Identification method of poor PVC sealing strip and high grade silicone rubber sealing strip:
1、 When burning, the PVC sealing strip will bubble, shrink, emit black pungent smoke, burn incompletely, and leave hard plastic residues,
The silicone rubber sealing strip burns almost smokeless, tasteless, fully burnt, and turns into white powder after burning.
2、 At the same time, place the PVC sealing strip and silicone rubber sealing strip in the refrigerator freezer. After several hours, the PVC sealing strip will become stiff and easy to break, and the physical properties of the silicone rubber sealing strip will not change. The physical properties of silicone rubber have no obvious change at - 50 ℃.
3、 Use your nose to smell if there is any smell. The general PVC sealing strip will have a very pungent smell. The normal silicone rubber sealing strip will only have a little mellow smell, which is very small and can hardly be smelled.
4、 Some cheap sealing strips have many fillers, so the surface will not be very bright and the color will be dim. When the sealing strip is cut off, the section will be very rough, feel stiff, and stretch almost inelastic. The silicone rubber sealing strip has bright color, soft feel, and stretch extremely elastic. When the sealing strip is cut off, the section will be fine and shiny.
5、 At the same time, place the PVC sealing strip and silicone rubber sealing strip under high temperature for a period of time (on the roof or in a sunny place). The PVC sealing strip will become very soft in a short time. The grease on the surface of the sealing strip will separate out, contaminate the dust, and become yellow (it is easy to absorb the soil if there is oil); The physical properties of silicone rubber sealing strip do not change. The pressure cooker sealing ring used in families is made of silicone rubber, which makes use of the high temperature resistance, non-toxic and environmental protection properties of silicone rubber. The physical properties of silicone rubber do not change significantly under the working environment of 200 ℃.
6、 Look at the specific gravity, how many meters per kilogram. PVC sealing strip vendors have made great efforts in the use of fillers. In order to pursue greater output, some manufacturers (save electricity) use talcum powder, heavy calcium and other things as fillers, which has greatly increased the proportion of sealing strip products (our users generally buy by kilogram and use by length). This has virtually increased the cost and seriously reduced the quality. Add heavy calcium PVC sealing strip, you stretch it back and forth for several times, and a small amount of white powder will appear on its surface. The density of PVC sealing strip shall be 1.4-1.6,. The silicone rubber sealing strip uses nano silica as the filling and reinforcement, with light texture and density ratio between 1.1-1.25, so the material yield is 20% more than that of PVC sealing strip.
With the rising prices of various petrochemical products, some bad manufacturers began to compete unfairly in terms of raw materials. These cheap silicone sealing strips are of poor quality and easy to damage the rights of consumers, so consumers should choose wisely.