Silicone material, worthy of the king of anti-sun!


About a year ago, a silicone company in the United States tested various materials on the roof of its main building in Philadelphia, Pennsylvania. Thirty-seven rubber polymer samples were tested, including SBR (styrene-butadiene rubber), chloroprene rubber, EPDM (propylene oxide dimer), ECH (epichlorohydrin), PORON (microporous polyurethane foam), silica gel sponge, silica gel foam, solid silica gel, fluorosilicone rubber, etc. The climate change in this area is relatively large. The temperature varies from - 15 to 38 degrees. The total annual precipitation is 1659 mm, and the maximum wind speed can reach 97 Km/h.


As predicted before the experiment, silicon-based materials perform best in the evaluation of exposure for up to one year, with the smallest change in material properties. Silicon-based materials hardly change in size or thickness, nor do they crack, only slightly discolored due to the accumulation of dust on the sample. Because organosilicon has the chemical structure of elastomer, its inorganic skeleton molecular structure model enhances the resistance of materials to other chemicals, so silicon-based materials will not degrade like similar materials. In addition, the high bonding strength of silicon-oxygen bonds at the atomic level makes the materials have high heat resistance and ultraviolet resistance.


Other polymer materials, such as Poron and mixed sponge, did not perform well in the experimental evaluation. Although Poron and other polyurethane foams are good sealing materials in indoor environments, serious cracking and embrittlement can occur when exposed to sunlight for a long time outdoors, especially under ultraviolet radiation.


The situation of low density polyurethane foam is even worse. With the increase of exposure time, the material gradually decomposes.


During the one-year experiment, the damage degree of chloroprene rubber and mixed sponge was similar, and the experimental samples of both materials were lost or damaged during the experiment. Due to the severe drying and corrosion of the sample materials caused by sunshine exposure and high temperature, a strong wind may blow the test samples off the test board.


Other experimental results include that the whole sample of non-silicone solid rubber material shrinks slightly. The electrical conductivity of silicon-based conductive materials decreases due to the remarkable increase of resistivity. Conductive neoprene rubber material has improved its conductivity because of losing its resistive surface coating.


When selecting materials for engineering design, people usually only pay attention to the mechanical, chemical or electrical process requirements of products. However, through this experimental evaluation, outdoor exposure and ultraviolet radiation should also become the focus of attention. For some materials, outdoor direct ultraviolet radiation may be a key factor in determining the reliability of product performance. Although different materials have their own material advantages, it is still important to ensure that outdoor exposure does not lead to material degradation.


From Silicone Public