Styrene history

The soap of modified rosin has a long history as an emulsifier for the polymerization of styrene—butadiene mbber. The rosin soap remains in the mbber after polymerization and increases the tack between the pHes of mbber required in the manufacture of tires. 

SDS [Sulzer Dainippon Sumitomo] A continuous process for polymerizing styrene. The reactants are mixed in a static mixer, which gives a very uniform time/temperature history for the polymer. Developed jointly by Sulzer, Dainippon Ink Chemicals, and Sumotomo Heavy Industries. Offered for license in 1990. 

The history of styrenic polymers is documented by Amos (1) and Scheirs (2). The first patent of the suspension or bulk polymerization, respectively, of styrene in presence of rubbers goes back to the 1950s (3,4). 

Styrene acrylonitrile copolymer (SAN) copolymers have been commercially available since the 1940s. Due to their comparatively high price, initially they have been used in rather special applications. The history of styrenic polymers has been reviewed by various authors (1,2). 

Anon), Static Spark Flashes Empty Styrene Drum, MCA Case History No. 41. 

MCM-22 is a commercial catalyst with a production history of over seven years, and operation history of over five years. Catalyst performance in these applications has been outstanding. In MCM-22 s first ethylbenzene commercial application at Denka s Chiba Styrene Monomer Company Ltd., a cycle length of over three years has been demonstrated without any significant aging of the catalyst or change in yields. Like ZSM-5, MCM-22 is regenerable, and is environmentally inert. 

In Figure 1 are shown experimental conversion histories from bulk polymerization of styrene, methyl methacrylate, and vinyl acetate. It appears that with any of these monomers the rate of polymerization increases substantially during reaction, i.e. gel-effect is important in bulk polymerization of these monomers. The effect is particularly pronoimced with methyl methacrylate. 

Figure 1. Conversion histories in bulk polymerization of methyl methacrylate, styrene, and vinyl acetate...

Since the polymerization conditions for styrene and methyl methacrylate often are chosen such that a in the early stages of polymerization (after N has become constant) lies between 10 2 and 1, it is understandable that gel-effect usually is important in emulsion polymerization of these monomers and therefore must be accounted for since it completely dominates the shape of the conversion history. 

Systems Where Radical Desorption is Negligible. Styrene and methyl methacrylate emulsion polymerization are examples of systems where radical desorption can be neglected. In Figures 4 and 5 are shown comparisons between experimental and theoretical conversion histories in methyl methacrylate and styrene polymerization. The solid curves represent the model, and it appears that there is excellent agreement between theory and experiment. The values of the rate constants used for the theoretical simulations are reported in previous publications (, 3). The dashed curves represent the corresponding theoretical curves in the calculation of which gel-effect has been neglected, that is, ktp is kept constant at a value for low viscosity solutions. It appears that neglecting gel-effect in the simulation of styrene... 

Figures 4, 5, 6. Comparison between experimental and theoretical conversion histories in emulsion polymerization of methyl methacrylate, styrene, and vinyl acetate. (—), model with gel-effect (—), model without gel-effect.

The development of high styrene content styrene-butadiene copolymers (SBCs), such as K-Resin SBC, is best thought of as a branch off the history of anionic polymerization and rubber. A number of excellent reviews cover this aspect of the subject in great detail, and should be obtained for detailed examination of the history of rubber and anionically synthesized rubber polymers [1-3]. What follows is a brief overview to fit the high styrene content SBC into a historical context. 

Figure 6.22 United States styrene and polystyrene production histories. (Data courtesy of CMAI.)...

Vinyl ester resins (VERs, epoxy methacrylates) are a major class of styrenated, free radically curable, corrosion- and chemical-resistant thermoset resins. They are largely used in fiber-reinforced structural applications, and they have a substantial history of long-term service in numerous environments at elevated temperatures and pressures, usually under load. 

SBS copolymers are used in blends as com-patibihzers, impact modifiers, or stabilizers of morphology and performance. As shown in Table 1.21, they have been frequently incorporated along other styrenics. There are many patents for mixtures of PO with SBS-type copolymers. Their history is outlined in Table 1.22. 

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