Biodegradation of a Starch Containing Thermoplastic in Standardized Test Systems

• Published in: Journal of macromolecular science. Part A, Pure and applied chemistry Pure and applied chemistry, 1998-04, Vol.35 (4), p.589-608
• Main Authors: SCANDOLA, M., FINELLI, L., SARTI, B., MERGAERT, J., SWINGS, J., RUFFIEUX, K., WINTERMANTEL, E., BOELENS, J., DE WILDE, B., MÜLLER, W. -R., SCHÄFER, A., FINK, A. -B., BADER, H. G.
• Format: Article
• Language: English
• Subjects: Applied sciences; Biodegradation; Exact sciences and technology; Natural polymers; Physicochemistry of polymers; Poly(ϵ-caprolactone); Standard Test; Starch; Starch and polysaccharides
• ISSN: 1060-1325; 1520-5738
• DOI: 10.1080/10601329808001999

Biodegradation of the commercial starch-based thermoplastic Mater Bi (MB) ZI01U was investigated in six different test systems: (1) aqueous aerobic (AQ-AE), (2) aqueous anaerobic (AQ-ANA), (3) in vitro in the presence of the microorganism Acidovorax avenae avenae (MICRO), (4) controlled compost (COCO), (5) composting bins (COBI) and (6) high solids anaerobic digestion (HSAD). MB ZI01U was found to biodegrade in all test systems. Samples in the form of pellets, films and ASTM-D638 test bars were used. The composition of MB ZI01U in the course and at the end of the biodegradation experiments was monitored by thermogravimetric analysis. Rapid loss from MB ZI01U of the water-soluble plasticizer (glycerin) was invariably observed. In the anaerobic tests (AQ-ANA and HSAD), the ratio of the two polymeric components of MB ZI01U (starch and Poly-ϵ-caprolactone, PCL) strongly changed with increasing exposure time, indicating preferential degradation of starch. During the aerobic tests AQ-AE and MICRO the starch-to-PCL ratio remained practically constant and equal to the initial value (0.54). At the end of the COCO tests (45 days), only sample fragments were recovered, composed of plain PCL. After the COBI tests, where high temperatures (73°C) were reached during the thermophilic phase, no samples were retrieved. MB ZI01U showed the following weight loss per unit surface area: 1 mg/cm 2 , both after one day of exposure to Acidovorax avenae in the MICRO test and after 5 days in the AQ-AE test system; 24 mg/cm 2 , after 5 days of HSAD testing.