Cellulose acetate
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Cellulose acetate is a modified form of refined cellulose that can be isolated from biomass and has applications for bioplastics, semipermeable membranes, water absorption, and lacquers. Cellulose is a polymer of B-1,4 linked glucose, and cellulose acetate is formed by replacing the glucoses' hydroxyl (OH) groups. Glucose has three hydroxyl groups (C2, C3, C6) that can be modified and the degree of substitution affects the characteristics of the polymer. For a high strength bioplastic polymer all three hydroxyl groups are replaced with acetate resulting in cellulose triacetate. Cellulose acetate with a lower degree of substitution can absorb water and has other applications. Cellulose acetate can be made by reacting cellulose biomass with acetic anhydride and an acid catalyst. Cellulose acetate has good optical and packaging characteristics but is not as durable as other bioplastics. Depending upon the degree of substitution cellulose acetate can be biodegradable. Cellulose acetate can also be composited with other materials improve product characteristics.
OSE context
Cellulose acetate is one of the oldest and easiest to manufacture forms of bioplastics. Unfortunately it is relatively unstable and not durable. Cellulose acetate or cellulose reacted with other anhydrides are useful for a number of applications but its use is more limited in existing OSE product ecologies. Lacquers, adhesives and applications that don't need robust or durable materials are a few possible OSE uses. Cellulose acetate is also flammable. A cellulose acetate lacquered Moldable mycelium could be an innovative, easily, and locally produced product. Cellulose acetate depending on its level of substitution and residual catalytic acid content can be biodegradable. Biodegradable cellulose acetate mixed with other biodegradable bioplastic products, such as starch and glycerol, can create a biodegradable product with favorable characteristics. Whether it is useful for OSE to pursue a biodegradable bioplastic is open for debate. Cellulose acetate would be the most easily produced bioplastic and could serve as a first step technology demonstration.
Proposed applications: Membranes/filters: reverse osmosis, dialysis membranes for continuous run fermentors and bioreactors, filters for chemical engineering processes
Thermomolded composite: a biodegradable composite of starch and plasticizer may be thermomolded by a 3D printer or plastic entruder
Lacquer: a fire resistant lacquer could be used to seal wooden materials or moldable mycelium parts for longterm use (OSE car interior?)
Light-weight packaging: cellulose acetate films for clear biodegradable packaging, the degree of durability and biodegradability can be controlled by the degree of substitution, type of anhydride substitution, and inclusion of other materials.