Biodegradation of some natural polymers in blends with polyolefines

The biodegradation of two-component blends containing synthetic and natural polymers was studied. Polyethylene, polypropylene and modified polyester were used as synthetic components. Three materials of natural origin, i.e. powdered cellulose, sodium alginate and chitosan in lyophilized form, were used as Filers. The samples were prepared in the form of films of different thicknesses and contained various amounts of natural components. In general the content of synthetic components ranged from 50 to 75wt%, natural polymers 5-21wt% and other additives 11-38wt%. The biodegradation tests were carried out in soil and water. The effect of microorganisms' action on the samples was estimated by the loss of mass, water sorption capacity and electron microscope studies. In some experiments the mass lass exceeds the sum of masses of all introduced natural components. It means that some art of synthetic polymer is also damaged during biodegradation. Generally the results obtained lead to the conclusion that biodegradability of two-component polymer films depends considerably on the dimensions of the natural component particles and their distribution in the film. Films containing large and weakly dispersed particles prove to be more sensitive to biodegradation. Accessibility of natural component particles for the bath containing microorganisms plays an important role in the biodegradation course. Films filled with cellulose are better degradable in soil while the films containing sodium alginate biodegrade in aqueous medium more easily. Copyright (C) 1999 John Wiley & Sons, Ltd.