Fully bio-based composite foams made of wheat gluten and disintegrated spruce tree bark

Abstract

New lightweight materials made from wheat gluten and disintegrated spruce tree bark were studied. Disintegration of bark by dry milling resulted in rather isodiametric particles, whereas steaming and refining resulted in a more fibrous material. All components were blended and mechanically foamed with a hand mixer and subsequently dried in a conventional oven. The density, thermal conductivity, mechanical properties and water absorption were characterized. Densities vary according to their composition from 60 kg m−3 up to almost 300 kg m−3, as well as thermal conductivity whose lowest values oscillate around 0.04 W m K−1. The mechanical properties are strongly influenced by the type of particle used as reinforcement, with refined particles showing the best results, due to their high aspect ratio. Moreover, the foams produced show water absorption rates ranging from 310 to 480% after 14 h.

Keywords

• Bark
• Gluten
• Foaming
• Insulation material
• Refined particles