(531e) Annealing Alters the Mechanical Properties of Chitosan Fibers
AIChE Annual Meeting
Thursday, November 12, 2009 - 10:10am to 10:35am
Introduction and Objectives:
Chitosan is a promising, biocompatible polymer currently being used in a number of tissue engineering applications. As with many natural polymers, one key concern is its low mechanical properties. In this study, we seek to improve the biomechanical properties of chitosan fibers by thermal modulation of its semi-crystalline nature. Specifically we investigated the effects of annealing temperature on the microstructure and mechanical properties of chitosan fibers.
Materials and Methods
Chitosan solution (1.5 wt% in 0.2M acetic acid) was extruded through a 24-gauge (0.045 mm ID) Teflon catheter directly into 10 vol% ammonia solution. The hydrogel fibers obtained were wrapped on a drying frame and then heated to different temperatures ranging from 40°C to 145°C, for 30 minutes and were then cooled to room temperature at ~1 °C/min. Ultimate tensile strength, breaking strain and modulus of elasticity (stiffness) were evaluated in a fully hydrated condition and compared to control chitosan fibers dried at room temperature.
Results and Discussion:
Mechanical properties showed that up to 80°C, fiber strength increased significantly with annealing temperature (2.5 MPa to 7 MPa). Beyond 80°C, strength decreased but remained significantly higher than for control fibers. The modulus of elasticity (stiffness) of the annealed fibers was significantly below control, but showed small increases with increasing annealing temperature (100 MPa to 150 MPa). Annealed fibers showed higher values of breaking strain compared to control fibers. However, there was no clear trend with regard to annealing temperature. Our results indicate that annealing significantly alters the mechanical properties of chitosan fibers and may be used to improve the strength of chitosan fibers. These effects may be due to changes in molecular organization. Ongoing studies seek to characterize the microstructural changes induced by annealing as well as any associated changes ion biological activity.