TEAM: Steven Spoljaric, Jukka Seppälä (Aalto University) Arja Puolakka, Tomi Hakala (Tampere University of Technology)
A combined process was utilised to firstly spin monofilaments prepared from enzymatically-fibrillated pulp blended with crosslinked polymer, then prepared knitted structures via circular knitting. Controlling monofilament viscosity (degree of crosslinking) was crucial, since the filament must be strong enough to withstand the knitting process, but soft enough to be able to form knitted loops. By utilising heating, the appropriate viscosity can be achieved, allowing the monofilaments to go from spinning to knitting almost instantaneously.
The filaments were elastic and soft upon spinning, similar to elastane. Following knitting, the filaments dried to become tough and hard. Monofilaments posses a rough feel, however smoothness can be achieved by utilising a cellulose-based coating. A limited degree of water stability is displayed by the monofilaments.
Dry tensile strength of monofilament is 40 ± 6 MPa and elongation at break 1-5 %. Wet tensile strength is 65 ± 4 MPa and elongation 17± 2 %.
Reference values for dry cotton yarn are 625 ± 225 MPa and 3-8%, and for wet cotton yarn 590 ± 150 MPa and 9 ± 2 %.
The knitted structures can be utilised in various textile applications, including interior decoration and décor products, furnishings, matts and coverings.
Photos: Eeva Suorlahti