Masters Theses

Date of Award

12-1993

Degree Type

Thesis

Degree Name

Master of Science

Major

Polymer Engineering

Major Professor

J. E. Spurlell

Committee Members

R. S. Benson, E. S. Clark

Abstract

The introduction of synthetic polymers has added a new dimension to the biomedical applications of fibers. Current biomedical applications of fibers include sutures, surgical implants, prosthetic devices, artificial ligaments, synthetic blood vessels, and controlled drug release. The 3M company has recently developed a new class of bioabsorbable polymers, known as the "poly(ester-amide)s", for potential application as surgical sutures. It is the purpose of the present research to conduct experimental and analytical studies on the processing of these materials into fibers for use as surgical sutures. The values of amorphous and crystalline densities were determined for the PEA-10,2 polymer. These values were then used to calculate the crystallinity in the PEA-10,2 fibers and films by measuring their density. The effect of moisture plasticization on the Tg of PEA-6,2 polymer was studied using the dynamic mechanical analysis, and the DSC. Melt spinning studies were performed on polymers PEA-10,2 and PEA-6,2. The melt spun fibers were drawn under several different drawing conditions, studying the effect of individual processing variables on the structure and properties of these fibers. It was found that the two stage drawing technique gave the best results, with the first stage drawing performed in-line. It was noticed that the molecular weight of these polymers dropped significantly during the processing, and had an adverse effect on the properties of the fiber. It was concluded after further analysis that this drop was mainly due to the long residence times at high temperatures during the processing. In an effort to improve the molecular weight retention, extrusion of this polymer was tried using the Maxwell extruder. The new extrusion technique and an improvement in the high temperature thermal stability of polymer together gave significantly better results. The suitability of gel spinning technique for the processing of PEA fibers was also considered and the very preliminary results are presented.

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