The development of fire and microbe resistant sustainable gluten plastics

This study shows the improvement of fire and microbe resistance of sustainable (protein) plastics (i.e. wheat gluten, WG), by using triethylene glycol diamine and dialdehyde. In addition, an anti-microbial agent (lanosol) was also used separately and in combination with the diamine/dialdehyde. The network formed by the diamine and dialdehyde, during the production of compression-moulded plates, resulted in high fire performance index, large amount of char and low thermal decomposition rate. The best fire resistance was obtained by the combination of the dialdehyde and lanosol, which also yielded a char with the intact surface. The peak-heat-release-rate of this material was only 38% of that of the pure gluten material. This material also showed anti-bacterial (E. coli) properties. However, the diamine was more effective than the combination of dialdehyde/lanosol. Gluten materials with diamine resisted mould growth during a 22 days test at a relative humidity of 100%. The gluten material with the lanosol applied to the sample surface resisted mould growth during a three-week test at both ambient temperature and 37 °C. Despite the relatively high contents of the difunctional reagents used (15 wt%), leading to an increased stiffness in most cases, only the network formed with glyoxal resulted in a decrease in water uptake as compared to the pure gluten material. •Gluten plastic (WG) suffers from susceptibility to fire, moisture and microbes.•WG was treated with diamine (triethylene-glycol), dialdehyde (glyoxal) and lanosol.•Lanosol improved the reaction-to-fire properties of WG.•Dialdehyde reduced water uptake of WG while imparting acceptable tensile strength.•Diamine imparted anti-microbial properties in WG plastic.