An Innovative Polypropylene/Waste Cork Composite Material for Spirit and Wine Stopper Caps

Abstract

In the wine bottling process, thermoplastics are commonly used to manufacture the crown of cork stoppers. The production of agglomerated cork stoppers generates a type of waste called cork powder (CoP) in large volumes with known properties but which are still underutilized. At present, although there are many agrocomposites available with additives such as natural fibers or solid residues from agricultural products, there are no studies describing the formation of these agrocomposites from petroleum-derived synthetic plastics combined with cork dust as a reinforcement for the polymeric matrix. The present study describes a novel agrocomposite, which has been obtained by mixing polypropylene-type materials, as they are some of the most widely used and versatile thermoplastics, with cork dust, which is a waste product obtained from the cork industry. The composite is obtained directly, without the need for grafting, adhesive polymers, or coupling agents. A superior mechanical performance compared to the unprocessed polymer was highlighted in the test results, thus evidencing the reinforcing function played by the waste in the polymer matrix. Therefore, this novel agrocomposite could be a promising alternative to replace some petroleum-derived synthetic plastics, which are currently experiencing high demand. The use of this new agrocomposite is well aligned with sustainability strategies, the principles of the circular economy, and oriented towards the fulfilment of the Sustainable Development Goals required by the European Union, considering that it contributes (a) to recycling agricultural waste that would otherwise be difficult to recover and valorize; (b) to the reduction in the CO2 footprint; and (c) to promoting the use of high-quality secondary raw materials.