SFB 1313 Publication "Chitin/Chitosan Biocomposite Foams with Chitins from Different Organisms for Sound Absorption"

A new SFB 1313 publication is published in "ACS Sustainable Chemistry & Engineering". The paper was written in collaboration with researchers from the Bundesanstalt für Materialforschung und -prüfung, the Fraunhofer-Institut für Bauphysik, and the University of Stuttgart, involved in research project Z02.

Chitin/Chitosan Biocomposite Foams with Chitins from Different Organisms for Sound Absorption

Authors

• Sebastian B. Wachsmann (University of Stuttgart)
• Matthias Ruf (University of Stuttgart, research project Z02)
• Carsten Prinz (Bundesanstalt für Materialforschung und -prüfung)
• Nina Oehlsen (University of Stuttgart)
• Xiaoru Zhou (Fraunhofer-Institut für Bauphysik)
• Michael Dyballa (University of Stuttgart)
• Christine Arweiler (University of Stuttgart)
• Philip Leistner (Fraunhofer-Institut für Bauphysik)
• Holger Steeb (University of Stuttgart, research projects B05, C05, and Z02)
• Harald Garrecht (University of Stuttgart)
• Sabine Laschat (University of Stuttgart)
• Linus Stegbauer (University of Stuttgart)

Abstract< 1 , which indicates a strong intensity of physical processes on the boundary, described by the inhomogeneity φ ε (the cases α = 1 and α > 1 were previously studied by the same authors). A complete Puiseux asymptotic expansion is constructed for the solution u ε as ε → 0 , i.e., when the diffusion coefficients are eliminated and the thin network shrinks into a graph. Furthermore, the corresponding uniform pointwise and energy estimates are proved, which provide an approximation of the solution with a given accuracy in terms of the parameter ε .

Foams are widely used for applications in construction, energy absorption, and building insulation. We developed sustainable chitin/chitosan-based foams derived from snow crab and Aspergillus niger (α-chitin) and from squid (β-chitin), which were obtained via a “shake and bake” process. The foam structure, mechanical, thermophysical, sound absorption, and flammability properties were studied. Stable foams were obtained from snow crab and squid chitin, whereas A.niger-based foams were inhomogeneous. Foams derived from the former biomass sources displayed densities of 0.07–0.30 g/cm³ and bulk porosities of 78–94% with only a minimal number of closed pores. According to mercury porosimetry (MP) and X-ray computed microtomography (μXRCT), pore sizes ranged from 3 μm to 1.5 mm, with the majority of pores being larger than 400 μm. In mechanical compression tests, β-chitin-based foams showed higher specific compressive strength and modulus (up to σ∗0.1 = 9.00 MPa/E* = 107.37 MPa) compared to the α-chitin-based series. Dynamic vapor sorption (DVS) measurements revealed that the β-chitin (from squid) series overall took up more water vapor (≤40 wt %) than the α-chitin (from snow crab) series (≤33 wt %). Flammability tests showed that the developed foams were suitable for fire protection class E, superior to common polyurethane (PU) foams, and sound absorption tests showed promising results for applications only little influenced by humidity.