Polycaproamide

The hybrid nanocomposite polymer-silica materials on the basis of oligomer alkoxysilane (polyethoxysilane (PES) obtained from tetraethoxysilane) with polycaproamide, polyacrylonitrile, chitosan and zirconyl oxychloride were investigated. 

Fig. 1. Relative MFI of Diflon polycarbonate (A), HDPE (B) and polycaproamide (C) as function of filler concentration (

Several polyheterocyclic compounds containing a condensed 1,2,4-triazole nucleus, such as 3,5-disubstituted thiazolo [2,3-r][ 1,2,4] triazoles, are thermostabilizers for polypropylene and polycaproamide <2003MI2>. Triazolo[3,4-A][l,3]benzothiazoledicarbonitrile derivatives are used to prepare hexazocyclanes-fluorophores as active media for liquid and solid lasers, scintillators, and for transformation of short-wave radiation to long-wave radiation <2004RUP2238276>. 

Fig. 15. Chromatograms of degradation products of polycaproamide by pyrolysis correlation chromatography.

Polycaproamide (PA-6), which is synthesized from s-caprolactam in the presence of catalysts such as sodium-e-caprolactam or magnesium bromide-caprolactam (obtained by the reaction of... 

Modelling non-isothermal crystallization is the next important step in a quantitative description of reactive processing. This is particularly important, because crystallization determines the properties of the end product. Therefore, the development the spatial distribution of crystallinity, a, and temperature, T, with time throughout the volume of the reactive medium must be calculated. It is also noteworthy that crystallization and polymerization processes may occur simultaneously. This happens when polymerization proceeds at temperatures below the melting point of the newly formed polymer. A typical example of this phenomenon is anionic-activated polymerization of e-caprolactam, which takes place below the melting temperature of polycaproamide. 

Figure 2.19. Isotherms of polycaproamide (a) and polyethylene terephthalate) (b) crystallization at different temperatures, a 180°C (curve 1) 184°C (curve 2) 188°C (curve 3) b 180°C (curve 1) 200°C (curve 2) 210°C (curve 3) 220°C (curve 4). Solid lines are calculated in accordance with Eq. (2.48) points are experimental data.

Figure 2.20. Temperature dependence of the equilibrium degree of crystallinity for polycaproamide.

By integrating Eq. (2.50) for different cooling rates, i.e., for different functions T(t), it is possible to find the time dependence of crystallinity and the rate of the crystallization process. It is also necessary to bear in mind the temperature dependence of the equilibrium degree of crystallinity, a x (T). As an example, this dependence is shown for polycaproamide in Fig. 2.20.97 It is evident from Eq. (2.53) that the functiona(T) must have a maximum whose location on the temperature axis depends on the cooling rate. This is illustrated in Fig. 2.21, where values of the rate of heat output dQ/dt, proportional to da/dt, and degree of crystallinity a are shown as functions of temperature. It is worth mentioning that all the curves in this figure are adequately described by Eq. (2.52). 

Figure 2.21. Temperature dependencies of the rate of heat output and time dependencies of the degree of crystallinity in the homogeneously cooled polycaproamide sample. The rates of linear decrease in temperature are 2 K/min (curves 1 and 8) 4 K/min (curves 2 and 7) 8 K/min (curves 3 and 6) 16 K/min (curves 4 and 5).

Experiments were carried out on the crystallization of polycaproamide slabs produced by the reactive processing method using the following values 97"99... 

Figure 2.23. Evolution of the spatial distribution of the degree of crystallinity on cooling of a polycaproamide plate at Tsur = 140°C. Figures on the curves show time from the beginning of the process.

As a typical example let us discuss the experimental data for the kinetics of polycaproamide crystallization obtained by differential scanning calorimetry." The primary experimental data are... 

Figure 2.28. Comparison of the results obtained by solving the inverse problem (solid lines) with experimental data (points) for cooling of a polycaproamide plate with constant rate 4 K/min (curve 1) and 16 K/min (curve 2).

Temperature dependencies of the volume and shear moduli for the solid phase were found experimentally145 for polycaproamide (PA-6). The results of the calculations are shown in Figs. 2.37-2.41. These results demonstrate the evolution of the stresses try during crystallization and the... 

Reactive extruders and extrusion dies of different designs can be easily included in standard technological scheme of polymer production plants, such as those for polycaproamide synthesis, as shown in Fig. 4.39. In this case, a reactive material premixed in a tank 1 is fed into a static device 2 for prepolymerization, where part of the polymerization process takes place. Then the reactive mixture enters the extruder-reactor 3. The necessary temperature distribution is maintained along the extruder. Transfer of the reactive mass proceeds by a system of two coaxial screws mounted in series in a common barrel. Controlling the relative rotation speed of both screws provides the necessary residence time for the reactive mass in the extrader, so that the material reaching the outlet section of the die is a finished polymer. 

Figure 4.39. Technological scheme for producing extruded parts from polycaproamide (for an explanation of the numbers see text).

Figure 4.40. A model reactor for front polymerization in the synthesis of slabs from "anionic" polycaproamide.

It can be shown that three different modes of front propagation during the formation of polycaproamide can be observed, depending on the relationship between the process parameters. In the first mode, which was found experimentally, the zones of polymerization and crystallization coincide. In the second mode these zones are separated in space. The third mode, which was predicted theoretically, is characterized by a non-monotonic distribution of the degree of crystallinity. However, it is not clear whether this situation can actually be observed in anionic e-caprolactam polymerization because even slight variations in parameters transfers the system into another regime. 

The most successful application of the RIM-process is in the production of polyurethane-based materials. Other systems, such as composites based on polycaproamide, epoxy resins, and unsaturated polyesters can also be processed by reactive injection molding. New reactive systems have also been specially created for the RIM-process260 because of the exceptional opportunities it offers for manufacture of finished articles from engineering plastics with a high modulus of elasticity and impact strength. The automotive industry, which is the main customer for RIM-articles, can utilize this technology to manufacture of massive parts such as body panels, covers, wings, bumpers and other made of newly developed plastics. 

Melting behaviour and spherulitic crystallization of polycaproamid (nylon 6). Polymer 3, 43—51 (1962). 

Ziabecki, A. Uber die mesomorphe Form von Polycaproamid und ihre Umwandlung in die kristalline Form. Kolloid-Z. 167, 132—141 (1959). 

Nylon. Nylon fibers are made predominantly from either poly(hexa-methylene adipamide) (nylon 66) or polycaproamide (nylon 6). In... 

Application Uhde Inventa-Fischer s VK-tube process polymerizes s-cap-rolactam (LC) monomer to produce polycaproamide (nylon-6) chips. 

Description Liquid LC is continuously polymerized in a VK-tube (1) in the presence of water, stabilizer and modifying additives at elevated temperatures. The polymerization process has proven to be very reliable, easy to operate and economical. Prepolymerization is available to reduce reactor volume for large capacity units. The polycaproamide chips are formed from the melt using strand cutters and are conveyed to the extraction column (2). 

Polycaproamide Urea-formaldehyde Kellogg Brown Root, Inc. 

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