Influence of intermolecular interaction on kinetics of conformational transitions in poly-m-phenyleneisophthalamide

Пахомов, П. М.; Novak, I. I.; Shablygin, M. V.; Korsukov, V. E.

doi:10.1007/bf00660770

J Appl Spectrosc

1985

DOI: 10.1007/bf00660770

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Influence of intermolecular interaction on kinetics of conformational transitions in poly-m-phenyleneisophthalamide

П. М. Пахомов¹,

I. I. Novak²,

M. V. Shablygin³

et al.

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1999

2006

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Cited by 3 publications

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“…The diminishing character of the tangential modulus E ε in the entire range of stretching of the fibres suggests that destructive processes begin in the initial stages of elongation and continue until the fibre breaks. It was shown in many previous studies that elongation of oriented polypropylene is actually accompanied by molecular-destructive processes in the entire range of elongation [8,9].…”

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confidence: 99%

Structural dependence of the deformation characteristics of polypropylene film fibre in stress relaxation

2006

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The deformational rigidity increases due to relaxation of stresses in oriented PP fibres. Elongation of PP fibres is accompanied by mechanical failure in all stages, which is a distinctive feature of deformation processes in these materials. Ordering of the structure of amorphous regions, manifested by an increase in the deformational rigidity of these fibres, is the result of stress relaxation in oriented PP fibres.Isotactic polypropylene is widely used for manufacturing industrial fibres, and the high strength at relatively low density should be noted above all [1][2][3]. The manufacturing process for polypropylene (PP) fibres is a multistage process, and the fibre undergoes temperature and deformation treatment in different stages [4,5]. To improve product quality and optimize industrial orientation of PP fibre, it is necessary to understand the structural processes that take place in fixing the fibre in the stitched state, i.e., as a result of stress relaxation [6].The relaxation processes that take place in stitched (loaded) fibres and yarns in many cases significantly alter their performance properties. There is currently no complete representation of the structural processes that cause such changes in the deformation properties of fibres and yarns. The change in the deformation characteristics of fibres in the stretched state must undoubtedly be taken into account for reliable prediction of the deformation properties of synthetic fibres and the articles made from them, which is not always done in practice.We established the character of the change in the rigidity of stretched film PP fibres during stress relaxation and elucidated the structural nature of these changes. We investigated PP film fibre (manufactured by Tverkhimvolokno OJSC) with a linear density of 130 tex and draw ratio of λ = 6, tensile strength of σ t = 580 MPa, and elongation at break of ε b = 22%.The deformation-strength properties in the stress relaxation and active stretching regime and the structural rearrangements that take place in stitched fibers and yarns were investigated. The studies of the mechanical properties of the fibres in active stretching (obtaining the stress-strain diagrams) and stress relaxation regimes were conducted on an Instron-1122. The tests in conditions of stopping stretching and then stretching again were performed on the same setup. IR spectroscopy was used to reveal the moleculardecomposition processes that take place in stretched oriented samples. The valence bond breaks in the macromolecules were recorded with this method based on the newly formed stable terminal groups formed as a result of decomposition. The data were obtained by frustrated total internal reflection on a Spectrum One Fourier IR spectrometer. The absorption bands at 1742 and 1650 cm -1 were considered the molecular-decomposition bands in the IR spectrum of PP [7]. Low-frequency Raman spectroscopy, which is sensitive to the regular segments of macromolecules of any type regardless of their localization both in amorphous and in crystalline ...

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Structural dependence of the deformation characteristics of polypropylene film fibre in stress relaxation

2006

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“…For the level of assigned deformation of ~ss = 2.5%, the stresses were calculated for a long segment of time (up to 128 min): curve 4 is for Lavsan thread and curve 8 is for Lavsan--Siblon thread. The good agreement of the experimental and calculated stress values suggests that the method proposed in [3,4] for the quantitative description and prediction of relaxation processes can be used for the synthetic thread examined here.…”

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confidence: 75%

“…For this reason, we will hypothesize that the quantitative description previously advanced in [3,4] for complex Lavsan thread for industrial application can be used for describing relaxation processes in shoe thread. In these studies, the quantitative description of the relaxation process is based on the assumption of the sufficient stability of the structure of the material during loading.…”

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Strength and relaxation properties of synthetic shoe thread

Tsobkallo¹,

Petrova²,

Turkina³

et al. 1999

Fibre Chem

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Modem shoe manufacture requires the use of high-quality materials, including shoe thread. Shoe thread is exposed to significant mechanical effects during manufacture and wear and for this reason improving its service properties is very pressing.The strength and deformation properties of shoe thread of two types are compared here: the polyester fibre Lavsan, widely used in the industry, and Lavsan fibre modified by adding the viscose fibre Siblon. In addition, our studies were directed toward investigating the residual component of strain of these threads as one of the most important properties appearing in stitched shoe uppers, the appearance of a dependence between residual stresses and the character of the stress--strain curve, and determination of the regions of deformation with different molecular mechanisms. We also wanted to quantitatively describe the family of stress relaxation curves and then predict this process for a long time.Lavsan shoe thread with a linear density of 70 tex and thread made from a blend of Lavsan (67%) and Siblon (33%) fibres were investigated. The threads were processed at the S. M. Kirov Spinning-Thread Combine in St. Petersburg.The strength and elastic relaxation properties of the threads were tested in different conditions. The experimental studies were conducted on an Instron-1122 tensile-testing machine. The stress--strain curves were recorded with a clamp speed of 100 mm/min and a sample base of 200 mm. The families of stress relaxation curves were obtained in a wide range of given strains, up to prebreaking strains. The duration of holding at a given deformation was 10 min. The samples were then unloaded and the residual strain in the thread was measured after 10 min of"rest."Since shoe thread is exposed to moisture during manufacture of shoes and finished articles, thread samples held in water for 24 h were also investigated. It follows from the stress--strain diagrams of the initial thread and the thread held in water (Fig. 1) that the breaking stress for these threads is almost the same (650-700 MPa), but the breaking strain is much higher for Lavsan--Siblon thread: e b = 19%, versus e b = 15% for Lavsan thread. Addition of Siblon fibres thus increases the elasticity of the thread.The insignificant effect of moisture on the properties of Lavsan fibre and the more pronounced changes in the stress--strain diagram of the starting Lavsan--Siblon thread and thread held in water should be noted: the strength decreased slightly and the elasticity of the "wet" thread increased. This result was not surprising, since poly(ethylene terephthalate) is a hydrophobic polymer, while hydrated cellulose (Siblon) is relatively sensitive to moisture.St. Petersburg State University of Technology and Design.

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“…IR spectroscopy is widely used in investigating the influence of various factors (temperature, stretching, and aggressive media) on the molecular and supermolecular structures of polymers [1][2][3][4]. Taking into account that polymers have a complex structure (consisting of polymer chains of various lengths and conformations) and in general are amorphous, interpretation of their IR spectra is rather difficult.…”

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confidence: 99%

Simulation of the influence of the polymer conformation, orientation, crystallinity, and stretching on its IR absorption spectrum

Abdulov

2005

J Appl Spectrosc

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535.43Using cis-1,4-polyisoprene as an example, the influence of the conformation and orientation of the polymer chain on its polarization absorption spectra has been simulated. It has been shown that if a change in the orientation of the polymer chain leads to a monotonic change in the intensities of the absorption bands with their maxima positions remaining unchanged, then changes in the polymer chain conformation additionally cause a shift and the appearance of new absorption bands. According to the results of the calculation of the vibrational spectra, the inversion of the IR dichroism of the absorption bands of polymers is associated with the conformation transition. We simulate the influence on the IR absorption spectrum of the degree of crystallinity of cis-1,4-polyisoprene, in which the amorphous and amorphous-crystalline states are considered as a mixture of noninteracting polymer chains, where each state is characterized by a certain ratio of conformers. Likewise, the changes in the IR absorption spectrum of cis-1,4-polyisoprene under its stretching have been investigated.

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Influence of intermolecular interaction on kinetics of conformational transitions in poly-m-phenyleneisophthalamide

Cited by 3 publications

References 4 publications

Structural dependence of the deformation characteristics of polypropylene film fibre in stress relaxation

Structural dependence of the deformation characteristics of polypropylene film fibre in stress relaxation

Strength and relaxation properties of synthetic shoe thread

Simulation of the influence of the polymer conformation, orientation, crystallinity, and stretching on its IR absorption spectrum

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