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Plastic based on renewable natural resources – packaging material of the future?

Polymeric materials from renewable resources have attracted a lot of attention in recent years. The development and utilization of vegetable oils for polymeric materials are currently in the spotlight of the polymer and chemical industry, as they are the largest renewable platform due to their renewable nature, world wide availability, relatively low price, and their rich application possibilities. These excellent natural characteristics are explored in research and development, with vegetable oil derived polymers/polymeric materials/composites for use in numerous applications including paints and coatings, adhesives, and nanocomposites.

However, the plastics industry is still highly reliant on feedstock based on oil and gas. Focus on circular economy is a potential way to reduce the demands on finite raw materials and minimizing negative environmental effects while still have possibility to increase prosperity. This requires:

  • A vision that plastics never becomes waste but re-enters the economy as valuable recycled materials or chemicals
  • A “green shift” to renewable feedstock

International brand name manufacturers as Unilever, Procter & Gamble (P&G), Danone, Coca Cola Company and NIKE Inc. are all aiming plastic packaging solutions being 100% recyclable and based on renewable natural resources.

P&G is working toward the long-term vision of[1]:

  • Using 100% renewable or recycled materials for all products and packaging
  • Having zero consumer and manufacturing waste going to landfills
  • Create technologies by 2020 to substitute top petroleum-derived raw materials with renewable materials, as cost and scale permit.

 Unilever commits to 100% recyclable plastic packaging by 2025.[2]

Global goals of Coca-Cola company are to help collect and recycle a bottle or can for everyone sold by 2030 and to make the packaging 100 percent recyclable globally by 2025.[3]

To reach some of these goals P&G, Coca-Cola, Ford Motor Company, H.J. Heinz Company, and NIKE. formed the Plant PET Technology Collaborative (PTC), a strategic working group focused on accelerating the development and use of 100% plant-based PET materials and fibre in their products.

In addition, a collaboration between IKEA and Nestle is established to utilize renewable residue and waste raw materials, such as used cooking oil, as well as sustainably-produced vegetable oils in the production of plastic products[4]. Thanks to this collaboration, IKEA and Nestle are now able to turn waste and residue raw materials, such as used cooking oil, as well as sustainable vegetable oils into polypropylene (PP) and polyethylene (PE) plastics. IKEA wants to use more renewable and recycled materials and explore new materials for IKEA products. As part of this journey, IKEA is working to change all of the plastics used in IKEA products to plastics based on recycled and/or renewable materials by 2030.

There are multiple pathways to obtain bio-based propylene, which is the starting monomer for PP, as shown in Figure 1[5]. Once the propylene monomer is obtained, the existing polymerization technologies yield high molecular weight polypropylene with identical properties compared to fossil fuel-based PP.  As many have stressed before, green PE and PP are bio-based, and like the fossil fuel counterparts, they are not biodegradable (or compostable).  The challenge for bio-PP producers is to develop cost efficient process technology that can compete in the market with fossil fuel-based polypropylene.

 

 Figure 1 – Different production routs to green propylene5

Plant oils and the fatty acids derived from them have been used for a long time by polymer chemists. Although many different synthetic approaches have been used, more recent examples are pointing in the direction of catalytic transformations and other efficient reactions to achieve a more sustainable production of polymers from these renewable resources[6]. Regarding the recent past, research results developed by different groups reveal a growing interest in the reactivity of their double bonds towards olefin metathesis, which enables the straightforward synthesis of a wide variety of monomers. Moreover, the great potential of fatty acids as building blocks for olefin metathesis polymerization (ADMET) is now a reality. On the other hand, the production of monomers and polymers by thiolene coupling reactions with fatty acid derivatives is a growing area. Furthermore, the versatility of plant oils as precursors of thermosetting materials has been demonstrated with the development of synthetic strategies leading to new polymeric materials. This development will continue, and new possibilities for the chemical utilization of this renewable feedstock will certainly develop in the future. Naturally occurring plant oils and fatty acids derived from them are considered to be the most important renewable feedstock processed in the chemical industry and in the preparation of bio-based functional polymers and polymeric materials[7].

Figure 2 shows the life cycle of polymers based on vegetable oils, according to which the biomass from plant-derived resources is extracted in order to yield the vegetable oil. Subsequently, the oil is submitted to chemical modification with the aim of enhancing its reactivity towards a given type of polymerization approach. The polymers are then made available to the consumers, and once used, they become waste, which after degradation and assimilation is reused as biomass and the cycle starts again.

 

Figure 2 – Life cycle of polymeric material based on vegetable oils7

As a global leader of industrial polymer R&D services, Norner operates an advanced technology centre for development and laboratory testing. Norner has a strong strategic focus on sustainability and circular economy in the plastics value chain through projects in the field of recycling and bio-based materials. By long term cooperation with international clients we have also acquired significant competence in this field.

The pressure on the polymer industry to develop new plastic materials based on renewable natural resources has also led to a quest for renewable polymer additive solutions that offer excellent technical performance. Typical examples are vegetable‐oil‐based additives made of oleo chemicals. Applications for such fatty ester based additives are; Lubricants, Antistatic agents, Antifogging agents, Plasticisers and Stabilisers. Oleochemistry is a tailor-made chemistry and by changing parameters as alcohol type, fatty acid, chain length, saturation, degree of esterification a wide variety of properties of the end products can be achieved. Palsgaard is a cooperation partner of Norner and an important contributor in this field. Their sustainable product philosophy and knowledge in the food industry has been a good platform to enter the additives to food packaging with 100% vegetable based products[8]

EU has defined new and ambitious targets for circular economy and recycling of materials. This includes packaging materials. The FuturePack project, with Norner as one of the research partners, develops know-how on technologies and requirements to reach these targets for plastics[9]. The major elements of the FuturePack project represent new knowledge and innovations for the partners and in the industry internationally.

The project will evaluate the fit of Norwegian biomass and plastics waste resources for polymer production followed by developing a technology for cost-efficient conversion of biomass and plastics waste by pyrolysis into building blocks for polymers. The chemical composition after pyrolysis needs further purification before olefins will be used in polymerisation of bio based PE and/or PP.

Another important aspect is the design and solutions for improved material recycling which is another important aspect of circular economy. The new technologies and value chains will be assessed by LCSA assessments.

 

[1] https://www.pg.co.uk/sustainability/at_a_glance/our_goals

[2] https://www.unilever.com/news/press-releases/2017/Unilever-commits-to-100-percent-recyclable-plastic.html

[3] ”2017 COCA-COLA SUSTAINABILITY REPORT” (https://www.coca-colacompany.com/2017-sustainability-report)    

[4] https://www.chemengonline.com/neste-and-ikea-to-launch-commercial-scale-production-of-bio-based-polypropylene/?printmode=1

[5] https://polymerinnovationblog.com/bio-based-polypropylene-multiple-synthetic-routes-under-investigation/

[6] L.M.de Espinosa, M.A.R. Meier, “Plant oils: The perfect renewable resource for polymer science?!”, European Polymer Journal 47 (2011) 837–852.

[7] N.B. Samarth, P.A. Mahanwar, “Modified Vegetable Oil Based Additives as a Future Polymeric Material—Review”, Open Journal of Organic Polymer Materials, 2015, 5, 1-22, Published Online January 2015 in SciRes. http://www.scirp.org/journal/ojopm  http://dx.doi.org/10.4236/ojopm.2015.51001

[8] L.H. Evensen, “Palsgaard - Heart working people - Venturing new markets”, Norner News no.8.

[9] S.B. Fredriksen, “FuturePack targets improved recycling” Norner News no.8

About the author

Jorunn Nilsen

Jorunn Nilsen has a background in physical chemistry with a master from the Norwegian University of Science and Technology. She has more than 30 years of experience in the international plastics industry with main focus on product and application development within polyolefin applications. Her functional experience includes project work and project management, and her current position is as Principal Researcher at Norner.