This Small Business Technology Transfer Research (STTR) Phase II project proposes to formulate and engineer chemically modified bio-based and biodegradable Poly(Lactide) based compounds, to generate a new class of materials that are, high strength, lightweight, multifunctional, environmentally friendly & cost-effective as an alternative to petroleum based polymers. NTIC has successfully commercialized a portfolio of reactive blended bio-based and/or biodegradable resins for extrusion, molding, and coating applications. However, it faces a major hurdle due to poor mechanical properties, high prices, and higher densities of current PLA materials. NTIC successfully developed novel chemistries of compatibilization to create advanced PLA bio-resins that offer improved toughness in Phase I of this work. The newly synthesized materials were applied in four different processing platforms to provide extruded films, injection molded cutlery, extrusion coated paper, and extrusion blow molded bottles. Phase II funding will allow NTIC to build on the success of the initial trials and build an improved, broader portfolio of high strength and economically viable PLA based products.

The broader impacts of this research are technical, environmental, and economical. This work will (1) widen the window of performance of PLA based applications; (2) further fundamental understanding of PLA and its chemistries (3) greatly increase the use of biobased products in larger industrial and packaging markets implying environmental preservation of fossil fuel resources; and (4) create new jobs for sales, manufacturing, technical support of newly developed Natur-Tec® products.

Project Report

Globalization has changed the landscape of global manufacturing and supply chains, creating huge opportunities for more efficient production of goods and services, but also significant sustainability issues. One such challenge is the waste of packaging materials throughout the supply chain. Manufacturers have made progress toward end-of-life product strategies by developing biodegradable and compostable packaging materials. But what about the beginning-of-life strategies — designing packaging materials that start from plant-based feedstock rather than fossil carbon? In other words, can plant-based carbon sequestered from CO2 in the environment be incorporated into packaging materials? Northern Technologies International Corp. (NTIC), a small business headquartered in Circle Pines, MN, has developed biodegradable, compostable, and, for the first time, bio-based, polylactide (PLA) for blown plastic packaging films and end products. Conventional PLA resins have several drawbacks that have limited their commercial success. PLA is a brittle polymer with poor flexibility and impact properties. Its glass transition temperature is around 50°C, making it unsuitable for applications that require heat resistance (e.g., disposable hot-food containers). Its crystallization rate is too slow and its cycle time too long for molding applications. And, because of its poor melt strength and integrity, it is difficult to form thin films out of PLA. To address these issues, NTIC developed an innovative reactive extrusion process to synthesize epoxy modified PLA molecules through transesterification and coupling chemistries. The new epoxy-functionalized PLA molecule can be reactively blended with regular PLA resin and other biodegradable polyester resins, such as poly(butylene adipate-coterephthalate) (PBAT), to achieve properties not found in traditional PLA resins — strain hardening properties for blown-film applications, as well as improved processability, heat resistance, and impact resistance. The epoxy modification not only improves the rheology of the PLA resin, but also functions as a surfactant to aid in blending the PLA with other biodegradable polyesters, which would otherwise phase separate. The resin can also be blended with fillers, modifiers, and additives to confer additional desired properties. NTIC developed the functionalized PLA technology in collaboration with Ramani Narayan’s Biobased Materials Research Group at Michigan State Univ., with support from the Small Business Technology Transfer (STTR) Program of the National Science Foundation. The company has successfully commercialized its innovation in bio-based and biodegradable-compostable specialty packaging films, coated paper/paperboard products, and cutlery. With its 100% bio-based carbon content, every kilogram of PLA effectively recycles 1.83 kg of CO2 from the environment, i.e., the CO2 is incorporated into the polymer molecule through plant-biomass photosynthesis. The functionalized PLA products are completely biodegradable in industrial composting systems and offer an environmentally responsible end-of-life option; microorganisms present in the composting environment readily utilize PLA and completely remove it safely and efficaciously. Building upon the initial commercial success of its injection-molded, bio-based and biodegradable-compostable cutlery, NTIC has now successfully introduced its sustainable packaging films into the marketplace. The company currently supplies biodegradable-compostable bags to global companies such as Levi Strauss & Co. About 76,000 m.t./yr of plastic packaging resins are used for packaging 5 billion garments in South Asia alone, translating to about $200 million in economic value.

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Northern Technologies International Corporation
Circle Pines
United States
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