Optical and color rendering long-term performance of monolithic aerogel after laboratory accelerated aging: Development of a method and preliminary experimental results

Fiorini, Costanza Vittoria; Merli, Francesca; Belloni, Elisa; Anderson, Ann M.; Carroll, Mary K.; Buratti, Cinzia

doi:10.1016/j.solener.2023.01.030

Cited by 8 publications

(5 citation statements)

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“…The prolonged aging of up to 12 years results in a yellowing of aerogel’s surface, related to the right shift of the reflectance spectra. This behavior was not perceptible after 2.5 years of aging when the reflection spectra of the new and aged material still appeared to overlap [ 20 ]. However, it is a very influential aspect for future improvements of the aerogel because transparency is a prerogative for a glazing element, with typical service life around 20 years.…”

Section: Resultsmentioning

confidence: 99%

“…A detailed description of the procedure for accelerated aging is included in [ 20 ]. In order to correlate the accelerating atmospheric agents with natural service conditions and to estimate the required aging time, factors were calculated for both temperature and radiation influence: the acceleration factor for temperature (AF T ) and the acceleration factor for radiation (AF RAD ).…”

Section: Methodsmentioning

confidence: 99%

“…Crucible tests were performed for three different heating rates (5, 7, and 10 °C/min) in an air atmosphere from 20 ° to 900 °C. The model-free isoconversional Starink and Ozawa–Flynn–Wall (OFW) methods were applied to the thermal degradation results in the 50–100 °C range, and an activation energy equal to 88 kJ/mol was obtained for hydrophilic aerogel (HY 0) [ 20 ]. Lower values were found for the hydrophobic samples (45 kJ/mol for HY 7.5 and 65 kJ/mol for HY 10).…”

Section: Methodsmentioning

confidence: 99%

“…However, no activation energy values for aerogel monoliths were found in the literature. In previous research, an experimental campaign with thermogravimetric analysis was carried out to address this issue with both granular and monolithic aerogel [ 20 ]. A reliable value of the activation energy was determined for use with the Arrhenius law to calculate the acceleration factor for temperature.…”

Section: Introductionmentioning

confidence: 99%

“…The samples were aged by combining temperature and solar radiation effects in an innovative experimental device developed at the University of Perugia. A service life equivalent to about 12 years was achieved in 4 months (determined by the acceleration factor (AF) found in [ 20 ]). Properties were evaluated before and after aging and include: spectral transmittance and reflectance, acoustic absorption coefficients, acoustic insulation properties, color rendering [ 19 ], density, surface area, porosity and contact angle.…”

Section: Introductionmentioning

confidence: 99%

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Long-Term Performance of Monolithic Silica Aerogel with Different Hydrophobicities: Physical and Color Rendering Properties after an Accelerated Aging Process

Fiorini

Merli

Belloni

et al. 2023

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Due to its excellent properties, monolithic silica aerogel is a promising material for innovative glazing systems. Since glazing systems are exposed to deteriorating agents during building service life, it is essential to investigate the long-term performance of aerogel. In the present paper, several 12.7 mm-thick silica aerogel monoliths produced by a rapid supercritical extraction method were tested, including both hydrophilic and hydrophobic samples. After fabrication and characterization of hydrophobicity, porosity, optical and acoustic properties, and color rendering, the samples were artificially aged by combining temperature and solar radiation effects in an experimental device specifically developed at the University of Perugia. The length of the experimental campaign was determined using acceleration factors (AFs). Temperature AF was evaluated according to the Arrhenius law using thermogravimetric analysis to estimate the aerogel activation energy. A natural service life of 12 years was achieved in about 4 months, and the samples’ properties were retested. Contact angle tests supported by FT-IR analysis showed loss of hydrophobicity after aging. Visible transmittance values in the 0.67–0.37 range were obtained for hydrophilic and hydrophobic samples, respectively. The aging process involved optical parameter reduction of only 0.02–0.05. There was also a slight loss in acoustic performance (noise reduction coefficient (NRC) = 0.21–0.25 before aging and NRC = 0.18–0.22 after aging). For hydrophobic panes, color shift values in the 10.2–59.1 and 8.4–60.7 ranges were obtained before and after aging, respectively. The presence of aerogel, regardless of hydrophobicity, results in a deterioration in light-green and azure tones. Hydrophobic samples had lower color rendering performance than hydrophilic aerogel, but this did not worsen after the aging process. This paper makes a significant contribution to the progressive deterioration assessment of aerogel monoliths for applications in sustainable buildings.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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