Fungal attacks

Thermoplastic polyurethane elastomers have now been available for many years (and were described in the first edition of this book). The adipate polyester-based materials have outstanding abrasion and tear resistance as well as very good resistance to oils and oxidative degradation. The polyether-based materials are more noted for their resistance to hydrolysis and fungal attack. Rather specialised polymers based on polycaprolactone (Section 25.11) may be considered as premium grade materials with good all round properties. 

Other ingredients. Bacterial and fungal attack can be a problem in poly-chloroprene latex formulations with pH below 10. It is manifested by odour, discolouration and gas evolution 500-1500 ppm of a biocide should be added. 

Fungal and bacterial deterioration are identified as microbiological and have always caused problems to materials. Fungal attack on plastics has received a great deal of attention beginning with the early days of World War II, when the tropical theaters served to focus attention on the overall problem of materials deterioration. 

To control bacteria on skin and surfaces To protect from bacterial spoilage To protect from fungal attack and spoilage To protect against insects To protect against algae... 

Some selected fungistats that are used to protect plastic materials against fungal attack are listed below ... 

Decaffeination of green coffee beans is most usually carried out with a water/solvent partition system. The green coffee beans are first steamed until they are hot, wet, and swollen, to make the caffeine available. Solvent is then used to extract the caffeine out of the aqueous phase of the beans. Finally, the beans are steamed to drive off residual solvent. The coffee beans lose their wax surface covering in the process, as well as some flavor components. For this reason, the Robusta and Brazilian Arabica coffees that are dry-processed and have the most powerful flavors are usually the types that are decaffeinated. They become milder in the process. Mechanical polishing is used to improve the appearance of decaffeinated green coffee beans if they are not to be roasted immediately. Extra care is required, however, to store these decaffeinated beans since the loss of wax covering as well as caffeine renders them much more susceptible to fungal attack. 

Fungal attack following coffee borer beetle damage leads to the formation of viridic acid . The viridic acid test (a color reaction) has been used to estimate the extent of preharvest damage, by the coffee borer beetle, to a batch of coffee beans.55... 

Polyurethane elastomers are exceptionally tough, abrasion resistant, and resist attack by oil. The polyester types (AU) are susceptible to hydrolytic attack at above ambient temperatures, and certain polyester thermoplastic polyurethanes have been known to stress crack in cable jacketing applications when in contact with water at ambient temperatures this latter effect has sometimes, incorrectly, been ascribed to fungal attack. Polyether types (EU) are far more resistant to hydrolytic attack. Certain polyurethanes can be attacked by UV light, the resistance to this agency primarily being determined by the isocyanate used. 

Polyphenoloxidase in Fungi and Defense against Fungal Attack... 

Fungal attack is a real problem in a humid atmosphere and another reason for keeping the plants out of your shower, a basically unhygenic place for plants. 

Imamura, Y., Rowell, R.M., Simonson, R. and Tillman A.-M. (1988). Bending creep tests on acetylated pine and birch particleboards during white- and brown-rot fungal attack. Paveri ja Puu, 9, 816-820. 

Takahashi, M. (1981). Bending creep behaviour of plywoods under long term exposure to fungal attack. International Research Group on Wood Preservation, Doc. No. IRGAVP 81-2163. 

Control of weeds in fruit is just as important as for vegetables—except where fruit trees are growing on vigorous rootstocks. A full-sized fruit tree surrounded by a wildflower meadow gains many benefits from it, and together this association forms a valuable wildlife habitat. But in the case of small trees and all soft fruits, weeds compete with the crop plants for light, water, and nutrients if very profuse, they can reduce air flow and increase the likelihood of fungal attack. Do not let weeds get out of hand. 

Watanabe M et al (2005) Cloning and characterization of saponin hydrolases from Aspergillus oryzae and Eupenicillium brefeldianum. Biosci Biotechnol Biochem 69(11) 2178 Osbourn A (1996) Preformed antimicrobial compounds and plant defence against fungal attack. Plant Cell 8 1821... 

---