A three-year, 1.6 million euro project has sought to make firms more familiar with processing bio-based polylactic acid (PLA) polymers in packaging applications.

The EU Eranet Cornet II Project – which has brought together 11 institutes and SMEs from six European countries – concludes that PLA is now better understood by the participants in terms of characterising its processability and temperature stability, and managing these elements to bring products to market.

Different organisations have led on these various aspects. The German DKI Institute in Darmstadt was in charge of testing raw materials. The DKI developed a procedure to determine the molar masses of PLA. This enabled them to characterise the material when subjected to extrusion or moulding processes.

Project Coordinator Alexander Komenda, of Ecoplus, the business agency of Lower Austria, says, ‘The brittleness problems have been solved with compounds. We have a lot of possibilities to make the material softer by blending of the material with additives’, including chain additives and core shell aggregates. Similarly, the project concludes that crystallinity can be improved by adding polyethylene glycol and talc powder, and barrier properties can be improved with polyamino-saccharides.

Overcoming barriers

Belgian research company Celabor, based in Herve, dealt with the compostability of the developed materials, lifecycle assessment and characterisation of the materials processed by the other partners. Project Engineer Olivier Houbiers says, ‘We found PLA provides lower greenhouse gas emissions compared to PET', though PLA has other shortcomings.

He said that, ‘Brittleness is a problem during the cutting of PLA bags or trays after thermoforming. Low temperature resistance is [also] a problem during transport and storage and [has] poor gas barrier properties.’ However, he mentions that they have improved gas barrier properties by 62% using additives.

Komenda adds that the manufacturing process for bio-based materials is not necessarily more environmentally friendly. ‘The disadvantage is during production. Of course, you can use corn or starch, but the machine you are using during production is not using biofuel…. so, the benefit of using bio-based materials is a little smaller’.

Nonetheless, the barrier properties of the biopolymers were found to be advantageous in fresh food packaging, according to Houbiers. He mentions that it, ‘can be a good opportunity for fruit and vegetables that continue to breathe in the packaging’.

Improving the process

Austrian manufacturer Schorm, based in St. Valentin, successfully managed the injection moulded PLA jugs. Bernard Schorm says that when they applied injection moulding to PLA jugs, they found that the ‘cost of raw materials is 45% higher, and the production time will also be a lot higher.’ He adds that the product is 60% less durable, though its lifecycle is 60% less than that of petrochemical polymers. He surmises that, ‘PLA has advantages,’ if customers are willing to pay the price.

Machinery is also an issue, as it is not built to manufacture bio-based packaging materials. However, Komenda notes that workforce education is a more important issue.

‘You have to train your workers not to use it as a standard polymer because the temperatures are very low compared to normal processing… If you process [normally] at 200-250ºC, you now have to process at 100-150ºC. A processor would fear that the machine is damaged when you use these low temperatures’.

Packing for the future

He notes that biopolymers have only been used for about 10 years, which makes it difficult to match the mechanical properties of standard polymers. Other problems include the shorter expiration dates for bio-based materials and storing products with higher degradability.

He is, however, optimistic about the future of degradable bio-based products, though he says success is contingent on improving collection methods. ‘When you recycle a standard polymer, the lifecycle analysis is better than a one-time use biopolymer that will not be recycled. This is a major factor. We need to develop a [better] collection system’.

The Cornet Project looks set to continue for a further three years due to continued interest. Komenda notes that there have been significant increases in biopolymer use globally, with China using twice as much PLA-based products in packaging applications as the USA and increasing production in Italy.

While he is encouraged about progress, he is also realistic, ‘The biopolymer will never push away standard polymers. Today, they have 0.02% [of the market]. How far can we go? In the next five years – five per cent. It is not a one-day flower’.