The technical advantages of bioplastic materials
The properties of bioplastic materials are often characterised as being inferior to those of conventional polymers.
Actually, there are differences for certain materials which require adaptations in the transformation and the properties of use. Others have the exact same capabilities, or even exceed those of petroleum-based materials, like Polyamide-11 for example.
There are several types of technical advantages in using bioplastics:
- Intrinsic properties
- New functionalities
Polyethylene Furanoate (PEF) is a concrete example of the technical advantages which may be derived from using bioplastics. It is a new polymer which will arrive on the market around 2020 to compete with PET, and has the following characteristics:
- 100% biobased and still transparent and recyclable: use and end-of-life identical to that of PET.
- Blocks dioxygen 10 times more efficiently and carbon dioxide and water vapour 2 times more efficiently: for example, allows for a reduction in the thickness of the sides of packaging material (bottles for carbonated beverages).
- The glass transition temperature (Tg) is higher by 12°C and thus ensures that it can be used with hot products, which is impossible with standard amorphous PET.
- The melting temperature is lower by 30°C, which results in an energy gain during transformation.
This property results in more functionalities which are appreciated by industrialists. It can be useful in manufacturing a product which has a given effective lifetime and which can then biodegrade in its place of use without polluting the environment. The main example today in the field of plastics engineering is the agricultural mulching film: its primary functions are regulating the temperature of the soil while retaining a relative humidity which ensures better crop growth. Today, these mulching films can be made using biodegradable polymers. This constitutes a dual advantage:
- The farmer can leave the fragments of the film on the soil to biodegrade once its use is complete, thus avoiding the task of gathering and processing a non-biodegradable film.
- The soil is enriched with organic matter and nutrients thanks to the biodegradation of the mulching.
There are other examples like clips for vineyards, links for horticulture (tomatoes, etc.) or in hunting (cartridges, etc.) or fireworks (refer to project MATADORE).
This property of biodegradability may also be used as an opportunity to impart new functionalities to the product. It is thus possible to incorporate beneficial additives which may be released during the use or end-of-life of the product. Biodegradation thus becomes a technical advantage even during use and no longer only after end-of-life.
Here is a non-exhaustive list of the possible functions:
- Attraction (pests, insects, etc.)
- Repulsion (pests, insects, etc.)
- Nutrition (plants, etc.)
- Depollution (water, soil, etc.)