Styrene continuous

DegussaAG Polystyrene, high impact Styrene Continuous bulk-process production of all grades of GPPS and HIPS 2 1990... 

Figure 2. Relaxation map of a- and JG f-relaxation of 5 wt.% of CNBz in mixture with tri-styrene. Continuous lines are VFT for v above Tg and linear regressions for Vp in the glassy state. Vertical dotted lines mark the Tg(P) crossing for each isobar. Horizontal dotted line marks the position ofJG f-relaxation at Tg(P).

Polymerization of styrene continued after removal of the initiator from the emulsion by filtration and eventually reached 100% conversion after 4 hr at 35 C. Monomers were added successively to the system, with each polymerization reaction carried to 100% conversion before the next monomer was added. Thin-layer chromatography was used to separate the homopolymers with block copolymers in order to determine the purity of the product. The existence of two separate phases in the extracted block copolymer was indicated by the observation of two distinct, glass transition temperatures. 

Dibromide formation. Dissolve 0 2 ml. of styrene in 0 5 ml. of CCI4 in a test-tube. Add slowly, drop by drop, a 10% solution of bromine in CCI4. Note the decolorisation of the bromine and absence of HBr fumes (therefore reaction by addition and not by substitution). Continue to add the bromine solution until a faint brown colour persists. Scratch the sides of the tube and cool it in ice-water. Filter off the crystals that separate and recrystallise the styrene dibromide from methanol m.p. 72 . 

Compositional control ia suspension systems can be achieved with a corrected batch process. A suspension process has been described where styrene monomer is continuously added until 75—85% conversion, and then the excess acrylonittile monomer is removed by stripping with an iaert gas... 

After the mbber latex is produced, it is subjected to further polymerization in the presence of styrene (CgHg) and acrylonitrile (C H N) monomers to produce the ABS latex. This can be done in batch, semibatch, or continuous reactors. The other ingredients required for this polymerization are similar to those required for the mbber latex reaction. 

Acrylonitrile—Butadiene—Styrene. Available only as sheet, ABS has good toughness and high impact resistance. It is readily therm oform able over a wide range of temperatures and can be deeply drawn. ABS has poor solvent resistance and low continuous-use temperature. It is often used in housings for office equipment (see Acrylonitrile polymers). 

Another type of polyol often used in the manufacture of flexible polyurethane foams contains a dispersed soHd phase of organic chemical particles (234—236). The continuous phase is one of the polyols described above for either slab or molded foam as required. The dispersed phase reacts in the polyol using an addition reaction with styrene and acrylonitrile monomers in one type or a coupling reaction with an amine such as hydrazine and isocyanate in another. The soHds content ranges from about 21% with either system to nearly 40% in the styrene—acrylonitrile system. The dispersed soHds confer increased load bearing and in the case of flexible molded foams also act as a ceU opener. 

The first resins to be produced on a commercial scale were the coumarone—indene or coal-tar resins (1) production in the United States was started before 1920. These resins were dominant until the development of petroleum resins, which were estabHshed as important raw materials by the mid-1940s. Continued development of petroleum-based resins has led to a wide variety of aHphatic, cyclodiene, and aromatic hydrocarbon-based resins. The principal components of petroleum resins are based on piperylenes, dicyclopentadiene (DCPD), styrene, indene, and their respective alkylated derivatives. 

Functionalization. Copolymers do not have the abiHty to exchange ions. Such properties are imparted by chemically bonding acidic or basic functional groups to the aromatic rings of styrenic copolymers, or by modifying the carboxyl groups of the acryHc copolymers. There does not appear to be a continuous functionalization process on a commercial scale. 

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). 

Propylene oxide [75-56-9] (methyloxirane, 1,2-epoxypropane) is a significant organic chemical used primarily as a reaction intermediate for production of polyether polyols, propylene glycol, alkanolamines (qv), glycol ethers, and many other useful products (see Glycols). Propylene oxide was first prepared in 1861 by Oser and first polymerized by Levene and Walti in 1927 (1). Propylene oxide is manufactured by two basic processes the traditional chlorohydrin process (see Chlorohydrins) and the hydroperoxide process, where either / fZ-butanol (see Butyl alcohols) or styrene (qv) is a co-product. Research continues in an effort to develop a direct oxidation process to be used commercially. 

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