Tuesday, November 9, 2010: 8:55 AM
150 C Room (Salt Palace Convention Center)
Alginate is a well known environmentally friendly material which has found many applications such as the preparation of dressings to treat exuding wounds, drug delivery, enzyme immobilization, etc.; however its use is limited due to low mechanical properties. Cellulose nanocrystals (CNC) isolated from cotton were added to calcium alginate fibers with the goal of improving its strength (tenacity), and modulus. The nanocrystals are elongated particles, with an average length of 130nm, an average width of 20.4nm, and an average height of 6.8nm; they were mixed with an aqueous sodium alginate dope solution, and wet spun into a CaCl2 bath to form fibers. Addition of the nanocrystals reduced the tenacity and modulus of the material when the processing conditions were kept constant. This unusual behavior may be explained by the degree of orientation of the nanocrystals inside the fiber; wide angle x-ray diffraction (WAXD) experiments showed a decrease in nanocrystals alignment as the CNC concentration is increased. However a small concentration of CNC in the dope solution allowed to significantly increase the apparent jet stretch during processing. Characterization of the fibers produced at the maximum stretch showed an increase of 38% in tenacity, and 123% in modulus when the CNC concentration was 10%wt. WAXD showed that the degree of alignment of the CNC was recovered by increasing the apparent jet stretch. CNC have potential to become a green, biocompatible, and cost effective solution to reinforce alginate fibers, as well as other biopolymers.