AGRICULTURAL FILM | MATERIALS


He described the company’s resins, which are all based on PBAT – a biodegradable though fossil- based material. Three of them (BG-7805, BG-7807 and BG-7887) are all PBAT/PLA blends. “They have different degradation mechanisms and mechanical strengths,” he said. In addition, the film gauge and its colour will also determine its degradation speed. Films have been tested at various US locations including those with strong sun, high rainfall and extreme heat. Different crops also thrive with different gauges


of mulch film – with watermelon preferring 0.9mil film which strawberries perform best with 1.6mil film. The films also have a wide spread of proper- ties, such as impact strength and puncture resist- ance. In the field, BG-7800 (PBAT/TPS) was efficient for short-term crops while BG-7880 (also PBAT/ TPS) was better for longer harvests. BG-7805 (PBAT/PLA) was still being assessed. “We found that BDM performance varies


strongly by resin, gauge, colour and environment,” he said. Some, like BG-7880, offer longer durability while others degrade too early in harsh conditions. Colour also matters: green and white-black degrade faster, making them good for short crops but risky for long cycles. The next research step is to match film choice to


crop cycle and climate and improve formulations for more reliable field degradation. “We need to continue multi-season trials to build real-world confidence,” he said.


Soil degradation Researchers at Carbon Nurture and Rutgers University say they have developed a mulch film based on ‘oxidisable polyethylene’. Yelena Kann, chief technology officer at Carbon


Nurture, told delegates that existing biodegrad- able mulch films have inferior physical characteris- tics, uncontrolled degradation rates and concerns


about microplastics. She said that the new film degrades via oxida-


tion rather than hydrolysis. “Oxidation-based degradation demonstrates superior environmental performance and practical utility compared to hydrolysis,” she said. For instance, she said oxidation can be catalysed – making it faster and more consistent – as well as allowing more complete degradation. Oxidisable film also has superior physical properties, longer shelf life and low probability of forming microplas- tics, she added.


While conventional PE requires high energy to


break its bonds, the new material has hydroperox- ide groups, which can be cleaved by visible light. This can also be achieved by a temperature of around 120°C. “A catalyst can lower the temperature of PO-OH homolysis to room temperature,” she said. These new mulch films tend to have higher physical and optical properties, she said, citing opacity, tensile strength, dart impact and biodegra- dation rate. The company incorporates a proprietary catalyst


into PE resin then forms compounds that are converted into mulch film.


� Engineered to perform. Think big – think efficiently


SML’s new turret winder is designed for the winding of CPP, CPE, mono-oriented and barrier films in premium quality.


We ensure high-volume production with a winding speed of up to 450 m/min and up to 3,900 end film widths.


Winder W1300 KEY FEATURES


• Max. roll diameter: 1,500 mm


• Different cross-cutting units available


• Precise film tension control


Above: Biodeg- radability is becoming a key attribute for mulch film


IMAGE: SHUTTERSTOCK


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