The glass transition behaviour of salted nylon 6

Mantia, Francesco Paolo La; Acierno, Domenico

doi:10.1007/bf01419312

Cited by 12 publications

(3 citation statements)

References 9 publications

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“…The glass-transition temperature of nylon 6 was found to increase with salt content [90,91], and the rate of increase was dependent on the type of salt.…”

Section: Glass-transition and Melting Behaviourmentioning

confidence: 94%

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The Structure and Properties of Typical Melt-spun Fibres

Mukhopadhyay¹

1988

Textile Progress

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“…The glass-transition temperature of nylon 6 was found to increase with salt content [90,91], and the rate of increase was dependent on the type of salt.…”

Section: Glass-transition and Melting Behaviourmentioning

confidence: 94%

“…Some typical responses of nylon 6 fibres at the glass-transition and melting temperatures have been discussed in Section 2.3. However, ^/Qry specific types of transitional behaviour are reported in different studies by several authors [277][278][279][280][281][282].…”

Section: "Hmentioning

confidence: 96%

The Structure and Properties of Typical Melt-spun Fibres

Mukhopadhyay¹

1988

Textile Progress

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“…Sodium and lead phosphates [12], copper chlorides and bromides [13,21,22], iron [2,22] and calcium chlorides [23], and lithium chlorides and bromides [19,20,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] were added to PA-6 as such modifiers. In many cases [21][22][23][24][25]29], PA-6 containing potassium chloride, which is almost insoluble in PA-6 melt, was used for comparison.…”

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confidence: 99%

The lower temperature boundary of liquid-phase synthesis of polyamide-6

Mizerovskii

Bazarov

Lytkina³

2006

Fibre Chem

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678.675:66 09 and N. I. Lytkina***The point of view that PA-6 with a minimal content of nonlinear macromolecules can only be obtained by twostage (in melt and solid phase) synthesis was advanced. The liquid-phase stage should take place according to a periodic scheme so that the maximum time the polymer remains in the melt state would be much less than the time of accumulation of a practically important amount of defective macromolecules in it. It was shown that when lithium halides are used, the temperature boundary of liquid-phase synthesis of PA-6 by hydrolytic polymerization of caprolactam can in principle be decreased to 483-473 K.Among the causes that make it difficult to attain strength in industrial polyamide (PA) fibres of the order of 100 cN/tex is the existence of side reactions in synthesis of PA-6 which cause formation of nonlinear macromolecules [1]. According to the available data [2][3][4], these reactions begin to take place at a marked rate at temperatures above 523 K. However, the specific features of all industrial variants of liquid-phase synthesis of PA-6 consist of the fact that more or less of the melt remains in the continuous polymerization units for an indefinitely long time and for this reason independently decreasing the synthesis temperature to T < 523 K cannot prevent the appearance of nonlinear macromolecules in the polymerizate.Moreover, it is probably more correct to assume that the formation of such macromolecules can take place at any melt temperature, and the number of them in the polymer is proportional to the total time in this state. As a consequence, it is very important to not simply lower the synthesis temperature but also to do so so that the maximum time the PA-6 melt remains at this temperature is much less than the time required for accumulation of a practically important number of defective macromolecules.This essentially means that high-molecular-weight PA-6 with a minimum content of nonlinear macromolecules can only be obtained with two-stage (in melt and solid phase) synthesis. The stage of synthesis in a melt should take place according to a periodic scheme and in a way to guarantee a maximum two-fold (in comparison with the average duration of the reaction) increase in the time melt residues from the preceding batch spend in the reactor.There are no published data on how the temperature of liquid-phase synthesis of PA-6 by hydrolytic polymerization of caprolactam (CL) affects the ratio of the rates of the basic and side reactions, although it is probably possible to hypothesize that the lower it is, the more this ratio will change to the benefit of the basic reactions. For this reason, it is extremely important to know the lower temperature boundary of such synthesis in general. The experimental data concerning this problem are discussed in the present article.We know [5] that crystallization of flexible-chain polymers only takes place in sufficiently strong (by 10-20°C in comparison to the melting point T m of the polymer) supercooling of the melt and it is pr...

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Untersuchungen zu Modifikationen von Polyamid‐6 und Polyamid‐4 mit eingelagerten Alkalihalogeniden

1984

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Polyamide-6 (PA-6) and polyamide-4 (PA-4) doped with alkali halides were investigated by X-ray diffraction, thermal analysis, infrared and far infrared spectroscopy at various temperatures (10 K-300 K). The solubility of the alkali halides in PA-4 is better than in PA-6. Small ions are molecularly dispersed in PA-6 and PA-4. Alkali ions are coordinated to the oxygen, halide ions to the nitrogen of the amide group. The degree of crystallinity of the polyamides depends on the concentration of the alkali halides and the ion radii. Alkali halides stabilize modifications of the polyamides with not fully extended chains. In polyamides crystallized from the melt some alkali halides stabilize the y-modification or similar structures. The modification is nearly independent of the alkali halide concentration and will not be destroyed by washing out the alkali halides. If the polyamides are crystallized from formic acid, alkali halides promote a pleated sheet structure with antiparallel chains. The factor group of the layer is D, , indicated by a low temperature splitting of the % vibration modes.

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The glass transition behaviour of salted nylon 6

Cited by 12 publications

References 9 publications

The Structure and Properties of Typical Melt-spun Fibres

The Structure and Properties of Typical Melt-spun Fibres

The lower temperature boundary of liquid-phase synthesis of polyamide-6

Untersuchungen zu Modifikationen von Polyamid‐6 und Polyamid‐4 mit eingelagerten Alkalihalogeniden

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