Polymethyl methacrylate contains polar methyl groups on the side of the main chain, and its electrical performance is not as good as non-polar plastics such as polyolefin and polystyrene. The polarity of the methyl ester group is not too great, and polymethyl methacrylate still has good dielectric and electrical insulation properties. It is worth noting that polymethyl methacrylate and even the entire acrylic plastic have excellent arc resistance. Under the action of the arc, the surface will not produce carbonized conductive paths and arc track phenomena. 20 ℃ is a second-order transition temperature, corresponding to the temperature at which the side methyl ester group starts to move. Below 20 ℃, the side methyl ester group is in a frozen state, and the electrical properties of the material will be improved compared to when it is above 20 ℃.