In 2010, Dordan began pursing sustainable materials for plastic packaging. Many materials were being introduced to the market that tried to reduce plastic waste and its carbon footprint by substituting fossil-fuel based carbon with annually renewable resources and addressing end of life management through biodegradability and recycling. "Biodegradability" is a catch all term for materials that break down in the intended disposal environment i.e. industrial composting facility and "recyclable" means that 60% of American communities have access to facilities that collect that kind of material for recycling.
Dordan investigated 9 bio-plastics, publishing a report that compared the specs, cost, and environmental profiles of each. These included: Cellulose Acetate, PHA, PLA, PLA & starch, Bio-PET, foamed RPET, DPET (not bioplastic but less carbon intensive to produce), Calcium Carbonate & Polypropylene, and algae plastic. Of these materials, only a few have successfully penetrated the market. Lets reflect on the history of bio plastics to identify areas of success and failure; in doing so, perhaps guidance will be provided to those looking to utilize sustainable plastics today.
"Bio-based" plastics mean that a portion or all the carbon required for production is derived from an annually renewable resource like sugar cane. This reduces the amount of fossil-fuel based carbon required to produce plastics. Below is a flow chart that shows how renewable and non renewable carbon feedstocks are converted to bio-based and traditional feedstocks.
The process to convert a renewable feedstock to bioplastics was expensive in 2010 when compared to traditional resins since the supply chain had yet to be established for scalability. This has since changed due to the efforts of the plastics industry to streamline operations to offer economically viable and ethically sourced bio-based plastics. However, achieving pricing parity with traditional materials fluctuates.
Today, PLA and bio-PET are the predominate players in bio-plastics. While PLA it is made from a renewable resource, the end-of-life management is disorganized. It can be recycled post-consumer, but it isn’t “recyclable” since there is no dedicated stream of PLA collection nationwide. The intended disposal environment is an industrial composting facility, where few welcome PLA packaging, because it doesn’t provide any value to the compost. If the PLA package makes its way into the municipal waste stream and is disposed of in a landfill, it will give off more methane when degrading then fossil-fuel based plastics. Methane is a more potent greenhouse gas then carbon. Some waste processing facilities utilize the methane emissions from the landfill to provide power, but some don’t. If fillers are added to PLA to enhance performance, it may compromise its ability to break down in an industrial composting facility.
Like PLA, Bio-PET derives a portion or all of its feedstock from a renewable resource, but has an established post-consumer recycling infrastructure, making this material ideal for sustainable packaging applications.This material is structurally identical to fossil-fuel based PET, which is why it can be recycled with post-consumer PET packaging.
Let's look back on the materials that defined sustainable plastics in 2010.
Cellulose Acetate
Physical properties
Acceptable for use in food contact packaging; High clarity and gloss, with low haze; High water vapor transmission rate; Good die cutting performance, printability and compatibility with adhesives; Available in matte or semi-matte finishes.
Environmental properties
Feedstock: Cellulose from Sustainable Forestry Initiative managed forestry in North America; acetic anhydride, a derivative of acetic acid; and, a range of different plasticizers.
End of life: Complies with EN 13432 and ASTM D 6400 Standards for industrial biodegradability and compostability; and, received Vincotte OK Compost Home certification. Can be recycled with paper products; check locally.
Classified in the paper category in the UK, in view of its cellulosic base; the levy on cellulose acetate is lower than that on other thermoplastic films.
PHA
Physical properties
Durable and tough; Ranging from flexible to rigid; Heat and moisture resistant; FDA clearance for use in non-alcoholic food contact applications, house-wares, cosmetics and medical packaging.
Environmental properties
Feedstock: Poly Hydroxy Alkanoate (PHA). Polymer made through microbial fermentation of plant-derived sugar; only class of polymers that are converted directly by microorganisms from feedstock to the polymetric form.
End of life: Complies with EN 13432 and ASTM D 6400 Standards for industrial biodegradability and compostability; complies with ASTM D 7081 Standard for marine biodegradation; received Vincotte OK Compost Home certification; and, received Vincotte OK Biodegradable in Soil certification.
There is no post-consumer recycling market for this material.
Bio-PET
Physical properties
Same clarity and performance properties as standard APET rigid films; With heat deflection temperature of over 145 degrees, no special handling needed; Available in clear or color; Suitable for food, pharmaceutical, and medical packaging.
Environmental properties
Feedstock: Derives a portion of its carbon from annually renewable resources (new carbon), as opposed to fossil fuel (old carbon); made in part from sugar cane.
End of life: Structurally identical to standard APET, which allows for easy integration into existing post-consumer PET recycling infrastructure.
Packages produced from these films can be marked with the SPI #1 and waste from converting operations is compatible with existing pre-consumer PET recycling streams.
PLA & Starch
Physical properties
Only available in one color and opacity; Known to have black or brown specs in or on the sheet; Good impact strength; Demonstrates superior ink receptivity over petroleum based products; Heat sensitive, care must be taken when shipping, handling, storage, printing and further processing this material.
Environmental properties
Feedstock: PLA polymer is a major ingredient; this material incorporates modified PLA polymer with plant based starches to enhance its impact strength. Fillers may compromise material's ability to degrade.
End of life: Complies with EN 13432 and ASTM D 6400 Standards for industrial biodegradability and compostability. Fillers may compromise material's ability to degrade. There is no post consumer recycling stream for this material.
PLA
Physical properties
Acceptable for use in food-contact packaging; Good clarity but can haze with introduction of stress; PLA sheet is relatively brittle at room temperature; PLA requires modified forming practices due to lower softening temperature and thermal conductivity when compared with PET or PS; Exposure to high temperatures and humidity during shipping or storage can adversely affect the performance and appearance of resin (air-conditioned plants, refer trucks, etc.).
Environmental properties
Feedstock: Polylactide or Polylactic Acid (PLA) is a synthetic, aliphatic polyester from lactic acid; lactic acid can be industrially produced from a number of starch or sugar containing agricultural products.
End of life: PLA resin complies with EN 13432 and ASTM D6400 Standards for industrial biodegradability and compostability. The material's ability to break down may be compromised with additional fillers. PLA is recyclable, but the infrastructure needs investment to establish PLA as a viable post consumer resin stream.
Expanded/foamed RPET
Physical properties
A grease and moisture proof, printable sheet; Improves RPET’s functionality in terms of temperature range, insulation, flexibility and impact strength; Available in a variety of finishes, including high-gloss, semi gloss, matte, and satin; Acceptable for use in direct food contact applications.
Environmental properties
Feedstock: Made from recycled PET, which is then expanded to reduce the amount of raw material required per application.
End of life: Material is not recycled but it could be, since RPET is recyclable.
Calcium Carbonate and PP
Physical properties
Material performs like PP; however, the higher the concentration of mineral “filler” the less predictable the properties.
Environmental properties
Though not new to plastic processing, PP + mineral-based filler i.e. calcium carbonate/talc has been reintroduced to the market as a sustainable alternative to 100% petro-based materials.
Feedstock: PP and talk or mineral filler
End of life management: Not recyclable at current or compostable
Algae Plastic
The material was formulated by ALGIX, Bogart, Ga., which partnered with the University of Georgia and Kimberly Clark to commercialize the cultivation of aquatic biomass, such as algae, as a feedstock for bioplastic conversion.
Physical properties:
In R&D stage when sampled. Behaved similar to the performance of base resin; however, the higher the concentration of algae the less predictable the hybrids’ properties. Algae plastics has successfully penetrated the sustainable sneakers market, replacing rubber with foamed algae.
Environmental properties:
Feedstock: Algae feedstock derived from industrial by-product of textile manufacturing i.e. eutrophication/algae-blooms in waste water. Combined with base resin (PP, PE, PU, PLAs, PHAs) to allow for the replacement of petro-based material with annually-renewable.
End of life management: Biodegradability depends on the formulation with base resins i.e. PLA. Not recyclable.