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The Bioplastics in Packaging event at this year’s Interpack occupied three times as much space as in 2005, underlining the increased interest in non oil-based polymers as packaging materials. However, concerns about source, sufficient supply and subsequent disposal (see below) have restricted commercial growth.

Last year, for example, Treofan stopped producing its Biophan polylactic acid (PLA) due to insufficient predicted sales growth to justify necessary investment in a new production line. Stanelco said shortage of supply of material was hindering product development and Innocent Drinks moved its bottles from PLA to recycled PET, citing the UK’s inadequate recycling infrastructure.

PLA, as produced by Natureworks, for example, and cellulose films from wood pulp, such as Innovia Films’ Natureflex, are the most widely known biopolymers and have made the biggest inroads into packaging. But there are others that are gaining ground, produced from a variety of materials and processes.

Last October, Meredian, a sister company to US PLA producer Danimer Scientific, acquired technology from Procter & Gamble to produce polyhydroxyalkanoate (PHA), using plant-based fatty acids as its source material. “The beauty of our product is we can use waste materials not destined for food,” says president S. Blake Lindsey.

Ethical sources
High food prices have raised questions about growing crops for industrial use, particularly for fuel. Although biopolymers use significantly less material than fuel, ‘ethical sourcing’ is still an issue and firms have been eager to prove their products’ origin. Earthcycle Packaging, for example, produces trays from a material derived from palm fibre – a waste product from the harvesting of palm oil. It has obtained certification that its packaging does not contain material from environmentally sensitive areas.

Brazilian petrochemicals firm Braschem uses sugar cane to manufacture PE, and bioplastics technology manager Antonio Morschbacker defends its use in plastics. “Brazil has a lot of degraded land, with low productivity, which is an opportunity for increased sugar production,” he says. “It’s also important to understand how sugar is grown; in rows, between which other products, such as beans and peanuts, can be planted.” 

Sufficient capacity is also important to make biopolymers a valid investment for converters. “Some companies have been waiting for a second or even third supplier to come online before committing to biopolymers,” says Harald Kaeb, chairman of industry association European Bioplastics. Kaeb adds firms in the sector are now investing in capacity.  Last month, for example, German chemicals manufacturer BASF announced it was expanding a plant to quadruple annual production of its Ecoflex polymer to 60,000 tonnes by 2010 to help meet growing demand.

Ecoflex is targeted at markets such as carrier bags and bin liners, which, alongside organic food ranges, have been the most common uses of biopolymers in packaging. But there are question marks over the range of suitable applications. “The mechanical properties of most of these plastics, at the moment, make them unsuitable for all types of packaging, so they are not going to replace oil-based plastics overnight,” says Laurence Hogg, materials and devices network manager at Faraday Packaging Partnership. Hogg suggests films for meat and fish trays, or a replacement for PET in drinks bottles, are “still some way off”.

Kaeb says the “current portfolio of products gives a glimpse of future development”. He says the properties of the materials mean that they are suited to some simple applications, “particularly for short-life products”. One of the features of some polymers is they allow more moisture to pass through than polyolefin plastics, which can be useful in vegetable packaging, for example.

Growing applications
US firm Telles believes its Mirel polymer made from corn sugar “fits into around 25% of today’s applications for traditional polymers”. “We’re also working to make the material usable with minimal changes to conversion equipment,” adds business development director Daniel Gilliland.

Although biopolymers share many characteristics with polyolefins, it is important for converters to assess how they will process them, warns Simon Balderson, managing director of Sirane, a packaging manufacturer that works with degradable and compostable materials. He says that factors such as lower melting temperatures and higher static mean that converters may need to adapt existing equipment. “If people think they are going to be using the same parameters as for PE, they need to do some work. But there’s no reason why, in the longer term, they shouldn’t be even easier to process than conventional polymers.”

Demand for biopolymers in packaging seems set to grow, although there are still several questions to answer, not least over what actually constitutes a ‘bio’, or renewable polymer. Novamont, the Italian firm that produces starch-derived Mater-Bi, advocates evaluation based on “a reasonable approach and consideration of the product and waste management”.

New business development manager Stefano Facco says: “The benefit to the environment is not just from renewability, or compostability, but how the products are used and disposed of. It’s not a race to replace petroleum-based materials.”

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Heap of compost concerns

The Composting Association is looking to adapt European Bioplastics’ seedling logo for use on ‘home compostable’ packs by the autumn. The seedling symbol certifies a product to the EN13432 compostability standard. But the average compost heap does not create the industrial conditions of the standard, meaning the plastics will not degrade. “It’s important to get labelling right, because people will think they’ve bought something that’s compostable, which isn’t,” says European Bioplastics chairman Harald Kaeb.

There have been attempts to create home composting standards, such as those by Belgian engineering firm Vinçotte, but it is more difficult to assess than industrial processes. There are also concerns that biopolymers in the waste stream are affecting the quality of recyclate, while Asda refuses to use compostable packaging materials because local authorities will not collect them for industrial composting and few people compost at home. “Things are moving in the right direction. But nobody wants to buy material if it’s contaminated,” adds Alan Campbell, packaging and manufacturing manager at Campden and Chorleywood Food Research Association.