Green polymer chemistry

The term ‘green polymer chemistry’ is being used here to describe the production of established thermoplastics and elastomers from renewable sources, including polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyamide (PA), epoxy resin and polyurethane.

The by-word in all types of industry these days is ‘sustainability’ as we all work to find ways to conserve the earth’s resources for future generations and reduce the harmful effects of climate change. In the plastics and rubber markets this will mean moving away from fossil fuels as sources of basic chemicals and moving to renewable sources like plants, waste products and waste gases. There are innovations worldwide in the chemical industry with a strong driving force to find sustainable fuel sources, and the technology that is being developed for fuel is now being transferred to the upstream polymer industry. However, as with petroleum, there will always be competition for resources.

As well as using plants as sources of chemicals, scientists are also using them for new engineering technology. Biological catalysts (enzymes) are being used alongside conventional catalysts to break down substrates like lignocellulose and to synthesise specific molecules. Alongside this, bioreactors containing single-cell organisms like yeast or bacteria are being tailored for chemical production using techniques like genetic engineering to enhance production of specific e enzymes. The EU is also looking at production in the oceans as land is in short supply and this may include algae farms.

This is no longer just an ideal but reality as chemical pathways to produce conventional plastics are now available and coming into commercial production. All the major polymer producers are looking at the viability of renewable sources and R&D is rapidly developing in this area. This is nothing new in some regions, as companies like Braskem, Quattor (now part of Braskem) and Chemplast Sanmar (India) have been using plant sources to generate ethanol and ethylene for some time when the cost has been competitive with petroleum. Brazil has the advantage of extensive land resources for sugar cane production and the economy is well advanced in ethanol production for automotive fuel, which can be diverted to supply ethylene for polyethylene and sources of monomers for PP and PVC production. As another example, in July 2011 Dow Chemical and Mitsui announced a joint venture in Brazil to generate polyethylene from sugar cane and Solvay Indupa is looking at biosourcing for PVC production in South America. Synthetic butadiene for tyre rubber was made from sugar-based ethanol in Brazil for several decades to avoid dependence on latex rubber. Lanxess is planning to produce elastomers from biosources, while Merquinsa Mercados Quimicos has already tested its bio-TPU in footwear applications.

There is an exceptional level of research taking place around the world on green chemistry, for example at the VTT Technical Research Centre (Finland), Materia Nova (Belgium), York University and the National Non-Food Crops Centre (NNFC, United Kingdom).

In Europe, Chemtex Italia (part of Mossi & Ghisolfi) and Sud Chemie are both looking at chemical production from a sugar platform including cellulosic sugars, while Global Bioenergies has worked out routes for production of olefins including propylene and butadiene. Companies like Genzyme are developing the biocatalysts needed for green synthesis.

China is making inroads in sustainably sourced plastics and already has several producers. The Rizhao Polytechnic College is looking specifically at the use of algal synthesis methods.

In terms of engineering materials, polyamide has been synthesised at least in part from plant oils for several years by companies including DuPont with Zytel RS polyamide 610 and PA 1010; Arkema with Rilsan PA 11; DSM with EcoPaxx PA410; Evonik with Vestamid Terra DS PA 1010 and Vestamid Terra HS PA 610; BASF with Ultramid BALANCE PA 610; Suzhou HiPro Polymers with Hiprolon70 PA 610, Hiprolon 90 PA 612 and Hiprolon PA1010. In a joint venture, Solvay Advanced Polymers and Mitsubishi Gas Chemicals are working on polyamide monomer production from castor oil. The Liebniz Institute for Catalysis has been reviewing the synthesis of monomers from plant oils including projects with Evonik.

Over the past years Dow Chemical has been looking at a variety of routes to different plastics including glycerine as a renewable route to epichlorohydrin, which is used to make epoxy resin. A leading agricultural company, Archer Daniels Midland (ADM), has developed technology to produce several monomer precursors from crops, which can be used in producing polymers such as unsaturated polyester resin. BASF has extensive research programs in several divisions on production of renewable chemicals and plastics, as does DuPont de Nemours and this includes polyols, which can be used in polymers such as elastomers and polyurethanes.

Brand owners like Coca-Cola and Pepsi have been pushing for green versions of polyethylene terephthalate (PET) for drinks bottles and both have made extensive progress. There are two key components of this polymer: the glycol, which can be sourced from plants as is currently produced by Indian Glycol, and the terephthalate, which has proven harder to synthesise. Wageningen University and Advantium are both conducting research in ‘green’ PET production. All brand owners are now focused on sustainable sourcing from L’Oreal in cosmetics and personal care products to Unilever and Procter & Gamble in foodstuffs and detergents.

The Wageningen University in the Netherlands is a leading research site for agriculture and is also heading up projects to make a range of polymers from biofeedstock including polystyrene, working with companies such as AkzoNobel.

Many brand owners are already testing biosourced materials in their products and packaging and are looking to do more. There are some issues surrounding the use of agricultural materials, for example the possibility of the chemical industry competing against food supplies, so the industry has to look at the big picture to make sure that the source is indeed sustainable. Unilever has been taking a lead in this area and LMC International is conducting market studies into the availability of agricultural materials. The ideal is to use something that is a waste product like methane on farms, CO₂, straw and wood shavings, or to use a crop that can be grown on land that is too poor in quality for foodstuffs. CO₂ is an ideal feedstock and several polymer companies have developed technology to convert it to plastics including BASF and Bayer Material Science.

The automotive, packaging and electronics markets are all looking for green sources of materials to improve carbon footprint and the use of green polymer chemistry could make a dramatic difference in this area. The Ford Motor Company has been particularly active in sourcing and testing innovative materials and is conducting research on renewables in automotive composites.

Applied Market Information (AMI) is organising an international forum to debate green polymer chemistry covering market drivers, agriculture crop availability, potential production methods and case studies of materials that have reached the marketplace. Green Polymer Chemistry 2012 takes place from 20-22 March 2012 at the Maritim Hotel, Cologne, Germany. www.amiconferences.com.