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Date of Award

2-2010

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Chemical Engineering

Supervisor

Andrew Hrymak

Co-Supervisor

Qiang Liu

Language

English

Abstract

The development of environmental friendly polymers from renewable resources, specifically for short term packaging and disposable applications, has been recognized as an important alternative to synthetic polymer based packaging materials. In this work, we focus particularly on the use of potato starch, because there is a significantly large by-product stream of potato starch from potato waste after food processing in Canada.

Poor processability and flowability are the main restrictions against the application of starch in granular form. Hence, thermoplastic starch (TPS) has been developed using starch in the presence of water and other plasticizers (e.g. glycerol) typically by using heat and shear. A microcompounder extruder was used for blending TPS, with an injection molding machine to prepare samples for testing. The sample test results show that TPS has severe limitations due to poor mechanical properties and high water sensitivity.

To overcome the mentioned weaknesses, while maintaining material biodegradability, one method is to blend TPS with a high performance biodegradable polymer. Poly lactic acid (PLA) was added to TPS to improve the mechanical properties. The addition of PLA improved mechanical properties and reduced water sensitivity. In order to improve the compatibility between the main phases in the blend, maleic anhydride (MA) was grafted unto PLA as a reactive compatibilizer.

Other methods to improve hydrophobocity and reduce water uptake were also investigated. Natural fiber reinforced TPS biocomposites were processed in order to improve blend performance and water sensitivity. For this purpose, sisal fiber was added to the TPS and TPS/PLA blends, and had major effects on the blend properties.

The addition of paraffin wax was also investigated. The incorporation of paraffin wax also reduced the water sensitivity of the samples significantly and improved the mechanical properties compared to TPS only samples.

McMaster University Library

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