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Attention: New Technology Of Sustainable Hyperelastic Graded Porous Cellulose Aerogel

2022/12/26 19:30:00 0

Cellulose aerogels are plagued by the structural plasticity induced by intermolecular hydrogen bonds. A strategy that does not use petrochemicals is to prepare hyperelastic cellulose aerogels by designing hierarchical structures at multiple scales. Dehydrated cellulose porous walls prepared by thermal etching not only reduce stiffness and viscosity, but also guide micro deformation, alleviate local large strain and prevent structural collapse. This aerogel has excellent stability, including high elasticity in a wide temperature range, fatigue resistance (about 5% plastic deformation after 105 cycles), and high angular recovery rate (1475.4 ° s-1), which is superior to most cellulose based aerogels. This benign strategy retains the biosafety of biomass and provides alternative filter materials for health-related applications, such as masks and air purification.

Preparation, characterization and properties of ACHAs. a) Schematic diagram of combination of freeze casting and thermal etching to prepare ACHAs.

The homogeneous aqueous dispersion containing CNFs and PHAs is directionally frozen cast, and the directional channel is established by extruding the dispersion. The thermal etching of PHA particles forms secondary pores on the cell wall. b. C) SEM images showing the anisotropy and layered microstructure of ACHA. Illustration b) shows an ultra light sample of ACHA placed on dandelion. d) FTIR spectra showed that when the characteristic peak was 1720 cm-1, the value assigned to C=O in ACHA disappeared, indicating that PHA was effectively removed. e) Mass manufacturing of custom shaped ACHAs. f) Photos showing the torsion and recoverability of ACHA at a large angle of 180 °.

Characterization of mechanical properties. A-c) Compressive stress-strain curves of three cellulose aerogels (DCA, ACA and ACHA) under 50% strain cycle test.

The illustration shows the height retention of the corresponding sample before and after the test.

d) The stress reduction, e) plastic deformation and f) energy loss coefficient of three cellulose aerogels under 10 compression cycles at 50% strain indicate that ACHA has the best elasticity.

g) The stress strain curve of ACHA under 105 cycles of 50% strain leaves~5% plastic deformation.

h) Compared with the cellulose base previously reported, the ACHA aerogel has a high retention rate. The percentage in parentheses represents the stress retained after the cyclic test, and the second number represents the relevant reference data. i) Photos showing the stability and elasticity of ACHA under large strain up to 80% in liquid nitrogen.

Macroscopic and microstructural deformation observation of ACHAs.

a) SEM observation of ACHA after 50% compression strain and release.

b) Schematic diagram of interaction between FIB-SEM nano manipulator and cell wall. In situ scanning electron microscope images were obtained during the slow upward movement of the nano manipulator and its contact with a single cell wall.

c) In situ scanning electron microscope images showed local deformation of porous cell wall of ACHA, which verified the ability of porous cell wall to enhance deformation.

d) SEM images of bending ACHA revealed the deformation mechanism of compression and tension sides. The bending direction is parallel to the orientation channel.

e) Foldable and recyclable photos of ACHA.

f) Real time image of high-speed camera shows that ACHA can be recovered from bending to 90 ° angle within 61 ms. a) Scale: 500 μ m. C) Scale 10 μ m. E, f) The scale is 1 cm.

Air filtration performance of ACHAs. a. B) PMs removal efficiency of different samples (5mm thick ACHA, 10mm thick ACHA and commercial masks) at a) 1 L min-1 and b) 5 L min-1 flow rates. The airflow direction is parallel to the directional channel. c) 30 cycle tests (1 L min-1) showed that 10 mm thick ACHA had stable removal efficiency of PMs and pressure drop. d) Schematic diagram of self-made PMMA smoking test box. Pm is produced by incense candles, and the airflow direction is indicated by arrows. e) Description of removal mechanism and f) Scanning electron microscope of 10mm thick ACHA after smoking test showed absorbed pmms. f) The sample after test is inserted in. The scale of flower arrangement is 1cm.