Processing of Polyamides

Newer developments include also RIM and RRIM machines for the processing of polyamide and epoxy formulations. 

Similar data come from processing of polyamide-6 with glass fibers. Diameter swell, thickness swell, and weight swell were all substantially decreased by the... 

In the process of polyamidation foaming of the polymer was not observed. Thermal stability of the dyes is satisfactory at warming - up for 48 hours and this shows that their introduction at the stage of - caprolactam polyamidation does not deteriorate PCA properties. 

These new PTFE-PA materials can be processed without any problems on commercial processing equipment like twin-screw extruders and injectionmoulding machines. The specific adjustment of the melt viscosity could be realised through additives (lowering of MFI additive [10,18] increase of MFI acid-terminated oligoamides [9,10]). The new materials combine the good material properties of PTFE and polyamide with the processability of polyamide and are particularly well-suited for wear-resistant maintenance-free bearings. 

Ballistreri, A., Garozzo, D., Giuffrida, M., and Montaudo, G., Thermal Degradation Processes of Polyamides Investigated by Collision Activated MS/MS, Polym. Deg. Stab., 16, 337, 1986. 

Martinache, J.D., et al.. Processing of polyamide 11 with supercritical carbon dioxide. Industrial Engineering Chemistry Research, 2001. 40(23) p. 5570-5577. 

Phosphorus compounds may bond various impurities contained in the polyamides, which might catalyze the process of polyamide destruction at high temperatures [39]. 

These experimental data show that the ratio A2 /Aj = R is approximately constant for various periods of irradiation of the film. The author explains all these facts by the following scheme of the radical chain process of polyamide photooxidation ... 

Extrusion processing of polyamide-6 (PA6) with aciylonitrile butadiene rubber (NBR) of different nitrile contents, and at elevated temperatures resulted in graft copolymerisation between the two components. Improvement of the impact strength of the PA6 was at a maximum with approximately 10 percent addition of NBR and blends were soluble in formic acid. Products were characterised using infrared and nuclear magnetic resonance spectroscopy, differential thermal analysis and mechanical properties. 16 refs. 

Lewis acids, such as the haUde salts of the alkaline-earth metals, Cu(I), Cu(II), 2inc, Fe(III), aluminum, etc, are effective catalysts for this reaction (63). The ammonolysis of polyamides obtained from post-consumer waste has been used to cleave the polymer chain as the first step in a recycle process in which mixtures of nylon-6,6 and nylon-6 can be reconverted to diamine (64). The advantage of this approach Hes in the fact that both the adipamide [628-94-4] and 6-aminohexanoamide can be converted to hexarnethylenediarnine via their respective nitriles in a conventional two-step process in the presence of the diamine formed in the original ammonolysis reaction, thus avoiding a difficult and cosdy separation process. In addition, the mixture of nylon-6,6 and nylon-6 appears to react faster than does either polyamide alone. 

In the final step the dinitrile is formed from the anti-Markovrukov addition of hydrogen cyanide [74-90-8] at atmospheric pressure and 30—150°C in the hquid phase with a Ni(0) catalyst. The principal by-product, 2-methylglutaronitrile/4j5 j5 4-ti2-, when hydrogenated using a process similar to that for the conversion of ADN to hexamethylenediamine, produces 2-meth5i-l,5-pentanediamine or 2-methylpentamethylenediamine [15520-10-2] (MPMD), which is also used in the manufacture of polyamides as a comonomer. 

Hydrolysis and Polycondensation. One of the key properties of polyamides relates to the chemical equihbrium set up when the material is polymerized. The polymerization of nylon is a reversible process and the material can either hydrolyze or polymerize further, depending on the conditions. 

Since large tonnage production is desirable in order to minimise the cost of a polyamide and since the consumption of nylons as plastics materials remains rather small, it is important that any new materials introduced should also have a large outlet as a fibre. There are a number of polyamides in addition to those already mentioned that could well be very useful plastics materials but which would be uneconomical for all but a few applications if they were dependent on a limited outlet in the sphere of plastics. Both nylon 7 and nylon 9 are such examples but their availability as plastics is likely to occur only if they become established fibre-forming polymers. This in turn will depend on the economics of the telomerisation process and the ability to find outlets for the telomers produced other than those required for making the polyamides. 

These polymers, typical of polyamides with fewer than four main chain carbon atoms in the repeating unit, decompose before melting and have to be processed from solution. Several of the polymers may, however, be spun into fibres. Over thirty years ago Courtaulds produced silk-like fibres on an experimental commercial scale from poly-(L-alanine) and from poly-(a-methyl-L-glutamate). The latter material is also said to be in use as a synthetic leather in Japan. The... 

We studied the polyamidation in the solid phase process of nylon 4,6, which has a high melting transition (264 - 320 C) and... 

This review is concerned with the engineering thermoplastic uses of polyamide materials in injection moulding and extrusion applications. Types of polyamides are described, and their key properties are considered. Commercial applications in the automotive, electrical/ electronic, engineering and construction, and packaging industries are discussed. Polyamide processing is... 

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