1106 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1957 



to this are the polyvinyl chloride resin and styrene polyester in Table 

 VII which could not be prepared in sheet form. 



Results for polyethylene are described in Tables IV and VII. The 

 oxygen consumption values in these tables are almost identical to the 

 control values obtained using only inoculated sea water. There is no 

 evidence in any of these tests of polyethylene being utilized as a source 

 of carbon by the bacteria. In fact, in Table IV, all of the eight week values 

 for polyethylene are slightly below those for inoculated sea water alone. 



The results with the polyvinyl chloride plastics vary according to the 

 manner in which the compounds are plasticized. The data are contained 

 in Tables V, VI and VII. First, as may be noted in Table Yll, there is 

 no attack on the polyvinyl chloride resin. This indicates that the sus- 

 ceptibility of these plastics can be attributed to materials added in com- 

 pounding. Every polyvinyl chloride plastic tested shows some evidence 

 of attack; (distinct oxygen consumption above the control rate), ex- 

 cept the semi-flexible copolymers which contain no added external 

 plasticizer. In these compounds, acrylates are employed as copolymers. 

 The most severe attack occurred on the plastic in Table Yl which con- 



2 



Q. 



32 



28 



24 



20 



O 



1 6 



Z 



o 



Q. 



D 

 iri 



Z 



o 



U 12 



3 4 5 



INCUBATION TIME IN WEEKS 



Fig. 3 — Examples of O2 consumption by marine bacteria in BOD test with 

 Poly (Vinyl Chloride) plastics as carbon source. 



