The effect of temperature and strain rate on the tensile properties of some new textile yarns

Fyfe, Ian A (1965) The effect of temperature and strain rate on the tensile properties of some new textile yarns. PhD thesis, University of Glasgow.

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The tensile properties of some new textile yarns have been studied with particular reference to the effect of temperature and rate of strain application on the stress-strain behaviour. The work has been split into two parts covering different types of material. In part 1, an Instron tensile tester was used to investigate the effect of strain rate and temperature on the stress-strain properties of two samples of polypropylene yarn. Differences in behaviour occurring between the samples were explained by measurements 6f structural properties such as isotactic index and average .molecular weight. Results were compared with data from the literature on an isotactic polypropylene yam. The method of reduced variables has been used to apply time- temperature superposition and obtain composite curves reduced to a standard reference temperature. This was done for the ultimate stress and strain values and values of stress at lower strains expressed as the tensile modulus. A similar superposition was obtained from stress relaxation data. In part 2, five samples of synthetic poly-urethane elastomeric yarns and one sample of natural rubber yarn have been studied under different conditions. The stress-strain curve, toughness, Schwartz value, elastic recovery and stress relaxation properties have been measured and compared. The stress-strain curve of one of the synthetic yams was studied at different temperatures and initial strain rates. Unlike polypropylene, the same superposition could not be applied to all the data in this case. The equivalence of changes in time and temperature alters with increasing strain as the molecular orientation alters. Yarns of completely different structure have been studied and it has been shown that time-temperature superposition can be applied, in a restricted form, to a non-linear semi-crystalline material. It is therefore possible to obtain data necessary to characterise the behaviour of a material over several decades of logarithmic time using a single instrument of a type used in normal tensile testing procedure.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: R Meredith
Keywords: Textile research
Date of Award: 1965
Depositing User: Enlighten Team
Unique ID: glathesis:1965-73067
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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