Acrylonitrile-butadiene copolymer, commercial blend with

Acrylonitrile—Butadiene—Styrene. ABS is an important commercial polymer, with numerous apphcations. In the late 1950s, ABS was produced by emulsion grafting of styrene-acrylonitrile copolymers onto polybutadiene latex particles. This method continues to be the basis for a considerable volume of ABS manufacture. More recently, ABS has also been produced by continuous mass and mass-suspension processes (237). The various products may be mechanically blended for optimizing properties and cost. Brittle SAN, toughened by SAN-grafted ethylene—propylene and acrylate mbbets, is used in outdoor apphcations. Flame retardancy of ABS is improved by chlorinated PE and other flame-retarding additives (237). 

Polystyrene is one of the most widely used thermoplastic materials ranking behind polyolefins and PVC. Owing to their special property profile, styrene polymers are placed between commodity and speciality polymers. Since its commercial introduction in the 1930s until the present day, polystyrene has been subjected to numerous improvements. The main development directions were aimed at copolymerization of styrene with polar comonomers such as acrylonitrile, (meth)acrylates or maleic anhydride, at impact modification with different rubbers or styrene-butadiene block copolymers and at blending with other polymers such as polyphenylene ether (PPE) or polyolefins. 

In 1983, Monsanto developed blends with co-continuous morphology, Triax 2000. These alloys comprised PC, ABS, and styrene-methylmethac-rylate-maleic anhydride (SMMA-MA) [Jones and Mendelson, 1985]. One year later, PC was reactively blended with either ABS, SAN-GMA, and NBR, or with graft copolymers of acrylonitrile-butadiene-a-methyl styrene-methyl-methacrylate (MeABS) and acryloiutrile-a-methyl styrene-methyl methacrylate copolymer (MeSAN) [Kress et al., 1986]. The blends were commercialized by Bayer as Bayblend . 

In the first one, the two materials are blended on a rubber mill or in an internal mixer. Blending of the two materials can also be achieved by combining emulsion latexes of the two materials together and then coagulating the mixture. Peroxide must be added to the blends in order to achieve some crosslinking of the elastomer to attain optimum properties. A wide range of blends are made by this technique with various properties. Most common commercial blends of ABS resins may contain 70 parts of styrene-acrylonitrile copolymer (70/30) and 40 parts of butadiene-nitrile rubber (65/35). 

The commercial names of polymers do not always fulfill what they promise. Not only more or less branched homopolymers of various molar masses are encountered under the name, poly(ethylene), but also copolymers of ethylene with propylene, butene-1, etc. Commercially, not only the homopolymers of styrene are included under the poly(styrene) designation, but also copolymers with acrylonitrile (SAN), blends of poly(styrene) with various elastomers (HIPS = high impact poly(styrene)) and graft copoly-mers-blends of acrylonitrile, butadiene, and sytrene. The styrene monomeric unit is the main component in all of these polymers thus, these polymers are all included in the poly(styrene) family, although their properties can differ from each other (Table 36-4). 

Patented or commercial polymer blends are in most cases multiphase, compatibilized systems. In the old but still popular blends of polyvinyl chloride or polycarbonate with acrylonitrile-butadiene-styrene copolymer, PVC/ABS or PC/ABS, the styrene-acrylonitrile copolymer, SAN, ascertains adequate compatibilization in the systems. Note that ABS went through a series of process and composition modifications to enhance performance in blends. 

Oligomeric aromatic phosphates have been patented and commercially used as flame-retardant additives mainly for impact-resistant polystyrene blends with polyphenylene oxide and polycarbonate blends with acrylonitrile-butadiene-styrene (ABS) copolymers (130,131). They have also been shown useful in thermoplastic polyesters (92). The principal commercial examples are based on phenol and resorcinol (Akzo-Nobel s Fyrolflex RDP) or phenol and bisphenol A (Akzo-Nobel s Fyrolflex BDP or Albemarle s Ncendx P-30). Although these have the diphosphate as their principal ingredient, they also contain higher oligomers. 

In the late forties, work began to improve the prcperties of a new thermoplastic blend. It had been revealed [2] in 1948 - 50 that poly(styrene-co-acrylonitrile), or SAN, could be blended with Buna N, a copolymer of butadiene and acrylonitrile, or Buna S, a copolymer of loutadiene and styrene, to get useful thermoplastics. These materials were impact resistant, with Izod impact values of 2 to 3 foot-pounds. The commercial use of these materials was hindered loy the lack of low tenperature impact strength. The rubber technologists of the narbon Division (as the Marsene Corporation had been named on assimilation into Borg-Warner) knew that polybutadiene remained "rubbery" at lower tenperatures than the copolymers cited above. However, blending experiments showed that polybutadiene and SAN were incompatible. The polymerization of SAN could be acconplished in solution, in bulk, or... 

There are many other commercial examples of polymer blends. Polycarbonate can be blended with an acrylonitrile-butadiene-styrene terpolymer to give a PC-ABS blend. Polypropylene impact can be improved by the addition of ethylene-propylene copolymers, which are sometimes called ethylene-propylene-rubber (EPR). Ethylene, propylene, and a diene monomer (EPDM), such as ethylidene norbomene, is also used to impart impact and flexibiUty to polypropylene. 

Acrylonitrile-butadiene-styrene (ABS) terpolymer. Acrylonitrile and styrene are grafted on polybutadiene. It is preferred over homopolymers because of impact resistance, dimensional stability and good heat-distortion resistance. It is an extremely important commercial copolymer and, in several applications, it is blended with other polymers (e.g., PVC or polycarbonates) in order to increase their heat-distortion temperatures. When methyl methacrylate and styrene are grafted on polybutadiene, a methyl methacrylate-butadiene-styrene MBS copolymer is formed. Vinylidene chloride-vinyl chloride copolymer. Because of its toughness, flexibility, and durability, the copolymer is used for the manufacture of filaments for deck chair fabrics, car upholstery, and doll s hair. Biaxially stretched copolymer films are used for packaging. 

Commercial barrier resins which are used as packaging films and blown bottles are produced by blending copolymers of acrylonitrile, ethyl acrylate, and butadiene with selected copolymers of acrylonitrile. These barrier resins have a Tg of about 125 C, a coefficient of linear expansion of 6.7 X 10 5 cm/cm C, a heat deflection temperature of 77 C, and an index of refraction of 1.511. These resins are resistant to nonoxidizing alkalis and acids and are decomposed by mineral acids. 

Additionally to the procedures described earlier, improvements for thermostabilization is copolymerisation of vinyl chloride with suitable monomers. A great number of monomers were investigated to optimize the properties of resins. But only vinyl acetate, vinylidene chloride, ethylene, propylene, acrylonitrile, acrylic acid esters, and maleic acid esters, respectively, are of interest commercially [305,436,437]. The copolymerization was carried out in emulsion, suspension, and solution in connection with water- or oil-soluble initiators, as mentioned elsewhere. Another possibility for modifying PVC is grafting of VC on suitable polymers [305,438], blends of PVC with butadiene/styrene and butadiene/ methacryl acid esters copolymers [433], and polymer-analogous reactions on the macromolecule [439,440] (e.g., chlorination of PVC). 

In this work we present a theoretical discussion regarding this interaction parameter for 10 polymer-polymer-solvent systems, 4 copolymer-solvent systems along with their corresponding polymer pairs. Our polymer blends are real mixtures of 5 homopolymers consist of poly(N,N-dimethyl methacrylamide) (PDMAA), poly(2-dimethyl aminoethyl methacrylate) (PDMAEMA), poly(acrylic acid) (PAA), a typical membrane of commercial soft-contact lens i.e. poly(2-hydroxyethyl methacrylate) (PHEMA), and poly(N-vinyl-2-pyrrolidone) (PVP) all with water solvent. Copolymers studied are poly(acrylonitrile-co-butadiene) in acetonitrile, poly(styrene co acrylonitrile) in 1,2 dichloroethane, poly (acrylonitrile-co butadiene) in hexane and poly (acrylonitrile-co butadiene) in pentane. 

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