Environmental Engineering Reference
In-Depth Information
6
Future Trends
Anju V. Nair, Ramasamy Venkatesan and Mukesh Doble
6.1 Monitoring and Predicting Biodegradation and Deterioration
of Polymers
6.1.1 Introduction
Formation of microbial bioilms is a prerequisite for biocorrosion and deterioration
of materials immersed in water including metals and polymers [1]. Biodeterioration
or biocorrosion is the undesirable and detrimental damage of surfaces by the
microbial community [1], resulting in early weakening and deterioration of the
materials [2], leading to serious safety and economic implications. In biodegradation
a nearly complete conversion of the material components takes place. However, bio-
deterioration and degradation tends to affect the performances of industrial plant
by reduced heat-transfer in heat exchangers, initiation of corrosion of the structural
material, increased pumping costs, increased loading on marine structures and
induction of corrosion fatigue or stress corrosion, obstruction of ilter systems and
spoilage of the inal product [3].
Although settlement of a microbial community on surfaces is a requirement for
microbially inluenced corrosion (MIC) of metals, it still remains to be explored just
how much a role MIC plays in corrosion and what are the key mechanisms involved
in it. Biocorrosion of metals leads to general pitting, crevice attack, stress corrosion
cracking, and enhancement of corrosion fatigue, inter-granular stress cracking and
hydrogen embrittlement and cracking of metals [4]. Formation and development of
bioilms on polymers damages the structure and function of polymers by masking the
surface properties and contaminating the media, increasing the leaching of additives
and monomers from the polymer matrix, causing embrittlement and loss of mechanical
stability, swelling and increasing the conductivity, and producing unwanted colours in
the polymer because of microbial pigments [5]. Because biocorrosion and degradation
reactions are very complex, a broad range of techniques have been used to identify
