Hello and welcome to a new post. With the arrival of new legislation to better protect the environment in Europe and other parts of the world, polymer manufacturers are extending their portfolio on bio-based polymers. In this post we investigate the question of what exactly the bio-content means of biopolymers.
In general, a
bio-based product is made from biomass (plants, trees, algae, marine organisms,
microorganisms) and there are two different concepts used in the plastics industry:
1. Bio-based content: refers to the amount
of biomass in a product; it considers four key elements: carbon, hydrogen,
oxygen and nitrogen; expressed as percentage of overall weight of product;
2. Bio-based carbon content: focus is on
the carbon; expressed as percentage of the carbon the product
contains;
Most of the bio-based polyamide
polymers use monomers from the sebacic acid chain which in turn is derived from
non-food competing castor oil.
EN 16785-1 – bio-based
content
Determination of the
bio-based content is done over the EN 16785-1 standard which includes the
measurement of the bio-based carbon (C14).
ASTM D6866 and EN 16640 – bio-based carbon content
For determination of the bio-based carbon content of polymers, ASTM D6866
standard was established with the working principle of radiocarbon analysis.
With this method, determination of the carbon fraction including the bio-based
percentage therein (C14 measurement) is done.
Illustrating the difference with an
example
We want to access the bio content of a PLA (plant-origin, containing 50%
carbon) and polypropylene (fossil-origin, containing 86% carbon) which are
blended in a ratio of 30/70%. According to EN 16785-1, the bio-based content of
this composition is in total 30%, whereas according to ASTM D6866 and EN 16640, the bio-based carbon content
is 20% (Figure 1).
 |
| Figure 1: Difference between bio-based content (EN 16785-1) and bio-based carbon content (ASTM 6866 / EN 16640) estimation for biopolymers |
I hope that this post helped to better understand bio-polymers and how to
read the amount of bio content.
Thanks
for reading and #findoutaboutplastics
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