The main reasons why extruded plastic board (XPS board) tends to warp under the sun include the following:
1. Thermal expansion and contraction
● Thermal expansion and contraction effect: When an extruded plastic panel is exposed to the sun, its temperature rises significantly. This temperature change causes the material to expand. As different parts of the sheet are not heated evenly, they expand to different degrees, resulting in internal stress. This internal stress, if it exceeds the capacity of the extruded plastic sheet, will cause warping or deformation.
2. Moisture evaporation
● Moisture effect: Although the closed cell structure of the extruded plastic board makes its water absorption rate extremely low, but in the long-term exposure to sunlight, the board may contain a trace of water inside will be accelerated evaporation. This rapid evaporation of moisture may lead to changes in the internal structure of the material, resulting in a loss of the original balance of the panel, which may result in warping.
3. Material properties
● Thermal stability: The material and production process of the extruded plastic sheet determine its thermal stability. Under high temperature environment, especially under prolonged exposure to the sun, the extruded plastic sheet may suffer from insufficient thermal stability. In this case, the material may not be able to effectively resist the stress brought about by temperature changes, leading to warping.
4. Production process and thickness
● Production process: The production process of an extruded plastic panel also affects its high temperature resistance. If the foaming and curing of the panels are not uniform during the production process, it may cause the panels to behave erratically at high temperatures.
● Thickness and density: Thinner or unevenly densified extruded panels are more likely to buckle under the effects of thermal expansion and contraction. Sheets with less thickness are at greater risk of warping when subjected to heat.
5. External environmental factors
● Exposure conditions: direct exposure to the sun may result in abnormally high temperatures on the surface of the sheet and relatively low temperatures in the shaded areas, and this uneven temperature change can exacerbate warping.
To summarise
To reduce the problem of warping of extruded plastic panels under sun exposure, the following measures can be considered:
● Reasonable shading: where possible, try to avoid exposing the extruded panels to direct sunlight for long periods of time.
●Improve the installation process: Ensure that the panels are installed with uniform force to reduce warping caused by improper installation.
● Selection of suitable materials: Use modified extruded panels or other materials with better thermal stability.
These measures can help reduce the problem of extruded panels warping due to high temperature exposure.
