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M. Rutkowska, A. Heimowska

Degradation of naturally occurring polymeric materials in sea water environment

Polimery 2008, No 11/12, 854


Summary

The presented investigations covered environmental degradation of polymer materials (thermoplastic starch, modified cellulose and two types of starch-cellulose composites) in The Baltic Sea at Nordic Wharf of Gdynia harbor. Degradation process was also tested in laboratory conditions in sea water with sodium azide (NaN3, eliminating the microorganisms activity) added. These tests let evaluate the part of chemical hydrolysis in the process of degradation in natural sea environment. During samples' incubation (from 14 to 336 days) the following characteristic parameters of sea water were inspected: temperature, pH, oxygen content, chlorides' content and salinity (Table 1). The progress of environmental degradation of polymeric materials has been evaluated on the basis of weight loss (Fig. 5-7), changes of the surface (Fig. 1-4) as well as changes of the structure of the material, observed microscopically (Fig. 8-10). It was found that in the natural environment of sea water the enzymatic hydrolysis of the tested materials occurred, what was demonstrated by clear erosion of the surface and weight loss. The samples of modified cellulose were more susceptible to attacks of microorganisms living in sea water than the samples of thermoplastic starch. In case of composites more distinct weight changes were observed for material A (film form) than for B one (sheet form) because of large surface development at phase boundary. Their degradation in sea water is of enzymatic character and first the amorphous phase is degraded then the crystalline one.


Key words: degradation, natural polymers, thermoplastic starch, modified cellulose, sea water, enzymatic hydrolysis, chemical hydrolysis


e-mail: rutmaria@am.gdynia.pl


M. Rutkowska, A. Heimowska

Degradation of naturally occurring polymeric materials in sea water environment