Põllumajandusministeeriumi ja Maaelu ... - bioenergybaltic

16. Smart energy networks (DG TREN and DG RTD)
17. Energy savings and energy efficiency (DG TREN)
18. Knowledge for energy policy making (DG TREN and DG RTD)
PRODUCTION OF BUILDING MATERIALS, BIOPLASTICS AND OTHER
MATERIALS FROM BIOMASS. USE OF BIOMASS AND RELEVANT
DEVELEOPMENT TRENDS
There are several possibilities to produce various polymers which in European Union are
conventionally called bio-based polymers (BBP). A composite material containing one or
several bio-based polymers is named bioplastic, mainly due to the marketing considerations.
Such a composite consists of the blend of different polymers and significant amount of
additives known as compounders which are of synthetic or mineral origin. Erroneously it is a
ubiquitous understanding that bioplastics are a priori biodegradable. As a matter of fact, only
certain types of bioplastics are biodegradable. Some BBP are extremely stable, both thermally
and chemically as well as mechanically (e.g., Rilsan). In the course of development of the
main BBP types, first their biodegradability has been reduced. In many biodegradable
composites the biodegradability is achieved and modified by respective polymers and
additives that are purely chemically produced.
The BBPs are classified in different documents and somewhat according to the interests of
entrepreneurs. That is why polymers composed of so-called potentially bio-based monomers
are named BBPs, although due to the price policy, these polymers are actually produced
synthetically.
BBPs can be divided according to their biomass ratio:
a) natural or chemically modified biopolymers,
b) polymers composed of completely or partially bio-based monomers.
The only natural biopolymers, which are used purely as bioplastics today, are
polyhydroxyalkanoates (PHA). For the production of PHA selected bacteria are cultivated,
bacterial biomass is lysed, followed by dissolving PHA from the lysed biomass by chemical
solvents. There are two large groups of modified BBP which are produced by processing
starch or cellulose, respectively. A large group of various polymers with distinct and different
characteristics is based on the both named raw materials. However, the starch modified group
is more important in the meaning of production capacity whereas thermoplastic starch forms
its majority. Based on different opinions, the starch-based polymers form altogether 50-80%
of the BBP used in bioplastics. The production involves chemical restructuration, several types
of (trans)esterification and etherification steps. Despite of a long application experience,
during the last decade the application of modified cellulose-based polymers has been
remarkably reduced, which is caused by the power and raw materials consuming cellulose
purification processes. Although the chemistry of cellulose production is quite similar to that
of starch, the conditions are harsher.
Polylactic acid represents a biopolymer completely produced from biological raw material and
according to the production aspects is defined as polylactide (PLA). The monomer for PLA is
produced via glucose fermentation to lactic acid, whereas purification of lactic acid and
sequential polymerization are parts of labour-intensive, energy and raw material consuming
chemical industry. Actually the pure PLA plastic is very rare in the market and the proposed
PLA-polymers are to a greater or lesser extent the mixed esters of lactic acid and synthetic
monomers (e.g., the mixed ester of lactic acid and glycolic acid – PLGA). The other important
groups of partially bio-based polymers are polyamides and polyurethanes. The production of
these plastics is practically identical to the conventional petroplastics; only with the difference
that one raw material is of agricultural origin.
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