Views: 17 Author: Vera Publish Time: 2018-10-10 Origin: Site
PP is a common plastic raw material and one of the commonly used modified raw materials. The modification methods can be divided into four kinds: filling modification, strengthening and toughening modification, blending modification and functional modification.
Filling modification
Inorganic fillers: Mica, calcium carbonate, talc, wollastonite, carbon black, gypsum, red mud, lithopone, barium sulfate, etc. Organic fillers: Wood flour, rice husk powder, peanut shell powder, etc. |
Examples of filling volume: |
The addition amount of mica is below 40%, the particle size is above 300 mesh; the amount of titanate coupling agent is about 30% of mica; and the amount of silane coupling agent is less, if the acrylic acid surface treatment agent is used, the dosage can be increased to 5-10%. The larger the L/D ratio of mica is, the better the enhancement effect is. Static mixer, pin-type mixing screw and twin-screw extruder help to improve filling effect. |
The amount of wollastonite is 30-40%. The particle size is 300-325 mesh. The tensile strength of filled composite decreases and the notched impact strength increases. |
When talcum powder, red mud and heavy calcium carbonate, etc. are filled with PP, the viscosity increases greatly. With the increase of shear rate, the viscosity increases gradually and the surface treatment agents such as polyethylene wax, fatty acid salt and twin-screw extruder can be used. |
When using organic filler like wood flour and corncob, it’s better to chose L/D ratio≥15, which can improve the toughness and load distortion. |
Low filling: When the amount of talc powder is 10-20%, PP composite can replace ABS or high impact polystyrene. High filling: when talc powder is more than 30%, they are mainly used for poducts with high thermal deformation temperature performance and high modulus performance. |
Critical value of calcium carbonate with different particle size in HDPE
Particle size | Critical value % | Particle size | Critical value % |
6.6 | 22.1 | 7.44 | 25.4 |
15.9 | 45.0 | 15.9 | No toughening effect |
Toughening effect: with the decrease of particle size, the toughening effect is getting better and better. | |||
