Polymerization butyl acrylate

Other authors observed that acrylic esters showed smaller gel effects, the larger the alkyl groups linked. According to Melville (25, 26), butyl acrylate polymerized in bulk shows no gel effect. If one assumes that EA shows no gel effect (at least under our conditions of y-emulsion polymerization), and that the pure monomer phase disappears at the maximum of Ubf, then the behavior of our system harmonizes well with theory after the maximum, the overnall reaction rate must decrease following first order with respect to [M],... 

Figure 4.11 Rayleigh-Taylor instability with a descending front of butyl acrylate polymerization.

Figure 3. Rayleigh-Taylor instability with descending front of butyl acrylate polymerization. Although the polymer product is hot (> 200 °C) it still is about 20% more dense than the monomer below it.

Scission events can occur in any system where mid-chain radicals are formed. However, scission is more temperature-activated than H-abstraction and thus becomes important only at elevated temperatures. The reaction is not believed to occur during butyl acrylate polymerization at 75 C [37], but is shown to be important at 140°C [29, 45], Scission is a dominant mechanism in styrene polymerizations at 260-340°C [26], and also occurs during LDPE production [30]. Scission of midchain radicals formed via intermolecular transfer to polymer can have a significant effect on the breadth and the shape of polymer MWD [46]. 

Kinetic treatment of these more complex mechanisms is often difficult. Equations (32)-(34) are a network of reactions developed to treat intramolecular transfer, short-chain branch formation, and jS-scission for butyl acrylate polymerization [47]. 

Willemse RXE, van Herk AM, Panchenko E, Junkers T, Bubackm M. PLP-ESR monitoring of midchain radicals in n-butyl acrylate polymerization. Macromolecules 2005 38 5098-5103. 

Hlalele L, Klumperman B. Reversible nitroxide trapping of the mid-chain radical in n-butyl acrylate polymerization. Macromolecules 2011 44 5554-5557. 

Figure 16 Front velocity of butyl acrylate polymerization as a function of applied pressure with AIBIN as the initiator (1.7% w/w) and 5.7% fumed silica. Adapted from Pojman, J. A. Ilyashenko, V. M. Khan, A. M.

Figure 3. The front velocity (1.09 cm/min) is determined from the slope of a plot of front position versus time for n-butyl acrylate polymerization under pressure. [AIBN]o = 0.00457 molal initial temperature = 18.9 "C...

Figure 16. Rayleigh-Taylor instability in a descending front of n-butyl acrylate polymerization.

As mentioned above, it is known that intramolecular chain transfer, in particular, 1,5-hydrogen shift, does also occur during the polymerization of monomers that yield very reactive macroradicals, such as acrylates and acrylic acid. This so-called backbiting reaction, by which a secondary radical (SPR) is transformed into a more stabilized tertiary (MCR) one, proceeds via a six-membered cyclic transition state with rate coefficient kbb (see Scheme 1.17). In principle, intramolecular chain transfer to a remote chain position and intermolecular chain transfer to another polymer molecule may also take place.These latter processes are, however, found to be not significant in butyl acrylate polymerization at low and moderate degrees of monomer conversion and temperature. ... 

PLP-SEC and (iii) single-pulse pulsed-laser polymerization coupled with online time-resolved electron-spin resonance spectroscopy (SP-PLP-EPR). The propagation rate coefficient for MCRs may be obtained via ft-PLP-SEC and SP-PLP-EPR. Termination rate coefficients kt , and kt are only accessible from SP-PLP-EPR," in which different types of radicals can simultaneously be traced as a function of time. Remaining kinetic coefficients can then be obtained via computer modeling. Table 1.5 collates kinetic coefficients for butyl acrylate polymerization as an example. 

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