Polycarbonate sheets are manufactured under rigid quality control
specifications to meet the desired criteria. Quality control begins from
the extrusion process through to the final treatment stages where
they are coated with various protective layers to prolong their service
lifespan.
The polycarbonate sheets UV coating protects these sheets from loss
of mechanical integrity. Some of the essential mechanical integrity of
polycarbonates includes high impact strength and durability. When a
polycarbonate sheet is exposed to UV-B radiation, the photo-degradation
transforms the polymers’ chain scission. As the molecular strength decreases, the
molecular weight decreases significantly. Furthermore, the presence of certain
metal compounds act as a catalyst in this process. This is one of the main reasons
why the polycarbonate manufacturers do indicate those cleaning agents
which should be used during the cleaning process.
The UV-A is responsible for the yellowing wavelengths. As the ozone
layer depletes due to global warming, the amount of UV-A and UV-B increases
significantly. Normally, the UV rays do not “penetrate” these sheets. They
mainly attack the outer layer of the polycarbonate sheet.
Since the amount of UV radiation varies from one
place to the other, PC sheets may have different degrees of polycarbonate
sheets UV coating. Therefore, you need to specify the exact region where you’re
planning to install these sheets. The nature the thin microscopic layer which
is used to coat the PC sheets will determine the warranty period. It is also an
important aspect which differentiates various types of PC sheets in the market.
The degradation process is determined based on the yellow index (YI)
of the sheet. The YI is calculated from the spectrometric data and it indicates
the change which exists between the test sample and the clear color (white).
Anyway, If no UV on the polycarbonate sheet, there will no any
quality warranty, when you buy polycarbonate sheet, remember check how
thickness your supplier will add the UV layers, this is the key factor to
affect your sheet quality.

没有评论:
发表评论