Biodeterioration processes

Microbial vulnerability of polymers is often ascribed to enzyme activity, enzymes being crucial players in the biological biodeterioration process. As enzymes are macromolecular polymers, their attack on the polymer is usually only possible via superficially exposed polymer structures readily accessible via a microporous structure. Alternatively, the enzymatic attack works indirectly via... 

Warscheid, T. Krumbein, W. E. (1994). Biodeterioration processes on inorganic materials and means of countermeasures. Materials and Corrosion, 45, 105-13. 

Provision of a better understanding of biodeterioration processes through the identification of key spectroscopic biomarkers... 

Wang J-S (1996) Hydrogen induced embrittlement and the effect of the mobility of hydrogen atoms. In Thompson AW, Moody NR (eds) Hydrogen effects in materials the minerals, metals and materials. Society, Warrendale PA, pp 61-75 Warcheid T, Oelting M, Krumbein WE (1991) Physico-chemical aspects of biodeterioration processes on rocks with special regard to organic pollutants. Int Biodeter 28 37-48... 

Materials of Construction MIC processes are those processes by which manufactured materials deteriorate through the presence and activities of microbes. These processes can be either direct or indirect. Microbial biodeterioration of a great many materials (including concretes, glasses, metals and their alloys, and plastics) occurs by diverse mechanisms and usually involves a complex community consisting of many different species of microbes. 

Li J, Gu J-D, Pan L (2005a) Transformation of dimethyl phthalate, dimethyl isophthalate and dimethyl terephthalate by Rhodococcus rubber Sa and modeling the processes using the modified Gompertz model. Int Biodeterior Biodegrad 55 223-232... 

MIC of Materials. Many cases have been documented of the biodeterioration by bacteria and/or fungi of architectural building materials, stonework, fiber-reinforced composites, polymeric coatings, and concrete.66 Biodeterioration then proceeds by the processes of staining, patina formation, pitting, etching, disaggregation, and exfoliation. (Dexter)5... 

Clearly, the deposition of a variety of microbial genera and their adaptation to live on an environment with limited nutrient availability are important in the colonization process of the polymer surface and subsequent degradation. The capability of these genera for secretion of extracellular enzymes and production of low-molecular-weight metabolites aids in the establishment of successive microflora and hence intensifies the biodeterioration and biodegradation processes (Webb et al., 1999, 2000). 

Abd El Aleem, F.A., Al-Sugair, K.A., Alahmad, M.I., Biofouling problems in membrane processes for water desalination and reuse in Saudi Arabia, International biodeterioration biodegradation, 1998,41,19-23. 

Biodeterioration of Metals. Cambridge University Press, Cambridge, UK, 1995. (b) AS Moffat. Science 1994 264 778. (c) J Haddadin, C Dagot, M Fick. Enzyme Microb Technol 1995 17 290. (d) DE Rawlings, ed. Biomining Theory, Microbes and Industrial Processes. Springer, Berlin, 1997. 

This chapter is presented from the point of view of a microbiologist but it will not be confined to the known facts of deterioration by soluble salts and biodeterioration. It will necessarily focus on the interactions between the different causes of damage and the effects of interventions, which may exacerbate the deterioration processes. 

An important established fact especially regarding the susceptibility of thermoplastic polymers is that while special-purpose additives in these polymers (such as plasticizers, stabilizers, fillers, dyes) can serve as nutrient sources to microorganisms and fungi, the degree of attack also depends on factors such as the lengths of the macromolecule chains, that is, polyethylene, polyvinylchloride, and polystyrene. Biodeterioration of polymers by microorganisms can be considered to be via two processes ... 

Hot-setting phenolic adhesives are processed for up to 15 minutes at 100-150°C and at 0.7-1.7 MPa bonding pressure. The film form is processed for up to 15 minutes at 120-150°C and at 0.7-1.4 MPa. This type of phenolic is resistant to weather, boiling water, and biodeterioration. It has superior temperature stability to that of the acid-catalyzed form. Applications of this adhesive include fabrication of exterior-grade weather- and boil-proof plywood and for bonding glass to metal for electric light bulbs. ... 

Aldehyde-releasing agents, particularly those which release formaldehyde, find application in a number of processes as preservatives, such as in cutting-oil emulsions and latexes [325]. Formaldehyde may be applied to natural keratin fibres in the leather and textile industry to prevent problems of anthrax contamination [341], in paints as preservatives [342] and in the construction industry as toxic washes to prevent microbial growth on large surface areas [343] or as additives in concrete itself [344]. Formaldehyde has long been used as a preservative for natural history specimens in, for example, museums, to prevent biodeterioration and maintain the structure of organs and tissues [345]. 

Starch can be nsed as a natural filler in traditional plastics (11,23-33) and par-ticnlarly in polyolefins. When blended with starch beads, polyethylene films (34) biodeteriorate on exposure to a soil environment. The microbial consumption of the starch component, in fact, leads to increased porosity, void formation, and the loss of integrity of the plastic matrix. Generally (32,35-38), starch is added at fairly low concentrations (6-15%) the overall disintegration of these materials is achieved by the use of transition-metal compounds, soluble in the thermoplastic matrix, as pro-oxidant additives which catalyze the photo- and thermooxidative process (39-44). 

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