Nitrile resins properties

The principal monomer of nitrile resins is acrylonitrile (see Polyacrylonitrile ), which constitutes about 70% by weight of the polymer and provides the polymer with good gas barrier and chemical resistance properties. The remainder of the polymer is 20 to 30% methylacrylate (or styrene), with 0 to 10% butadiene to serve as an impact-modifying termonomer. 

Nitrile rubber/phenolic resin blends. Blends of equal parts by weight of a nitrile rubber and a phenolic resin in methyl ethyl ketone (at a 20-30 wt% total solids content) is suitable for many adhesive purposes. The more phenolic resin in the formulation, the greater the bond strength and brittleness of the NBR adhesive [67]. Table 10 shows the effect of phenolic resin on nitrile rubber properties. On the other hand, the higher the acrylonitrile content in the rubber. 

Nitrile resins n. Used principally in the packaging of foods other than beverages, and in non-food packaging in USA and abroad. The monomer used primarily is acrylonitrile, which provides a good gas barrier, chemical resistance, and taste- and odor-retention properties. Harper CA (2000) Modern plastics encyclopedia. McGraw-Hill Professional, New York. 

In addition to their outstanding gas-barrier properties, nitrile resins have good resistance to most organic solvents (but not acetone and methyl ethyl ketone) and acids and bases. Nitrile resins may be melt-processed by all the usual methods, e.g. injection moulding, blow moulding and sheet extrusion. Applications include containers for agricultural, automotive and household products. 

Uses. The principal use of adiponitrile is for hydrogenation to hexamethylene diamine leading to nylon-6,6. However, as a result of BASE s new adiponitrile-to-caprolactam process, a significant fraction of ADN produced may find its way into nylon-6 production. Adipoquanamine, which is prepared by the reaction of adiponitrile with dicyandiamide [461-58-5] (cyanoguanidine), may have uses in melamine—urea amino resins (qv) (see "Benzonitrile, Uses"). Its typical Hquid nitrile properties suggest its use as an extractant for aromatic hydrocarbons. 

Copolymers of acrylonitrile [107-13-1] are used in extmsion and molding appHcations. Commercially important comonomers for barrier appHcations include styrene and methyl acrylate. As the comonomer content is increased, the permeabiUties increase as shown in Figure 3. These copolymers are not moisture-sensitive. Table 7 contains descriptions of three high nitrile barrier polymers. Barex and Cycopac resins are mbber-modified to improve the mechanical properties. 

Effect of the phenolic resin content in the mechanical properties of nitrile rubber... 

Our studies of the absorption, permeation, and extraction properties of containers produced from high nitrile barrier resins have demonstrated that they meet or surpass the basic criteria established for retention of taste and odor characteristics of carbonated soft drinks. Sensory tests, which can isolate and identify end results as well as integrate collective effects, have confirmed this judgement and have established the general compatibility of these containers with a variety of beverage products from a taste and odor standpoint. Furthermore, these materials have the excellent physical properties required for containers which will find wide use in food and beverage packaging. 

NR, styrene-butadiene mbber (SBR), polybutadiene rubber, nitrile mbber, acrylic copolymer, ethylene-vinyl acetate (EVA) copolymer, and A-B-A type block copolymer with conjugated dienes have been used to prepare pressure-sensitive adhesives by EB radiation [116-126]. It is not necessary to heat up the sample to join the elastomeric joints. This has only been possible due to cross-linking procedure by EB irradiation [127]. Polyfunctional acrylates, tackifier resin, and other additives have also been used to improve adhesive properties. Sasaki et al. [128] have studied the EB radiation-curable pressure-sensitive adhesives from dimer acid-based polyester urethane diacrylate with various methacrylate monomers. Acrylamide has been polymerized in the intercalation space of montmorillonite using an EB. The polymerization condition has been studied using a statistical method. The product shows a good water adsorption and retention capacity [129]. 

Composite Particles, Inc. reported the use of surface-modified rubber particles in formulations of thermoset systems, such as polyurethanes, polysulfides, and epoxies [95], The surface of the mbber was oxidized by a proprietary gas atmosphere, which leads to the formation of polar functional groups like —COOH and —OH, which in turn enhanced the dispersibility and bonding characteristics of mbber particles to other polar polymers. A composite containing 15% treated mbber particles per 85% polyurethane has physical properties similar to those of the pure polyurethane. Inclusion of surface-modified waste mbber in polyurethane matrix increases the coefficient of friction. This finds application in polyurethane tires and shoe soles. The treated mbber particles enhance the flexibility and impact resistance of polyester-based constmction materials [95]. Inclusion of treated waste mbber along with carboxyl terminated nitrile mbber (CTBN) in epoxy formulations increases the fracture toughness of the epoxy resins [96]. 

ZnCFO is the effective vulcanization active component of the sulfur, thiuram, peroxide and metaloxide vulcanization systems for isoprene, nitrile-butadiene and chloroprene rubbers at the same time it is not effective in resin vulcanization system for butyl rubber. On a degree of positive influence on the properties of elastomeric compositions vulcanization systems with ZnCFO are arranged in a line ... 

Block copolymers based on nitrile rubber and on epoxy and phenolic resins and on polystyrene (50-54) have been intensively studied in Russia The generated block copolymers were investigated by turbidimetric and IR methods. Thermomechanical experiments were also run on fractions. As may be seen from Fig 13, fractions which combine the properties of the polymers (Curves 2,3, and 4) were obtained together with fractions characteristic of the raw rubber (Curve 1) and of the resin (Curve 5). The copolymer is soluble in solvents which are typical for both components. Solubility studies on the products showed that for any given ratio of the original components, 15 to 20% of the resin combines with the rubber. The properties of the block copolymer, however, depend on the initial ratio of components nitrile rubber confers elasticity and the phenolic resin processability. 

Stephens et al.70-72 examined the commercial potential of SX-reinforced rubber. SX reinforced styrene-butadiene and nitrile-butadiene rubber compounds, but displayed no reinforcement of natural rubber. The addition of resorcinol-formaldehyde resin at 8% of the starch weight significantly improved the mechanical properties for all three rubber compounds. The preparation of starch xanthide-rubber compounds by crosslinking the SX with sodium nitrite produced results similar to those obtained by adding resorcinol-formaldehyde resin. 

A variety of polymers, both thermosets as well as thermoplastics, can be blended and coreacted with epoxy resins to provide for a specific set of desired properties. The most common of these are nitrile, phenolic, nylon, poly sulfide, and polyurethane resins. At high levels of additions these additives result in hybrid or alloyed systems with epoxy resins rather than just modifiers. They differ from reactive diluents in that they are higher-molecular weight-materials, are used at higher concentrations, and generally have less deleterious effect on the cured properties of the epoxy resin. 

Typically tape or film epoxy adhesives are modified with synthetic thermoplastic polymers to improve flexibility in the uncured film and toughness in the cured adhesive. Epoxy resins can also be blended with phenolic resins for higher heat resistance. The most common hybrid systems include epoxy-phenolics, epoxy-nylon, epoxy-nitrile, and epoxy-vinyl hybrids. These hybrid film adhesives are summarized in Table 13.2, and structural properties are shown in Table 13.3. 

Blends with Nitrile Rubbers. The data in Table III show the importance of using a terpolymer rubber to obtain good impact strength in a blend with styrene-acrylonitrile-DBPF terpolymer resin. Blend No. 1 gives the properties of a conventional nitrile rubber blend type ABS. Blends 2-4, involving terpolymer resins with the same amount of the rubber used in Blend 1, have a much lower impact strength. 

Graft Blends. The properties of ABS-type polymers involving mixtures of terpolymer resins and graft rubbers are shown in Table IV. As with the nitrile rubber types, there is a pronounced gain in impact strength at a given rubber level when DBPF is present in both phases (Blends 1 vs. 3 and 2 vs. 4). 

This study (3) was done to produce an ABS type resin by dry and melt blending SAN and a nitrile rubber in a motionless mixer. In polyblends of two semicompatible polymers, the particle size of the dispersed phase is an important factor concerning final properties, particularly if a rubber is dispersed to improve impact strength. Motionless mixers should give precise control over the final particle size since for laminar flow the number of fluid layers and the striation thickness can be predicted mathematically. The hypothesis that the impact strength should peak out at a precise number of mixing elements was thus investigated. 

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