MATERIALS | BIOPLASTICS
PHAs can also be crystalline, semi-crystalline or amorphous – which leads to a variation in proper- ties. Crystalline PHA, for instance, has a flexural strength of around 1400MPa, while that of amor- phous PHA is around 4MPa. The material is also far more biodegradable than materials such as PLA – with both amorphous and semi-crystalline versions biodegrading under both industrial and home composting conditions – as well as in soil and the sea. “PHA is enzymatically digested, while synthetic
biodegradable polymers are hydrolysed,” he said. In addition, CJ Bio and PLA manufacturer
Above: The BeonNat project has demonstrated the potential of wood as a source of bioplastics
developers have come up with new biodegradable film formulations that can also help to improve soil properties.
Chelo Escrig Rondán, agriculture and aquatic
environment group leader at Spanish research organisation Aimplas, explained how active substances – such as fertiliser – can be incorporated into biodegradable plastic film, for applications such as mulching. The active substance can be adsorbed by
porous materials such as hydrophilic silica, which is then incorporated into a plastic matrix such as an extruded film. One example is to add an anti-fungal additive to mulch film, at a loading of around 0.3%. Aimplas tested it against typical fungi, in compari- son with standard biopolymer film. At 24°C, a standard film saw 50% infection with both Botrytis cinerea and Aspergillus niger after seven days. In each case, the anti-fungal film reduced this to zero. At 8°C, Botrytis cinerea managed to infect the standard film completely – but this was reduced to 67% on the anti-fungal film.
“Mulching with anti-fungal film can be used for
watermelon crops, as a measure to combat fungal growth during all stages of cultivation,” he said. Compost containing 10% of the biofilm also
broke down completely over three months, with no toxic effects, he added.
Faster composting At the same event, Hugo Vuurens, VP of business development at CJ Biomaterials, told delegates that the company’s polyhydroxyalkanoate (PHA) material – when combined with PLA – could help to speed up the composting of agricultural film. PHA is made industrially using bacterial fermen-
tation, in various carbon-chain lengths. “Many bacteria produce and use PHA as an
energy storage material,” said Vuurens. “Theoreti- cally, more than 150 types of PHA can be created.”
20 FILM & SHEET EXTRUSION | July/August 2023
NatureWorks recently created a partnership to develop materials based on their PHA and PLA portfolios. One area is to combine the two in products such as agricultural film in order to improve properties and speed up composting. Adding 5-10% amor- phous PHA to PLA can help to make the film more ductile, said Vuurens. In addition, it could speed up industrial com- posting – though he stressed that tests were still ongoing, and not yet conclusive. Because of this, he said it could find wide use in agricultural film, as it will biodegrade quickly in soil – meaning that it can be left on the land at the end of the season. In a small screening study, it did not affect cabbage yield compared to commercial PE and PBAT mulch films. Microscopic analysis showed that decomposition occurred on the surface after three months.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.avantium.com �
www.vttresearch.com �
www.bc.edu �
www.aimplas.es �
https://beonnat.eu �
https://www.preserve-h2020.eu �
www.iap.fraunhofer.de �
www.totalenergies-corbion.com �
https://citroniq.com �
www.mitsuiplastics.com �
www.braskem.com �
www.basf.com �
www.versalis.eni.com �
www.novamont.com �
www.kikcompounds.ro �
www.upm.com �
www.selenis.com �
www.amiplastics.com �
www.cjbio.net �
www.natureworksllc.com
www.filmandsheet.com
IMAGE: AIMPLAS
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