Styrene production post

Styrene—butadiene, acrylonitrile—butadiene, and butyl latices have also been prevulcanised, but this usually results in a lower wet gel strength. Where the mbber is to be deposited onto a fabric substrate, as in manufacture of fabric-lined gloves, the lower gel strength is not a problem. For unsupported dipped synthetic mbber products, however, the use of post-vulcanised compounds is more common. 

The polyester product is first dissolved in styrene at a level of 60 % polyester and 40 % styrene. The initiators, either benzoyl peroxides (BPOs) or methyl ethyl ketone peroxide (MEKP), with appropriate co-catalysts, are added. The mixture is then poured into a glass mold and cured at room temperature for the MEKP system or at 100 °C for the BPO systems. A post-cure at 100 °C or 130 °C, respectively, for 5 h is then carried out. Blending experiments were carried out by using a dicyclo pentadiene (DCPD) resin, 61-AA-364, from GLS Fiberglass (Woodstock, IL, USA). This sample is pre-promoted , so we could only use the MEKP system. 

To overcome this issue Kureshy et al. [55, 56] reported dimeric form of Jacobsen s catalysts 3, 4. They used the concept of solubility modification by altering the molecular weight of the catalyst so that in a post catalytic work-up procedure the catalyst is precipitated, filtered and used for subsequent catalytic runs. The complexes 3, 4 (0.2 mol % of Co(lll)-salen unit) (Figure 2) were effectively used for HKR of racemic epoxides, e.g., styrene oxide, epichlorohydrin, 1,2-epoxypropane, 1,2-epoxyhexane, 1,2-epoxyoctane, and 1,2-epoxydodecane to achieve corresponding epoxides and 1,2-diols in high optical purity and isolated yields. In this process, once the catalytic reaction is complete the product epoxides were collected by reduced pressure distillation. Addition of diethylether to the residue precipitated the catalyst which was removed by filtration. However, the recovered catalyst was required to be reactivated by its treatment with acetic acid in air. The catalysts were reused 4 times with complete retention of its performance. 

Besides Hnear polystyrene, spherical beads of sHghtly crossHnked copolymers of styrene with 0.3—4% DVB, swollen to a maximum in EDC, have also been used as an initial polymer for the subsequent intensive post-crossHnking with MCDE. Spherical particles are preferable for many practical appHcations of the final products. 

Spectrum. On the other hand, this band is revealed in the spectrum of the styrene-0.6% DVB copolymer intensively crosslinked with 1 mol of MODE, which contains a comparable amount (1%) of pending chlorine. It is quite possible that industrial MN-200 contains chlorine of a different kind. A part of rather inert chlorine in the form of chloroethyl groups may have originated by the involvement of EDO into the Friedel—Crafts reaction. One may also assume that the initial copolymer of that product incorporates more DVB thus the unreacted pendent double bonds may have interacted with MCDE during the post-crosslinking reaction, leading to the formation of methyl chloropropyl ether fragments [105] ... 

This decisive topological factor largely accounts for the fact that, at equivalent degree of crosslinkings, the swelling abilities of the products of post-crosslinking linear polystyrene in solution or swollen styrene—DVB copolymer are much higher than that of conventional gel-type... 

In order to rmderstand the dramatically strong shrinking, nearly collapse, of the networks at high temperatures, it is necessary to consider the results given in Fig. 7.45. When heated in air the product of a styrene—2.7% DVB copolymer post-crosslinked to 200% starts to shrink at a temperature slightly above 200°C. However, when heated in an inert atmosphere, the... 

Great Lakes produces its brominated styrene polymers in a different way from its competitors. Competitive products are made by post-brominating the polystyrene polymer. This can be a difficult reaction and sometimes by-products are formed that can reduce thermal stability in the resultant material. To reduce the impurities, the competitors have developed additional steps that then improve the thermal stability, albeit not entirely. 

The sucrose esters could be oxygenated and the oxygenated products were essentially stable peroxides. The peroxides were stable even if dispersed in water and could be dispersed with the help of their own, lower esters. One could polymerize them with styrene, styrene-butadiene, or vinyl acetate. We did not try hard to achieve all the possibilities, but there were some indications that through this post-oxidation route. 

Carpet waste generated each year and accumulated in landfills represents a considerable potential resource, as it may be converted into various useful products The rate of carpet disposal is about 2-3 million tons per year in the US A, and about 4-6 million tons per year worldwide. A carpet typically consists of two layers of (i) backing (usually fabrics from polypropylene tape yams), joined by CaCOj filled styrene-butadiene latex rubber (SBR), and (ii) face fibers (the majority being nylon 6 and nylon 66 textured yams) tufted into the primary backing. To use post-consumer carpet (PCC) as concrete or soil reinforcement, the carpet is shredded to recover fibers. It is generally not necessary to disassemble yams in the carpet into individual fibers. The size-reduction process yields the following from PCC ... 

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