Structuring Peculiarities of Polytetrafluoroethylene Modified with Boron Nitride when Activated with Ultrasonic Exposure

Negrov, D. A.; Eremin, E. N.

doi:10.1016/j.proeng.2016.07.657

Cited by 7 publications

(8 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The spectral shape of halo II can be approximated by two Gaussians (Table 3, Figure 4a,b), which suggests the existence of two independent non-crystalline components in the smectic phase of PTFE, the first of which includes partially ordered PTFE macromolecules, and the second, disordered layers of specific structural formations, so-called hexagons [44]. This agrees with the conclusion made in [50], where the nature of halo II was attributed to the presence of low molecular weight impurities in the polymer. Possibly, the origin of halo II can be attributed to the presence of pores also (more accurately, to the presence of a smectic phase on the surface of pore walls) [51].…”

Section: Description Of Characteristics Dimensionsupporting

confidence: 88%

“…Within the framework of the three-phase model of an amorphous-crystalline polymer, the structure of PTFE can include crystalline, amorphous, and smectic phases [49]. In polyethylene and in poly-L-lactic acid, the smectic phase is a layer of partially ordered polymer chains around the lamella, which has a thickness of ~40-50 Å [49,50]. Possibly, the smectic phase can also be formed on the walls of lamella, as well as pores in PTFE.…”

Section: Characterization Of X-ray Diffraction Patterns Registered For Initial and Thermal-radiation Modified Polytetrafluoroethylenementioning

confidence: 99%

See 1 more Smart Citation

Structure of Polytetrafluoroethylene Modified by the Combined Action of γ-Radiation and High Temperatures

et al. 2021

View full text Add to dashboard Cite

By means of X-ray computed microtomography (XCMT), the existence of a developed porous structure with an average pore diameter of ~3.5 μm and pore content of ~1.1 vol.% has been revealed in unirradiated polytetrafluoroethylene (PTFE). It has been found that the combined action of gamma radiation (absorbed dose per PTFE of ~170 kGy) and high temperatures (327–350 °C) leads to the disappearance of the porous structure and the formation of several large pores with sizes from 30 to 50 μm in the bulk of thermal-radiation modified PTFE (TRM-PTFE). It has been established by X-ray diffraction (XRD) analysis that the thermal-radiation modification of PTFE leads to an increase in the interplanar spacings, the degree of crystallinity and the volume of the unit cell, as well as to a decrease in the size of crystals and the X-ray density of the crystalline phase in comparison with the initial polymer. It is assumed that the previously-established effect of improving the deformation-strength and tribological properties of the TRM-PTFE can be due not only to the radiation cross-linking of polymer chains but also to the disappearance of the pore system and to the ordering of the crystalline phase of PTFE

show abstract

Section: Description Of Characteristics Dimensionsupporting

confidence: 88%

Section: Characterization Of X-ray Diffraction Patterns Registered For Initial and Thermal-radiation Modified Polytetrafluoroethylenementioning

confidence: 99%

Structure of Polytetrafluoroethylene Modified by the Combined Action of γ-Radiation and High Temperatures

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The spectral shape of halo II can be approximated by two Gaussians (Table 3, Figure 4, a, b), which suggests the existence of two independent non-crystalline components in the smectic phase of PTFE, the first of which includes partially ordered PTFE macromolecules, and the second, disordered layers of specific structural formations, so-called hexagons [18]. This agrees with the conclusion made in [24], where the nature of halo II was attributed to the presence of low molecular weight impurities in the polymer.…”

Section: Characterization Of X-ray Diffraction Patterns Registered For Initial and Thermal-radiation Modified Polytetrafluoroethylenesupporting

confidence: 88%

Structure of polytetrafluoroethylene modified by the combined action of γ-radiation and high temperatures

Smolyanskiĭ¹,

Политова²,

Koshkina³

et al. 2021

Preprint

View full text Add to dashboard Cite

By means of X-ray computed microtomography (XCMT) the existence of a developed microporous structure having an average pore diameter of ~3.5 μm and pore content of ~1.1 vol.% has been revealed in unirradiated polytetrafluoroethylene (PTFE). It has been found that the combined action of gamma radiation (absorbed dose per PTFE of ~170 kGy) and high temperatures (327-350 °C) leads to the disappearance of the microporous structure and the formation of several large pores with sizes from 30 to 50 μm in the bulk of thermal-radiation modified PTFE (TRM-PTFE). It has been established by X-ray diffraction (XRD) analysis that the thermal-radiation modification of PTFE leads to an increase in the interplanar spacings, the degree of crystallinity and volume of the unit cell, as well as to a decrease in the size of crystals and the X-ray density of the crystalline phase in comparison with the initial polymer. It is assumed that the previously established effect of improving the deformation-strength and tribological properties of the TRM-PTFE can be due not only to the radiation cross-linking of polymer chains but also to the disappearance of the micropore system and to the ordering of the crystalline phase of PTFE.

show abstract

“…Therefore, the development of compositions and technology for the production of polymer composite materials based on PTFE requires a comprehensive approach that takes into account not only the characteristics of the original structure of the components [13], but also its transformation under the influence of technological and operational factors [14]. One of the most effective and low-cost ways to implement this approach to the formation of the structure of composites based on PTFE is the method of mechanical activation [15,16] and the introduction of fiber or/and dispersed fillers [17,18].…”

Section: Introductionmentioning

confidence: 99%

Mechanically Activated Polytetrafluoroethylene: Morphology and Supramolecular Structure

Berladir¹,

Hovorun²,

Rudenko³

et al. 2022

J. Nano- Electron. Phys.

View full text Add to dashboard Cite

The nanoscale structure of polytetrafluoroethylene before and after mechanical activation was comprehensively studied by a set of modern physical research methods. The formation of a polydisperse mixture of a mechanically activated fluoropolymer with different molecular weights, the habit of single particles and arbitrary mass, size and morphology of cluster nanostructures was proved by electron microscopy. Two indicators were used to interpret the results of IR spectroscopy: the ratio of the intensities of the band maxima and the half absorption bandwidth. It was revealed that there is an increased concentration of CF2 end groups in the composition of activated polymer, which correspond to the low molecular weight fraction and provide small sizes of its macromolecules. It was proved that filling of polytetrafluoroethylene leads to a decrease in their number, contributing to the formation of a nanostructured polymer with fewer defects. It was established that the combined use of energy exposure and dispersed filler has a positive effect on the physical and mechanical properties of the fluoropolymer. The mechanical activation increases the strength level by 2.6 times and relative elongation by 4.3 times compared to the inactivated polymer; filling the activated polymer with sodium chloride increases the strength level by 2 times and relative elongation by 3.8 times.

show abstract

Structuring Peculiarities of Polytetrafluoroethylene Modified with Boron Nitride when Activated with Ultrasonic Exposure

Cited by 7 publications

References 2 publications

Structure of Polytetrafluoroethylene Modified by the Combined Action of γ-Radiation and High Temperatures

Structure of Polytetrafluoroethylene Modified by the Combined Action of γ-Radiation and High Temperatures

Structure of polytetrafluoroethylene modified by the combined action of γ-radiation and high temperatures

Mechanically Activated Polytetrafluoroethylene: Morphology and Supramolecular Structure

Contact Info

Product

Resources

About