Polymerization temperature profiles during

Figure 4.76 Temperature profiles during ethylene polymerization versus time for different positions along the reactor tubing [1].

Illustration of the pulsed thermal polymerization (FTP) procedure (left) with cycles of alternating hot and cold stages and the temperature profiles during polymerizations with pulsed and permanent heating (right). 

The temperature profile during the polymerization has no influence on the achievable conversion for a given initiator concentration but a strong influence on the average molecular weight (cf. Figure 5). The PTP results in polymers with much higher... 

Cutting GR, Tabner BJ. Radical concentrations and reaction temperature profiles during the (batch) core—shell emulsion polymerization of methyl methacrylate and butyl acrylate, studied by electron spin resonance spectroscopy. Eur Polym J 1997 33 213-217. 

Fig. 2. Temperature profile in the middle of a 5 cm cylindrical mould during the polymerization of a GMA-EDMA monolith. The increase of the temperature by 77 °C significantly influences the structure of the GMA-EDMA monolith...

Figure 2.18. Development of temperature profiles along the length of the reactor (at three arbitrary points) vs. time during front polymerization.

In an effort to investigate the incapability of clays to fully disperse in PA matrices derived from diamine and diacid monomers, during the solution-melt process [48, 67], Boussia et al. [30] studied the formation of PA n.6-clay nanocomposites (n = 2, 6, and 12) through applying an anhydrous melt polymerization process. The latter is characterized by the absence of water as solvent and benign time-temperature profiles, so as to minimize ionic conditions that have been considered to affect clays dispersability [67], as well as the risk of thermal degradation of organoclays surfactants. 

Figure 11.7 shows the temperature history at a fixed point in the reaction tube as a front passes. The temperature at this point is ambient when the front is far away and rises rapidly as the front approaches. Hence, a polymerization front has a very sharp temperature profile (Pojman et al., 1995b). Figure 11.7 shows five temperature profiles measured during frontal free-radical polymerization of methacrylic acid with various concentrations of BPO initiator. Temperature maxima increase with increasing initiator concentration. For an adiabatic system, the conversion is directly proportional to the difference between the initial temperature of the unreacted medium and the maximum temperature attained by the front. The conversion depends not only on the type of initiator and its concentration but also on the thermodynamic characteristics of the polymer (Pojman et al., 1996b). 

A polymerization front has a very sharp temperature profile, and profile measurements can provide much useful information. The temperature profiles help elucidate the reasons for incomplete conversion and the stmcture of the front. Two temperature profiles measured during FP of methacrylic add are shown in Figure 8. The first profile is for benzoyl peroxide in methacrylic add at different initial temperatures. The other profile was obtained for the same monomer with tert-butyl peroxide (tBPO). Conversion is directly proportional to the... 

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