We all know that single-use plastics are a problem for our environment, but many single-use products can be convenient and more economic than less-problematic alternatives. So how do we get the convenience, cost-effectiveness and ease of a single-use product without harming the environment? One possible solution is the development and use of bioplastic.
In New Zealand, Scion’s Biopolymers and Chemicals division specialises in formulating bioplastics to meet mechanical and biodegradation requirements for a wide range of applications, including replacements for single-use plastics. An example is the biospife – a tool for eating kiwifruit developed by Scion and Zespri.
Another product Scion has developed is a faster-degrading vine clip for use in vineyards using a waste product biomass from the wine industry.
Collaborating to find new materials
Scion approached Villa Maria Wines to find out where the opportunities lay in the viticulture industry around potential uses of biopolymers. Net clips (the kind used as bread bag closures) were identified as one such opportunity.
The net clips are required for about 6–8 weeks to hold nets in place over ripening grapes to prevent loss from birds and other pests attracted by an all-you-can-eat buffet in the vineyard! Because of their size and number, it is uneconomic to collect and recycle the plastic clips, which generally fall to the ground as the nets are rolled up and put away for the following year. This leaves a growing pile of non-biodegradable clips in vineyards around the country. The clips are particularly problematic as, like many plastics, they do not biodegrade, but they do break down into smaller microplastics.
Market studies have estimated that around 16.8 million plastic clips are used each year in the New Zealand wine industry.
Developing the vine net clip
Villa Maria Wines provided grape marc as raw material for Scion to use in the development of a more sustainable vine clip. Marc is the skins and seeds left after the grapes have been crushed and is a significant waste product of the wine industry.
Scion scientist Dr Stephanie Weal and her team developed the grapevine net clip from grape marc and bioplastics including PLA (polylactic acid).
PLA is the least expensive and most widely available bioplastic – made from renewable resources (like sugar cane or corn starch). The bioplastic is soft when heated and solid when cooled. Because of this, it can be extruded into various shapes and is often used in 3D desktop printing.
Common products made from PLA include cups, plastic bags, cutlery and medical implants. It is biodegradable under certain conditions. In industrial composters, PLA will break down in 180 days (but that requires temperatures of around 60°C and the addition of digesting microbes). In water, it takes around 48 months to break down. In a domestic compost bin or tightly packed landfill, it has been estimated that it could take from 100 to 1,000 years to break down into carbon dioxide and water.
Other bioplastics exist, like PHAs and bio-PBS, that are home compostable and soil biodegradable, but these are more expensive than PLA, which limits their use.
The addition of marc to the bioplastic formulation for the vine net clips results in more rapid degradation than PLA or bioplastic alone. The addition of PLA to the formulation gives the resulting bioplastic formulation the necessary mechanical strength for the application.
Testing biodegradation
Dr Stephanie Weal inserts a prototype vine clip into a soil sample for testing at the Scion Biodegradation Facility. This facility is used to measure the aerobic compostability of materials such as bioplastics, paper and wood and to quantify the time it takes for materials to biodegrade.
Scaling up and the future
In order to move from a small lab-based trial product, Scion teamed up with Elastomer Products to help commercialise the vine clip. Elastomer Products optimised the clip to enable production to scale up to produce the millions of clips that are required by the wine industry. The clips are marketed as PolyDegrade™ Vine Clips. The company is now looking to other possible applications such as the replacement of the plastic clips on bread packaging.
In June 2021, the New Zealand Government announced a plan to phase out a number of plastics that are difficult to recycle. As part of this plan, a new Plastics Innovation Fund was launched to help support projects that reimagine how we make, use and dispose of plastics. It is expected that some of the work that will be funded will be in the development of other bioplastics.
Related content
The Rethinking Plastics in Aotearoa New Zealand report by the Office of the Prime Minister’s Chief Science Advisor highlighted the need for innovation to find alternatives to single-use plastics.
In the video Net clips from grape skins, Scion Science Leader Biopolymers & Chemicals Dr Florian Graichen summarises the vine net clip research.
In the article The future of plastics: reusing the bad and encouraging the good, Professor Kim Pickering states it is unrealistic to think we can recycle every plastic, and she explores some of the different options available – such as bioplastics – to address the ‘plastic problem’.
Useful links
Listen to this 2023 RadioNZ interview with Gareth Innes, general manager for sales and marketing PolyNatural®, in which he talks about the development of the bioplastic vine clip and how it has changed over the years.
This Farmers Weekly article covers the long development of these biodegrable clips, from the early work of Dr Dawn Smith and Dr Stephanie Weal, to further improvements and the challenges of commercialisation.
Acknowledgement
The article is adapted from the article by Rural Delivery researcher and director Kirsty Cooper. Rural Delivery is a television programme that looks at excellence and innovation within the primary industries in New Zealand.
The Science Learning Hub thanks Showdown Productions for the use of this article and the accompanying video clip.
