Views: 69 Author: Vera Publish Time: 2017-08-09 Origin: Site
Polypropylene is one of the most commonly used plastics, but its higher crystallinity also gives PP the disadvantage of porr toughness in low temperature , forming shrinkage and large notch sensitivity, which limits its wider application to some extent. Blending modification is the most effective way for PP toughening. It utilizes the principle of compatibility or reaction blending between two or more polymers and assistants to mechanically blend at a certain temperature, and finally forms a new material with macroscopic uniform and microscopic separation. Through blending modification of PP, its comprehensive performance can be greatly improved, and will compete with engineering plastics and polymer alloys in many fields of application.
The main blends and modification effects of PP blending were as follows:
| Modification effect | Modification Additives |
| Improve the resistance to low temperature impact | Ethylene Propylene Rubber, EPDM, POE, EVA, SBS |
| Improve transparency | LDPE, ethylene propylene rubber, POE |
| Improve coloring | polyamide, polyurethane, polyacrylamide, polyacrylate, Polyester, Polyvinylidene chloride |
| Improve air tightness (gas barrier) | Polyamide, Polyvinylidene chloride |
| Improvement of Antistatic | Polyvinyl |
Introduction of specific modification formula and process
| Formula | Processing technology | Performance | |
| PP/LDPE Modification | Resin: PP 100; Compatibility agent: Pe-g-mah5; LDPE 20; Lubricant HSt 0.3; | According to the proportion of formula, mixing PP with PE, compatibility agents and additives, through extruding and granulating, the modified material is made. The extruder barrel temperature is: the first section of 210 ℃, the second section 215 ℃, the third sections 210 ℃, the screw length-diameter ratio is 25:1, and the screw speed is 120~160r/min. | PP blending with PE can improve the toughness of PP and increase the impact strength of falling ball in low temperature. The yield stress of the blend material that in proportion to the formula is 6MPa; yield strain rate is 12.3%, fracture stress is 4.78MPa; Fracture strain rate is 114.6%. |
| PP/HDPE Modification | Resin: PP 57.35; Antioxidant: 10760.2; HDPE40; PEPQ0.2; Crosslinking Agent: tert-butyl phenoxy isopropyl benzene 0.15; Processing aids: Magnesium stearate 0.1; Filling agent: Wollastonite 2; | At ambient temperature and pressure, the components are mixed in a high speed mixer for 10 minutes according to the formula proportion, and then use twin-screw extruder for melting and blending and extruding granulation. The extrusion temperature is 150-220 ℃, the screw speed is 300r/min, and the PP/HDPE blending material is made by pelletizing and drying process. | The tensile strength is 34.8MPa, and the impact strength of cantilever beam is 49.3j/m. The material surface extinction effect is good, can be used in packaging, daily necessities and building materials and other fields. |
| PP/LLDPE Modification | Resin pp (epf30r) 60-70; Appropriate amount of titanate coupling agent (ND2-311); lldpe 15-20; Antioxidant toughening Agent Poe (8150) 5~10; Appropriate amount of light Stabilizer; Filler: talc powder (average particle size 12μm) 10~15; | After the high speed mixer preheated to 110 ℃, add a certain amount of inorganic filler, mixing for 15 minutes in low speed; add coupling agent that with 2% filler, mixing for 5 minutes in high speed, repeated three times, and then release the filler standby. According to the proportion of the formula, accurately weigh PP, PE, POE, fillers and other additives, after mixed, adding into twin-screw extruder hopper, extrusion and granulation. Extrusion temperature should be 190-220 ℃, main screw speed should be 200r/min, feed screw speed should be 20r/min. After drying, the granule material can be injected into the required products, injection temperature is 190-210 ℃, injection molding and pressure MPA, pre-plastic pressure 6MPa. | Blending with LLDPE can improve the toughness and environmental stress cracking of PP, while adding POE, so that the toughness of the blender is improved greatly; while adding talcum powder to increase firmness, ensure the material is rigid enough. The tensile strength is ≥26mpa, the elongation of rupture is ≥400%, and the flexural modulus of elasticity is ≥1.6GPa, thermal deformation temperature ≥110℃, forming shrinkage rate 1.15%. This product is mainly used for light vehicle door liner material. |
