The structural factor in the orientation processes of fibres and films of flexible-and rigid-chain polymers

Perepelkin, K. E.

doi:10.1007/bf00546948

Cited by 2 publications

(4 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In addition, in order to study the effect of heat treatment on orientation, polarized FTIR spectra of unheated CPA films are shown in Figure 5, and the R values are also shown in Table 1. When the films were heated, the R values decrease more at 3300 and 1650 cm À1 band and increase more at 1515, 1490, and 1320 cm À1 relative to the unheated CPA samples with the same draw ratio, which clearly indicates that the macromolecular orientation is enhanced after heating at 380 C. This phenomenon of improvement of orientation after heat treatment is called spontaneous orientation, which was found in many rigid-rod polymers on exposure to heat, such as PI, 28 cellulose, 29 and polyamide, 30 resulting in the improvement of mechanical properties. What's more, when cold-drawing ratio is 0%, the R value of unheated CPA-0 and CPA-0 films are the same (R ¼ 1).…”

Section: The Orientation In the Filmsmentioning

confidence: 86%

Ultrahigh strength and modulus copolyamide films with uniaxially cold-drawing induced molecular orientation

Luo

Huang

Yan

et al. 2016

High Performance Polymers

View full text Add to dashboard Cite

The tensile strength of polymer films is generally lower than 200 MPa. Copolyamide (CPA) films with ultrahigh strength (approximately 317-865 MPa) and high modulus (approximately 3.96-11.76 GPa) were obtained by uniaxial cold-drawing and heat treatment. The relationship between structures and properties in the orientation state was also investigated. The results of Fourier transform infrared (FTIR) spectroscopy indicate that hydrogen bonding interactions change a little with drawing. Wide-angle X-ray diffraction patterns show orientational stretch induces -ordered packing after drawing 100%. The tensile strength and modulus of the drawn CPA films are improved approximately 41%-173% and 9%-197% compared to undrawn films. Dichroic ratios obtained under polarized FTIR spectroscopy represent overall orientation factors. The decrease of dichroic ratios at about 3300 cm À1 and 1650 cm À1 and the increase of dichroic ratios at 1515 cm À1 prove that the orientation of macromolecular chains is improved along stretch direction. What's more, the degree of orientation is further increased after heat treatment, which is the phenomenon of spontaneous orientation. The degree of spontaneous orientation increases with the increase of cold-drawing ratio. Thus, the initial orientation in colddrawing and spontaneous orientation during heat treatment leads to ultrahigh modulus and high strength.

show abstract

Section: The Orientation In the Filmsmentioning

confidence: 86%

Ultrahigh strength and modulus copolyamide films with uniaxially cold-drawing induced molecular orientation

Luo

Huang

Yan

et al. 2016

High Performance Polymers

View full text Add to dashboard Cite

show abstract

“…Известно, что наибольшее влияние на стабильность процесса электроформования и наличие дефектов в получаемом материале оказывают такие свойства раствора, как динамическая вязкость, коэффициент поверхностного натяжения и удельная объемная электропроводность [1].…”

Section: результаты и обсуждение 1 исследование параметров раствораunclassified

“…С ростом электропроводности раствора увеличивается вероятность и число последовательных расщеплений дрейфующей, но еще не полностью отвержденной струи, и, соответственно, эффективная скорость волокнообразования, то есть, в конечном счете, производительность процесса электроформования. С повышением электропроводности раствора степень ориентации молекулярных фрагментов в волокне увеличивается [1].…”

Section: результаты и обсуждение 1 исследование параметров раствораunclassified

“…Одним из наиболее перспективных способов получения нановолокон и наночастиц из растворов полимеров является процесс электроформования. Электроформование -это процесс, который приводит к получению нановолокон в результате действия электростатических сил на электрически заряженную струю полимерного раствора или расплава [1][2]. За счёт варьирования технологических параметров процесса электроформования можно получить структуры различной степени упорядоченности [2].…”

Section: Introductionunclassified

See 1 more Smart Citation

Investigation of the fabrication of nanofibers from aqueous polyvinyl alcohol solutions by electrospinning

Lebedeva,

Vu,

Olekhnovich

et al. 2022

Vestn. Voronež. gos. univ. inž. tehnol.

View full text Add to dashboard Cite

Polyvinyl alcohol (PVA) refers to polymers that have great potential for medical and technical applications. Especially, the possibility of its medical application in nanofibres is of great interest due to its good water solubility, high biocompatibility and non-toxicity. PVA is used for various pharmaceutical and biomedical purposes, as a carrier for the delivery of proteins and drugs, as dressings, filter materials, and as artificial organs. Currently, many drug delivery systems have been developed, such as hydrogels or complex electronic microchips. Nanostructural materials are particularly advantageous for rapid drug release due to their high surface area to volume ratio. Both natural and synthetic polymers can be used to produce nanofiber materials, but the combination of different polymers (synthetic and natural) and the incorporation of various biologically active substances into them provides special properties to the finished materials. In this work, the properties of aqueous solutions based on polyvinyl alcohol were investigated: electrical conductivity, viscosity and pH. The influence of technological parameters of electroforming process on obtaining nanofibers from aqueous solutions of PVA. The optimum PVA concentration for the formation of nanostructures was determined equal to 8 wt.%. At this concentration, the PVA solution has electrical conductivity, viscosity and pH equal to 571 µS/cm, 107.23 mPa·s and 6.14 respectively. As part of the study, the electroforming process parameters were obtained to enable the production of nanofibers with a diameter of about 170 nm: distance between needle and collector 140 mm, spinning solution feed rate 0.2 ml/h and voltage between needle and collector 30 kV.

show abstract

The structural factor in the orientation processes of fibres and films of flexible-and rigid-chain polymers

Cited by 2 publications

References 5 publications

Ultrahigh strength and modulus copolyamide films with uniaxially cold-drawing induced molecular orientation

Ultrahigh strength and modulus copolyamide films with uniaxially cold-drawing induced molecular orientation

Investigation of the fabrication of nanofibers from aqueous polyvinyl alcohol solutions by electrospinning

Contact Info

Product

Resources

About