Palram PALSU - Manual (Page 12)

12
Weather Resistance
Solar UV radiation attacks many polymeric materials. The rate of deterioration and crazing on the exterior surface will vary for
different polymers. Further erosion is accelerated by water, dirt, air pollution, chemicals etc. The extent of attack depends on
environmental factors such as location, altitude, local weather conditions, air pollution etc. The best initial indication is yellowing,
followed by a significant reduction in light transmission and structural strength.
All PALSUN sheets (excluding those designated PALTUF, which are UV stabilized) are manufactured with a co-extruded, UV
protective layer on one or two sides. This protective layer assures a long lifetime of service. PALSUN sheets retain their toughness
and optical quality under intense UV exposure, with minimal reduction in their properties.
2000 hours of accelerated weathering (UV exposure, QUV - ASTM G154) tests, simulating 20 years of exposure in hot, sunny
climates cause only a minor decrease in light transmission and a slight increase in yellowness Index for PALSUN. The changes
in UV stabilized PALTUF sheet are greater.
The effect of QUV on 3 mm PALSUN & PALTUF sheets appears in the graphs below.
Flammability
General
As a thermoplastic, PALSUN eventually melts and burns under the intense heat of a blazing fire. However, PALSUN does not propagate
flame, and is solidified and self-extinguished as soon as the direct flame is taken away. PALSUN doesn’t produce any toxic fumes or
gases when it burns.
PALSUN® FR
PALSUN FR is a fire retardant flat solid polycarbonate sheet with improved flammability ratings. The flame retardant additives make
the it virtually non-combustible. When flame licks the sheet, it will only get scorched and eventually melt, solidifying quickly when the
direct heat source is removed. Drippings do not ignite other combustible materials, as they do not actually burn.
Smoke and heat extraction
In an actual, full-scale combustion, when PALSUN overhead glazing (as in skylights) is exposed to intense heat it will soften at 150°
-160°C and produce apertures in the glazing, enabling heat and smoke to escape. Reduced temperatures inside the structure help
to extinguish the fire.
Figure 6b
Yellowness Index Change in 3mm Sheets
10
9
8
7
6
5
4
3
2
1
0
0 100 250 500 750 1000 1500 2000
PALSUN® Change in
Yello
wness I
ndex
Accelerated Weathering (QUV Hours)
PALTUF®
Figure 6a
% Light Transmission Loss of 3mm Sheets
95
94
93
92
91
90
89
88
87
86
85
0 100 250 500 750 1000 1500 2000
Accelerated Weathering (QUV Hours)
PALSUN®
%Light T
ransmission
PALTUF®