The Pros and Cons of TPE and EPDM
In this article we would like to present an interesting and up-to date information on the properties, specifications and comparisons of the weathestripping materials made of TPE (thermoplastic elastomer) and EPDM (ethylenepropylene rubber, specifically, a rubber made of this material) for windows, doors and other systems.
Let’s start from the TPE-based materials:
The TPE-based weatherstripping materials are tear-resistant and are not vulnerable to impacts of the alkali, acids and domestic detergents. The TPE-material is not flammable or toxic, and is a good insulator with a low conductivity. The TPE is made of the interpolymers of the styrene-ethylene-butylene-styrene. Consequently, the weatherstipping sections made of TPE, having the properties of “volcanized rubber”, can be manufactured in a wide color range. The weatherstripping elements manufactured from the TPE, have occupied a segment in the field of the PVC windows installation. They are cheaper than the EPDM weatherstrippers, which is important under conditions of the ailing economy. The TPE materials is easily recycled, and unlike EPDM, it is easier for manufacturing, its production requires more expenses.
• mechanical properties strongly depend on the temperature (heat/cold), under low temperatures conditions the TPE weatherstripping “solidifies”, while under high temperatures it “softens”.
• bad elastic properties, and, consequently, a high residual deformation
• low resilience to ultraviolet impact
• low mechanical resistance
• welding in the corners of the window section (PVC windows), small bending radius of the weatherstripping
• does not sustain combustion
• wide color range
And now let’s discuss the EPDM:
Nowadays different research institutions assess the quality of the EPDM weatherstripping materials higher than the TPE-based ones. The EPDM weatherstripping materials have the operating temperature range from -60 to +1200С, have low sensitivity to ultraviolet, ozone impacts, and to quick cyclic changes of temperatures, they show high mechanical properties and resilience to mechanical impacts. Under the low indices of the permanent deformation, the elasticity of the EPDM-weatherstripping materials can be preserved during a long period of deployment (i.e., the operational lifetime of the EPDM is much higher than the operational lifetime of the TPE, and reach up to 20 years, while the maximum term of guarantee for the TPE is up to 5 years). The EPDM weatherstipping materials do not leave any markings on the working surfaces, since they do not have a contact discoloration.
• the non-weldable seald
• the colored weatherstripping materials are more expensive than the black ones
• big tolerance spaces in the opening
• research institutions assess the quality of the EPDM weatherstripping materials higher than the TPE-based ones
• operating temperature range from -60 to +1200 С
• low sensitivity to quick cyclic changes of temperatures
• low sensitivity to ultraviolet, ozone impacts
• high elasticity of the EPDM-weatherstripping materials can be preserved during a long period of deployment, low indices of the permanent deformation
• 40 – 90 hardness in the Shore range
• tightcornersundercontinuousextensionoftherubber, smallbendingradius
Let’s try to make conclusions:
- The TPE weatherstripping materials, in contrast with the EPDM ones, can be integrated into the sections, and have one advantage, namely, the reducing of the hand labor related to installation of the weatherstripping. This feature is convenient in the automated manufacturing lines. But there is a rind formed in the corners of the welding joints, both on the section and on the integrated weatherstripping, that can be removed manually or with use of the costly clearing machines. When using the EPDM weatherstripping, a compaction circuit has a single glued joint at the top of the window, and thus the circuit becomes airproof. In case if the TPE is used, we’ll get two fissures of the compaction circuit at the joint of the transom bar, and this will result in the deterioration of the airproof quality.
The TPE weatherstripping materials significantly lack the elasticity, resilience to the ultraviolet radiation of the EPDM, have a high permanent deformation and small temperature range of deployment.
It means that the term of deployment of windows (and other systems) with using of the EPDM weatherstripping is much longer than that of TPE. Serious problems with the TPE weatherstripping arise during winter, when the temperature is lower than -20С. This fact was confirm during the cold winter of 2006. Number of complaints to manufacturers of the windows with TPE weatherstripping have gone beyond any reasonable limits. The TPE weatherstripping lost their elasticity during cold weather and turned into rugged layer between the window frame and casement, which consequently led to the loss of air tightness of the window.
3. It should be noted that the simple repair works for changing the weatherstripping in case of use of the TPE could lead to the need of replacement of the whole window casement. The TPE weatherstripping is welded into the section in the corners of the casement, and thus the dismantling of the weatherstripping becomes laborious, and can lead to deterioration of the casement. In case of the EPDM weatherstripping, the repair works require only a few minutes.
4. Installation of the impost with the TPE weatherstripping becomes more complicated, since it is necessary to remove or cut out the weatherstripping from the window frame in the zones of intersection of the impost with the window frame, which decreases the efficacy of labor.
Materials of questionable quality can be offered under the TPE name, for instance, the PVC-compositions modified with rubber. Actually, that PVC is the TPE-based, but “all that glitters is not gold”.
The weatherstripping made of such materials can lead to unexpected consequences during installation. At first sight of a person who is not familiar with this field, the black weatherstripping made of TPE and EPD can seem identical when he sees or touches it. But there is an easy way to define whether the weatherstripping is made of EPDM or TEP. You can expose a piece of weatherstripping to the open fire; if it is made of TEP, it will start melting and “flowing”, and will immediately cool down, like a candle wax. If it is made of EPDM, it can burn and there will be combustion products (such as soot and others).
P.S. When writing this article, we partly used the open-source materials, such as :