The flame retardancy and pyrolysis mechanism of polyimide fibers investigated by cone calorimeter and pyrolysis–gas chromatography–mass spectrometry

2017 ◽  
Vol 48 (2) ◽  
pp. 465-481 ◽  
Author(s):  
Xiansheng Zhang ◽  
Xiong Yan ◽  
Meiwu Shi
Keyword(s):  
Electron Microscopy ◽  
Heat Flux ◽  
Flame Retardancy ◽  
Cone Calorimeter ◽  
Gas Chromatography Mass Spectrometry ◽  
Pyrolysis Gas ◽  
Pyrolysis Mechanism ◽  
Pyrolysis Gas Chromatography ◽  
Polyimide Fibers ◽  
Scanning Electron

In the present research, the flame retardancy and pyrolysis mechanism of polyimide fibers were investigated by cone calorimeter, scanning electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and pyrolysis–gas chromatography–mass spectrometry. As it turned out, the polyimide fibers possessed excellent thermal stability and flame retardancy. The onset thermal degradation temperature ( Tonset 10%) of polyimide was 587℃ and 610℃ at nitrogen and air atmospheres, respectively. The polyimide fibers cannot be ignited at the heat flux of 35 and 50 kW/m2, while they can be ignited at the heat flux of 75 kW/m2 with the time to ignition of 33 s and peak heat release rate of 53.4 kW/m2. Moreover, the flame retardancy of woven and knitted fabrics was also discussed, which demonstrated that knitted fabric was easier to become thermally thick than woven fabric. Scanning electron microscopy analysis of the residual chars of fibers showed that the shape of fiber can be maintained irrespective of heat flux, but the chemical structure of the fiber was destroyed at the heat flux of 75 kW/m2. The pyrolysis combustible volatiles at 700℃ include benzonitrile, aniline, and phenol, which can interpret the ignition of polyimide fibers. The results obtained in the present research revealed the flame retardancy and pyrolysis mechanism of polyimide fibers, which can guide its application and further modification.

scholarly journals Analysis of paint traces to determine the ship responsible for a collision

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
H. Lee ◽  
D. Lee ◽  
J. M. Seo
Keyword(s):  
Electron Microscopy ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Gas Chromatography Mass Spectrometry ◽  
Pyrolysis Gas ◽  
X Ray ◽  
Pyrolysis Gas Chromatography ◽  
Ship Collision ◽  
Derivative Thermogravimetry ◽  
Scanning Electron

AbstractAlthough there have been many instances of ship collision at sea in recent times, not much research has been conducted on the topic. In this study, paint from an actual site of ship collision was collected and analyzed as evidence. The amount of evidence collected from the ships involved in the collision is either small or has inconsistent morphology. In addition, the contaminants and samples are often mixed in this evidence, making its analysis difficult. Paint traces of the damaged ship and the ship suspected to be responsible for the collision were compared through scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDS), attenuated total reflection–Fourier transform infrared spectroscopy (ATR–FTIR), thermogravimetry (TG) and derivative thermogravimetry (DTG), and pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) analyses. The ship responsible for the collision could be identified by characterization and by performing a comparative analysis of the extracted paint. Among the methods used in this study, Py–GC/MS can sensitively analyze even similar paints, and identified styrene and phthalic anhydride as the most prominent components of the paint used as evidence. The results obtained can be used to investigate the evidence collected from collision sites and to determine the ship responsible for the collision.

The fire retardant properties and pyrolysis mechanism of polysulfonamide (PSA) fibers

2017 ◽  
Vol 88 (11) ◽  
pp. 1299-1307 ◽  
Author(s):  
Xiansheng Zhang ◽  
Xiaoning Tang ◽  
Ran Wang ◽  
Rui Wang ◽  
Xiong Yan ◽  
...  
Keyword(s):  
Heat Flux ◽  
Fire Retardant ◽  
Heat Fluxes ◽  
Gas Chromatography Mass Spectrometry ◽  
Cone Calorimetry ◽  
Small Molecular Weight ◽  
Absorption Bands ◽  
Pyrolysis Gas ◽  
Pyrolysis Mechanism ◽  
Fire Retardant Properties

In the present work, the fire retardant properties and pyrolysis mechanism of polysulfonamide (PSA) fibers were investigated by cone calorimetry, scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and pyrolysis-gas chromatography-mass spectrometry. The fire retardant behaviors were reflected by the cone calorimeter data under heat fluxes of 35, 50, and 75 kW/m2. This demonstrated that, when exposed to higher heat flux, PSA fibers were ignited easier and burned more completely, indicated by lower time to ignition and higher peak heat release rate. It was further confirmed from the morphology of the residual chars that the original fiber shape can be kept at lower heat flux, but it changed into coherent carbonaceous chars with holes at higher heat flux. In comparison of the FTIR spectra of raw fibers with residual chars, it was noticed that upon heating, the amide linkage was more liable to be broken than that of sulfone groups. Additionally, with elevated heat flux, most of the absorption bands vanished and transformed into the typical feature of carbonaceous material. The pyrolysis products showed that some volatile products with small molecular weight, such as benzene, benzonitrile, and aniline, can be created at high temperature, which can be easily ignited. With this research, the fire retardant properties of PSA fibers are revealed and the corresponding pyrolysis mechanism is proposed, which can guide its application in practice.

Enhancing cellular structure, mechanical properties, thermal stability and flame retardation of EVA/NR blend nanocomposite foams by silicon dioxide-based flame retardant

2021 ◽  
pp. 147776062110420
Author(s):  
Alif Walong ◽  
Bencha Thongnuanchan ◽  
Nattapon Uthaipan ◽  
Tadamoto Sakai ◽  
Natinee Lopattananon
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Silicon Dioxide ◽  
Flame Retardant ◽  
Flame Retardancy ◽  
Cellular Structure ◽  
Gas Chromatography Mass Spectrometry ◽  
Pyrolysis Gas ◽  
Nanocomposite Foams ◽  
Blend Nanocomposites

Flame retardant rubber foams of ethylene vinyl acetate (EVA)/natural rubber (NR)/layered silicate blends filled with silicon dioxide (SiO2) were prepared by using azodicarbonamide (ADC) as a blowing agent. Specifically, SiO2 was added in EVA/NR blend nanocomposites to produce good flame retardant foams. The properties of EVA/NR blend nanocomposite foams with different SiO2 loading (0, 20, 30, 40 parts per hundred rubber, phr) were investigated through transmission electron microscopy (TEM), scanning electron microscopy (SEM), rheological property test, mechanical property measurement, flammability tests, thermogravimetry analysis (TGA) and pyrolysis-gas chromatography-mass spectrometry (Pyrolysis-GC-MS). Compared with the simple EVA/NR blend nanocomposite, the added SiO2 increased the blend compatibility between EVA and NR phases and melt strength/viscosity of the EVA/NR blend nanocomposites, thus promoting cellular structure of the EVA/NR nanocomposite foams. Increasing SiO2 loading resulted in higher cell density, smaller cell size, and lower volume of void. These improvements caused higher strength and elastomeric recovery. The LOI test results showed that flame retardancy of the EVA/NR blend nanocomposite foams increased at higher SiO2 loading as a result of formation of insulation silicon dioxide-based char. TGA and pyrolysis-GC-MS analyses also validated the finding that the silicon dioxide-based char in the foamed samples containing higher SiO2 loading was more effective on improving thermal stability, which was responsible for lower material combustibility and better flame retardancy. Based on our finding, it was concluded that a good flame retardant EVA/NR blend nanocomposite foam with the best improvement in strength and elastomeric recovery was achieved when combined with 40 phr SiO2.

CHARACTERISATION OF DISSOLVED ORGANIC CARBON (DOC) LEACHED FROM LEAVES IN WATER

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Markus Heryanto Langsa
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Total Organic Carbon ◽  
Gas Chromatography Mass Spectrometry ◽  
Pyrolysis Gas ◽  
Pyrolysis Gas Chromatography ◽  
Chromatography Mass Spectrometry ◽  
Pinus Radiate

<p>Penelitian ini bertujuan untuk menentukan senyawa organik khususnya organic karbon terlarut (DOC) dari dua spesies daun tumbuhan (<em>wandoo eucalyptus </em>and <em>pinus radiate, conifer</em>) yang larut dalam air selama periode 5 bulan leaching eksperimen. Kecepatan melarutnya senyawa organic ditentukan secara kuantitatif dan kualitatif menggunakan kombinasi dari beberapa teknik diantaranya Total Organic Carbon (TOC) analyser, Ultraviolet-Visible (UV-VIS) spektrokopi dan pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS).</p><p>Hasil analisis DOC dan UV menunjukkan peningkatan yang tajam dari kelarutan senyawa organic di awal periode pengamatan yang selanjutnya berkurang seiring dengan waktu secara eksponensial. Jumlah relatif senyawa organic yang terlarut tergantung pada luas permukaan, aktifitas mikrobiologi dan jenis sampel tumbuhan (segar atau kering) yang digunakan. Fluktuasi profil DOC dan UV<sub>254</sub> disebabkan oleh aktifitas mikrobiologi. Diperoleh bahwa daun kering lebih mudah terdegradasi menghasilkan senyawa organic dalam air dibandingkan dengan daun segar. Hasil pyrolysis secara umum menunjukkan bahwa senyawa hidrokarbon aromatic dan fenol (dan turunannya) lebih banyak ditemukan pada residue sampel setelah proses leaching kemungkinan karena adanya senyawa lignin atau aktifitas humifikasi mikrobiologi membuktikan bahwa senyawa-senyawa tersebut merupakan komponen penting dalam proses karakterisasi DOC.</p>

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