Caprolactam thermal

Sulfur Donors. MBSS, DPTH, and the thiuram disulfides (see Table 2) ate examples. The morpholine disulfide and caprolactam disulfide examples in Table 4 can also donate one atom of sulfur from their molecular stmcture for cross-linking purposes. Monosulfide cross-links provide better thermal stabiUty than the sulfur—sulfur bonds in di- and polysulfide cross-links, which predominate when elemental sulfur is used. 

Snia Viscosa. Catalytic air oxidation of toluene gives benzoic acid (qv) in ca 90% yield. The benzoic acid is hydrogenated over a palladium catalyst to cyclohexanecarboxyhc acid [98-89-5]. This is converted directiy to cmde caprolactam by nitrosation with nitrosylsulfuric acid, which is produced by conventional absorption of NO in oleum. Normally, the reaction mass is neutralized with ammonia to form 4 kg ammonium sulfate per kilogram of caprolactam (16). In a no-sulfate version of the process, the reaction mass is diluted with water and is extracted with an alkylphenol solvent. The aqueous phase is decomposed by thermal means for recovery of sulfur dioxide, which is recycled (17). The basic process chemistry is as follows ... 

A further approach is used by Bayer with their polyesteramide BAK resins. A film grade, with mechanical and thermal properties similar to those of polyethylene is marketed as BAK 1095. Based on caprolactam, adipic acid and butane diol it may be considered as a nylon 6-co-polyester. An injection moulding grade, BAK 2195, with a higher melting point and faster crystallisation is referred to as a nylon 66-co-polyester and thus presumably based on hexamethylene diamine, adipic acid and butane diol. 

Many impurities are present in commercial caprolactam which pass into the liquid wastes from PCA manufacture from which caprolactam monomer may be recovered. Also, the products of die thermal degradation of PCA, dyes, lubricants, and other PCA fillers may be contained in the regenerated CL. Identification of die contaminants by IR spectroscopy has led to the detection of lower carboxylic acids, secondary amines, ketones, and esters. Aldehydes and hydroperoxides have been identified by polarography and thin-layer chromatography. 

Caprolactam is a thermally unstable compound which on distillation may form methyl-, ethyl-, propyl-, and n-amylamines. Also, at high temperatures, CL reacts widi oxygen to form hydroperoxides which in the presence of iron or cobalt ions are converted into adipimide. /V-alkoxy compounds are also formed by the reaction of CL with aldehydes during storage. 

The use of various thermal methods to investigate e-caprolactam polymerization allowed us to determine the expression for the kinetic function f(P) for this monomer 29 32... 

Nylon 6, or nylon caprolactam, is a polymeric fiber derived from only one constituent, caprolactam, giving the polymer [-(CH2)5CONH-] . It has a lower melting point than nylon 6,6, but it is superior to it in resistance to light degradation, elastic recovery, fatigue resistance, and thermal stability. 

The thermal polymerization of /3-carboxymethyl caprolactam results in a novel polyimide which has been identified as a poly(2,6-dioxo-l, 4-piperidinediyl)trimethylene. The formation of this structure is explained by a mechanism that consists in an initial isomerization of the caprolactam derivative to 3-(3-aminopropyl)glutaranhydride or its linear dimer and subsequent polymerization by condensation involving the terminal amino group and the anhydride moiety. Suggested reaction schemes and corresponding kinetic equations are based upon the premise that the extent of polymerization is represented by the concentration of imide linkages. Results of rate studies carried out at 210°-290°C. support the proposed mechanism. 

In conclusion, the results of our study indicate that the principal features of the formation of poly (2,6-dioxo-l,4-piperidinediyl) trimethylene by thermal polymerization of / -carboxymethyl caprolactam consists in an initial isomerization of the caprolactam derivative to a reactive species and subsequent polymerization of the latter by condensation. The reactive intermediate is in all probability either or both the 3-(3-aminopropyl)-glutaranhydride or its linear dimer. Both the conversion of the lactam by isomerization and the polycondensation follow second-order kinetics. 

The work [9] discusses publications analysing physico-chemical indices and the specifics of the chemical structure of cast aminoplasts modified with 20-50% (with respect to the mass of melamine) of caprolactam and other lactams. Materials of this type, havin an increased impact strength, thermal stability, strength and elasticity modulus in bending, are manufactured in Czechoslovakia under the trade mark UmaLur MK-1, MK-2, MK-3. 

A potentially important industrial application of this reaction involves the thermal rearrangement of 3,3-pentamethylene-oxaziridine 67 to e-caprolactam, a reaction that is strongly catalyzed by transition-metal ions. ... 

For nylon-6,10 the smallest cyclooligomer contains 18 atoms in a ring. However, for nylons prepared from amino-acids, much smaller rings are possible. Nylon-6 at 270°C contains about 8 wt. % of caprolactam, the cyclic monomer [81]. Nylon-4 degrades thermally to form the very stable cyclic monomer, pyrrolidone, and the attempted preparation of nylon-4 at conventional high temperatures produces very little polymer [86]. 

A number of polyamide copolymers are known to have practical uses. The copolymers include those with different amides such as poly(caprolactam-co-laurolactam), poly(2,2,4-trimethyl-1,6-hexandiamine-co-2,4,4-trimethyl-1,6-hexandiamnie-co-1,4-benzendicarboxylic acid), poly(s-caprolactam-co-hexamethylene diamine-co-terephthalic acid), poly(hexamethylenediamine-co-terephthalic acid-co-isophthalic acid), etc. The addition of longer alkyl chains in an aromatic polymeric amide may improve some mechanical properties, but thermal resilience is in general reduced. For example, poly(hexamethylenediamine-co-m-xylylenediamine-co-isophthalic acid-co-terephthalic acid) starts decomposing at about 310° C, significantly lower than Nomex , for example. The same decrease in the decomposition temperature is seen for other mixed copolymers such as nylon 12 copolymers that include cycloaliphatic and aromatic segments. 

Figure 1. Proposed mechanism for the thermally initiated anionic polymerization of caprolactam.

Aud.nopropyl triethoxysilane, 140 Amorphous systems, polyurethane elastomers, 33 Anionic polymerization, caprolactams, 136-38 initiation, 138 thermal initiation, 137f termination reaction, 136 Annular cone and plate, 100-102 Annular vs. truncated cones, 101f Aromatic diisocyanate(s), RIM elastomers, 81... 

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. 

Thermal isomerization of oxaziridines into amides and lactams, one of the most widespread reactions of oxaziridines, fails with the compounds unsubstituted at nitrogen. Obviously NH-transfer reactions predominate. Lactam formation from 34 could be brought about only by a kind of flash pyrolysis slowly adding 34 to preheated paraffin at 300°C gave caprolactam 44 (85%). 

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