Hexamethylene diamine HMDA

In 1930, DuPont launched the synthetic fiber industry with the discovery of nylon-6,6.2 In 1938, a pilot plant for nylon-6,6 production was put into operation, and in 1939, production was commenced at a large-scale plant in Seaford, Delaware. The classical method for the synthesis of nylon-6,6 involves a two-step process. In the first step, hexamethylene diamine (HMDA) is reacted with adipic acid (AA) to form a nylon salt. Polymerization of the aqueous salt solution is carried out at temperatures in the range of about 210-275°C at a steam pressure of about 1.7 MPa. When 275°C is reached, the pressure is reduced to atmospheric pressure and heating is continued to drive the reaction to completion. 

Figure 6.7 Reaction of wood with succinic anhydride (SA) and subsequent reaction of the activated surface with hexamethylene diamine (HMDA), using diisopropyl carbodiimide (DIPCI) as a reaction promoter.

With neat hexamethylene diamine (HMDA), each amine group leads to a crosslink and, consequently, DGEBA/HMDA networks have the highest crosslink density. 

Cyclohexanone, a six-membered carbon ring with a ketone as functional group, is almost exclusively applied as a precursor for the production of aliphatic polyamides. Pure cyclohexanone is mainly converted, via cyclohexanone oxime and caprolactam, to nylon-6 (also called polycaprolactam) [1]. Mixtures of cyclohexanone and cyclohexanol, often called K4 oil, are converted via oxidation into adipic acid that reacts with hexamethylene diamine (HMDA) to nylon-6,6 (poly-hexamethylene adipamide). Other applications of these products can be found in the field of polyurethane and polyester production. 

The most important of these compounds were the monomers of nylon 66, hexamethylene diamine (HMDA) and adipic acid. During World War II, I.G. Farben (and Du Pont) prepared both compounds from coal tar products, but Reppe and his coworkers devised several new routes from propargyl alcohol and butynediol. Similarly, caprolactam, the monomer of the rival nylon 6, was also synthesized from butynediol. ... 

PP-Based CPNC In PP, Tg 0°C, and at r< T, as for PS or PA-6, for different clay loadings the dynamic moduli of CPNC versus T nearly parallel each other hence, the relative moduli E j. = E (CPNC)/ (matrix) is almost constant. Wu et al. [2005b] prepared PP-based CPNC by solution blending of PP -I- PP-MA with MMT preintercalated with cetyl pyridinium and hexamethylene diamine (HMDA)-modifled PP-MA. The nanocomposites contained 0 to 5wt% of well-dispersed organoclay. DMA... 

The diamine (AA) monomer used for the PA610 AABB polyamide is hexamethylene diamine (HMDA), which is produced petrochemically from butadiene. 

Table 8 shows the 15N chemical shift of glycine-organized clay and hexamethylene diamine (HMDA). Because glycine contains amphohte ions in the neutral state, the HMDA values were used as the chemical shift values of neutral N. 

Hydrolysis of Nylon 6,6 and Nylon 4,6 The depolymerization of nylon 6,6 and nylon 4,6 involves hydrolysis of the amide linkages, which are vulnerable to both acid- and base-catalyzed hydrolysis. In a patent granted to the DuPont Company in 1946, Myers [33] described the hydrolysis of nylon 6,6 with concentrated sulfuric acid, which led to the crystallization of adipic acid from the solution. Hexamethylene diamine (HMDA) was recovered from the neutralized solution by distillation. In a later patent assigned to the DuPont Company by Miller [34], a process was described for hydrolyzing nylon 6,6 waste with aqueous sodium hydroxide in isopropanol at 180°C and 2.2 MPa pressure. After distillation of the residue, HMDA was isolated and on acidification of the aqueous phase, adipic acid was obtained in 92% yield. Thorbum [35] depolymerized nylon 6,6 fibers in an inert atmosphere at what was reported to be a supeiatmospheric pressure of up to 1.5 MPa and at a temperature in the range of 160-220°C in an aqueous solution containing at least 20% excess equivalents of sodium hydroxide. 

Fig ure 7.9 Cross-linking of epoxidized mcl-PHA using hexamethylene diamine (HMDA) as a cross-linker. 

Bio-nylon Adipic acid Hexamethylene diamine (HMDA)... 

Diamines give effective vulcanizates, but those leading to the best properties are very scorchy [19,21]. Derivatives of diamines designed to stiffen the amine fimction, so as to reduce the scorching tendency, are by far the most widely used curing agents [19,21]. The most common examples are the carbamate and bis-cinnamylidene derivatives of the hexamethylene diamine (HMDA) ... 

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