Poly(l-lactic acid) (PLLA) fibers are used
in different forms like sponges, films, fibers as tissue engineering
scaffolds. PLLA fibers can be used as woven and knitted fabrics
for 3-D scaffolds to support cell growth and subsequent tissue
harvesting. The biodegradability and biocompatibility of PLLA
makes it highly useful for transplantations in humans. One
of the essential requirements of PLLA fibers is good mechanical
properties. Presently these fibers are produced either Melt
spinning or Dry spinning process. While the former show significant
degradation of fiber resulting in poor mechanical properties,
the later process has limitations in spinning speed and produces
chloroform which is environmentally hazard. From this point
of view a new Dry-jet-wet process has been developed.
Introduction
PLLA is initially dried to remove moisture
from the matrix. Different solvents such as chloroform, THF,
Dichloromethane are used in individual and mixture for preparing
the dope of different concentration (weight/volume basis).
The dissolution is carriedout in moisture free glass tube
fitted with a stirrer and flushed with nitrogen so that a
transparent viscous solution is formed. The spinning is carried
out using a Dry-jet-wet spinning unit, as shown in the schematic
diagram. The coagulation bath consists of alcohols as well
as alcohol-polyethylene glycol mixture with different compositions
as nonsolvent for PLA fibers. Spinning is carried under ambient
condition at different take up speeds. The fiber emerging
from first coagulation bath is passed through another bath
containing alcohol for complete removal of solvent from the
fiber matrix. Drawing and heat setting is done on drawing
machine with different draw ratios. Single and two stage drawing
is carried out to produce the fiber with maximum tensile strength.
The drawing temperature is varied from 80 degree C to 140
degree C and heat setting temperature of the drawn fiber is
kept between 1200 degree C to 180 degree C.
Special Features
The Dry-jet-wet process has the following
advantages: The PLLA spinning is simple to handle; Degradation
of the polymer is least; Mechanical strength of the fiber
is in the range of 1 - 1.4 gpd which is extremely good for
end applications; Coagulation bath consists of cheap solvents
in the form of methanol and polyethylene glycol; Monofilaments
of PLLA has been produced for the first time; Crystallanity
is higher than those obtained by Melt spinning or Dry spinning
process.
Prospective Users:
Major and Minor surgical centers
Keywords:
Spinning, Fiber, Drawing
Type of Technology:
Method/Process
Contact
Managing Director
Foundation for Innovation and Technology Transfer (FITT)
Indian Institute of Technology, Delhi
Hauz Khas, New Delhi-110016, INDIA
Tel : 91-011-26597167, 26857762, 26581013, 26597153
Fax : 91-011-26851169
E-mail : drkdpn@gmail.com
