Lauroyl peroxide polymerization

In the suspension polymerization process, the autoclave reactor is filled with water. PVA, polyvinyl alcohol is the dispersing agent that helps stabilize the suspension. Lauroyl peroxide is the free radical catalyst that starts it all off. The reaction temperature is around 130°F, and the process takes 10—12 hours per batch, with 95% conversion. 

Emulsions may be polymerized by use of a water-soluble catalyst (initiator), such as potassium persulfate, or a monomer-soluble catalyst, such as benzoyl peroxide, lauroyl peroxide or azobisisobutyronitrilc. Suspension and solution polymerizations employ the monomer soluble catalysts only. In addition to the above-mentioned initiators, diisopropyl pcroxydi-carbonatc may also be employed, where lower-temperature polymerization may be desired, e.g., to reduce branching and minimize degradation. 

Chemistry. Vinyl acetate is polymerized commercially using free-radical polymerization in either methanol or, in some circumstances, ethanol. Suitable thermal initiators include organic peroxides such as butyl peroxypivalate, di(2-ethylhexyl) peroxydicarbonate, butyl peroxyneodecanoate, benzoyl peroxide, and lauroyl peroxide, and diazo compounds such as 2,2 -azobisisobutyronitrile (205—215). The temperatures of commercial interest range from... 

Other peroxides—2,6-dichlorobenzoyl peroxide lauroyl peroxide, tert-butyl hydroperoxide, and methyl ethyl ketone peroxide—are also highly effective for the free radical reaction at low temperatures. On the other hand, azobisisobutyronitrile (AIBN) is ineffective. Hence, the mechanism cannot be simple, free radical formation which then initiates polymerization. 

The mixed peroxides, t-butylperoxy 2-ethylhexyl, (I), and isobutanoyl-lauroyl peroxide, (II), were prepared by Overkamp [2] and Tammer [3], respectively, using t-butyl peroxide and isobutanoyl chloride with 30% hydrogen peroxide in the presence of sodium hydroxide in a two-phase system. Both agents were used in vinyl chloride polymerization. 

In a related study, Lusinchi [11] reported the synthesis of a new soluble polymer containing a p-alkoxybenzyl alcohol linker, analogous to Wang resin. The polymer was utilized in intermolecular radical addition reactions. The polymer was synthesized by subjecting xanthate 65, formed in three steps from alcohol 63, to styrene polymerization in the presence of lauroyl peroxide... 

General. Aqueous solutions of hydrophilic monomers were emulsified in xylene using water-in-oil emulsifiers, and polymerized using oil-soluble initiators. Typical hydrophilic monomers were sodium p-vinylbenzene sulfonate, sodium vinylbenzyl sulfonate, 2-sulfoethyl acrylate, acrylic acid, acrylamide, vinylbenzyl-trimethylammonium chloride, and 2-aminoethyl methacrylate hydrochloride. Typical oil-soluble initiators were benzoyl and lauroyl peroxides. In some cases, water-soluble potassium persulfate was used, both separately and in mixtures with oil-soluble peroxides. Of the water-in-oil emulsifiers, one of the most effective was Span 60 (technical sorbitan monostearate. Atlas Chemical Industries, Inc.). 

The polymer is commonly obtained from vinyl chloride with a peroxide initiator such as peroxydicarbonates, fert-butylperpivalate, benzoyl or lauroyl peroxide, acetyl cyclohexylsulfonyl peroxide, or azobis(2,4-dimethylvaleronitrile). The polymerization can be done by suspension, emulsion or solution techniques. Low polymerization temperatures are used when high MW material is required. Suspension polymerization employs water suspension agents, such as poly(vinyl alcohol) or methylcellulose. The resulting polymer Is a partially syndiotactic material but with low crystallinity. The macromolecules typically have head to tail linkages (H-T) and a small proportion (less than 1.5%) of branching. Ziegler-Natta catalysts are not used to produce PVC. 

Use Surfactant, polymerization initiator, antienzyme agent, foamer synthesis of lauroyl peroxide, sodium A-lauroyl sarcosinate, and other sarcosi-nates. 

Many initiator-accelerator systems that contain accelerators other than amine have been suggested for vinyl pol3rmerization, but only a few have been employed in dental resins. Substitution of p-toluenesulfinic acid, alpha-substituted sulfones and low concentrations of halide and cupric ions for tertiary amine accelerators, yields colorless products (43-48). Most of these compounds have poor shelf-life. They readily oxidize in air to sulfonic acids which do not activate polymerization. Lauroyl peroxide, in conjunction with a metal mercaptide (such as zinc hexadecyl mercaptide) and a trace of copper, has been used to cure monomer-pol3rmer slurries containing methacrylic acid (49-50). Addition of Na salts of saccharine to monomer containing an N,N-dialkylarylamine speeds up pol)rmerization (51). 

Most functional monomers and cross-linkers contain one or more vinyl functionalities. Polymerization of this type of compound for the preparation of MIPs is traditionally performed as a free-radical polymerization, initiated via either ther-molytic or photolytic homolysis of an initiator. One of the most commonly used free radical initiators for this purpose is 2,2 -azobis (isobutyronitrile) (AIBN). Other examples of free-radical polymerization initiators are phenyl-azo-triphenyl-methane, tert-butyl peroxide (TBP), acetyl peroxide, benzoyl peroxide (BPO), lauroyl peroxide, tert-butyl hydroperoxide and tert-butyl perbenzoate. 

The polymerization is a two-step batch operation initiated with 2,2 -azobisisobutyronitrile (AIBN) or lauroyl peroxide or with a mixture of AIBN and acetyl cyclohexyl sulfonyl peroxide (ACSP). The process has the obvious advantage of eliminating the need for protective colloids, emulsifier, buffers, and other additives. The reaction is started in a vertical reactor equipped with a high-speed agitator operating at 130 r/min at 140 F and requires 3 h. The reaction is continued to 10% conversion, when the batch is dropped... 

Laurox Lauroyl peroxide Laurydoi LYP 97 LYP 97F NSC 670 Peroxide, bis(l-oxododecyl)- Peroxide, didodecanoyl Peroxyde de lauroyle. Initiator for bulk, solution, and suspension polymerization, high-temperature curing of polyester resins, and cure of acrylic syrup. White plates mp = 49 insoluble in H2O, soluble in CHCI3. Elf Atochem N. Am. 

AI3-52409 Dodecanoic acid, chloride Dodecanoyl chlori.de n-Dodecanoyl chloride EINECS 203-941-7 HSDB 5567 Laurie xid chloride Lauroyl chloride. Surfactant, polymerization initiator, antienzyme agent, foamer synthesis of lauroyl peroxide, sodium lauroyl sarcosinate, other sarcosinates. Liquid mp = -17 bpis = 145 d = 0.9169 very soluble in Et20. Degussa-HIlls Corp. Elf Atochem N. Am. PPG Ind. 

Many peroxides affect pol mierization, but those used are available in quantity and the choice is based both on economics and performance. It has been shown that the activity of the organic peroxides in any polymerization is related to their decomposition rates at various temperatures. If elevated cure temperatures, 200- 250°F (93-121°C), are used, benzoyl peroxide is preferred. The amount required is about 1.0 per cent. It is preferred because a long catalyzed tank life results at room temperature. If lower temperatures in the 120 180 F (49-82°C) range are employed, hydroperoxides are more effective. Methyl ethyl ketone peroxide and cumene and ter- tiary butyl hydroperoxide all find application. Lauroyl peroxide, cyclohexanone peroxide, and <-butyl perbenzoate are used in limited amounts. Mixtures of two peroxides are often used, one to initiate the reaction and a second to promote the polymerization once it is started. 

Lanroyl peroxide is nsed as an initiator for free-radical polymerization in making polyvinyl chloride. Lauroyl peroxide constitutes about 4% of all organic peroxides consumption in the United States. 

The usual initiators are monomer-soluble ones sueh as dibenzoyl peroxide, lauroyl peroxide, and di-o-toluyl peroxide. Hydrogen peroxide and a few other water-soluble initiators usually associated with emulsion polymerizations have also been used. The molecular weight of the polymer may be controlled by variations in the concentration of the initiator. This effect is illustrated in Procedure 4-1. It is interesting to note that this procedure which goes back to FIAT Final Report 1102, i.e., a report compiled toward the end of World War II [4], was still used in 1974 according to Bravar et al. [117]. We have adapted these procedures to a laboratory scale. 

Polymerization conditions Polymerization was conducted using 250 ml vinyl acetate (233 gm, carefully purified), 500 ml distilled water containing 50 gm sodium thiosulfate (when indicated), and 6 ml of 6% solution of poly(vinyl aleohol) (Rhodoviol HS 100). To control the reaction temperature at 63.5°C, under nitrogen, water was gradually added. The water temperature was 20°C. During the preparation a total of 1430 ml of water was added. The initiator used was lauroyl peroxide or AIBN. On 250 ml of vinyl acetate, 0.5-3 gm of initiator was used. 

The usual initiators such as 2,2 -azobisisobutyronitrile, benzoyl peroxide, and lauroyl peroxide have to be decomposed to generate the free radicals which bring about the polymerization process. While there are methods which involve the use of radiation to accomplish this, these are rarely advocated it is more common to use thermal means to generate the initiating species. In order that the product be formed in a reasonable time interval, it is usual to attempt the use of these initiators at temperatures in the range of 60° to 80°C (with the notable exception of diisopropyl peroxydicarbonate which may be used in the range of 25°C to 50°C). Such temperatures are above the critical temperature of vinyl fluoride (54.7°C). Consequently, regardless of applied pressure, the monomer cannot be liquified above 54.7°C, the temperatures at which the initiators are... 

Figure 7.2 Relationship between initiator concentration and polymerization rate for different initiators A, bis(p-chlorobenzoyl)peroxide B, benzoyl peroxide C, acetyl peroxide in dimethylphthalate D, lauroyl peroxide E, myristoyl peroxide F, caprylyl peroxide G, bis(2,4 dichlorobenzoyl) peroxide. [A.I. Lowell and J.R. Price, J. Poly. Sci, 43, 1 (1996). With permission.]... 

Refiners and Schork used lauroyl peroxide as the initiator and also as the costabUizer, and found that diffusion instability was reduced to the point where nucleation in the monomer droplets and polymerization conld be carried ont before significant diffusional degradation of the droplets took place. Alduncin et al. compared different oil-solnble initiators in conjunction with hexadecane as the costabUizer, and fonnd that only lanroyl peroxide was water-insolnble enongh to stabilize the monomer droplets against degradation by molecnlar diffusion. ... 

Most of the minionulsion polymerization processes have been carried out by using water-solnble initiators following the conventional mnulsion polymerization, althongh a number of researchers have looked at the possibilities of using oil-soluble initiators. Refiners and Schork used lauroyl peroxide as both the initiator and also as the costabilizer. Alduncin et al. used other oil-soluble... 

When the ester 247 was treated with lauroyl peroxide in the presence of 15 equivalents of styrene, the polymer 248 was obtained. This was soluble in many common organic solvents but which could be precipitated with methanol, making the technique potentially useful for parallel synthesis. 5 -0-Methacryloyl-uridine and -adenosine have been polymerized onto a silica support, using Cu(I) mediated radical polymerization, under conditions favouring products of narrow polydispersity. ... 

Dioctyltin diisooctylthioglycollate catalyst, PU two-pack coatings Dibutyltin bis (laurylmercaptide) catalyst, PU elastomers Ferric acetylacetonate N-Hydroxyethy I pi perazi ne catalyst, purified terephthalic acid polyesters Manganese acetate (ous) catalyst, PVC suspension polymerization Lauroyl peroxide catalyst, pyridine synthesis Cobaltocene... 

Acetyl cyclohexane sulfonyl peroxide n. A polymerization initiator, often used in conjunction with a dicarbonate such as di-sec-butyl peroxydicarbonate in vinyl chloride polymerization. The initiators have largely replaced enzoyl and lauroyl peroxides, the principal initiators in the early years of PVC production. 

Activator, initiator n. It is usually necessary to add an activator (e.g., FeS04 7H2) to attain reasonable rates of polymerization when redox initiators (lauroyl peroxide and fructose) are used at zero degree temperature or below. 

Lauroyl peroxide [CH3(CH2)ioC(0)-]2. A peroxide used as an initiator in free-radical polymerizations of styrene, vinyl chloride, and acrylic monomers. 

Other initiators that have been used in polymerizing vinyl chloride are diisopropyl peroxydicarbonate, di-5ec-butyl peroxydicarbonate, terUhwiyX peroxypivalate, as well as lauroyl peroxide and benzoyl peroxide. All of these initiators, after allowances are made for variations in their half-lives at a given temperature, behave similarly as far as the two-phase polymerization of vinyl chloride is concerned [79]. There is considerable advantage, from the economic standpoint, in using an initiator such as diisopropyl peroxydicarbonate, which is active at a relatively low temperature. 

Lauroyl peroxide (0.5% of VCM charged) — 50 Polymerization under greatly reduced pressure 45... 

The most commonly used initiators in this system are AIBN, benzoyl peroxide, lauroyl peroxide (LPO), and diisopropyl peroxydicarbonate (IPP). The last two are probably of most interest industrially. In aromatic solvents, LPO has a half-life of 10 hr at 62°C while that of IPP is 10 hr at only 35[92]. Therefore one may expect that at the same temperature, polymerizations initiated with IPP proceed significantly more rapidly than LPO-initiated ones this, indeed, has been found. 

While most suspension polymerizations are carried out with monomer-soluble initiators, there are cases where totally water-soluble initiators have been used an interesting intermediate situation is a redox initiation system consisting of lauroyl peroxide and ferrous caproate or of tert-b xiy hydroperoxide and tributyl borate. These initiators seem to be useful at... 

Table XII gives the half-lives of several initiators which are of interest in suspension polymerizations of vinyl chloride. While these data are a rough guide to the temperature-time relationship to be expected, many other factors need to be considered. For example, lauroyl peroxide brings about a polymerization process of vinyl chloride in which the maximum rate takes place between 60% and 80 o conversion whereas the rate of polymerization with diisopropyl peroxydicarbonate is much more uniform throughout the process. Also, particle structure varies with the initiator used [139]. The development of initiators has been in the direction of molecules with unsymmetrical substitution about the peroxide bridge. Data on these compounds are also included in Table XII [139, 140].

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