MATERIALS | AGRICULTURAL FILM


Exceed S 9272 grade is the stiffest product to hit the dart A testing limit, for instance. In addition, the grades are easy to process – with Exceed S 9333 delivering very low melt pressure. The materials have been used to create a silo bag with higher dart, puncture and folding perfor- mance. It can be achieved with up to 10% down- gauging potential. “Exceed S9272 significantly improves dart


impact, Elmendorf tear, and needle puncture while delivering less extensible films with improved procesability,” they said. Overall, they concluded that Exceed S-based


Above: ExxonMobil’s PE grades have been used to create tough, hard-to-punc- ture silo bags


tant, they said – as it can cause problems that appear to be film-related.


Silage cover


Another joint paper – from Viaflex and Kuraray – explained the benefits of thinner, lighter and stronger films for silage applications. Derek Coover – director of engineering at Viaflex – and Edgard Chow, director of technical service and development at Kuraray, said that effective silage covers (such as Feedfresh films from Viaflex) reduce spoilage thanks to high puncture and tear strength, a high oxygen barrier and longevity. This is typically achieved using multi-layer film – in which the strength is provided by PE layer and the oxygen barrier by EVOH. Testing showed the effectiveness of adding the EVOH layer – as this type of film allowed higher carbon dioxide reten- tion, better product quality, higher germination power and increased commercial value. For instance, infrared thermal imaging showed spoilage and heating (under a plain PE film) due to oxygen penetration.


Thin film performance Morgan Heeke, polyethylene market developer, and Mauricio Leano, principal customer and application developer at ExxonMobil, told delegates that their company’s PE grades can be used to create tough, hard-to-puncture silo bags – while using less material. “Performance polymers give an opportunity to downgauge while enhancing performance,” they said. The global market for silo bags is expected to


grow with a CAGR of more than 6%, reaching almost 520,000 tonnes in 2032, they added. One example is Exceed S polyethylene, which helps to raise stiffness and toughness in films. The


14 FILM & SHEET EXTRUSION | April 2024


formulations could create films with 20% better creep resistance, up to 10% downgauging poten- tial, 20% better needle puncture and twice the dart impact.


Mulching away John Licata, vice president of polymers R&D at CJ Biomaterials, told delegates how amorphous PHA – a bio-based plastic – can be used as an enabler in biodegradable mulch film. The company offers a number of PHA grades,


from crystalline to amorphous. Amorphous grades offer more ‘rubbery’ properties, he said. CJ Bio produces its PHA using fermentation. PHA has potential to be incorporated into film for a number of agricultural applications including mulch film, greenhouse film and both silage and bale wrap. These could then be ploughed into the soil after harvesting. “Amorphous PHA can modify the performance


of other biodegradable polymers and accelerate or provide targeted biodegradation,” he said. The company carried out a number of biodegra-


dation tests on material blends. These revealed that, in ‘normal’ soil, a 30%PHA/70%PBAT blend largely maintained performance over the four- month test period. (Molecular weight, for instance, remained largely intact.) However, under compost- ing conditions, the material’s molecular weight fell to a relatively low level, indicating decomposition. In addition, a small screening study showed that


PHA film did not affect cabbage yields compared to commercial PE and PBAT mulch films.


Citrate answer At Jungbunzlauer, Anton Zhloba – team leader at Applitech Chicago – explained how citrate esters can be used as plasticisers for mulch film. Its Citrofol materials are produced from raw


materials – via fermentation and chemical modifica- tion. They are used for a wide range of applica- tions, including within the food and pharma


www.filmandsheet.com


IMAGE: SHUTTERSTOCK


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