Influence of gas atmosphere on electron-induced reactions of polyacrylonitrile homopolymer powder at elevated temperature

Gohs, Uwe; Böhm, Robert; Brünig, Harald; Fischer, Dieter; Leopold, Anne-Katrin; Malanin, Mikhail; Müller, M.; Cherif, Chokri; Richter, Mirko; Wolz, Daniel Sebastian Jens; Jäger, Hubert

doi:10.1016/j.radphyschem.2018.12.035

Cited by 7 publications

(17 citation statements)

References 29 publications

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“…and therefore a more pronounced crosslinking behavior. [ 7 ] Using Equation () gel doses were calculated and summed up in Table 4. The gel dose at a modification temperature above T g is about 10 kGy, beneath T g it is ≈ 41 kGy.…”

Section: Resultsmentioning

confidence: 99%

“…The gel content measurement was realized using a rotary evaporator in which the extracting was performed in DMF at 80 °C for 24 h in accordance to Gohs et al. [ 7 ] The remaining gel was washed in methanol and dried at 60 °C for 48 h in vacuum. Afterward, the residual mass ( m 1 ) was determined and the gel content ( X g ) was calculated using Equation ().…”

Section: Methodsmentioning

confidence: 99%

“…The first transition, the glass transition, is referred to relaxation processes and weakening van‐der‐Waals bonds between the nitrile groups. [ 4–7 ] The second transition within the paracrystalline structures was described as a result of strong dipole–dipole‐forces within the amorphous parts of the polymer. [ 4,6 ]…”

Section: Introductionmentioning

confidence: 99%

“…Radical induced chemical reactions strongly depend on the polymer properties like constitution, [ 19 ] glass transition temperature, [ 20 ] orientation of macromolecules as well as the processing conditions during irradiation such as dose D (absorbed energy per mass) and dose rate D R (absorbed dose per time), [ 19 ] temperature, [ 21 ] and atmosphere. [ 7,22 ]…”

Section: Introductionmentioning

confidence: 99%

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Influence of Temperature and Dose Rate of E‐Beam Modification on Electron‐Induced Changes in Polyacrylonitrile Fibers

Leopold

Müller

Zimmerer

et al. 2022

Macro Chemistry & Physics

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The present study investigates the influence of modification temperature and the dose rate of electron modification on the progress of these and the three important thermal induced reactions namely: cyclization, dehydrogenation, and oxidation. Since electron induced chemical reactions strongly depend on the polymer chain segment mobility, temperatures below the glass transition temperature (T g ) and above T g are tested. Electron paramagnetic resonance (EPR) spectroscopy measurements show the presence of alkyl-, peroxy-, and polyimineradicals alongside each other. Gel measurements identified a temperature dependent crosslinking behavior at doses ⩽ 150 kGy, but no dose rate depending on crosslinking. Changes in chemical structure are investigated using Fourier transform infrared spectroscopy (FT-IR), showing a dependency of stabilization behavior depending on dose and temperate more than on dose rate. Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements complete the analyses by describing the behavior during further thermal treatments and measuring the residual mass at 800 °C.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Temperature and Dose Rate of E‐Beam Modification on Electron‐Induced Changes in Polyacrylonitrile Fibers

Leopold

Müller

Zimmerer

et al. 2022

Macro Chemistry & Physics

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“…The production of "green" fibres based on renewable raw materials such as lignin is therefore a new way to open up the market for the construction industry. This will provide a sustainable and at the same time cost-effective fibre alternative [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Advanced Carbon Reinforced Concrete Technologies for Façade Elements of Nearly Zero-Energy Buildings

et al. 2022

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The building sector accounts for approx. 40% of total energy consumption and approx. 36% of all greenhouse gas emissions in Europe. As the EU climate targets for 2030 call for a reduction of greenhouse gas emissions by more than half compared to the emissions of 1990 and also aim for climate neutrality by 2050, there is an urgent need to achieve a significant decrease in the energy use in buildings towards Nearly Zero-Energy Buildings (nZEBs). As the energy footprint of buildings includes the energy and greenhouse gas consumption both in the construction phase and during service life, nZEB solutions have to provide energy-efficient and less carbon-intensive building materials, specific thermal insulation solutions, and a corresponding design of the nZEB. Carbon reinforced concrete (CRC) materials have proven to be excellent candidate materials for concrete-based nZEBs since they are characterized by a significantly lower CO2 consumption during component production and much a longer lifecycle. The corresponding CRC technology has been successively implemented in the last two decades and first pure CRC-based buildings are currently being built. This article presents a novel material system that combines CRC technology and suitable multifunctional insulation materials as a sandwich system in order to meet future nZEB requirements. Because of its importance for the life cycle stage of production, cost-efficient carbon fibers (CF) from renewable resources like lignin are used as reinforcing material, and reinforcement systems based on such CF are developed. Cutting edge approaches to produce ultra-thin lightweight CF reinforced concrete panels are discussed with regard to their nZEB relevance. For the life cycle stage of the utilization phase, the thermal insulation properties of core materials are optimized. In this context, novel sandwich composites with thin CRC layers and a cellular lightweight concrete core are proposed as a promising solution for façade elements as the sandwich core can additionally be combined with an aerogel-based insulation. The concepts to realize such sandwich façade elements will be described here along with a fully automated manufacturing process to produce such structures. The findings of this study provide clear evidence on the promising capabilities of the CRC technology for nZEBs on the one hand and on the necessity for further research on optimizing the energy footprint of CRC-based structural elements on the other hand.

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Hybride semi‐parametrische Modellierung der thermooxidativen Stabilisierung von PAN‐Precursorfasern

Mädler

Richter

Wolz

et al. 2022

Chemie Ingenieur Technik

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Kohlenstofffasern sind aufgrund ihrer hohen massespezifischen mechanischen Belastbarkeit ein unverzichtbarer Werkstoff im Leichtbau. Diese werden mittels eines zeitaufwendigen, thermooxidativen Stabilisierungs‐ und eines inerten Carbonisierungsprozesses hergestellt. Bedingt durch die kommerziell dominierte Forschung basiert der Großteil der veröffentlichten Optimierungsansätze für diese Prozessschritte bis heute auf unvollständigen, empirischen oder nicht‐parametrischen, datengetriebenen Modellen. In der vorliegenden Arbeit werden hybride semi‐parametrische Ansätze unter Berücksichtigung der Eigenschaften des Precursorsystems und der Prozessparameter für die Modellierung des Stabilisierungsprozesses untersucht.

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Influence of gas atmosphere on electron-induced reactions of polyacrylonitrile homopolymer powder at elevated temperature

Cited by 7 publications

References 29 publications

Influence of Temperature and Dose Rate of E‐Beam Modification on Electron‐Induced Changes in Polyacrylonitrile Fibers

Influence of Temperature and Dose Rate of E‐Beam Modification on Electron‐Induced Changes in Polyacrylonitrile Fibers

Advanced Carbon Reinforced Concrete Technologies for Façade Elements of Nearly Zero-Energy Buildings

Hybride semi‐parametrische Modellierung der thermooxidativen Stabilisierung von PAN‐Precursorfasern

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