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236 10 Highly Toughened Polylactide-Based Materials through Melt-Blending Techniques

Biopolymers

Biodegradable polymers Bio-based polymers

Fossil resources Renewable resources

i.e., Polycaprolactones From biomass From micro-organisms From biotechnology

i.e., Starches i.e., Polyhydroxyalkanoates i.e., Polylactides

Figure 10.1 Classification of biopolymers.

of an organic material caused by biological activity, mainly the enzymatic action
of microorganisms. During these processes, the carbon of the plastics has to be
completely converted into carbon dioxide, new biomass, and water (aerobic con-
ditions) or methane (anaerobic conditions). It further involves the assimilation
of these by-products by microorganisms within a precise range of time and their
absence of environmental toxicity, which is known as eco-toxicity [4]. Accordingly,
various worldwide standardized tests have been developed to assess “biodegrad-
able” labels. For instance, the fundamental requirements for a complete biodegra-
dation under composting conditions are [5] as follows:
• conversion to carbon dioxide, biomass, and water under micro-bacterial action
on the test polymer material in powder, film, or granule form;
• ninety percent of conversion to carbon dioxide and less than 10% of tested mate-
rial with asizeof2 mm or less;
• same rate of biodegradation as natural materials (leaves, papers, grass, and food
scraps);
• time of biodegradation less than 180 days;
• nontoxicity to the environment of the resulting compost.
In contrast, renewability is related to the concept of sustainable development.
The American Society for Testing and Materials (ASTM) defines a bio-based
material as an organic material in which the carbon is derived from a renewable
resource via biological processes [6]. These sustainable polymers can be directly
derived or after a fermentation process from vegetable and animal feedstocks,
including wood, wood wastes and residues, corns, soybeans, grasses, crops,
crop by-products, and crustaceans [7]. In addition, combining petroleum-based
polymers with renewable polymers is more and more envisioned as a sustainable
way to achieve some properties that consumers desire, as well as to increase the
overall “bio” content of these materials. In this regard, ASTM D6866 has set a
testing method for the determination of the bio-based content within plastic
materials using radiocarbon and isotope ratio mass spectrometry analysis [6].