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1- Typical Polycarbonate Molecule
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Precise control of chemical processing and stat-of-the-art
compounding technology allow us to provide many different
CALIBRE* resins. Figure
1 shows the typical repeating molecular structure
for CALIBRE polycarbonate resin. The bisphenol
A component (moiety A) of the molecule is the principal
contributor to the resin's relatively high glass transition
temperature of 302°F (150°C). And, the high rotational mobility
of the carbonyl group within the carbonate (moiety B) contributes
to the high ductility and toughness of CALIBRE
polycarbonate resins over a wide temperature range.
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| Figure
2- Molecular
Weight-Melt Flow Relationship of Polycarbonate Resins
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To translate
the chemistry of CALIBRE polycarbonate resins into part
performance, several key properties must be considered.
The molecular weight of the resin has an inverse relationship
to the melt flow rate (MFR)-or, in other words, the higher
the molecular weight, the lower the MFR. This relationship
is illustrated in Figure 2. along with other properties
affected. The physical and mechanical properties of CALIBRE
resins increase with decreasing MFR. However, Processing
becomes more difficult as MFR decreases. Thus, a compromise
is necessary - and engineers, designers and fabricators
must choose between optimum physical and mechanical properties
and high flow characteristics that permit the filling
of complex molds. |
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"*" Trademark of the Dow Chemical Company, licensed for use by LG DOW
Polycarbonate LTD.
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