Glossary sustainable plastics

Plastics whose components are biodegradable.

The degradation process of biodegradable plastics can include various abiotic and biotic steps occurring in parallel or subsequently, but the final step of biological mineralization must always be included.

Biodegradation of plastics occurs when the organic material of the plastic is used as a source of nutrients for biological systems (organisms).

Biodegradable plastics can be based on renewable raw materials (e.g., starch) or on non-renewable/fossil raw materials (e.g., crude oil) that have been processed in chemical or biotechnological processes. The source or process by which the materials are produced does not affect their classification as biodegradable plastics.

The rate of biodegradability of a plastic article not only depends on the specific material but also on the surface-to-volume ratio of the product, e.g., its material thickness.

BASIC KNOWLEDGE
Microorganisms recognize biodegradable plastics as food and consume and digest them.

Degradation (mineralization) of a substance by biological activity.

Biodegradability must involve the action of living organisms in the degradation process, but abiotic processes may also be involved. Biodegradation occurs through the action of enzymes, either in the digestive system of living organisms and/or through isolated or excreted enzymes. Organisms perform biodegradation on substrates that are recognized as food and serve as a source of nutrients.

The end products of biodegradation are known digestion products such as carbon dioxide or methane, water and biomass,. This final step is known as ultimate biodegradation or biological mineralization.

For practical use, the degree of biodegradation and the end products of biodegradation should be known.

... Derived from biomass.

 See Bio-based plastic

Biomass-derived carbon content as a mass fraction of the total organically bound carbon content in the material.

The bio-based carbon content is accurately determined by measuring the content of the ¹⁴C isotope. This is much higher in renewable raw materials than in fossil ones. The method is the basis for the ASTM D-6866 standard: »Standard Test Methods for the Determination of the Biobased Content of Solid, Liquid and Gaseous Samples by Radiocarbon Analysis«.

Certificates and certification logos according to ASTM D 6866 are available for materials indicating their bio-based contents.

 The European standard DIN EN 16785-1: »Biobased products - Biobased content - Part 1: Determination of the biobased content using radiocarbon and elemental analysis« takes into account the total bio-based mass fraction, i.e. also bio-based oxygen, bio-based hydrogen and bio-based nitrogen, in relation to their overall contents .

Plastic from biomass (except fossil sources).

 Plastics can be completely or partially based on biomass (= renewable raw materials). The use of renewable raw materials can lead to higher sustainability of plastics.

Although fossil raw materials are retrieved from natural sources, they are not renewable and, thus, not sustainable. They are not regarded as a basis for biobased plastics. For a definition of the biobased content of plastics, see Bio-based carbon content.

Bio-based materials are often referred to as biomaterials, although in professional usage the terms are not synonymous (see Biomaterials). The use of biomaterials as a synonym to the term bio-based plastics should therefore be avoided.

Material of biological origin, excluding fossil or geological materials (= renewable raw materials).

The terms biomass and renewable resources describe the same thing in terms of origin and recovery time.

A renewable resource is a raw material that is produced again at a rate comparable to that at which it is consumed.

 Biomass can come from animal, plant, fungal or microbial sources.

Materials used in medicine for therapeutic or diagnostic purposes that come into direct contact with biological tissue of the body.

See the website of the International Society for Biomaterials:

www.biomaterials.org

Plastic that is biodegradable, bio-based, or both.*

The above definition is widely used in the plastics industry, however, other definitions exist in science.

 Alternative definition 1:
May also mean biocompatible plastics for safe use in surgery, e. g. (CEN/TR 15932).

 Alternative definition 2:
Naturally occurring plastic material. There are very few known bioplastics. An example is polyhydroxyalkanoates - a natural thermoplastic polyester.


^{* Definition according to European Bioplastics and U. S. Plastics Industry Association}

Polymer produced by living organisms*

 Biopolymers (=natural polymers) are important components of living organisms. They mainly include polysaccharides (e.g. cellulose, starch, glycogen, chitin) and proteins (e.g. gluten, collagen, enzymes), nucleic acids (DNA, RNA). Other forms such as lignin and polyester are also included.

 Definition according to CEN/TR 15932:2009: Fully or partially biobased polymer.

^{*Adapted from PAC, 1992, 64, 143 (Glossary for chemists of terms used in biotechnology (IUPAC Recommendations 1992)), definition on page 148.}

Plastics that biodegrade under certain conditions and within the time frame of a composting cycle.

Composting is a type of biowaste treatment that takes place under aerobic conditions (presence of oxygen), in which the organic material is broken down by naturally occurring microorganisms. In industrial composting facilities, the temperature in the compost pile can reach 70 °C. Composting takes place under humid conditions. The composting process takes several weeks.

 It is important to understand that biodegradable plastics are not necessarily compostable plastics (they may require a longer period or different conditions to degrade), while compostable plastics are always biodegradable plastics. Defining the criteria for compostable plastics is important because materials that are not suitable for composting can degrade the final quality of the overall compost.

 Compostable plastics are defined by a variety of national and international standards (e.g., EN 13432, ASTM D6400), most of which relate to industrial composting.

 EN 13432 defines the necessary properties of packaging material to classify it as industrially compostable. EN 14995:2006 extends the framework to plastics in applications other than packaging. These standards are the basis for a variety of certification systems.

 According to EN 13432, a compostable material must have the following properties:

• Biodegradability: An ability of the compostable material to be converted to CO₂ under the action of microorganisms. This property is measured under the EN 14046 standard (also published as ISO 14855-1 - Biodegradability under controlled composting conditions). To show complete biodegradability, 90% of the material (absolute or compared to the reference) must have degraded in less than six months.
• Disintegration: physical fragmentation and loss of visibility in the final compost product measured in a pilot composting plant (EN 14045) after three months.
• Absence of negative effects on the composting process.
• Low content of heavy metals and other chemical components and absence of negative effects on the final compost product.
  
  Home composting systems differ from industrial composting systems in that the temperature in the compost pile is lower. Plastics must be tested separately to determine if they are compostable under home composting conditions. Certification is done according to the standards AS 5810 "Biodegradable plastics - Biodegradable plastics suitable for home composting" or NF T51-800 "Plastics - Specifications for home compostable plastics".

Polymer-based material characterized by malleability.

 The main component of plastics or plastic (from Greek: plastikos - suitable for molding, plastos - molded) is a polymer that has been "formulated" by the addition of additives and fillers to yield a technological material - plastic. Plastics are defined by their moldability - they exhibit a state as a viscous "viscous" liquid at some point during processing.

 Definition according to EN ISO 472: material that contains a high molecular weight polymer as its main component and which has undergone a plastic state at some stage of its processing.

Macromolecule consisting of many repeating units

A polymer (from the Greek: poly - much, meros - parts) is usually considered an organic compound, although inorganic polymers are also known. Polymers contain thousands of linear or branched repeating units (monomers) and can reach molecular weights above one million daltons (dalton = g/mol).

 Polymers are formed in nature or produced artificially (synthetically). Natural polymers (=biopolymers) are special and important components of living organisms. They are mainly polysaccharides (e.g., cellulose, starch, glycogen), proteins (e.g., gluten, collagen, enzymes), and nucleic acids. Additionally, many other polymers such as lignin, hemicelluloses and polyesters are known. Artificial polymers, also called man-made polymers, are a large and diverse group of compounds not found in nature. They are synthesized by chemical or biochemical methods. The annual world production of polymers was estimated at 391 million tons in 2021 (Plastics - The Fact 2022).

The main use of man-made polymers is in the production of plastics. Polymers differ from plastics in that they are pure compounds, while plastics are formulated, ready-to-use materials made from polymers and additives.

 
BASIC KNOWLEDGE
A simplified analogy of a polymer is a long string of individual beads (like monomers), arranged in a linear form..

Sustainability as a guiding principle for process and product development

Sustainability is most often described by the definition of sustainable development that emerged from the 1987 Brundtland Report of the UN Commission on Environment and Development" (UNCED) as development that "meets the needs of the present without compromising the ability of future generations to meet their own needs": The point is that sustainability is not compatible with depleting resources. The second definition recognizes the sun as the only source of energy (also needed for biomass production).

The main tools for determining sustainability can be grouped into four main categories :

1. Instruments for "Sustainable Government" (e.g. Global Governance Programme GGP).
2. Methods and tools for assessing ecological, economic or social impacts, like Life Cycle Assessment 8LCA)  for ecological impacts.
3. Instruments for ecological environmental management and certification (e.g. Eco-Management and Audit Scheme EMAS).
4. Tools for sustainable design (e.g. ecodesign)

Life Cycle Assessment

The ecological part of  Sustainability can be determined by means of Life Cycle Assessment (LCA).  This is a systematic and objective method for assessing and quantifying the energy and environmental consequences and potential impacts associated with a product, process or activity. The period of consideration is the complete life cycle, from the procurement of raw materials to the end of life ("from cradle to grave" or better "cradle to cradle"). In this method, all phases of the manufacturing process are considered as interconnected and interdependent in order to capture cumulative ecological impacts. At the international level, LCA is governed by the ISO 14040 and ISO 14044 standards. LCA is the main tool for the implementation of 'Life Cycle Thinking' (LCT). LCT is fundamental as a cultural approach, as it involves looking at the entire product chain and identifying opportunities for improvement and innovation.

LCA is also known as life cycle analysis.