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CALIBRE* polycarbonate resins meet
a wide range of impact requirements- from 1.5 to 18.0
ft-lb/in (80 to 950 J/m) notched Izod impact strength.
However, understanding the "balance" of end-use
temperature and impact requirements is crucial in selecting
a resin for a specific application.
Tensile Strength
Tensile properties provide an important
indication of a material's strength. They are a measure
of the force required to pull the resin apart, and of
the amount of stretching it can withstand before breaking.
Tensile properties are calculated from a stress-strain
plot.
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11- Stress-Strain Plot at 73¡ÆF(23¡ÆC), CALIBRE 300 Series Resins
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A typical stress-stain curve for CALIBRE polycarbonate
resins is shown in Figure 11. The data were generated
according to ASTM D 638. Ultimate tensile strength is
the maximum stress a material can withstand at the point
of rupture. Yield tensile strength is stress at which
non-elastic deformation begins or where an increase
in strain occurs without an increase in stress at the
yield point. Ultimate elongation is the total elongation
of the sample at the point of rupture. The modulus of
elasticity is the ratio of stress to strain in the elastic
region.
The area under the curve of a stress-strain diagram
indicates the relative toughness of a material. CALIBRE
resins have a high tensile yield strength, a high ultimate
tensile strength and a high ultimate elongation. They
therefore have a large stress-strain area, which is
indicative of high toughness. CALIBRE polycarbonate
resins are among the toughest engineering thermoplastics.
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12- Yield Tensile Strength at Various Temperatures, CALIBRE 300 Series Resins
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The yield tensile strength, ultimate tensile strength
and tensile modulus for CALIBRE polycarbonate resins
are relatively constant, showing no significant change
over the range of commercially available MFRs. However,
there properties do decrease with increasing temperature.
Figure 12 indicates how yield tensile strength values
are affected by changes in temperature.
Impact Strength
Instrumented Dart Impact
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