Why is it not 100% Bio-Based?
To define a bio-based material, tests and measurements are carried out to determine how much of the carbon in a bio-based product actually comes from biomass and not from oil. It is generally expressed (according to ASTM D6866) as the ratio of carbon obtained from biomass to its total carbon content. Specifically, the bio-based percentage represents the amount of carbon of plant origin in the product. For example, a bio-based percentage value of 75% means that 75% of the carbon content is bio-based while the remaining 25% is of petrochemical origin.
Depending on the type of plastic (PP/PET/PE), different percentages of bio-based can be achieved, but never 100%.
Bio-based PE is the material in which the highest proportion of carbon of plant origin is obtained, because the processing of sugar cane produces the ethylene (monomer) that makes up polyethylene (polymer). 100% is not achieved because there are also carbons of non-plant origin resulting from contamination naturally occurring in all plants and from reagents involved in polymerisation processes. Bio-based PET contains 20% carbon of vegetable origin because chemically the polymer is obtained by a polymerisation reaction. One of the reactants is of plant origin and will make up 20% of the final weight of the polymer, while the other reactant of non-plant origin takes up the remaining 80%. Bio-based PP is derived from a blend of standard petroleum-derived PP and bio-based HDPE. This blend of up to 30% is designed to achieve and guarantee processing performance suitable for the industry.