PACKAGING PRODUCTS FROM CONTEIRA LEAFS: A MARKET INVASIVE PLANT!

Presently, polymeric materials are used in many objects of our daily life, and their use is still growing. They play an important role in the economy, particularly in the packaging industry. However, there are two major... [ view full abstract ]

Presently, polymeric materials are used in many objects of our daily life, and their use is still growing. They play an important role in the economy, particularly in the packaging industry. However, there are two major drawbacks related to these products: 1) they are obtained from fossil fuel resources in decline; and 2) they are non-biodegradable wastes after use. During the last years there has been a renewed interest in natural materials as substitutes for a wide range of polymers motivated by potential advantages of weight saving, lower raw material price, and 'bio-recycling' or the ecological advantages of using resources which are renewable. An adequate, abundant and renewable resource is that which comes from invasive plants. In particular, conteira is a plant of the species Hedychium gardnerianum originally from the Himalayas that became invasive in the Azores, an archipelago of volcanic origin with fertile soils and humid forests, where it was placed as an ornamental plant. Presently this plant is seen by the people as a resource without any utility and by the scientific community as a threat to local biodiversity. Stopping the spread of an invasive plant is almost impossible and very expensive and so instead, it can be transformed into value-added products. A promising solution is using their leaf as a source of raw material to develop packaging and disposable daily objects. In this work, green leafs from conteira were used to create eco-designed packaging products in the framework of a sustainable business approach through the commercial valuation of endogenous Azorean products, under the motto "from nature to the market". However, the range of products is for now restricted to non-structural components such as daily domestic pieces (e.g. plates) that usually are made of polymers. Their use is clearly limited to situations of low impact properties. Although leafs are natural composites, they have their shortcomings, namely lower durability and lower strength, and these have to be solved in order to be competitive with polymeric materials. Recently our group has developed a leaf transformation procedure that has improved these properties considerably. Tailored sizes and shapes and relative high thickness transversal sections are possible. Therefore, our thermopressing technique enables the manufacture of products with suitable mechanical properties. To understand its behavior and how this kind of natural materials should be treated, a closer look into their structure is required. Fourier Transform Infrared (FTIR) analysis revealed that structurally, such leafs are rich in hydroxyl and phenolic groups. Moreover, the conteira leaf exhibits hydrophobic properties and a peculiar geometric fiber/matrix combination together with an inherent surface roughness that was characterized by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The leaf’s mechanical properties were derived from the force versus displacement curves obtained using the AFM probe. In addition, the related adhesion forces maps and histograms provided also valuable information about it surfaces adhesion properties. Thermal decomposition analyses of conteira leaf were investigated in terms of global mass loss by thermogravimetric analyzer (TGA) and Differential Thermal Analyzer (DTA).