Production of PLLA Fibers and the Resultant Fiber

Background

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

For further information please 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