written by dr. Carmelo A. Spadaro
Bachelor of Science in Physics-University of Messina,Italy
Master of Science degree in Applied Polymer Science and Technology from ProPlast Consortium & Polytechnic of Turin,Italy
Researcher at Polytechnic of Turin/involved in research projects dealing with the exploitation of renewable and alternative energy sources.
A polymer (from the Greek poli meros = several parts) is a chain structure of a great number of small molecules, the so-called monomers, also called repetition units within the polymer, as they are repeated by the same type of chemical bond.
Polymers are macromolecules, that means molecules with a high molecular weight. Polymeric macromolecules can be divided into three main groups, that are:
- Natural Polymers
- Synthetic Polymers
- Biopolymers
Some examples of natural polymers are proteins, whose monomers are amino acids, and cellulose, whose monomers are glucose units.
Synthetic polymers cover the vast majority of plastic materials that consumers can find on the market, and are produced in petrochemical refineries from petroleum and since its refining process. Some examples are polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), etc
The definition of biopolymers given by the EBA (European Bioplastics Association) include two kind of materials, that might have completely different sources and characteristics:
1. Polymers with high biodegradability (according to UNI EN 13432 norm).
2. Polymers produced from renewable raw materials.
This means that polymers of the first kind can be either from renewable sources or from fossil origins, but have to be biodegradable, while polymers of the second kind can be either biodegradable or not, but the sources must be renewable and not depletable. Some examples of biopolymers are polylactic acid (PLA), whose monomer is lactic acid, and polyhydroxybutyrate (PHB), whose monomer is hydroxybutyrate.
According to ISO (International Organization for Standardization) standard, a polymer can be considered biodegradable if it is able to comply with modifications of its own chemical structure when subjected to the effect of some bio-organisms like bacteria, fungi, algae, etc…, with a loss of some of its starting characteristics. Biodegradability must be proven for each significant organic component, i.e. for constituents present in more than 1% with respect to the dry weight of substance. Keeping the biodegradability epithet needs at least 95% of all constituents to be biodegradable.
Nowadays biopolymers are able to replace conventional plastic materials in a number of application, with undoubted environmental benefits. According to a research conducted by Utrecht and Fraunhofer University, biopolymers are able to replace 33% of conventional plastic materials (15.4 Mioton/year). Unfortunately, biopolymers have a poor economic competitiveness, mainly due to their low production volumes. Biopolymers are coming down in price, about 5 times in 10 years, but still prices remain higher than the petrochemical counterpart.
Anyway at present it’s a niche market, bound to packaging and agricultural segment, with an estimated production of about 0.3 - 0.4% with respect to global world production.
But the situation may change drastically in the near future, due to normatives and tax incentives, and also due to oil price increase, of which consumers and companies are helpless witnesses in these very days.
According to the EBA, both market and production capacity will strongly increase in the next few years, getting boosts from a number of factors, e.g. more competitive prices, the ability to improve in technical performances and in tailorization, the come into effect of a specific legislation, a higher education and acceptance by consumers, etc…
Biopolymer is a very active and rich field for the search of good opportunities in the R&D field. Bioplastics are now coming under the spotlight with several uses that spread from the everyday use to applications with a high technical performance content, with the huge advantage of a reduced environmental impact.
Awareness campaigns and consumer culture are key factors that can determine a switch from the current niche market to a large scale demand and production, that will influence the plastics division and the whole world.
Keywords: polymers, biopolymers, plastic, bioplastic, biodegradable, EBA, European Bioplastics Association
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