Styrene bulk polymer

Similar craze breakdown morphologies have been observed for dust-free films of polymethylmethacrylate (PMMA), poly(a-methylstyrene) (PaMS) and poly(styrene-acrylonitrile) (PSAN) Large pear-shaped voids nucleate at the craze-bulk polymer interface, never in the craze mid-rib, and thus this mode of craze breakdown seems to be a dominant one for all glassy polymers. 

The oxidative process is driven either by oxygen itself or by any source of free radicals. If a polymer backbone is attacked, leading to either a polymeric carbon or oxygen radical, backbone cleavage is possible. For polyethylene, polypropylene and butadiene- or isoprene-containing polymers, this may be accompanied by elimination of formaldehyde or acetaldehyde. For styrene-containing polymers, formaldehyde and benzaldehyde are products from the cleavage [74], Such reactions could take place either in the bulk oil phase or in deposits in which the polymer is physically trapped. 

Spontaneous copolymerization of styrene and maleic anhydride in the presence of a molten polymer or a bulk polymer undergoing deformation at elevated temperatures is a rapid and convenient route for carboxylating polymers. The reaction is carried out on the bulk polymer at 120° to 200°C. (depending upon the softening or melting point of the polymer) by injecting an equimolar solution of maleic anhydride in styrene into the molten polymer (II, 12). 

Acrylonitrile/Butadiene/Styrene (ABS) Acry-lonitrile/butadiene/styrene (ABS) polymers are not true terpolymers. As HIPS they are multipolymer composite materials, also called polyblends. Continuous ABS is made by the copolymerization of styrene and acrylonitrile (SAN) in the presence of dissolved PB rubber. It is common to make further physical blends of ABS with different amounts of SAN copolymers to tailor product properties. Similar to the bulk continuous HIPS process, in the ABS process, high di-PB (>50%, >85% 1,4-addition) is dissolved in styrene monomer, or in the process solvent, and fed continuously to a CSTR where streams of AN monomer, recycled S/AN blends from the evaporator and separation stages, peroxide or azo initiators, antioxidants and additives are continuously metered according to the required mass balance to keep the copolymer composition constant over time at steady state. 

Polyethylene terephthalate (PET) is susceptible to deterioration by UV at wavelengths below 315 nm, causing embrittlement, crazing and yellowing of thin films and sheeting [40], Both PET and polybutylene terephthalate (PBT) bulk polymers, however, are used in stabilized form for exterior mouldings, sometimes in admixture with other polymers such as acrylonitrile styrene acrylate. 

Styrene-Acrylonitrile Copolymers (SAN). Styrene-acrylonitrile polymers are copolymers prepared from styrene and acrylonitrile monomers. The polymerization can be done under emulsion, bulk, or suspension conditions. The polymers generally contain between 20 to 30 percent acrylonitrile. The acrylonitrile content of the polymer influences the final properties with tensile strength, elongation, and heat distortion temperature increasing as the amount of acrylonitrile in the copolymer increases. 

Styrene acrylonitrile (SAN) copolymers. Styrene acrylonitrile polymers are copolymers prepared from styrene and acrylonitrile monomers. The polymerization can be done under emulsion, bulk, or suspension... 

A review of the photo-degradation of polystyrene includes a mechanism proposed to explain the breakdown of that polymer. A novel technique for following the extent of photo-oxidation of bulk polymer has been developed by Weir who measured the dielectric loss of films during irradiation in vacuum and in oxygen. Under these conditions the increases in dielectric constant were attributed to products of degradation, and measurement of the loss-peak due to carbonyl compounds provided a sensitive indicator of extent of reaction. - A study of the role of stabilizers showed that for specific types the stabilization mechanism involved the screening effect as well as the ability to quench excited states of the polymer. A study of photo-oxidation (A>300nm) of films of styrene-type copolymers produced a mechanism in which it was proposed that initiation of the... 

Figure 2. Plot of molecular weight as a function of polymerization time for the bulk polymer of styrene obtained at 100°C in nitrogen using 0.1 bis(trimethylsilyl)benzopinacolate, I. 

Queslel JP, Jarry JP, Moimerie L (1986) Statimiaiy fluorescence depolarization study of mobility of rigid probes in bulk elastomcax—motion of dimethylanthracene and 3 trans-diphenylpolyenes inserted in polyisoptene, polybutadiene and random butadiene-styrene copolymers. Polymer 27(8) 1228-1234. doi 10.1016/0032-3861(86)90011-x... 

Lousberg HHA, Boelens HFM, Le Comte EP, Hoefsloot HCJ, Smilde AK. On-line determination of the conversion in a styrene bulk polymerization batch reactor using near-infrared spectroscopy. J Appl Polym Sci 2002 84 90-98. 

Online NIR spectroscopy has been used to measure conversion versus time traces for cumyl dithiobenzoate (CDB)-mediated styrene bulk polymerizations up to 2.5 kbar. MMDs of the resulting polymer were determined by SEC. ° ... 

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