By Karen Hanna
Cassava, corn, almond shells, olive pits, the pennycress weed, seaweed and seashells, and even some of the byproducts of bacterial processes all have the chemical building blocks to be transformed into materials that can be melted and reshaped.
According to European Bioplastics, a Berlin-based association that represents the biomaterials market, bioplastics can be considered sustainable because they are sourced from renewable resources, such as crops that, in some cases, can be used, recovered and reused. Compared with other materials, they require a smaller carbon footprint and using them results in less greenhouse gas emissions.
As materials enter the market, so do new terms. According to an email from Beatrice Miñana, communications director for Closed Loop Partners, a company dedicated to the circular economy: “... biomaterials are inclusive of conventional plastics that are bio-based, as well as compostable plastics – these materials are different and their use cases are different. Conventional plastics that are bio-based are recyclable and chemically indistinguishable from conventional plastics made from fossil fuels (i.e. PET, PP, PE). Compostable plastics, on the other hand, represent new types of polymer groups, including PLA and PHA.”
Below are some other pertinent definitions, based on information from the websites of European Bioplastics and the Association of Plastic Recyclers, as well as a Plastics Machinery & Manufacturing (PMM) webinar:
Biomaterials. Materials that are either bio-based or biodegradable, or have features of both. A “biopolymer is any kind of material that is produced or derived from living organisms,” said KraussMaffei process engineer Lauryn Burdette during the PMM webinar, “Taking the mystery out of bioplastics.” Biopolymers come from natural renewable sources, while traditional plastics — like PET and PE — come from fossil sources.
Biodegradable materials. Materials that can be converted by microorganisms into water, carbon dioxide and biomass. The exact process depends on the material and surrounding environmental conditions, such as temperature and humidity. Biodegradable materials “can be biopolymers, but are not necessarily biopolymers, and those are just materials that can degrade by microorganisms or enzymes in a reasonable length of time under ambient conditions,” Burdette said. Both biomaterials and fossil fuel-based plastics can be either biodegradable or non-biodegradable.
Compostable materials. Materials that are biodegradable under industrial or home composting conditions.
Bio-based or partly bio-based, non-biodegradable plastics. Materials made from renewable biomass, such as corn, sugarcane, plant oil, wood or other biological waste streams, including bio-based polyamides and polytrimethylene terephthalate (PTT); and totally new polymers, such as polyethylene furanoate (PEF). Biomass also can be used as feedstock to make bio-based versions of traditional plastics. Typically, development of these “drop-in” materials is faster than R&D associated with brand-new materials. Bio-based versions of traditional plastics include bio-based PP, bio-based PET and bio-based PE — which already is produced in large volumes and can be recycled in the same streams as their traditional plastics counterparts. Bio-based, non-biodegradable plastics usually last years, making them appropriate for use in a wide range of parts including packaging, casings, cables, hoses, covers and foams for automotive seating; they also can be used as textiles.
Bio-based and biodegradable plastics. This category includes polylactic acid (PLA), polyhydroxyalkanaotaes (PHAs), polybutylene succinate (PBS), thermoplastic starch (TPS) and polyhydroxybutyrates (PHBs). Applications include packaging and other parts intended for short-term use. Necessary conditions for composting vary. Some of the materials can be mechanically and chemically recycled.
Fossil-based plastics that are biodegradable. This relatively small category includes polybutylene adipate terephthalate (PBAT) and polycaprolactone. In some cases, in the future, these plastics might be produced at least partly from bio-based feedstock. Today, these plastics mainly are used in combination with PLA or other biodegradable plastics, to enhance the other materials’ mechanical properties.
Contact:
Association of Plastic Recyclers, Washington, D.C., www.plasticsrecycling.org
Closed Loop Partners, New York City, 347-630-2368, www.closedlooppartners.com
European Bioplastics e.V., Berlin, 49-30-28482-350, www.european-bioplastics.org
KraussMaffei Corp., Florence, Ky., 859-283-0200, www.kraussmaffei.com
