Nitrile rubber/polyvinyl chloride blend

FTIR spectroscopy has been applied in the study of polymer blends including Neoprene rubber, chlorosulfonated PE, nitrile rubber, polyvinyl chloride (PVC) containing carbon black and other fillers [86], Nylon 6 inorganic [87], polyhydroxyether sulfone/poly(N-vinyl pyrrolidone) [88], graphite-based low-density polyethylene [89], caprolactone/Nafion blends [90], polybutylene terephthalate/polyamide [91], polyphenylene sulfide/acrylonitrile - butadiene - styrene [92], PMMA/polypyrrol [93], and lower or high performance liquid chromatography (LDPE/HDPE) [94]. 

The ductility of GRT-polyethylene blends drastically decreases at ground rubber concentration in excess of 5%. The inclusion of hnely ground nitrile rubber from waste printing rollers into polyvinyl chloride (PVC) caused an increase in the impact properties of the thermoplastic matrix [76]. Addition of rubber powder that is physically modihed by ultrasonic treatment leads to PP-waste ethylene-propylene-diene monomer (EPDM) powder blends with improved morphology and mechanical properties [77]. 

Nevertheless, it would seem reasonable that, in the absence of any liquid plasticizer medium at all, mobility of ionic impurities would be reduced to such a low level that volume resistivity would remain high. For example, it is well known that polyvinyl chloride can be blended with nitrile rubber, such as Goodrich Hycar 1032 butadiene/acrylonitrile copolymer, and such polyblends are quite soft and flexible without the use of any liquid plasticizer at all (Table VII). 

At first glance the use of solid nitrile rubber in place of liquid plasticizers would appear to improve the volume resistivity of plasticized polyvinyl chloride somewhat but when the lower plasticizing efficiency of the nitrile rubber is considered, only little improvement remains at equal tensile modulus or hardness. This is difficult to explain in terms of the flow of ions through a liquid plasticizer medium. As we can see, the volume resistivity of nitrile rubber alone is much lower than that of polyvinyl chloride, and the volume resistivity of these blends is simply the resultant of the two components. Actually the same reasoning might well apply to conventional blends of good quality polyvinyl chlorides with good quality liquid plasticizers, in the absence of any added ionic soluble impurities, as we can see from our earlier data. 

Except for the monomers used, the production of NBRs is quite similar to that described for the SBRs. The NBR family is sometimes referred to as the nitrile rubbers. The acrylonilnle-buiadiene ratios cover a wide range from 15 85 to 50.50. NBRs are noted for their solvent resistance, increasing wiih the acrylonitrile content Thus, they are used for gaskets and oil and gasoline hoses, solvent-resistant electrical insulation, and Ibod-wrnpping films. Nitrile lattices also are used in treating fabrics for dry-cleaning durability. Because the NBRs become quite inflexible (stiff) at low temperatures (actually brittle at about -20 C). they arc blended with polyvinyl chloride for some applications. 

Weather Resistance Many rubbers are affected adversely by outdoor exposure, particularly by the traces of ozone, which are always present in the atmosphere and which cause rapid cracking of lightly stressed rubber articles. Nitrile rubber is no exception and thus it is not suitable for use in exposed conditions. However, the incorporation of a proportion of PVC (Polyvinyl chloride) into the nitrile compound results in improved resistance until, with a blend of 70/30 nitrile/PVC, a material with almost complete resistance to ozone attack is produced. The presence of PVC produces stiffer compounds, with lower resiliance and inferior low temperature properties, but the oil and solvent resistance is enhanced. 

Acetone and methyl ethyl ketone are components of solvent blends in urethane, nitrile rubber, and neoprene industrial adhesives. Acetone is the primary solvent in resin-type adhesives and pressure sensitive chlorinated rubber adhesives. Methyl isobutyl ketone is a solvent component for nitrile rubber and acrylic adhesives as well as in polyvinyl chloride and polyvinyl chloride-polyvinyl acetate copolymer bonding adhesives. Again, the desired evaporation rate of the adhesive formulation will often determine the ketone selected. 

The predictions of both models were then compared with measurements of the temperature variation of storage and loss moduli for a film made from a blend of polyvinyl chloride and nitrile butadiene rubber (Figure 8.10). It is seen that the... 

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