PP is very sensitive to oxygen, and yellowing may be oxidized degradation during processing. PP is a semi -crystalline polymer. The level of crystallization and the size of the crystalline size are very large to the mechanical properties of the product and the optical properties. Due to the different refractive indexes of the crystal area and the amorphous area, the interface will be refracted or reflected. When the crystallization of the polymer increases, the mechanical properties will be significantly improved, but the transparency will decrease. Therefore, the reduction of size is an increase in increased Pelletizing line The transparency of the polymer is very effective. The melting point of the PP is 170-172 ° C, the decomposition temperature is above 300 ° C, and the contact temperature of the oxygen starts to turn yellow at 260 ° C. Therefore, the suitable processing temperature is between 180-225 ° C.
Therefore, if you want to obtain PP products with higher transparency, you can use the following methods: