Polypropylene (PP) / talc is widely used in automotive plastics due to its low cost excellent mechanical properties. Haicheng talc powder, but the material still has some shortcomings, such as high density, which is conducive to lightweight vehicles. The micro-foamed PP / talc powder material only has the excellent properties of composite materials, but also has a reduced density reduced quality.
1.Effect of talc on mechanical properties of micro-foamed composites
Specific strength is an important indicator for measuring the light weight high strength of materials. Compared with pure PP materials, the 5% of talc powder's unfoamed PP material's specific tensile strength decreases, specific bending strength increases, specific impact strength remains basically unchanged. As the mass fraction of talc powder further increases, The material's specific tensile strength, specific flexural strength, specific impact strength are all reduced.
Compared with pure PP material, the 5% talc powder PP material foamed, the specific tensile strength specific bending strength increased, the specific impact strength decreased slightly; continue to increase the talc powder mass fraction, foamed material The specific tensile strength, specific bending strength, specific impact strength are all reduced. For the same material, the specific strength of the foamed material is lower than that of the unfoamed material.
According to the analysis of the specific strength of the above materials, after the material is foamed, the specific strength of the PP material with a 5% talc powder content is higher, the continuous increase of the talc powder content decreases the specific strength of the material. Therefore, a small amount of talc powder filling is beneficial to improve the mechanical properties of the PP material after foaming.
(1) PP / talc powder masterbatch
Co-rotating twin-screw extruder is used for extrusion granulation. Process parameters: screw rotation speed is 140 r / min, feeding rate is 1.2-1.5 r / min, the temperature of the extrusion heating zone is 160-188 ° C.
(2) Micro-foamed PP / talc powder composite material
PP / talc powder masterbatch foaming agent masterbatch are re-molded in an injection molding machine to prepare dumbbell-shaped splines that meet the test standards. The injection temperature was 175 ° C, the injection rate was 95%, the injection pressure was 500 kPa.