Poly ( m -phenylene isophthalamide)/graphene composite aerogels with enhanced compressive shape stability for thermal in
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ORIGINAL PAPER: NANO- AND MACROPOROUS MATERIALS (AEROGELS, X E R O G E L S , CR Y O G E L S , E T C. )
Poly (m-phenylene isophthalamide)/graphene composite aerogels with enhanced compressive shape stability for thermal insulation Weiwang Chen1 Sha Liu1 Yutong Dong1 Xiaomeng Zhou ●
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Fenglei Zhou2,3
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Received: 2 June 2020 / Accepted: 18 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract To develop graphene-based composite aerogels with improved compressive shape stability that suitable for high-temperature applications, poly (m-phenylene isophthalamide, PMIA) with excellent heat resistance and flame retardancy was used as the supporting material. The effects of PMIA content on aerogel morphology, structure, mechanical and thermal properties were discussed. Unlike other polymers, PMIA in the composite aerogels appeared as separate or stacked particles instead of interconnected framework or uniform coatings. Higher PMIA content tended to result in denser aerogels with smaller pores and thinner graphene sheet walls. The densified structure with plenty of PMIA particles incorporated was found to make the aerogel more rigid and less flexible. Their compressive strength therefore was greatly enhanced. Besides, it was also observed that the thermal conductivity of the prepared aerogels increased with the increase of PMIA content. Nevertheless, their thermal conductivity was still 2000 times its own weight, indicative of enhanced compressive strength. ● PGAs are good at thermal insulation with thermal conductivity values 220 °C) is not recommended for PGAs. 3.2.2 Thermal decomposition Thermal decomposition behavior of the prepared PGAs in nitrogen was studied by a thermo-gravimetric analyzer. The results are plotted in Fig. 7. It is apparent that as-prepared PGA-2 without thermal treatment (230 °C for 6 h) show a typical three-step decomposition process. At the very beginning before 100 °C, the sample experienced a gradual weight loss of 7.6%, which can be attributed to the evaporation of moisture and residual solvents. After that, organic branched chains were removed, as shown by an obvious weight loss of 1.2% within 100–400 °C. The organic branched chains mentioned here refer to oxygencontaining groups on the surface of graphene sheets and their derivatives by reacting with MPD. As the temperature further increased over 400 °C, PMIA macromolecules began to degrade. This process involved not only polymer rupture but also rearrangement reactions [39, 40]. In details, the two weight loss rate peaks observed between 400 and 600 °C in Fig. 7b correspond to polymer heterolysis and
Journal of Sol-Gel Science and Technology Fig. 6 IR images of PGAs-2 placed a on and b below a hot plate with the temperature of 250 °C
Fig. 7 TG and DTG curves of the prepared PGAs: a, b N2 atmosphere, c, d air atmosphere
hemolysis, respectively, while the following weight loss over 600 °C mainly results from dehydrogenation and condensation reactions. The residue
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