A client asked how the flexibility of plastics could be tested. One of our engineers responded, and I thought it might be interesting to reproduce it here.
Better quality plastics are usually more flexible.
There is NO standard value for each type of plastic. Chinese manufacturers usually base their promises on what their resin manufacturer claims. Needless to say, there are all types of resins in China, from the very worst to very good ones.
The four tests listed below are useful for comparing those resins and the flexibility they give to the plastic.
1. Impact test: the plastic is hammered with a device. This test will tell how tough the plastic is. Higher toughness means “more difficult to be broken”.
Usually from this test we can also tell if it broke as a cut off, or if there was elongation before it broke. For certain applications, this is an important property to test.
2. Fatigue test: the plastics is flexed back and forth until its breaks. The higher the number of cycles, the better the plastic’s property.
3. Destructive pull test: this test will tell if the plastic breaks with longer elongation (better quality plastic) or a short elongation (lower quality).
4. UV resistance impact test: the plastics is placed a UV chamber, and then an impact test is performed (see No.1 above). What is interesting is the difference between the impact test results with and without UV exposure.