What are the advantages and disadvantages of No. 5 plastic and No. 7 plastic?

Shaking cups are mostly made of No. 5 plastic, and ordinary water cups are usually No. 7. What are the similarities and differences in heat resistance and drop resistance?

Why does my shaker cup break when it is dropped? Is it due to its material or mechanical structure?

1.Plastic No. 5 is polypropylene (PP), which is known as the cleanest plastic. It is marked with a plastic container for microwave ovens. It is basically made of it. As for No. 7 plastic, there was no specific reference, but it has now been established by convention, which stands for polycarbonate plastic (PC).
2.The situation of PP is that it is an olefin plastic, and its strength is not particularly high. In addition, it is easy to crystallize. There are some interfaces inside the plastic. Once it is dropped a few times, the interface will crack due to stress. The term is called "Silver Streak", which describes this phenomenon. The specific manifestation is that the crack will show total reflection at certain angles, that is, the degree of reflectance is 100%, like a mirror, a little more observation in life, you can notice the silver streak.
3.In terms of heat resistance, PP and PC are half a catty. According to the models of different manufacturers, the deformation temperature varies between 120-140℃, and hot water is definitely no problem.
4.However, PC plastic is not suitable for food containers, because it contains BPA. Long-term use may cause the body's BPA content to exceed the standard, and BPA is a confirmed environmental hormone. , May be related to many diseases. Therefore, in the current food container standards, the allowable space for PC plastics has been reduced a lot, especially for baby products that have completely banned PC products.