Polyamide kinetic data

Table 3. Kinetic data on the thermal degradation of polyamides in nitrogen Reprinted from [a. 115] with permission from Elsevier ...

Analysis of the non-isothermal polymerization of E-caprolactam is based on the equations for isothermal polymerization discussed above. At the same time, it is also important to estimate the effect of non-isothermal phenomena on polymerization, because in any real situation, it is impossible to avoid exothermal effects. First of all, let us estimate what temperature increase can be expected and how it influences the kinetics of reaction. It is reasonable to assume that the reaction proceeds under adiabatic conditions as is true for many large articles produced by chemical processing. The total energy produced in transforming e-caprolactam into polyamide-6 is well known. According to the experimental data of many authors, it is close to 125 -130 J/cm3. If the reaction takes place under adiabatic conditions, the result is an increase in temperature of up to 50 - 52°C this is the maximum possible temperature increase Tmax- In order to estimate the kinetic effect of this increase... 

Blends of polypropylene (PP) with other polymers are used widely and are of great commercial importance. Many of these are immiscible at all compositions and temperatures of interest for example, the blends of PP and polyamides (PAs) that are used in fiber applications are highly incompatible. However, recent work has shown that PP is miscible with a number of other polyolefins, and the strength of the interactions between these polymers has been measured. Here the data that have been obtained on PP blend miscibility are compiled and work on the kinetics of phase separation for such blends is described. 

Various polyamides are usually used as acceptors of formaldehyde, the liberation of which accelerates the decomposition of polyformaldehyde. There are no comparative data in the literature pertaining to the kinetics and mechanism of the bonding of formaldehyde by polyamides of various structures. 

Figure 11.20 shows crystallization rate data as a function of the crystallization temperature for both polyethylene copolymers and for the polyethylene component within the blends. The linear low-density-type PE-1 crystallizes at much lower supercoolings than the very low-density-type PE-3. In the case of the blends, a nucleation effect caused by the previously crystallized polyamide phases was reported (the PA phases crystallize at higher temperatures than the PE phases see Ref [69]). This nucleation effect accelerates the overall crystallization kinetics and therefore the polyethylene component in the blends crystallizes faster than the corresponding neat polyethylene material, as shown in Eigure 11.20. 

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