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Sustainable Packaging Research Receives a Push From Europe

In an industry that is facing challenges to combine added functionality with environmental sustainability, the €30 million ($44 million), four-year SustainPack project aimed to plug a gap in the packaging market. The initiative was a vast study into the materials science and subsequent use of renewable natural fibers, combined with bio-based polymers, in the packaging of the future.

The consortium, part funded by the EU Sixth Framework Programme, comprised 35 European partners from packaging research organizations, academia and industry from 13 countries.

"Fiber-based packaging needs to perform better with new fibers, improved barrier properties and increased interaction with the user. All without adding any non-renewable resources. The purpose is to ensure that fiber-based packaging is a dominant player," said Staffan Erenmalm, a member of the Supervisory Board at STFI-Packforsk, an R&D company covering paper, pulp and packaging, headquartered in Stockholm, Sweden.

But while his introduction to the conference, which concluded SustainPack, held from May 6-7 in Prague, Czech Republic, set the agenda for the event, it was inevitable that the notion of what is sustainable would still be up for debate.

Taking Stock

"It is difficult to identify priorities as sustainability is all encompassing," said Paul Earl-Torniainen of General Mills Inc., an international marketer and manufacturer of food products based in Golden Valley, Minn.

Materials such as steel, aluminum and PET are made from non-renewable resources but have established recycling streams. Meanwhile, bio-based polymers reduce the use of finite resources such as petroleum, and in turn carbon emissions, but some varieties open up concerns about diverting crops away from food and release methane as they biodegrade. A material advantage at one end of the lifecycle can therefore be offset by a disadvantage elsewhere.

Arno Melchior, global packaging director at Reckitt Benckiser, UK, which specializes in home cleaning, health and personal care products, provided an industry perspective from a non-SustainPack partner. "We have launched a project called Carbon 20, which is to achieve a 20 percent reduction in our carbon footprint," he explained.

"The objective is to use packaging materials for which a recycling stream exists in those countries where we sell our products -- so we do not use biodegradable products at the moment. If there's enough biodegradable material, we need a (national) recycling/composting stream. Consumers need guidance from legislation."

This view was echoed by Cecilia Giardi of R&D Strategic Projects at Novamont, in Novara, Italy, which manufactures Mater Bi, a biodegradable and compostable polymer based on vegetable starches. She said, "How do you build a sustainable base for bio-based plastics? It can only be achieved with a separate waste collection."

She added, "If a normal plastic tray is contaminated with food, it goes to landfill. If you use a bioplastic, then it is homogeneous with the organic food waste as both fractions can be composted."

Making Moves

Earlier this year, Reckitt Benckiser re-launched its Air Wick Freshmatic air freshener in Europe in a cardboard box, moving away from the traditional plastic blister pack. The team behind it optimized the amount of material used by moving the flaps of the box from the top and bottom ends to the sides and developed a hooked design that eliminates the need for a hot melt adhesive to glue the walls together. In turn, the company reduced the size of the box from 400 grams per square meter to 300 grams per square meter, which has saved 3,000 tons of cardboard per year, and diverted 300,000 kilograms of hot melt glue per year away from landfill.

However, Melchior added, "Paper has the largest CO2 footprint in the distribution chain. In France, we distribute with our competitors so the lorry is not half empty."

It is therefore a complex life cycle assessment, he argues. "If we do an assessment in Germany and Brazil for the same packaging, I would get different results. Even on the same manufacturing site, I could get different results depending on where the (raw material) supplier is. We need to develop a standard value."

Laying the Foundations

With this in mind, as researchers presented their materials science advances and packaging demonstrators resulting from SustainPack, many delegates questioned the ability for such materials to be industrially processed and the disposal methods required.

Much R&D and complex analysis remains to be done but significant progress has been made. Kennert Johannson, coordinator of SustainPack from STFI-Packforsk, is optimistic about the future of the research.

He says, "If we develop a material that has good and competitive properties, I think there will also be methods developed to take care of them. We have had recyclability tests for the materials and so far found it is possible to recycle them. Coming from a Nordic country, we see incineration with energy recovery as equally important."

He adds, "We have already seen E.U. research projects follow up on SustainPack. Some findings are close to commercialization."

Technical Research Projects

SustainPack comprised six technical research projects that encouraged collaboration across organizations and borders. Numerous packaging demonstrators were developed. The projects were:
  • Research coordination -- to determine the market needs and identify research requirements to direct other technical research projects.
  • Lean and effective fiber-based packaging -- creating a nano-facility to produce nanoscale cellulose and mineral structures, and exploring surface modification, multilayering and grafting of fibers.
  • Fiber-based composite films -- incorporating nanofibers and bio-based polymers to compete with the properties of synthetic polymer films.
  • Protective coatings -- to develop coating and printing technologies to enhance barriers and other functional properties.
  • Three-dimensional composite packaging -- comprising fiber-reinforced bio-based polymers.
  • Communicative packaging -- to add value to packs with devices such as time-temperature and humidity indicators for food products, reducing food waste.
Biocomposites Packaging

Researchers at the French Engineering School of Paper and Printing (EPFG) and the University of Aveiro, Portugal, collaborated on research, as part of SustainPack, to incorporate cellulose fibers into bio-based polymers such as PLA, Mater Bi starch and cellulose acetate butyrate, or biodegradable polymers such as polyester-like polycaprolactone or Mater Bi polyesters. The aim was to improve the mechanical properties of such bioplastics to compete with petroleum-based alternatives for films and 3D packs.

Dr. Julien Bras of EPFG says, "Cellulose fibers have several advantages: (they are) renewable, low density and already exist in industry. But they have one drawback, hydrophilicity, which creates problems of mechanical compatibility with hydrophobic polymers." Bras explains that previous fiber modification techniques, such as co-polymerization of fibers to the matrix using fatty isocyanates and anhydrides, do not create a strong enough link between the materials. Two new techniques have been developed to ensure effective grafting of the fibers, covalent bonds and compatibility -- a copolymerization technique that uses a difunctional molecule and a proprietary "click chemistry" technique. Grafting gives an enhanced Young's modulus.

Bras adds, "We will also work on 3D packaging obtained by injection moulding (and) new ways of grafting to increase compatibility but also give active properties, such as anti-microbial and photoluminescence." On the theme of active packaging, the team has already explored the potential for an anti-ripening pack using inorganic nanoparticles, such as non-toxic titanium dioxide, to improve the properties of cellulose fibers. By preparing a 3D composite with a biodegradable polymer, researchers found the nanoparticles did not impact on the mechanical properties, but rather further delayed water penetration of the material. Titanium dioxide also destroys ethylene, which is produced by fruit and vegetables and accelerates ripening and decomposition.

Spot Coating

"Some of the bio-based barrier coating materials which are currently under development exhibit poorer heat sealability than conventional polymers," says Isabel Mira of the Institute for Surface Chemistry in Stockholm, Sweden. She worked on a SustainPack project to develop a novel spot coating technique that involves "localized application of protective or priming functions to target areas." For example, materials commonly used as paper coatings -- latex, a polymer dispersion and a water soluble polymer, such as polyvinyl acetate -- have been formulated into a heat-sealing ink that can be printed using flexography or ink-jet to reinforce paper-based packs along creases and folds, and reduce cracking of the barrier coating. This minimizes the "use of non-bio-derived (barrier) lattices in packaging," adds Mira.

Microfibrillated Fibers

A number of scientists involved in SustainPack explored the use of microfibrillated cellulose fibers (MFC), such as from spruce pulp or carboxymethylated dissolved pulp with 6 percent hemicellulose. These fibers are derivatives of the fiber walls. One project looked at replacing expanded polystyrene as a cushioning material in packaging with a MFC-reinforced vegetable starch polymer.

Professor Lars Berglund of the Royal Institute of Technology, in Stockholm, Sweden, explained how amylose-rich starch alone could not be used for foam production due to poor rheology during expansion. He said, "You need to monitor the stress-strain curve. Starch has a high density and low energy absorption. It absorbs a lot of water at ambient conditions.

"You can solve this by looking at a plant structure -- primary cell walls are strong and tough despite high moisture and cellulose content. What's important is the network. It's a sophisticated structure. Cellulose stiffness is equivalent to Kevlar," he added. By reinforcing the starch foam with MFCs from wood, and freeze drying it, the team claim to have created a porous structure with strong mechanical performance. Industrial-scale compression and injection molding manufacturing techniques have also been investigated.

Opto-active Paper

On display at the SustainPack conference was an opto-active paper, made from a combination of renewable materials such as microfibrillated cellulose, gelatine and carragennan, that changes color when exposed to moisture. The color change reverses in about five seconds and the different hues depend on the thickness of the interference films (about 100-200 nanometers), which are created by spraying water-soluble polymers or particle dispersions on the paper.

Papers that respond to other external stimuli could also be manufactured. Hjalmar Granberg of STFI-Packforsk in Sweden says, "Stimuli-responsive films are new and can be used for interactive displays, product safety, sensors and anti-counterfeiting."

SustainPack published its final report in September 2008. A version of this feature was originally published by Materials World.

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