Flame retardant regenerated cellulose fibers

Challenge

The huge concern with textile materials, especially in the domestic environment, is their high risk in fire initiation and propagation. According to statistics, around 50% of all fires in the world are caused by textiles. Especial attention to this problem was payed during the Second World War and, as a result, 1950-1960 was the decade when the most of today’s flame-retardant treatments for fibers and textiles was developed. Nowadays, when markets become more critical in terms of environmental sustainability, chemical toxicological acceptability, performance and cost, most of the previously developed flame retardants is questioned. For instance, a huge number of them was already discarded in late 1970s upon discovery of their high toxicity.

Most of these flame retardants were developed as coatings (finishes), which can be used for cotton fabrics. On the other hand, regenerated cellulose fibers, e.g. viscose, have an important advantage of possibility to incorporation the flame retardants into cellulose solutions (dopes) prior to fiber spinning, resulting in fiber bulk modification, which is not possible to achieve with cotton.

Solution

One of the possible alternatives for the highly toxic conventional flame retardants, like halogen-based ones, are silica nanoparticles, which is low-cost, earth-abundant and non-toxic material.

Goal

In this project, the development of flame-retardant fibers will be studied by introducing silica nanoparticles into regenerated cellulose fibers fabricated using a sustainable process, i.e., cold alkali dissolution and regeneration. It is envisioned that by controlling the amount of silica nanoparticles in the dope and the time of maturing of silica nanoparticles in strong alkali, fibers with tunable properties can be obtained. The interactions between silica nanoparticles and cellulose both in solution and in solid state are of fundamental importance.

Effect

The successful accomplishment of this study will demonstrate the viability of such an approach and may attract further interest and investments from textile end-customer oriented companies, forest industries as well as the producers of silica nanoparticles. This research has also a chance to strengthen the competitiveness of Swedish forest industry particularly in the field of textile manufacturing and reinforce the position of Sweden as the world's third largest exporter of forest-based products. This research is also in line with the global transition to a fossil-free, circular and bio-based society. It meets the Responsible consumption and production, and Climate change Sustainable Development Goals of the United Nations, set for 2015–2030.