AGRICULTURAL FILM | MATERIALS
In addition, storing the film at higher
temperatures (up to around 40°C) ensured the best development of cling properties. “Good cling properties largely contribute to the integrity and the stability of the load,” he said. “The selection of raw materials, LLDPE, storage and extrusion conditions together determine the development of cling properties.”
Stable performance To extend the life of plastics used in agriculture, stabilisation – especially against the effects of UV radiation – is critical. Hanna Schwartz, R&D manager at Kafrit, told delegates about the company’s additives that can help greenhouse film resist the effect of UV. These needed to work in concert with sulphur treatment – which is seen as an effective ‘environmentally friendly’ fungicide, which is allowed in organic farming. It has carried out field trials of its UVA 00701 LD and 07160 LD grades. In one case, it evaluated the effect of the additives on the stability of greenhouse films that are subjected to sulphur treatment. Three- and five-layer films, 180 microns thick, were produced and exposed to up to 3,000 ppm sulphur. The new grades were compared to three existing grades. These had a time to failure of 24, 26 and 33 months. The two new grades saw failure times of 33 and 36 months. In a three-year trial with rose and pepper
I M growers, film made with 00716 LD retained 68% of
its tensile strength after 36 months. In addition, it found that the 00701 LD grade was still actively blocking 70% UV after three years. “Longer-lasting UV absorbers slow down the
degradation rate of the greenhouse films,” she said. “Combining these with chemically resistant HALS significantly prolongs greenhouse film service life in a harsh chemical environment.” In a second study, Kafrit looked at whether UV absorption and blocking had any effect on pollination activity by bees. Here, it studied 16 greenhouses – half of which used the sulphur-resistant UV film. The crop grown inside was melons. Researchers spent part of their time counting bees inside the greenhouses. They also found a correlation between UV
A transmittance (at 365-375nm) and
pollination. Greenhouse film based on 00701 LD led to the highest yield of melons. n The next edition of Agricultural Film runs in Houston in the USA, on 15-16 August 2023. For more details, contact Angelina Ruocco on +1 610 478 0800 (
angelina.ruocco@
amiplastics.com).
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.ami.international �
www.aimplas.es �
www.cjbio.net �
www.plastiblends.com �
www.wur.nl �
www.ineos.com �
www.kafrit.com
Left: Kafrit found that its UV stabilisers did not affect pollination by bees
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