LMA_PRO – DEVELOPMENT OF A FIBROUS MULTILAYER SYSTEM FOR CUT PROTECTION
The LMA PRO project (NSRF Project No. 2012/24739), sponsored by the LMA- Leandro Manuel Araújo Lda (Portugal) is co-financed by the European Regional Development Fund (FEDER) through the National Strategic Reference Framework (QREN).
The protective clothing for people working in the forestry sector is extremely important. I Germany, for example, there are about 25,000 people who work in this area. The protective clothing should be resistant to cutting, meaning that it should be able to catch any cutting machine at work so quickly in order to protect the user. It is estimated that there are about 1 in 12 accidents caused by the use of chainsaws when working in forestry.
Under this project, created through a joint venture between LMA and Fibrenamics Platform of the University of Minho, the goal was to develop a multilayer innovative structure to protect the cut caused by a manual chainsaw, using materials and advanced fibrous structures.
An innovative multi-layer structure that is designed to perform various functions, using weave mesh technology was developed. Thus, the structure contemplated three layers providing the following functions:
– Body contact layer: comfort through thermoregulation, moisture management, breathability, etc.;
– Middle layer: protection against cutting through the use of mesh structures with auxetic behaviour in combination with high rigidity fibrous materials;
– Outer layer: comprised of bags containing loose fibres that when in contact with the saw chain, make it stop immediately due to the locking mechanism provided by the fibres that are released from the bags.
In addition to protection, the development of this product gave particular attention to the ergonomic requirements for the targeted users. Since working in forestry sector is a profession that requires sudden movements, the developed clothing design features allows the users for mobility, facilitating their daily tasks.
Multilayer structure characteristics:
- Movements freedom
- Easy to perform maintenance actions
- Insects repellent properties
- High resistance to cutting by chainsaw
The end result was the development of protection trousers against chain saws with the following properties:
The structure selected for the protective layer was taffeta fabric comprised of 100 % Cordura® polyamide with a silicone finish. It was concluded that the best fabric was the fabric with the finishing treatment due to the fact the chain does not cut immediately the fabric, occurring a sliding effect, an advantage property for the protective clothing against chainsaw action because it allows a greater reaction time when an accident occur.
The structure selected to build the intermediate layer was the weft-knitted composed of multifilament polypropylene yarns inserted in the direction of the rows. 4 superimposed layers of the knit were placed with 90˚-oriented yarns. This was done after analysing the results which showed the best results with the orientation at 90˚. In addition to the stopping time being lower when applied to the knit with orientation at 90˚, this also presented a reduced cutting depth.
Layer of comfort:
For the comfort layer it has been selected to knit web with the composition of 100% Coolmax polyester, due to the fact that this fabric possess excellent comfort properties.