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Combocal produces soles based on banana fibres

- 27 Sep 2021

News Combocal produces soles based on banana fibres
Banana is one of the most recognized products from Madeira Island, but its plantations have now a destination in plus: banana fibres can be found in the soles of the shoes. The responsible is Combocal, a footwear components company focused on the production of soles, that has developed sustainable rubber soles incorporating banana fibres from Madeira which, after being treated, are integrated into the product. However, innovation does not stop here. The company has been investing in the development of new sustainable solutions, such as the assimilation of waste textile fibres from the production of tyres, coffee and rice husks or even coffee grounds.

APICCAPS’s newspaper spoke with Ricardo Pinto, in charge of the polymers’ area at Combocal.

How did this project of incorporating banana fibres in the soles come about?
While doing research, in collaboration with the polymer engineering department at the University of Minho, Combocal realized that banana fibres are undervalued despite their fine properties, such as low density, good tensile strength, among others. This very fibrous biomass results from the thinning of the plant right after the harvest. In consequence, the idea of creating a biocomposite material made of SBR rubber with incorporated banana fibres from Madeira Island for the production of footwear soles arose. The main objective was to find the ideal balance between the incorporated fibre content and the good physical and mechanical properties of the final sole.   

What are the properties of this material?
Bananatreefiber_rubber, the designation given to the product by Combocal, has differentiating characteristics that add value to the final product from an aesthetic and ecological point of view. In the sole, it is possible to observe small fibres on the surface, and the elastomeric matrix (SBR) has natural pigmentation obtained after incorporating the fibres, thus adding a biodegradable component to the final product.

Is sustainability one of the company’s priorities?
Combocal has established environmental protection in its principles and goals since the very beginning of the company, sustaining a clear position concerning the development and production of this type of product.
In 1985, the company was already incorporating into its elastomeric compositions crushed rubber residues from tires at the end of their life, and also rubber chips resulting from the retreading of tires, for the production of a certain type of soles.
Currently, with the continuous development of more environmentally friendly materials with natural exploration residues, the company’s goal is mainly to contribute to the use of these materials to reduce the environmental impact of footwear at the end of its useful life. Thus, every percentage that can be incorporated is diminishing the synthetic raw material content and increasing the biodegradable material content in the product. Alongside this, natural waste is being valued, instead of being discarded in landfills (which causes energy to be wasted). In addition to the natural waste, the company has been testing the incorporation of synthetic industrial waste, intending to give new life to these materials, hence favouring the circular economy.  
At the same time, the company is working in the process of certification of its Environmental Management System under the ISO 14 001 standard, to validate the company’s good environmental practices.

How has the market been reacting?
These products are having an excellent acceptance in the market, being already on sale in some national and international brands.

What other projects in the sustainability area are being developed?
At present, Combocal has been developing a range of rubber biocomposite materials, such as Coffeehusk_rubber (resulting from the incorporation of coffee husks into the rubber), Coffeegrounds_rubber (resulting from the assimilation of coffee grounds into the rubber), ricehusk_rubber (rubber material with husk content of rice), or even cork_rubber (from the incorporation of cork shavings).
In addition to the biocomposite, the company has been working on formulations that value industrial synthetic waste, such as Tex_rubber, in which the elastomeric formulation contains textile fibre waste from tire production, or even the incorporation of waste produced by Combocal, where they are incorporated in the compound in the form of recycled rubber, obtaining a completely homogeneous material, or are incorporated in the form of crushed rubber residues, where the different particles can be observed on the surface of the sole.
In these materials, the percentages can vary up to 20% of incorporation, always guaranteeing the ideal properties of a vulcanized rubber sole to ensure a final product of high-quality.