The action of polar adsorbates on nylon 66

Sarda, Girdhari S (1963) The action of polar adsorbates on nylon 66. MSc(R) thesis, University of Glasgow.

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The present investigation deals with two broad aspects of fibre research both directed towards the elucidation of the role of the polar groups in polyamides and polypeptides. (1) The study of the Interaction of certain disaggregating polar reagents like lithium bromide, lithium perchlorate and magnesium perchlorate with nylon 66. (2) The study of changes in sorption of water, when polyamide (nylon 66) and polypeptide (silk) fibres are subjected to a tensile deformation. The effect of polar reagents on the dimensions and tensile characteristics suggests a possibility of interaction at the polar group. The changes in X-ray diffraction patterns revoal a significant decrease in the ? form, and an annealing effect. The interaction is confined to the polycrystalline regions, and the reagents do not produce setting of nylon. It is suggested that ? form appears towards the edges of the crystallites. The N.M.R. and the infrared study of N-ethyl acetamide (model compound) suggests a possibility of an interaction between polar reagent and the CONH groups. Nylon filme treated with polar reagents show a new absorption peak at 3390 cm-1. which changes on deuteration to 2518 cm-1. It has been shown that this is a new NH peak and that it may have slight parallel dichroism. An ion-dipole interaction mechanism has been suggested which favours the possibility of co-ordination of ions with the lone pair electron of the nitrogen atom. The change in regain of nylon with strain, at different humidities (13, 35, 52, 66 and 93% r.h.) have been measured. Regain increases with increased strain, but, except at 13% r.h., the changes have been found to be independent of humidity. It is interesting to note that the changes in regain are quite appreciable (about 1.0% moisture regain for 8% strain), and are in agreement with those calculated from stress relaxation of nylon at different humidities. The calculated changes in volume from the known value of poisson's ratio for nylon. agrees fairly well with the observed change in regain. The changes in regain of silk under strain vary with the changes in surrounding humidity. At 65% r.h. the changes are comparable to those for nylon 66. The results have been interpreted in terms of stress relaxation mechanism. The longitudinal swelling of nylon has been measured under a constant load of 2.4g/denier. On substituting suitable values from the above experiments in the thermodynamic equation a reasonable agreement between the calculated and the experimental values of the reversible modulus for nylon 66 has been found. It has been postulated that the interaction of water with nylon is confined to the rotational energy levels of the systems. This postulate has been extended to various observed phenomena as follows. (a) The change in ?'-loss modulus peak for nylon as a result of increase in temperature or humidity, involves two different molecular mechanisms. (b) The similarity between stress relaxation behaviour of different fibres in water has been attributed to a possibility of interaction of water with the rotational energy levels of various fibrous systems; regardless of the presence of specific interchain interactions in some hydrophilic fibres. (c) An alternative explanation for the sigmoid shape of the curves of rigidity modulus against humidity for nylon has been proposed: this is in conformity with the spectral evidence that there are no free NH groups in nylon 66. (d) A possible mechanism for setting of nylon 66 has been suggested, and it has been shown that the weakening of inter-chain interaction alone is not sufficient to impart desirable dimensional stability. A hypothetical system has been proposed which explains that the relative movemont of segments is not the sole contributor to stress relaxation, and that the main chains may play an important role.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Additional Information: Adviser: N Peacock
Keywords: Textile research
Date of Award: 1963
Depositing User: Enlighten Team
Unique ID: glathesis:1963-73310
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56

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