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  • Rights: Showdown Productions
    Published 20 July 2021 Referencing Hub media

    Crown research institute Scion worked with Villa Maria Wines to develop a bioplastic vineyard net clip using marc – or pomace – a biomass waste stream from the wine industry.

    Here, lead scientist Dr Stephanie Weal and Dr Gildas Lebrun explain the process to develop and trial the clip.


    Roger Bourne

    Crown research institute Scion has developed a biodegradable bioplastic net clip incorporating waste from the winemaking process. The clips are used to keep nets on the vines to protect the fruit as it ripens. Studies have estimated that around 16.8 million plastic clips are used each year in the New Zealand wine industry.

    Dr Stephanie Weal

    Scion’s done a lot of research looking at bioplastics and adding in different waste streams, so different biomasses, from the New Zealand economy. So things like wine pomace, kiwifruit waste, pāua – pāua powder’s another project we’ve done.

    There’s a few drivers. One is the production of waste. So what can we do with that waste, not just composting. Can we add value to it? One is to make things more sustainable – so products that everyone’s using – can we add the waste in? Another one is trying to create a circular economy so that the waste isn’t just put into landfill. It can be used for other applications.

    Within the wine industry in New Zealand, there’s 60,000 tonnes of wine pomace produced after they’ve made the wine. So we looked at what we could do with that wine pomace and also what they’re using in industry. And with a collaboration with them, we talked about what they use, and vine clips came out as a product.

    The vine clips are put on from February to March – it’s put on the nets to protect the grapes, as they’re maturing, from birds and other pests from eating them. So the vine clip holds the net in place, and then after 6–8 weeks, they pull the nets off and gather them up, and the net clips fall onto the ground. Because they’re so little, it’s not really viable to pick them up to recycle or anything else, so the vine clips stay on the ground where they fall.

    What we’ve developed with our formulation is that, when those net clips fall onto the ground, they will biodegrade. So over a period of time, you won’t see them any more as opposed to the conventional polystyrene clips, which will stay there for hundreds of years.

    A lot of the wine industry is very sustainable. They like sustainable principles, so a product that they can use that was sustainable or biobased they were quite keen to use. And we’ve done a trial last year at Villa Maria in the Hawke’s Bay. We tried four combinations last year, and we’ll try another four this year. So the results from that helped us to do the next trial. And we do all the research here, and we can do up to sort of like 10–20 kilo lots and then we’ll be handing on to industry, so getting industry partners involved at that point to make the clips.

    A biopolymer is a polymer that’s produced in nature, so it’s produced from things that are living. So with PLA, it’s produced from corn starch, the fermentation of corn starch. Corn is renewable every year and it also biodegrades, so it breaks down into carbon, water and CO2. With conventional petrochemical polymers, they don’t degrade, but they may degrade over thousands of years but not within our lifetime. So what they’ll do is they may break down into smaller particles, but they’ll still be in the food chain, so they’ll be still present for, yeah, thousands of years.

    PLA is a polymer, it is quite brittle, it snaps quite easy. So what we’re doing is we’re blending in other biopolymers that are more flexible and we’re adding in biomasses, so biomasses are anything that comes from nature that’s currently underutilised. So we’re adding in the biomass to increase the properties so make it more flexible, make it degrade faster and also give it a nice colour – so good visual appearance. So what we do is, using an extruder, we add the polymer and the grape marc and other biomasses. And the polymer melts and the biomass gets mixed in with the extruders, and what comes out is a strand. So with this strand, then we cut it up and use it in to make films or injection moulding, or it could be used to do 3D printing.

    Dr Gildas Lebrun

    With our extruder we are producing some plastic sheets so made of the formulation that we’ve been talking about. And with these sheets, we’ve been laser cutting the clips to then go to the field with the vineyard and use those net clips on the nets. Here at Scion, we can do the lab scale, so we are preparing those sheets and then cutting them into clips with laser-cutting equipment.

    But we are looking at scaling it so we are looking at different options. We are in touch with some engineering companies in New Zealand to design a stamping cutter to be able to produce those clips in a faster way with more quantity, more volume to have a better cost efficiency instead of using the laser-cutting tool that we are doing at the moment. And then the industry partner would take up the formulation and the process to produce those clips.

    Another application that those net clips could be used for, because it’s the same shape of the bread clip, the clip that we use for the bread bag closure, that could be an option.

    Dr Stephanie Weal

    At Scion, we’ve got a test facility that does biodegradation, compostability and disintegration. So what we would do is we would put our net clips either in soil or water or seawater and see over time that they degrade. So we can set the temperature with most commercial composting. It’s done at higher temperatures than normal home composting. And then we look at the CO2 uptake over a period of time – and for commercial composting, it’s 45 days – so we would mimic that in this facility here.

    With the clips that we’ve designed, they can be either left on the ground and they will biodegrade over a time period or they can be collected up and put into a compost. And they may even be lawnmowed up into tiny bits as well. So those options are all viable because they will eventually biodegrade or compost. What we’ve seen in lab is that our vine clip degrades faster than PLA alone, and it degrades significantly faster than the conventional polystyrene. The net clip that we’ve developed will degrade in the environment under the vine clip, and it will degrade within a few months to years.


    Video clip courtesy of Showdown Productions.

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