Date of Award

7-2003

Type

Thesis

Major

Earth and Space Science - Environmental Science Track

Department

Earth & Space Science

First Advisor

Floyd R. Jackson

Abstract

Biodegradable polymers are desirable for a variety of applications, such as in packaging, agriculture, and medicine. Its biological degradation by microorganisms accelerated the interest in biodegradable polymers during the last decades. Within this group of innovative environmentally friendly biodegradable polymers, starch or Amylpectin plays a predominant role, due to their potential biodegradability. This research was attempted to characterize Amylopectin to obtain its physio-chemical properties. In addition, characterizations were extended to include blends of Amylopectin and biodegradable diluents. Blends of Amylopectin with biodegradable diluents including Polycaprolactone, Poly(DL-lactide-co-glycolide), and Poly(3- hydroxybutyric acid) were prepared. The physical properties and the thermodynamic characteristics of these blends were investigated using the Inverse Gas Chromatography (IGC) method. This was conducted over a range of temperatures until a complete set of data was obtained. Nineteen solutes with different chemical natures were selected in this study. Solutes, including a series of alkanes, acetates, alcohols, diethylamine, formic acid, and water, were injected into Amylopectin and its blends chromatographic columns. The retention times of solutes were measured for each solute. Slopes and heats of mixing of solutes with pure Amylopectin and its blends were calculated. All columns except the 50-50 Amylopectin-Polycaprolactone column showed a minimum of two regions in the retention diagram. These regions were identified as crystalline and amorphous regions. A third region was identified above 200°C as the polymer started to decompose. However, for 50-50 Amylopectin-Polycaprolactone column, a straight line was observed in most solutes due to the lack of data at higher temperatures All columns except for some solutes of 50-50 Amylopectin-Polycaprolactone column showed a glass transition temperature (T g ) that has a range from 90°C to 140°C. The T g is the first minimum temperature in the curvature that can be identified. In addition, all columns except for some solutes of 50-50 Amylopectin-Polycaprolactone column showed maxima of the curvature. These maxima were identified as the melting point (T m ) of the polymers, which ranged from 100°C to 170°C. By blending Amylopectin with other polymers, the Tm was decreased or a depression phenomenon was formed and this is due to less melting amorphous. The dispersive surface energy value of the 100% Amylopectin column was 0.07 mJ/m 2 at 200°C. The dispersive surface energy values of the 75-25 Amylopectin-Polycaprolactone column were ranged from 18.59 mJ/m 2 at 170°C to 10.27 mJ/m 2 at 260°C. In addition, the dispersive surface energy values of the 50-50 Amylopectin-Poly(DL-lactide-co-glycolide) column were ranged from 46.30 mJ/m 2 at 160°C to 39.03 mJ/m 2 at 180°C, while, the dispersive surface energy values of the 50-50 Amylopectin-Poly(3-hydroxybutyric acid) column were ranged from 55.46 mJ/m 2 at 160°C to 1.31 mJ/m 2 at 200°C. Therefore, blending Amylopectin with other polymer will increase its mechanical properties and thus, the surface energy.

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