HNBR properties

Influence of Acrylonitrile Content and Unsaturation on HNBR Properties... 

Choudhury et al. [86] have studied the effect of polymer-solvent and clay-solvent interaction on the mechanical properties of the HNBR/sepiolite nanocomposites. They chose nine different sets of solvent composition and found that chloroform/methyl ethyl ketone (Qi/MEK) (i.e., HNBR dissolved in Ch and sepio-lite dissolved in MEK) is the best solvent combination for improvement in mechanical properties. XRD, AFM, , and UV-vis spectroscopy studies show that the dispersion of clay is best in the Ch/MEK solvent combination and hence polymer-filler interaction is also the highest. images shown in Fig. 14a, b clearly elucidate the aforementioned phenomena. Consequently, the tensile strength and modulus are found to be higher (5.89 MPa and 1.50 MPa, respectively) for the Ch/MEK system due to the minimum difference in interaction parameter of HNBR-solvent (xab) and sepiolite-solvent (Xcd)- Choudhury et al. have also studied the effect of different nanoclays [NA, , 15A, and sepiolite (SP)] and nanosilica (Aerosil 300) on the mechanical properties of HNBR [36]. The tensile... 

It has been found that the HNBR/SP nanocomposite provides the best thermal and mechanical properties when HNBR is dissolved in Ch and SP is dispersed in MEK. XRD, AFM,TEM, and optical transmittance studies show that the dispersion of clay is best in the Ch/MEK solvent combination and, hence, polymer-filler interaction is also highest in this system. Thus, rather than implying that the solvent selection directly affects the physical properties of the nanocomposite, solvent acts on the properties through its influence on the developed morphology. 

In order to understand the relationship between the difference in the interaction parameter of rubber-solvent (Xab) and clay-solvent (xcd) systems and the properties of HNBR/SP nanocomposites, the plots of modulus at 100% elongation and tensile strength versus Xab-Xcd are represented in Fig. 45a, b. An exponential decay in both modulus and tensile strength is observed with the increase in difference of interaction parameter. 7) and 7max follow the same trend as above. 

Chemical modification of polymers continues to be an active field of research [1-5]. It is a common means of changing and optimising the physical, mechanical and technological properties of polymers [5-7]. It is also a unique route to produce polymers with unusual chemical structure and composition that are otherwise inaccessible or very difficult to prepare by conventional polymerisation methods. For example, hydrogenated nitrile rubber (HNBR) which has a structure which resembles that of the copolymer ethylene and acrylonitrile, is very difficult to prepare by conventional copolymerisation of the monomers. Polyvinyl alcohol can only be prepared by hydrolysis of polyvinyl acetate. Most of the rubbers or rubbery materials have unsaturation in their main chain and/or in their pendent groups. So these materials are very susceptible towards chemical reactions compared to their saturated counterparts. 

Hydrogenated nitrile rubber (HNBR) can be blended with NR to improve its oil and ageing resistance without drastically alfecting the dynamic properties. HNBR is widely used to make vibration dampers, timing belts, power transmission belts and bearings because of its ideal balance of properties like excellent heat and oil resistance coupled with good mechanical properties. It combines the oil and fuel resistance of NBR with the heat and oxidation resistance of EPDM rubber. The polarity dilference between the polymers could be reduced by the incorporation of small quantities of dichlorocarbene modified NR (DCNR), which is formed during the alkaline hydrolysis of chloroform in the presence of NR. Some studies in this respect have been reported in the literature. ... 

The new co-agents revealed high tendency to agglomeration in elastomer matrix what had a beneficial effect on vulcanizates mechanical properties. ApplicatitMi of unsaturated acids and metal oxides as the new co-agents in peroxide vulcanization of HNBR caused mostly a decrease of vulcanization time, considerable improvement of vulcanizates mechanical properties, as well as the increase of cross-link efficiency. Thus, they may be used successfully in rubber technology. 

Gatos KG, Karger-Kocsis J (2007) Effect of the aspect ratio of siheate platelets on the mechanical and barrier properties of hydrogenated acrylonitrile butadiene rubber (HNBR)/layeted silicate nanocomposites. Eur Polym J 43 1097-1104... 

In a patent issued to the US Army in the late 1980s, the zinc salts of acrylic acid and methacrylic acid were used to upgrade the properties of hydrogenated nitrile rubber (HNBR) [3]. The goal of this work was to develop abrasion-resistant materials that could be used to extend the service life of tank treads. Zinc dimethacrylate (ZDMA) proved to be the best material in the study for improving the tear strength, abrasion resistance, and high temperature performance of HNBR. 

Li Q, Zhao S, Pan Y (2010) Structure, morphology and properties of HNBR filled with N550, Si02, ZDMA, and two of three kinds of fillers. J Appl Polym Sci 117(l) 421-427... 

This paper concerns the use of elastomeric seals offshore. General properties and fluid compatibility for five most common elastomeric types used in oil and gas are described. These are NBR, HNBR, fluorocarbon elastomers, perfluoroelastomers and tetrafluoroethylene-propylene. 

Hydrated nitrile rubber (HNBR) reliably withstands extreme temperature under the hood, as well as the effects of oils and fuels. HNBR grades exceed previous resistance ratings. They close the gap between oil-resistant nitrile rubbers and the extremely heat-resistant, but very expensive fluoropolymers. At the same time, the classic rubber properties of nitrile rubbers are maintained, especially its low-temperature flexibility. 

Additives are utilized to extend service life and improve performance of oils in the engine room. These additives can reduce mechanical properties of elastomers and cause surface hardening [697]. The type of additive depends on the type of oil used. Table 5.105 compares the behavior of HNBR, NBR, and CPE exposed to ASTM oil no. 2 with various additive contents [796]. 

Table 5.106 Comparison of essential properties of HNBR, NBR, and CSM following exposure to ATF oil of Japanese manufacturers [796]...

Hydrated nitrile-butadiene rubber is used mostly at elevated temperatures in aggressive media, Table 5.108. Its swelling resistance increases with increasing acrylonitrile content, Figure 5.353. HNBR owes its excellent oil resistance to its oil-resistant base product, NBR however, HNBR has even superior properties especially at higher temperatures. In fuels, HNBR is swelling more than NBR, Figure 5.354 [697]. 

HNBR is resistant to pressurized steam (14 d/160°C) and to water vapor with traces of alkalis that can cause degradation in fluoro-elastomers. Hot water also does not have a negative influence on the properties of HNBR. 

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