Bonding of Formaldehyde by Polyamides

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. 

To solve this problem, a special procedure was developed in [22], permitting the evaluation of the effectiveness of polyamide resins as formaldehyde acceptors. The authors utilized 100 200 300 400 500 600 700 PcHjOCinidal) the reaction of direct absorption 

The following were investigated polyamide, polycaproamide, polyamide 68 (polyhexamethylenesebacamide), and polyamide-54 (condensation product of 1 1 caproamide and hexamethyleneadipamide). 

The rate of achievement of the maximum absorption of formaldehyde, as is shown on Figs. 73 and 74, increases sharply with increasing initial pressure of formaldehyde and temperature. Thus, when the initial formaldehyde pressure is raised from 300 mm to 600 mm Hg, the rate of its absorption for polyamide 68 increases sevenfold, and five- to sixfold for capron and polyamide 54. However, the final volume of the formaldehyde absorbed by the resins (Fig. 73) falls with increasing temperature. 

Such a dependence was also observed in [23], where the decrease in the absorption of formaldehyde by the polyamide resin was partially explained by an increase in the number of cross-links in the sample on account of the interaction of methylol derivatives. 

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