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PVC is very widely used in the building and construction
industry due to excellent mechanical properties at a lower cost.
However, with heat distortion temperature of about 70 degree C,
PVC cannot be used at elevated temperatures. In fact, PVC tends
to lose its mechanical strength at 50 degree C and therefore PVC
pipes are not recommended to be used beyond 50 degree C.
PVC window profiles are required to withstand higher temperatures,
particularly in the tropical regions. Many times Acrylic cap stock
material is used over the PVC profiles to provide weather resistance.
However, to increase heat resistance, Acrylonitrile Styrene Acrylate
(ASA) modifier can be used. Recently a newer ASA grade called Luran
S 778TE from BASF has been developed and is commercially available.
This grade of ASA has heat distortion temperature of 105 degree
C. It can therefore increase the heat distortion temperature of
PVC significantly from 70 degree C. This new grade also has excellent
outdoor resistance and therefore does not reduce the weatheribility
of PVC.
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