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Abstract Foam materials are widely used in packaging and buildings for thermal insulation, sound absorption, shock absorption, and other functions. They are dominated by petroleum‐based plastics, most of which, however, are not biodegradable nor fire‐proofing, leading to severe plastic pollution and safety concerns. Here, a fire‐proofing, thermally insulating, recyclable 3D graphite‐cellulose nanofiber (G‐CNF) foam fabricated from resource‐abundant graphite and cellulose is reported. A freeze‐drying‐free and scalable ionic crosslinking method is developed to fabricate Cu2+ionic crosslinked G‐CNF (Cu‐G‐CNF) foam with a low energy consumption and cost. Moreover, the direct foam formation strategy enables local foam manufacturing to fulfil the local demand. The ionic crosslinked G‐CNF foam demonstrates excellent water stability (the foam can maintain mechanical robustness even in wet state and recover after being dried in air without deformation), fire resistance (41.7 kW m−2vs 214.3 kW m−2in the peak value of heat release rate) and a low thermal conductivity (0.05 W/(mK)), without compromising the recyclability, degradability, and mechanical performance of the composite foam. The demonstrated 3D G‐CNF foam can potentially replace the commercial plastic‐based foam materials, representing a sustainable solution against the “white pollution”.
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Compostable, fully biobased foams using PLA and micro cellulose for zero energy buildings
Abstract Ecological, health and environmental concerns are driving the need for bio-resourced foams for the building industry. In this paper, we examine foams made from polylactic acid (PLA) and micro cellulose fibrils (MCF). To ensure no volatile organic compounds in the foam, supercritical CO2(sc-CO2) physical foaming of melt mixed systems was conducted. Mechanical and thermal conductivity properties were determined and applied to a net zero energy model house. The results showed that MCF had a concentration dependent impact on the foams. First structurally, the presence of MCF led to an initial increase followed by a decrease of open porosity, higher bulk density, lower expansion ratios and cell size. Differential Scanning Calorimetry and Scanning Electron Microscopy revealed that MCF decreased the glass transition of PLA allowing for a decrease in cell wall thickness when MCF was added. The mechanical performance initially increased with MCF and then decreased. This trend was mimicked by thermal insulation which initially improved. Biodegradation tests showed that the presence of cellulose in PLA improved the compostability of the foams. A maximum comparative mineralization of 95% was obtained for the PLA foam with 3 wt.% MCF when expressed as a fractional percentage of the pure cellulose reference. Energy simulations run on a model house showed that relative to an insulation of polyurethane, the bio-resourced foams led to no more than a 12% increase in heating and cooling. The energy efficiency of the foams was best at low MCF fractions.
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- Award ID(s):
- 1728096
- PAR ID:
- 10198547
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 10
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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