Propagation methyl acrylate

Analytical A proc is described for the quant titrimetric analysis of TeNMe in nitric acid (Ref 35)s and a spectrophotometric method is described in Ref 41 for the detn of small amts of TeNMe in air and w Critical Diameter. The crit diam for deton propagation of TeNMe thickened with poly-(methyl acrylate) and loaded with up to 75% inert solids was detd and found to decrease with increasing solids loading. It was postulated that the solids acted as reaction foci ahead of the deton front (Ref 45)... 

The susceptibility of the polymerization of a given monomer to autoacceleration seems to depend primarily on the size of the polymer molecules produced. The high propagation and low termination constants for methyl acrylate as compared to those for other common monomers lead to an unusually large average degree of polymerization (>10 ), and this fact alone seems to account for the incidence of the decrease in A f at very low conversions in this case. 

Figure 5. Propagation Rate Constant (kp) for the Thermal Degradation of a Vinylidene Chloride/Methyl Acrylate (Five Mole Percent)/ 4-Vinylpyridine (0.1 Mole Percent) Terpolymer at 170 °C.

Similarly, from a plot of In (k/T) versus 1/T, the enthalpy of activation for each process may be obtained. This is also illustrated for the determination of the activation enthalpy for the propagation of degradation of a vinylidene chloride/methyl acrylate (five mole percent)/4-vinylpyridine (0.1 mole percent) copolymer in figure 7. The slope of the plot of In (kp/T) versus 1/T (figure 7) is given by -AH /R and the enthalpy of activation, AH, for the propagation reaction is calculated to be equal to 27.92 kcal/mol. The activation parameters for both the initiation and propagation reactions are recorded in table 3. 

Both methyl acrylate and butyl acrylate have been used to prepare vinylidene chloride copolymers with sufficient stability to permit thermal processing. The presence of alkyl acrylate units in the polymer mainchain limits the size of vinylidene chloride sequences and thus the propagation of degradative dehydrochlorination. More importantly it lowers the melt... 

Either addition sequence works if the two monomers are in the same family (e.g., methyl acrylate and butyl acrylate or methyl methacrylate and butyl methacrylate or styrene and 4-acetoxystyrene), because the equilibrium constants (for activation) for both types of chain ends have about the same value. The situation is usually quite different for pairs of monomers from different families. Chain ends from monomers with large equilibium constants can initiate the polymerization of monomers with lower equilibrium constants thus, cross-propagation is efficient. Methacrylate works well as the first monomer to form methacrylate-acrylate and methacrylate-styrene blocks. 

The heat of an emulsion polymerization is the same as that for the corresponding bulk or solution polymerization, since AH is essentially the enthalpy change of the propagation step. Thus, the heats of emulsion polymerization for acrylic acid, methyl acrylate, and methyl methacrylate are —67, —77, and —58 kJ mol-1, respectively [McCurdy and Laidler, 1964], in excellent agreement with the AH values for the corresponding homogeneous polymerizations (Table 3-14). 

Solvent effects including 2-methyl-l,3-dioxepane (MDOP), as a solvent, on the propagation kinetics of methyl acrylate (MMA) have been investigated using the PLP-SEC technique (PLP = pulse laser polymerization) <2005MI267>, and the composition of dioxolane-dioxepane copolymers has been studied by IR and differential scanning calorimetry (DSC) <2004PB349>. 

Hydroxy alkyl) mercury(II) acetates and NaBH4 react to form carbon-centered radicals through the reaction steps shown in Figure 1.14. When methyl acrylate is present in the reaction mixture, these radicals can add to the C=C double bond of the ester (Figure 1.15). The addition takes place via a reaction chain, which comprises three propagation steps. 

Because of the relative rates of chain propagation versus chain walking, polymers from the bis(imine) catalysts can be quite different depending on the metal. Nickel complexes form polymers with mostly shorter-chain branches and more crystallinity while polyethylene from the palladium analogs is more highly branched, to the point it can be amorphous. The palladium complexes also have the abihty to incorporate remarkably high (1 10 mole percent) amounts of polar monomers such as methyl acrylate and methyl vinyl ketone, though at considerable loss in activity. ... 

In contrast to methacryllc esters, methyl acrylate (MA) and n-butyl acrylate (BA) did not polymerize at all upon plasma treatment. The observation holds true even when the initiation period was increased to 15 minutes (see Table 1), despite the fact that the propagation constants from photopolymerization studies ( ), indicate that its value is higher for MA (k = 720 Jl/mole-sec) than for MMA (k = 143 /mole-sec) at 30°C. ... 

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... 

Figure 4.6-12 Variation of the propagation rate coefficient kp with (a) temperature at ambient pressure and (b) pressure at 30°C for the following monomers methyl methacrylate (MMA), butyl methacrylate (BMA), and dodecyl methacrylate (DMA) methyl acrylate (MA), butyl acrylate (BA), and dodecyl acrylate (DA) for references see text.

Smooth, but one-way, mechanistic crossover from olefin polymerization to group-transfer polymerization is possible with lanthanocene catalysts, since insertion of an acrylate into the propagating metal alkyl to form an enolate is energetically favorable. Block copolymers of ethylene with MMA, methyl acrylate, ethyl acrylate, or lactones have been prepared by sequential monomer addition to lanthanide catalysts and exhibit superior dyeing capabilities. However, the reverse order of monomer addition, i.e., (meth)acrylate followed by ethylene, does not give diblocks since the conversion of an enolate (or alkox-ide) to an alkyl is not favored. Therefore, although... 

The product formed from ethyl -[(allyloxy)methyl]acrylate was more complex. After initiation, during the propagation step, 5-membered, tetrahy-drofuran-structures form by an intramolecular addition step. Figure 7 shows the proposed stmcture of this polymer [80a]. 

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