Methyl acrylate , free-radical polymerization

Methyl acrylate Free radical polymerization similar to the above —CHr-CH— ( OOCHs 0 Amorphous, even when stretched. Soft, rubbery if molecular weight is high. Readily soluble... 

The extruder can be used for a variety of polymerizations even if no preformed polymer is present.89 These include the continuous anionic polymerization of caprolactam to produce nylon 6,90 anionic polymerization of capro-lactone 91 anionic polymerization of styrene 92 cationic copolymerization of 1,3-dioxolane and methylal 93 free radical polymerization of methyl methacrylate 94 addition of ammonia to maleic anhydride to form poly(succin-imide) 95 and preparation of an acrylated polyurethane from polycaprolactone, 4,4 -methylenebis(phenyl isocyanate), and 2-hydroxyethyl acrylate.96 The technique of reaction injection molding to prepare molded parts is slightly different. Polyurethanes can be made this way by... 

Statistical (random) ABBABABAAABBABAABBAABA Methyl methacrylate, butyl acrylate Free-radical polymerization Ftoly(methyl methacrylate-sfaf-butyl acrylate)... 

Poly (methyl Acrylate). The monomer used for preparing poly(methyl acrylate) is produced by the oxidation of propylene. The resin is made by free-radical polymerization initiated by peroxide or azo catalysts and has the following formula ... 

Treatment of 2-methylthiirane with t-butyl hydroperoxide at 150 °C in a sealed vessel gave very low yields of allyl disulfide, 2-propenethiol and thioacetone. The allyl derivatives may be derived from abstraction of a hydrogen atom from the methyl group followed by ring opening to the allylthio radical. Percarbonate derivatives of 2-hydroxymethylthiirane decompose via a free radical pathway to tar. Acrylate esters of 2-hydroxymethylthiirane undergo free radical polymerization through the double bond. 

Lignin, brown coal polymer of methacrylic acid, methacrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, vinyl acetate, methyl vinyl ether, ethyl vinyl ether, N-methylmeth-acrylamide, N,N-dimethylmethacrylamide, vinyl sulfonate, or 2-acrylamido-N-methylpropane sulfonic acid free radical polymerization of a water-soluble vinyl monomer in an aqueous suspension of coals [705,1847]... 

In 1981 we reported (2, 3) the first examples of free radical polymerizations under phase transfer conditions. Utilizing potassium persulfate and a phase transfer catalyst (e.g. a crown ether or quaternary ammonium salt), we found the solution polymerization of acrylic monomers to be much more facile than when common organic-soluble initiators were used. Somewhat earlier, Voronkov and coworkers had reported (4) that the 1 2 potassium persulfate/18-crown-6 complex could be used to polymerize styrene and methyl methacrylate in methanol. These relatively inefficient polymerizations were apparently conducted under homogeneous conditions, although exact details were somewhat unclear. We subsequently described (5) the... 

A similar result has been recently found for the free radical polymerization of methyl methacrylate in 14 solvents (32). All differences (Aff. — AHf/8) were found to be positive, but only three of the 14 differences (AH /g — AH. ). Again, isotactic triad formation is favored over heterotactic triad formation and heterotactic triad formation over syndiotactic with increasing temperature as long as the individual modes of addition are considered and not the net result. Except for meth-acrylic acid in alcohols (cf. Lando et al. (28)) no model is known which shows why a certain solvent acts differently from another one with respect to stereocontrol in free radical polymerization. 

Free radical polymerization of styrene, of acrylate and of methacrylate monomers in solutions at 60° C in the presence of this preformed polymer produced graft copolymers in high efficiency, the chain transfer constants for these mercapto groups with styrene and methyl methacrylate being similar to those found with simple mercaptans (80, 85). 

MALDI-TOF mass spectrometry analysis of poly(methyl acrylate) prepared by the free-radical polymerization of methyl acrylate (MA) in the presence of a cyclic dixanthate under y-ray irradiation revealed that there are at least three distributions, i.e., molecular mass for [ 1-(MA) -H]+ of cyclic polymers, [1-(MA) -THF-H]+, and [1-(MA) -(THF)2-H]+ of linear polymers were observed. The relative content of the cyclic polymers markedly increases at a lower temperature, which may be related to the reduced diffusion rate and the suppressed chain-transfer reaction at the low reaction temperature [39]. 

Figure 103 shows the sequence of curing a letterpress ink, with benzilketal (an initiator often used) and epoxydiacrylate as acrylate oligomer. Free-radical polymerization of an acrylate oligomer can be initiated by both the methyl and benzoyl radical it has been found that the latter makes the greater contribution, as shown in Figure 104. 

The free radical polymerization of acrylic anhydride has been shown (37) to proceed predominantly by alternating intramolecular and intermolecular propagation steps. The product after hydrolysis and methylation has been found to yield a polymethyl acrylate exhibiting considerable crystallinity (37). 

Solution polymerization. Solution polymerization involves polymerization of a monomer in a solvent in which both the monomer (reactant) and polymer (product) are soluble. Monomers are polymerized in a solution that can be homogeneous or heterogeneous. Many free radical polymerizations are conducted in solution. Ionic polymerizations are almost exclusively solution processes along with many Ziegler-Natta polymerizations. Important water-soluble polymers that can be prepared in aqueous solution include poly(acrylic acid), polyacrylamide, poly(vinyl alcohol), and poly(iV-vinylpyrrolidinone). Poly(methyl methacrylate), polystyrene, polybutadiene, poly(vinyl chloride), and poly(vinylidene fluoride) can be polymerized in organic solvents. 

Gosh and Gosh [105] studied photoinitiated polymerization of methyl methacrylate initiated by the BP-TV,A-dimethylaniline couple, and Clarke and Shanks [106] tested the influence of a variety of amines on benzophenone-initiated polymerization. That amino radicals resulted during the initiation the polymerization by benzophenone-tertiary aromatic amines was shown by Li through the use of ESR and spin-trapping methods [107]. It was shown that the rate of photoinitiated polymerization depends on the structure of the amine. More recently [108] benzophenone-tertiary aromatic amines were studied as initiators of the free-radical polymerization of polyol acrylates. Illustrative kinetic curves recorded during photoinitiated polymerization of TMPTA are shown in Figure 23. 

Turning to the comparison between the rate constants for the chain propagation in the free radical polymerization of methyl and butyl acrylayes, it can be observed that both these reactions should occur with the same entropy decrease, because identical double bonds are involved. From the experimental data by Melville and Bickel (1 3) and by Bengough and Melville (14) relative to butyl acrylate, 4 pairs of activation energy and entropy can be calculated, which are collected in Table IV. It is evident that the experimental activation entropy which is closest to the calculated ASp for alkyl acrylates (i.e. the ASp value reported for methyl acrylate in Table III) is -12.+. f j/mol K, whereas all the other activation entropies seem to be too high. The rate constant calculated at JO°C from... 

---