The research group of Polymers, Characterization and Applications from the Universidad Politécnica de Madrid in collaboration with the Polymer Engineering Laboratory from de department of Chemical Engineering and Environmental Technology at the Universidad de Oviedo, have carried out a study research that enables to recover agricultural plastic waste and turns them into new materials with higher added value, low price and improved recyclability. This would reduce the environmental impact generated by agricultural waste.
The plastic usage in agriculture for greenhouse, tunnel and fillings has rapidly increased since the fifties due to worldwide population increase and the growth of food production need. Within Europe, Spain is the country with the largest area allocated to greenhouses (over 60,800 ha) although internationally this figure is largely overcome by other countries such as China that has over 1,000,000 ha.
However, recycling end-of-life plastics is still low. Only the 23% of plastics are mechanically recycled even though the mechanic recycling of plastic waste can lead to better materials. This can be an optimized solution for plastic waste.
This research is based on two essential actions that can promote the mechanical recycling of agricultural plastics. Firstly, the usage of residual cellulose fibers from the papermaking process as reinforcement for agricultural waste plastics. The mixture of agricultural plastic waste and cellulosic waste allow us to obtain eco-composites materials. And secondly, the usage of a selected amount of plastic from urban waste and selected additives in order to enhance the mechanical properties of the obtained recycled materials. The residual cellulose fibers are of great environmental, financial and social interest since these materials are biodegradable, low cost, light weight and from renewable source.
Throughout the first part of the project, researchers characterized the plastics used in agriculture and obtained the eco-compounds with residual cellulose. The plastics used in agriculture include diverse polymers and complex additive formulations to fulfill their function and enhance their durability. But, due to the outdoor usage in extreme weather, these plastics experience a degradation which leads to loss of their properties. It was observed that this plastic waste still contain remnants of valuable light stabilizer additives that can be interesting for outdoor usage.
Researchers studied the effects of the cellulose percentage and the effects of the added additives over the eco-compounds properties which were obtain in order to determine the most suitable formulations. The reinforcing effect of the cellulose fibers was proved over plastic waste which resulted in substantial increases of the eco-compounds mechanical strength. This study has shown the feasibility of obtaining these eco-composite materials at pilot plant scale.
Thus, to develop new recycled eco-composite materials from plastic waste and cellulosic has enabled to obtain materials with good mechanical properties suitable for extrusion processes or injection molding. These recycled materials have enough properties to be used in diverse applications, including the outdoor usage.
The approval of the good properties of these materials is essential to boost the agricultural waste recycling because the factor that limits recycling is the approval by the recycled products market. The research findings can help to reduce abandoned waste and increase the percentage of mechanical recycling obtaining important savings on raw materials, energy and emissions.
This research was supported and funded by the Ministry of Agriculture, Food and Environment (General Secretariat for Pollution Prevention and Climate Change) and the Asturian Plan for Science, Technology and Innovation. Likewise, the BEFASA Pásticos and CIBA companies have supported this project.
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