From comparison of the three degradation techniques, it can be inferred that some
phenomenon is taking place during the bacterial degradation of LDPE/TPS40 blends.
Weight losses for acid hydrolysis and biodegradation were 100% and 92%, 66 and 39%, and
38% and 22%, respectively for PE1/TPS40 (38:62), PE1/TPS40 (68:32), and PE2/TPS40
(69:31). In the case of PE1/TPS40 (38:62), the difference can be neglected due to the
possibility of bacterial waste accumulation inside polyethylene cavities. At around 30%
TPS40, however, differences are more prominent. This could be related to other phenomena.
Micrographs of the surface of PE1/TPS40 and PE2/TPS40 blends (reported elsewhere) show
that pores on PE1 matrix left after TPS40 extraction are below 1 m, while those observed on
PE2 ranged between 3 to 10 m (Tena-Salcido et al., 2008). On the other hand, different
microorganisms have a length between 0.4 and 14 m and width of 0.2 to 12 m (Gibbon,
1997). In the case of blends having about 30% TPS40, it is possible that microorganisms or
their colonies can restrict starch diffusion by obstructing the polyethylene pores to result in
a significant reduction of the final extent of biodegradation