Gamma-irradiation-induced micro-structural variations in flame-retardant polyurethane foam using synchrotron X-ray micro-tomography

Agrawal, A. K.; Singh, Balwant; Kashyap, Yogesh; Shukla, Mayank; Manjunath, B.S.; Gadkari, S. C.

doi:10.1107/s1600577519009792

Cited by 11 publications

(6 citation statements)

References 74 publications

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“…At first glance, the results [67][68][69] contradict the effect of pore dissolution discovered in our study in the case of PTFE irradiation in the melt. However, it was shown [70] that an increase in the irradiation temperature has a strong effect on the volume concentration, shape, and size of helium bubbles in boron carbide.…”

Section: Discussioncontrasting

confidence: 79%

“…At the same time, the radiation heating of solids, which occurs as a result of the dissipation of the absorbed energy of ionizing radiation [63,68], turns out to be insufficient for the development of pore formation processes. This is confirmed by the results of a study by the method of X-ray computer microtomography of radiation-induced changes in the characteristics of the porous structure in foamed polyurethane samples, gamma-irradiated to various doses at room temperature [69]. It is shown that the observed changes in the porous structure of the polymer are caused by the processes of increasing the size of micropores and coalescence, which are caused by radiation crosslinking of macromolecules.…”

Section: Discussionsupporting

confidence: 58%

“…(ii) Radiation-induced formation of a system of closed pores is one of the main radiation effects that leads to a change in the structure of condensed media [17][18][19][67][68][69]. Discussion of possible mechanisms of pore formation during irradiation of condensed media showed that radiation-chemical processes of destruction, crosslinking and gas release have a decisive effect on the formation of a porous structure in irradiated solids [67,68].…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2021

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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

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Section: Discussioncontrasting

confidence: 79%

Section: Discussionsupporting

confidence: 58%

Section: Discussionmentioning

confidence: 99%

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

et al. 2021

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“…(Agrawal et al, 2017;Singh et al, 2017). The facility has been successfully used for numerous applications in a variety of domains in research and industry (Chhajed et al, 2019;Thomas et al, 2019;Choudhary et al, 2018;Agrawal et al, 2019;Mishra et al, 2020;Manzoor et al, 2019;Fatima et al, 2017;Yadav et al, 2018). Monochromatic beam has been used quite successfully with advantages such as availability of diffraction enhanced imaging for high-sensitivity phase contrast, improved edge enhancement in propagation-based phase-contrast imaging, and removal of beam-hardening artefacts in tomography.…”

Section: Introductionmentioning

confidence: 99%

The white beam station at imaging beamline BL-4, Indus-2

et al. 2021

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The high flux density of synchrotron white beam offers several advantages in X-ray imaging such as higher resolution and signal-to-noise ratio in 3D/4D micro-tomography, higher frame rate in real-time imaging of transient phenomena, and higher penetration in thick and dense materials especially at higher energies. However, these advantages come with additional challenges to beamline optics, camera and sample due to increased heat load and radiation damage, and to personal safety due to higher radiation dose and ozone gas hazards. In this work, a white beam imaging facility at imaging beamline BL-4, Indus-2, has been developed, while taking care of various instrumental and personal safety challenges. The facility has been tested to achieve 1.5 µm spatial resolution, increased penetration depth up to 900 µm in steel, and high temporal resolutions of ∼10 ms (region of interest 2048 × 2048 pixels) and 70 µs (256 × 2048 pixels). The facility is being used successfully for X-ray imaging, non-destructive testing and dosimetry experiments.

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“…Polymeric foam materials, defined as a dispersion of gas into polymeric matrix, has the properties of low density, exceptional strength to weight ratio, lightweight, excellent thermal and acoustic insulation properties, energy absorption ability, etc. [10][11][12] These materials were reported with varied densities ranging from 1.6 to 960 K gm −3 and approximately, 70%-80% of all the commercially prepared foam is based on polyurethane, polystyrene and polyvinyl chloride. 13,14 These polymeric solid foams find wide applicability in a variety of applications including packaging, cushioning, insulation etc.…”

Section: Introductionmentioning

confidence: 99%

Macroporous open cell polyester amphigel using citric acid and PEO: Solvent absorption, thermal behavior, and slow release of pesticide

Sarkar

Shakil

Kumar

et al. 2020

J of Applied Polymer Sci

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This article describes citric acid cross-linked amphiphilic poly(ethylene oxide) (PEO) macroporous open cell polyester amphigel, optimally synthesized using response surface methodology by applying central composite design to screen significant reaction parameters for maximizing percent water sorption. The chemical structure of the amphigel was confirmed by proton nuclear magnetic resonance (1 H NMR), FT-IR and the thermal behavior was studied using thermo-gravimetric and DSC. Due to amphiphilic nature, the amphigels also showed high chloroform (1151.33%-1193.33%) and water (755.33%-865%) absorption capacity. Thermal analysis revealed that amphigels are less thermal stability as compared to PEO, however, the degradation process was found to be multi step. The amphigel was effectively used as a carrier for easy loading of a hydrophobic pesticide and showed a slow release of the same.

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Gamma-irradiation-induced micro-structural variations in flame-retardant polyurethane foam using synchrotron X-ray micro-tomography

Cited by 11 publications

References 74 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

The white beam station at imaging beamline BL-4, Indus-2

Macroporous open cell polyester amphigel using citric acid and PEO: Solvent absorption, thermal behavior, and slow release of pesticide

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