Styrene/methyl methacrylate copolymer blend with

Styrene-butadiene copolymers are often blended with other polymers. Transparent blends can be made with styrene, styrene-acrylonltrlle copolymers, or styrene-methyl methacrylate copolymers. Blends with styrene have low impact strength even at low styrene levels, while blends with styrene-methyl methacrylate copolymers can have greatly Improved impact strength. Blends with high impact polystyrene, polypropylene, and polycarbonate are opaque. 

Physical Properties of Blends of Polystyrene with Poly(methyl Methacrylate) and Styrene/ (methyl Methacrylate) Copolymers... 

Figure 1. Room-temperature miscibility diagrams for blends of polystyrene with poly(methyl methacrylate) and styrene/(methyl methacrylate) copolymers. Shaded area is compatible region.

In a related patent (46) Amagi et al. synthesized a triple latex IPN. In brief, polymer 1 was a crosslinked SBR, polymer 2 was a crosslinked styrene-methyl methacrylate copolymer, and polymer 3 was a crosslinked poly (methyl methacrylate). All three were sequentially synthesized on the same latex particle. The latex material was then mechanically blended with linear poly (vinyl chloride). Also, Torvik (47) blended together four polymers that had different glass transition temperatures. 

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 . 

Blends of styrenic pol5m ers (PS, high impact poly (styrene)) and biodegradable polymers (PLA) can be extruded and thermo-formed to produce very low density food service and consumer foam articles (29,31). The blends are compatibilized with styrene-based copolymers a styrene-maleic anhydride copol5mier, or a styrene methyl methacrylate copolymer. As blowing agent for foaming the compositions z-pentane is used. 

A variety of other blends have been examined, including mixtures of various molecular weight polyethylene glycols (228), styrene/methacrylic acid ionomer in combination with polyoxyethylene or polyoxypropylene (229), methyl methacrylate/methacrylonitrile copolymers and methyl methacrylate/glycidyl methacrylate copolymers blended with polyepichlorohydrin (230). Poly(ethyl methacrylate) and poly(ethylene oxide)... 

Methyl methacrylate has been copolymerized with a wide variety of other monomers, such as acrylates, acrylonitrile, styrene, and butadiene. Copolymerization with styrene gives a material with improved melt-flow characteristics. Copolymerization with either butadiene or acrylonitrile, or blending PMMA with SBR, improves impact resistance. Butadiene-methyl methacrylate copolymer has been used in paper and board finishes. 

In addition to forming polymers with molecules of their own kind, many monomers can form copolymers with other monomers. The scale of possibilities is thus widely extended. In free radical polymerization, for example, styrene is converted to poly(styrene), methyl methacrylate to poly(methyl methacrylate), and vinyl acetate to poly(vinyl acetate). A mixture of styrene and methyl methacrylate gives poly(styrene-co-methyl methacrylate) even at the lowest conversions. From a mixture of styrene and vinyl acetate, on the other hand, practically pure poly(styrene) is first formed, and then, when the styrene is exhausted, almost pure poly(vinyl acetate). This is therefore a mixture (blend) and not a copolymer. Whereas stilbene, free-radically initiated, does not give a unipolymer, and maleic anhydride gives one of only low molecular weight, a mixture of both monomers leads to a copolymer of the composition 1 1. 

Commercial impact-modified acrylic resins (Table 19.15) exhibit five- to tenfold improvement in the notched Izod impact strength and the ultimate tensile elongation compared to the neat PMMA resin. These impact-modified acrylics are usually blended captively by the manufacturers of the acrylic resins. The base resin in a typical weatherable grade (Plexiglas DR, Rohm and Haas) could be a methyl methacrylate copolymer with ethylacrylate and styrene, while the rubber additive (ca. 10 %) could be an emulsion-polymerized, PMMA-grafted, cross-linked poly (n-butylacrylate) rubber of controlled particle size (<200 nm). The nonweatherable impact-modified acrylic (XT, CYRO) typically consists of a MMA/S/AN copolymer with MBS (ca. 10 %) rubber particle dispersions. 

From studies of styrene-aaylonitrile copolymer (SAN) and poly(methyl methacrylate) (PMMA) blends, Higashida et al. [75] used previously determined values of the interaction parameter between styrene (S) and acrylonitrile (AN) units [76] and phase diagrams of PCL/SAN blends obtained by Chiu and Smith [20] to estimate values of Xs/pcl Xan/pcl functions of temperature and AN content On this basis they calculated phase diagrams similar to that determined experimentally by Chiu and Smith [20]. They also predicted that mixtures of PS and PCL oHgomers should be miscible at low temperatures and that such mixtures should exhibit UCST behaviour which was in agreement with experimental observations values of the interaction parameters determined by Higashida are quoted in Table 4. 

To achieve good toughness, required for many applications, impact modifiers are added to PVC. Chlorinated polyethylenes, ethylene-vinyl acetate copolymers, styrene-methyl methacrylate grafted elastomers, vinyl rubbers, and polyacrylates are the most frequently used (316). These polymers are blended together with other additives. Blending conditions are extraordinary important for morphology control and consequently for final properties of the blends. 

Other interesting ternary systems exist. Polystyrene is not miscible with polycarbonate, poly(methyl methacrylate), or poly(vinyl acetate). However, addition of copolymer p-(hexa-fluoro-2-hydroxypropyl)styrene forms a ternary blend with miscible regions for polystyrene with polycarbonate or polystyrene with poly(methyl methacrylate) or polystyrene with poly(vinyl acetate) [86,90]. 

Examples of photothermoplasts include polyacrylates, polyacrylamides, polystyrenes, polycarbonates, and their copolymers (169). An especially well-re searched photothermoplast is poly(methyl methacrylate) (PMMA), which is blended with methyl methacrylate (MMA) or styrene as a monomer, and titanium-bis(cyclopentadienyl) as a photoinitiator (170). 

Nitrile rubber (NBR), a copolymer of 1,3-butadiene with 20-40% acrylonitrile, is noted for its oil resistance. More than 150 million pounds are produced annually in the United States. Applications include fuel tanks, gasoline hoses, and creamery equipment. Nitrile resin is made by copolymerizing acrylonitrile with about 20-30% styrene or methyl methacrylate in the presence of NBR or SBR rubber to yield a blend of the graft terpolymer and homocopolymer. Applications include extruded and blow-molded containers for household, automotive, and other products as well as some nonbeverage foods (spices, vitamins, candy). 

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