RESEARCH ARTICLE

 

Degradation studies of β-cyclodextrin polyurethane polymers using soil burial experiments

 

 

Bhekie B. Mamba^*; Rui W. Krause; Tshepo J. Malefetse; Soraya P. Sithole

Department of Chemical Technology, Doornfontein Campus, University of Johannesburg, P.O. Box 17011, Doornfontein, Johannesburg 2028, South Africa

 

 

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ABSTRACT

Degradation studies of β-cyclodextrin polymers cross-linked with toluene-2,4-diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) were carried out by exposing the polymers to different soil types for up to 120 days. The aim of the study was to determine the fate of these novel polymers in the environment. The polymers were either digested with sulphuric acid prior to performing a soil burial test or buried undigested. Results from the study indicate that the β-CD/TDI polymers with aromatic links underwent a greater mass loss during soil burial when first digested in sulphuric acid (ca. 50 % maximum mass loss). The β-CD/HMDI polymers, on the other hand, underwent the same mass loss for both the digested and undigested polymers (ca. 30 % maximum mass loss). Although the Fourier transform infrared (FTIR) spectroscopy data suggested no changes in the overall polymer structures, the scanning electron microscopy (SEM) micrographs revealed changes in the surface morphology of the polymers. Moreover, results of thermogravimetric analysis (TGA) point to polymer degradation under all conditions tested.

Keywords: Degradation, cyclodextrin polyurethanes, scanning electron microscopy, soil burial test, microorganisms

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Acknowledgements

The authors wish to thank the University of Johannesburg, the Department of Science and Technology/National Research Foundation (DST/NRF) Africa scholarship programme, the Water Research Commission (WRC), Eskom's TESP programme and Rand Water for funding this work. Thanks also to Industrial Urethanes for kind donation of diisocyanates.

 

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Received 12 October 2007
Revised 25 September 2008
Accepted 13 October 2008

 

 

* To whom correspondence should be addressed. E-mail: bmamba@uj.ac.za