Nitrile content

Elastomers, syntpietic-nitrile rubber). It is the nitrile group, —C=N, that confers oil resistance to this polymer, and the nitrile content can vary from 10 to 40%, leading to increasing solvent resistance. 

Most of these properties can be attributed to the high nitrile content of these polymers. 

Figure 4. Water permeability of AN/S copolymers vs. nitrile content...

The most interesting aminomethyl derivative of condensation polymers that we have prepared to date Is derived from direct reduction of poly(2-cyano-l,3-phenylene arylene ether), 20. Enchainment of benzonitrile repeat units Is accomplished by coupling 2,6-dichlorobenzonitrile with the potassium salt of bisphenol-A copolymers with lower nitrile contents can be produced by copolycondensation of bisphenol-A, 2,6-dichlorobenzonitrile and 4,4 -dichlorodiphenyl sulfone.21 The pendent nitrile function provides an active site for further elaboration. 

Chromium metal may be oxidized by Cl2, Br2 or I2 in ethanenitrile solution to give the octahedral complexes [CrCl3(MeCN)3]-MeCN, CrBr3(MeCN)3 and [CrI2(MeCN)4]I although the nitrile content of the bromo complex is somewhat variable.658 The chloro complex loses the uncoordinated nitrile when heated at 80 °C under vacuum. Some properties of these complexes are listed in Table 72. Reaction of CrCl3 with propanenitrile and acrylonitrile affords the dark purple complexes CrCl3(nitrile)3.6M... 

To control compatibility and other properties of butadiene/acrylonitrile copolymers with PVC, there is an optimum acrylonitrile content of 37%. For practical handling, the nitrile rubber is treated on rolls at normal temperatures, and afterwards the mixture is rolled with PVC at elevated temperatures. The reverse process—plasticizing PVC first and mixing with nitrile rubber afterwards—is not so favorable because discoloring and decomposition may occur. This can be avoided by simultaneously applying the liquid plasticizers. Nitrile content in-... 

Figure 14. Glass transition temperature vs nitrile content for acrylonitrile-butadiene co-polymers.

Compression tests, as well as tension tests, were carried out on the samples of varying AN content. All samples exhibited a compressive yield stress, and with further increase of strain, a subsequent drop in stress, occurred before the stress again started to rise. From the test data, the elastic modulus and the yield strength were determined as a function of nitrile content and the results are shown in Fig. 29. 

Obviously, adhesive performance was closely associated with compatibility between the PPU/ETBN blend and epoxy matrix as well as between PPU and ETBN. As in CTBN-modified epoxy adhesives (Figure 6), the nitrile content of CTBN played an important role. When PPU containing a polypropylene oxide) segment with Mn 2000 g/mol was blended with ETBN, both lap shear strength and T-peel strength increased with increasing nitrile content. The best results were obtained with ETBN derived from CTBN containing 26 wt% acrylonitrile. 

This is one of the most important synthetic thermoplastic elastomers. Nitrile rubber is a copolymer of butadiene and acrylonitrile. The copolymer usually contains enough acrylonitrile (>25%) so that good resistance to oil and grease can be obtained. Adhesive properties also increase with increasing nitrile content. These adhesives are used to bond vinyls, other elastomers, and fabrics where good wear, oil, and water resistance are important. Compatibility with additives, fillers, and other resins is another advantage of this material.Table 5.1 summarizes the properties of nitrile rubber. 

Because nitrile rubbers are polar elastomers, their vulcanizates are very resistant to swelling in hot oil, gasoline, grease, and other nonpolar substances. The resistance to swelling in nonpolar oils, solvents, and so on, is improved greatly with increasing nitrile content. Here we see the need for compromises increasing nitrile content improves oil resistance but reduces elasticity and set resistance and most severely reduces low-temperature flexibility. Plasticizers are very necessary to surmount this problem. 

NBR vulcanizates are less permeable to gasses than are NR and SBR, with permeability decreasing with increasing nitrile content. Permeability by gasoline vapors and the like, however, is very high. 

The subscripts 1 and 2 refer to downstream and upstream conditions, respectively. The ratio of the two diffiision coefficients is commonly called the diffusivity selectivity of a membrane and the ratio of the two solubilities, the solubility selectivity. A typical range of permeabilities and selectivities achievable with rubbery materials is indicated in Table 3 for several gas pairs of commercial interest. More extensive tabulations are available (41). The presence of polar groups in the polymer molecule generally leads to low diffusivity for penetrants (15) eg, the diffusivity decreases strongly on increasing the nitrile content in a series of... 

Solution styrene butadiene rubber (S-SBR) (Sprintan SLR-4601, Styron Deutschland GmbH) and acrylonitrile butadiene rubber (NBR) (Perbunan 3445F, Lanxess GmbH) with a nitrile content of 34% as well as NR (SMR 10, Standard Malaysian Rubber) were used as rubbers. The silica used was Ultrasil 7000 GR (Evonik Industries) with a specific surface area CTAB of 160 m /g and BET of 170 m /g. Stearic acid, zinc oxide (ZnO), N-cyclohexyl-benzothiazole-2-sulfenamide (CBS) and sulfur were used as processing and curing additives, respectively. The experimentally determined values of surface tension and Mooney viscosity of the materials used are given in Table 6.1. 

TABLE 10.5 Rotary seal compound with high nitrile content rubber... 

Permeability of rubbers to gases is a function of solubility and diffusivity. The relative permeability of rubbers to gases is shown in Table 10.26. Permeabilty is a function of the internal structure of the rubber mixture, for instance butyl rubber has low permeability because of the presence of methyl groups, whereas nitrile rubber has low permeability to non-polar gases because of the polar groups in the chain. The higher the nitrile content, the lower the permeability. Below 32°F (0°C), butyl and nitrile rubbers are practically impermeable. 

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