transition temperature, and tensile properties was investigated. The results showed that the crosslinking reaction did not occur for PVC, NBR, or the PVC/NBR blend. Introducing the SR groups into PVC caused the crosslinking reaction to occur and the high gel contents of the crosslinked samples were obtained in 15 min. The degree of crosslinking increased with the degree of functionality of PVC‐SR. The mechanism of the crosslinking reaction was discussed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 634–638, 2001     

Friction and wear properties of NBR/PVC composites

Acrylonitrial butadiene rubber (NBR)/Polyvinyl chloride (PVC) composites with different PVC content were prepared. The effect of PVC content on the mechanical strength and tribological properties of the NBR/PVC composites was investigated. The morphologies of the worn traces and debris of NBR/PVC composites and worn traces of mating ball were observed using a scanning electron microscope (SEM). It was found that the friction and wear of NBR/PVC was lower than that of NBR without PVC. The NBR/PVC composite with 30% PVC content showed the best synthetic mechanical and tribological properties. The inferior elastic properties and the lesser deformation under the applied load of composites with PVC resulted in hysteric force and adhesion force decrease, which leading to a lower friction and wear of NBR/PVC composites. The frictional failure unit of NBR70/PVC30 composite being smaller should be an important reason of the wear of the composite being lowest. The lubricating effect of PVC played an important role in decreasing the friction coefficient and wear of NBR/PVC composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Morphological,thermal, and mechanical properties of poly(vinyl chloride)/acrylonitrile butadiene rubber blend using CuSO4·5H2O as cross‐linking agent

Novel rigid poly(vinyl chloride) (PVC)/cross‐linked acrylonitrile butadiene rubber (NBR) blend using copper (II) sulfate pentahydrate (CuSO₄·5H₂O) as cross‐linking agent was prepared by melt mixing. Fourier transform infrared analysis showed that the coordination cross‐linking occurred between NBR and CuSO₄·5H₂O in the PVC matrix, in which a novel morphology was first observed by scanning electron microscopy analysis. The thermal stability and degradation behavior of the PVC/NBR/CuSO₄·5H₂O blend were examined by means of dynamic mechanical thermal analysis and thermogravimetric analysis. It was found that the glass‐transition temperature (T_g) of the PVC/NBR/CuSO₄·5H₂O blend was enhanced by adding the coordination cross‐linked NBR into the PVC matrix. In spite of the onset decomposition temperature and the first rapidest decomposition temperature of the resultant blends reduced in comparison to neat PVC, the second rapidest decomposition temperature and the residues of the resultant blends were significantly enhanced. In addition, the thermal degradation kinetics and mechanical properties of the resultant blends were also investigated. POLYM. ENG. SCI., 54:1864–1870, 2014. © 2013 Society of Plastics Engineers     

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。     

Dynamic mechanical properties of semi‐interpenetrating polymer network‐based on nitrile rubber and poly(methyl methacrylate‐co‐butyl acrylate)

In this article, semi‐interpenetrating polymer network (Semi‐IPNs) based on nitrile rubber (NBR) and poly(methyl methacrylate‐co‐butyl acrylate) (P(MMA‐BA)) were synthesized. The structure and damping properties of the prepared Semi‐IPNs blends were characterized and by fourier transform infrared spectrum (FTIR), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), thermogravimetric analysis (TGA/DTG), and tensile mechanical properties. The results showed that interpenetrating network based on P(MMA‐BA) and NBR was successfully obtained, which showed the improved thermal stability compared to NBR/P(MMA‐BA)‐based two‐roll mill blends. Furthermore, Semi‐IPNs showed significantly better the dynamic mechanical properties than that of the two‐roll mill system. With the increasing feed ratio of BA and MMA during the preparation of Semi‐IPNs, the loss peak position for P(MMA‐BA) in NBR/PMMA IPNs shifted to a lower temperature from 20°C to ?17°C, and when NBR in Semi‐IPNs was accounted for 40 wt %, the dynamic mechanical thermal analysis showed that much more advanced damping material with wider temperature range (?30°C < T < 80°C) as tan δ > 0.45 can be achieved. Therefore, it was expected as a promising way to obtain the excellent damping materials with good oil‐resisted properties according the Semi‐IPNs system. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40217.