As displayed in Fig. 4a, the aerogel can be easily and repeatedly bent 180◦ without damaging the shape of the
sample. The flexibility of the recycled cellulose aerogel is comparable to that of nanocellulose aerogels [29]. A qualitative test was performed for the sample to investigate its mechanical strength by loading a 200-g weight on the sample for 1 h, 5 h, one day, and five days (Fig. 4b). It was seen that no shape change of the aerogel was found after the test durations. For further understanding, the mechanical property of the material, tensile and compression tests were performed with an Instron 5500 microtester. The results in Fig. 4c and d show thatthe yield and tensile strengths ofthe aerogel
are ca. 1080 and 1470 N m−2, respectively, with a Young’s modulus of 11 kPa.
Fig. 6. (a) >SEM image ofthe sample coated with the commercial water repellent agent.(b) SEM image ofthe sample coated with MTMS.(c) Water contact angle measurement of the sample coated with the commercial water repellent agent. (d) Water contact angle measurement of the sample coated with MTMS. (e) Effect of exposure time on the
average water contact angle.