Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Free styrene

The free styrene monomer is restrained within the gel and further reaction with fumarate groups is determined by the spacial arrangement the styrene polymerizes in homopolymer blocks as it intercepts fumarate reaction sites. As individual micelles expand and deplete available fumarate sites in the short polymer chains, the remaining styrene forms homopolymer blocks that terminate at the boundaries between overlapping micelles (Fig. 4). [Pg.318]

To a flask covered with aluminum foil, over a 1 hr period, a solution of 35 gm (0.336 mole) of inhibitor-free styrene in 90 ml of ether is added to 525 ml of the ether solution of phenyldiazomethane prepared as above. The reaction mixture is allowed to stand at room temperature overnight. Then approximately 200 ml of the ether is evaporated off under reduced pressure. The flask is immersed in an ice bath and stirred for a total reaction time of 36 hr. After thorough cooling in an ice bath, the precipitated product is removed by filtration and washed with ice-cold ether until all the red coloration has been removed. The ether washings and filtrate may again be partially evaporated and... [Pg.164]

Fig. 4. Micellular gelation mechanism. A shows micelle nuclei, highly cross-linked B, boundary where micelle growth terminates in styrene block polymers. Styryl free radicals simultaneously initiate micelle nuclei at points of high fumarate concentration. The micelles continue to expand, interacting with free styrene until the fumarate groups are depleted. The micelles eventually overlap at the boundaries that contain higher levels of terminal styrene... Fig. 4. Micellular gelation mechanism. A shows micelle nuclei, highly cross-linked B, boundary where micelle growth terminates in styrene block polymers. Styryl free radicals simultaneously initiate micelle nuclei at points of high fumarate concentration. The micelles continue to expand, interacting with free styrene until the fumarate groups are depleted. The micelles eventually overlap at the boundaries that contain higher levels of terminal styrene...
Figure 5(b) Electron micrograph of inhibitor free styrene polymerized in a... [Pg.73]

A more recent study of the course of the polymerization used 50 gm of inhibitor-free styrene, 0.5 gm of potassium persulfate dispersed in 400 ml of deionized water heated in a 500 ml four-necked flask and using a Teflon-coated steel shaft with a dual-bladed mixing paddle at 70° 0.5°C under nitrogen with a rate of stirring of 200 20 rpm. It was found that there was a limited conversion phenomenon to the process. After conversion between 89 and 95%, the process came to a stop. After prolonged heating conversion barely reached 100%. (In this particular preparation, the particle diameter was 0.54 /im [79]. [Pg.396]

Rubber grade 1,3-butadiene was purchased from the Phillips Petroleum Company. Two columns, one packed with the potassium form of a sulfonic acid ion exchange resin (Dowex MSC-l-K) and the other packed with an activated alumina, were used to purify the butadiene. Isoprene was purchased from Aldrich Chemical Company. Stabilizer-free styrene monomer was obtained directly from the Dow styrene monomer plant. Alpha-methylstyrene (AMS) was purchased from U.S. Steel Corporation. The last three monomers were all purified by passing through a column packed with activated alumina and then vacuum distilled over calcium hydride. [Pg.130]

Fig. 18 Change of electrical conductivity of UPR during radiation induced crosslinking at the dose rate B = 0.345 kGy/h at 290 K in non-logarithmic (solid symbols) and logarithmic scale (open symbols). The logarithm of conductivity is calculated from the data presented in non-logarithmic form. The changes of free styrene content after extraction are also shown (large solid squares). Reprinted from (1999) Radiat Phys Chem 54 95 [159] with permission... Fig. 18 Change of electrical conductivity of UPR during radiation induced crosslinking at the dose rate B = 0.345 kGy/h at 290 K in non-logarithmic (solid symbols) and logarithmic scale (open symbols). The logarithm of conductivity is calculated from the data presented in non-logarithmic form. The changes of free styrene content after extraction are also shown (large solid squares). Reprinted from (1999) Radiat Phys Chem 54 95 [159] with permission...
The experiments illustrated in Eqs. (6) and (7) clearly indicate that the reaction proceeds in an irreversible and direct manner. (1) In Eq. (6), the coexistent hydroamination adduct 29 afforded neither free styrene nor crossover products, indicating that the hydroamination is an irreversible process. (2) In the reaction of 2,5-dimethylstyrene (27) with morphorine (28) in Eq. (7), an additive, Markovnikov-type adduct 31, did not isomerize to anti-Markovnikov-type adduct. (3) The kinetic study on the amination process revealed a large negative of —213 J mol s , which is similar to the value of the nitroalkene amination. The first-order rate constant of the arene exchange process is comparable to that of the amination process. (4) The conjugate addition nature was confirmed by using... [Pg.124]


See other pages where Free styrene is mentioned: [Pg.253]    [Pg.183]    [Pg.106]    [Pg.243]    [Pg.291]    [Pg.396]    [Pg.77]    [Pg.143]    [Pg.751]    [Pg.4]    [Pg.143]    [Pg.239]    [Pg.240]    [Pg.191]    [Pg.200]    [Pg.137]    [Pg.328]    [Pg.3692]    [Pg.6154]    [Pg.602]    [Pg.270]    [Pg.410]    [Pg.534]    [Pg.938]    [Pg.82]    [Pg.32]   
See also in sourсe #XX -- [ Pg.20 ]




SEARCH



Free Radical Polymerization of styrene

Free energy, styrene epoxidation

Free radical copolymerizations with styrene

Free radical styrene

Free-radical-initiated chain polymerization styrene-acrylonitrile copolymer

Living Free Radical Polymerization of Styrene

Stable free radical polymerization styrene-acrylonitrile

Styrene free radical polymerization

Styrene living free radical

Styrene stable free radical polymerization

Styrene, free-radical copolymerization

Styrene-butadiene copolymers free-radical polymerization production

© 2024 chempedia.info