MATERIALS | AGRICULTURAL FILM
Above: Polyisobutene grades can help improve cling properties in silage film, says Ineos
Microscopic damage on the film included cracks on the surface and pesticide residue. The company also found a high level of iron in the film. Other tests found other contaminants, including
copper, silicone and sulphur. These came from sources such as aluminium pigments (used on silver mulch films), pesticides and pesticide dispersing agents. Possible solutions for mulch films included: using only pesticide-resistant UV stabilisers; adding a higher dosage of antioxidants; and using iron metal deactivators. “Film thickness – and the amount and type of pesticide used – are also important factors,” he said.
Finding microplastics Maarten van der Zee, senior scientist for bio-based products at Wageningen University in the Netherlands, explained how the pan-European Minagris project is assessing the accumulation – and effects – of micro- and nano-plastics (MNPs) in the soil.
“Plastics can improve production efficiency and be beneficial in reducing pesticides, fertilisers and water use in farming,” he said. “However, today’s plasticulture may also cause soil pollution. There is insufficient knowledge on long-term environmental sustainability.” Conventional plastic pollution in soil is difficult to solve – so policies and practices must consider long-term soil sustainability, he said. The project’s objectives include: monitoring plastics contamination in agriculture across Europe; assessing its impact on factors such as plant productivity; and recommending how plastics can be used more sustainably in future. It has 20 partners from across Europe, with 11 case study sites across six different ‘biogeographical’ regions (including Mediterranean, Alpine and Atlantic). By the end of the project, it expects to have developed standardised methods for analysing
16 FILM & SHEET EXTRUSION | April 2023
plastic debris in agricultural soil; determined the sources of plastic found in agricultural soil in the EU; developed a smartphone app for monitoring plastic debris; and gained insight into the impact of MNPs on crop productivity and plant physiology. “Not all plastics used in agriculture will contribute to soil contamination,” he added. He explained that, in addition to products such as mulch film, other plastics products – such as general plastic litter – can end up polluting agricultural soil. In addition, agricultural practices such as irrigation and soil enrichment (with additives such as manure) are also potential sources of MNPs in soil, he said. Some potential sources have already been identified. Mulch films, when not properly removed, can lead to 12-62 kg of plastic debris per hectate. Coatings of controlled-release fertilizers, seeds and pesticides account for another 40 kg/ha, while the use of urban compost can result in amounts as high as 28 kg/ha, he said. “Several reports address how much plastics is on
the market – and used in agriculture – but quantification of the resulting soil pollution and impact requires attention,” he said.
Clinging on Szilard Csihony, customer technology service and market development for polyisobutene at Ineos Oligomers, told delegates how its polyisobutene grades can help to improve cling properties in silage and stretch film. Its Indopol materials are typically used at a level
of around 10% on the inner layer of a silage film. They are stable to UV light and have barrier properties against air and water. The improvement in cling properties helps them maintain the integrity of a load (such as a hay bale) after wrapping – and during prolonged storage. “They contribute to holding force – thanks to good inter-layer cohesion – and limit air and moisture ingress between the film layers,” he said. They work by slowly migrating to the surface of an LLDPE matrix. On the day of production, the polyisobutene (PIB) will be fully homogeneous within the LLDPE; after one month, it will have migrated to the surface. A grade with higher molecular weight will give a higher peel force, while one with a molecular weight will give a faster, higher lap cling force. A lower density LLDPE matrix will also produce a higher cling force. This is because the lower density LLDPE has less crystallinity, allowing the PIB to migrate to the surface. For the higher-density LLDPE, there is more crystallisation – trapping the PIB.
www.filmandsheet.com
IMAGE: SHUTTERSTOCK
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50
