Typical properties for Coxwell Polycarbonate
|DTUL, 1,82 MPa
|Coefficient of linear thermal expansion
|Tensile strength, yield
Value measured on injection-moulded laboratory sample.
Coxwell Thermoclear sheet has outstanding impact performance over a wide temperature range, -40°C to +120°C, and also after prolonged outdoor exposure.
As a roof glazing material Coxwell Thermoclear sheet is subject to extremes of weather ; storms, hail-stones, wind, snowfalls and ice formation. Under these conditions, the product is virtually unbreakable and is able to withstand the subsequent temperature change to sunny conditions without breaking or buckling.
In a test developed by the Dutch Testing Institute TNO, samples of Coxwell Thermoclear sheet have been subjected to simulated hail-stones of varying diameters without significant damage. A test sample is clamped into a metal frame 3.2 m x 4.0 m and polymide balls of varying diameters are fired at the surface of the sample using a pressurized airgun.
In practice, hail-stones with a diameter of 20 mm can reach a terminal velocity of around 21 m/s. Under these conditions materials such as glass and acrylic fail.
It should be noted that when the glass and the acrylic are tested their failure characteristics are typically brittle, whilst the Coxwell Thermoclear shows ductile behavior: upon impact the ball will leave indentations but the sheet will not break.
GE Structured Products offers a Ten Years Limited Warranty* on Coxwell Thermoclear sheet covering loss of strength or impact due to weathering
Hail Simulation Test Results
|Acrylic multi-wall sheet t=16 mm
|Float glass t=4 mm
|Coxwell Thermoclear sheet t=10 mm
|Coxwell Thermoclear sheet t=16 mm
|Equilibrium velocity of hail stones in practice
The sunlight which reaches the surface of the earth has a wavelength that ranges between 295 – 2140 nanometres(10-9 metres). This optical window is divided into the following sections:
UV-B Middle ultraviolet region 280 – 315 nm
UV-A Near ultraviolet region 315 – 380 nm
Visible light region 380 – 780 nm
Near infra-red region 780 – 1400 nm
Middle infra-red region 1400 – 3000 nm
As shown in Figure 2 below, Coxwell Thermoclear has the highest transmission in the visible light.
Despite transmitting visible light very well, Coxwell Thermoclear sheet is almost opaque to radiation in the UV and far infra-red region. This useful shielding property can prevent discolouration of sensitive materials such as fabrics or other organic materials placed under or behind Coxwell Thermoclear sheet glazing in, for example, a factory warehouse, museum or shopping centr