Biomod/2014/UANL/Jesus
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Chemical Resistance of Polycarbonate Sheets
The mechanism of chemical attack on polycarbonate sheets differs
significantly from the mechanism of corrosion of metals.
Corrosion of metals results in a gradual loss of surface material as a
result of electrolytic action by the relevant chemicals.
In the cases where chemical attack on polycarbonate sheet occurs, all
or a portion of a range of effects can be observed.
Ethylene choride, chloroform, tetrachloroethane, m-cresol, pyridine and
other chemicals can cause partial dissolution of
polycarbonate. Swelling agents include benzene, chlorobenzene,
tetralin, acetone, ethyl acetate, acetonitrile and carbon
tetrachloride. Additional effects include color change and/or
whitening. These effects may not always lead to product
failure, especially for non-loaded sheets. Nevertheless, the level of
measured mechanical properties will be reduced.
The most critical effect of chemical attack is stress cracking or
crazing, which may range in size from being visible to the
naked eye to being only observable under a microscope. Stress cracks
will always result in sheet failure which will eminate
from areas of greatest stress (screws, fixings, bends, etc.)
Polycarbonate sheets are generally not recommended for use with
acetone, ketones, ethers, and aromatic and chlorinated
hydrocarbons in addition to aqueous or alcoholic alkaline solutions,
ammonia gas and its solutions and amines.
Polycarbonate is resistant to mineral acids, many organic acids,
oxidizing and reducing agents, neutral and acid salt solutions,
many greases, waxes and oils, saturated, aliphatic and cycloaliphatic
hydrocarbons and alcohols, with the exception of
methyl alcohol. The resistance of polycarbonate to water may be
described as good up to approximately 60°C. At higher
temperatures, degradation occurs, the extent of which depends on time
and temperature. Polycarbonate should therefore
not be exposed for long periods of time to hot water. However, brief
contact with hot water has no effect. For example,
polycarbonate tableware can be washed over 1000 times in a dishwashing
machine with no adverse effects being observed.
Physicochemical properties
| Enzyme | Some inhibitors | KM value mM | pH optimum | pH range | Temperature optimum | Temperature range |
Urease Canavalia
ensiformis |
(2-[[(2-[[2-(hydroxy-kappaO)ethyl]amino-kappaN]ethyl) imino-kappaN]methyl]-4-nitrophenolato-kappaO)
imino-kappaN]methyl]-4-nitrophenolato-kappaO) prop-2-en-1-one |
2.7 | 5.5 | 5.5-7 | 25 | NR |
| Catalase Bos taurus |
2-mercaptoethanol,
3-amino-1H-1,2,4-triazole, dinitrosyl iron complex, Glutaraldehyde, hydroxylamine, NaCN |
28.6 | 7 | 6-7.5 | 25 | 25-35 |
| Uricase Arthrobacter globiformis |
8-Azaxanthine, Cu2+, | 0.075 | 8.5-9.5 | 6-9.5 | 30 | 25-40 |
References
<a href="http://www.palramhort.com/pdffiles/PC_Products_General_Info/PC_Chemical_Resistance.pdf">Polycarbonate
membranes</a>
<a href="http://brenda-enzymes.org/">Enzymes proerties</a>
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