Formerly, synthetic polymer has been looked upon as not degraded by microbes. However, recently, some kinds of synthetic polymer have been turned out to be degraded.
For example, oligomeric polyethylene easily suffers microbial degradation ; even high molecular weight polymer suffers the degradation in poly (vinyl alcohol) and aliphatic polyester ; and poly (ethylene glycol) suffers the degradation depending on the conditions. Based on such examples, the relation between the chemical structure and the microbial degradability are discussed, and the prospects are mentioned from an environmental point of view.

View full abstract

Principles and recent trends of photodegradable plastics are reviewed with 13 references, and their prospects are discussed. The items described in this review are as follows :
1) Photooxidative degradation mechanisms of polyethylene
2) Typical photodegradable plastics
3) The prospects of photodegradable plastics

View full abstract

The investigation was made on the deterioration mechanism of aged silk fabrics, those were treated in various ways. When we studied on the deteriorated silk fibroin by thermal analysis and amino acid analysis, it was found that the decomposition temperature of aged silk was higher than that of the recent one, and amino acid in amorphous region of aged silk was reduced more than that of crystalline region. Therefore, the degree of crystallinity of silk fibroin increased relatively as long as it is aged. Moreover the decomposition temperature of silk treated with γ-rays was lower than that of the untreated one, and all amino acids in crystalline and amorphous regions were reduced without distinction. Amino acid analysis of coagurated silk fibroin in silkgland by heat treatment showed that the amino acids were reduced remarkably over 300 t in air, reduction of tyrosine and phenylalanine in amorphous region were less in nitrogen gas.

View full abstract

A growth of aspergillus niger on surface of polyethylene (PE), polypropylene (PP), and polyisobutylene (PIB) films were observed by FT-IR and scanning electron microscope (SEM).
Aspergillus niger grew easily on each samples through the medium of soluble organic substance. From the observation of SEM it was clear that aspergillus niger grew not only the surface of PE, PP, PIB but also in the inside of PIB. A good condition for the growth of aspergillus niger were expected that a high concentration of carbonyl groups existed in a molecule by analysis of FT-IR.
Aspergillus niger grows faster on PIB film surface than that of PE and PP. Since a rough surface of PIB has ditches, cracks, and holes, where a nourishment for growth of spores is stored, a stable growth of spores is possible.

View full abstract