When the plasticizer content is less than 10 phr, the effect on mechanical strength is not obvious. When the plasticizer content is about 5 phr, the mechanical strength is the highest. It is generally believed that the reverse plasticization phenomenon is the increase of the activity of macromolecular chain after adding a small amount of plasticizer. The impact strength of hard products with plasticizer is smaller than that without plasticizer, but when the plasticizer is added to a certain amount, the impact strength increases with the increase of plasticizer dosage, which meets the universal law. In addition, with the increase of plasticizer, the heat resistance and corrosion resistance of the products decrease. With each addition of plasticizer, the heat resistance decreases by 2-3. Therefore, generally hard products do not add plasticizer or add less plasticizer. Sometimes a few portions of plasticizer are added to improve processing fluidity. Soft products need to add a lot of plasticizer, the greater the plasticizer dosage, the softer the products.