pps proceeding - Abstract Preview
pps proceeding
Symposium: S05 - Novel processing technologies
Oral Presentation
 
 

Modified lyocell process for producing biopolymer fiber

Lidhure Ashwini (1)*, Jadhav Sachin (2), Ganvir Vivek (3), Thakre Shirish (4)

(1) Scientist, Aditya Birla Science & Technology company - Maharashtra - India, (2) Senior Research Associate, Aditya Birla Science & Technology Company - Maharashtra - India, (3) Lead Scientist, Aditya Birla Science & Technology Company - Maharashtra - India, (4) Senior Vice President, Aditya Birla Science & Technology Company - Maharashtra - India

Cellulose is an abundantly available biopolymer. Semi-crystalline cellulose cannot be melted directly to form the fibre. Hence to form polymer,it is dissolved directly into solvent called N-Methyl Morpholine Oxide (NMMO) which is conventionally termed as Lyocell process. It is a multiple step process that involves swelling and dissolution of cellulose in NMMO solvent and spinning of the solution by dry jet wet method to produce fiber. The conventional process of lyocell manufacturing consists of a single stage of slurry preparation in which swelling of cellulose fiber in NMMO takes place. It is necessary at slurry stage to have optimum pulp swelling and higher NMMO to cellulose ratio to achieve better uniformity of slurry for fast dissolution and homogeneous polymer formation. To achieve this, pulp sheets are shredded before they are added to NMMO solution in conventional process. The shredding of pulp sheet raises safety concerns due to the cellulose dust explosion. This makes conventional process commercially and operationally unviable. New method is developed to overcome safety concern. This new method of slurry preparation consists of two stages, in first stage dilute solvent is used to prepare slurry with low (4-6%) solid. This slurry is later pressed to upto 45-50% solid percentage, the pressed solvent removes metal ion impurities and short chain hemicellulose from pulp by 10-20%. In second stage, the pressed cake of cellulose is again mixed with high concentration of NMMO to form the slurry.To start dissolution, excess water from the mixture is removed to achieve monohydrate state of NMMO. This polymeric solution is then spun into fibers. The polymer prepared by new process has better quality as it shows reduction in undissolved fiber and metal ion impurity with no change in fiber properties as compared to conventional process. The advantage of new process is that high impurity pulp can be easily blended with good quality pulp in first stage of slurry-making, while the excess impurity is removed before second stage to get better quality of solvated cellulosic polymeric solution to get the biodegradable fiber.