Polycarbonate products are commonly used in a number of applications where contact with oils,detergents or chemicals cannot be avoided or is intended.
Therefore,it is prudent to establish the degree of polycarbonate chemical resistance before it is used in any of these applications.
It is for these reasons why Excelite Plastics has set up a testing laboratory for their products.The test involves establishing the general behavior of polycarbonates when they get in contact with these substances.
There are a number of parameters which determine the extent to which polycarbonates react to various chemicals. They include:
This is one aspect which determines the degree of polycarbonate chemical resistance.
When they are subjected to higher magnitude of stress,they become susceptible to chemical attack.The internal stress may occur during the manufacturing process.
This is the reason why the manufacturing process is controlled to eliminate any traces of stress within the polycarbonate structure.
When there’s an excess load,polycarbonates may experience stress within its structure.This step is crucial more so for those polycarbonates which are to be used in industrial setup.
Nature and strength
Polycarbonates are intrinsically strong however,the degree of strength may vary depending on the manufacturing process and the additives which have been used.
When they are exposed to chemicals,the degree of damage will depend on the strength of the polycarbonate.
Polycarbonates are not affected by dilute chemical solvents however,certain concentrated chemical solvents can cause considerable harm on the polycarbonates structure.
In case there is a severe chemical attack,their structure will be altered.The most common implications include:
- A change in molecular weight of the polymer – as the weight increases,the extent of chemical attack will reduce and as the molecular weight decreases,the severity of chemical attack will increase.
- Crystalline nature of the polymer – as the crystalline nature increases the level of chemical attack decreases and vice versa.
- Level of chain branching – an increase in the level of chain branching reduces the degree of chemical attack
This implies that,during the manufacturing process,to improve polycarbonate chemical resistance,it is vital to improve the above properties.
At very high temperatures,the degree of chemical attack will increase.Therefore,in environments where the polycarbonate panel could be exposed to higher temperature for a long time,there are chances that such polycarbonates will be at a higher risk of chemical attack.
Effects of chemical attack
Obviously,when polycarbonate are attacked by chemicals,their performance may decrease significantly.
Such polycarbonates can absorb chemicals,plasticize,dissolve partially and react chemically.This doesn’t imply that the product will actually fail,but,the mechanical properties may change significantly.
Ideally,chemical attack will cause fine cracks which can be described as stress cracks.They can be microscopic or large enough.Generally, polycarbonate products are designed to resist a most chemicals.
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