Polypropylene (PP) / talc is widely used in automotive plastics due to its low cost and excellent mechanical properties. Talcum powder manufacturers, but the material still has some shortcomings, such as high density, which is not conducive to lightweight vehicles. The micro-foamed PP / talc powder material not only has the excellent properties of composite materials, but also has a reduced density and reduced quality.

1.Effect of talc on mechanical properties of micro-foamed composites

Specific strength is an important indicator for measuring the light weight and 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, and specific impact strength remains basically unchanged; as the mass fraction of talc powder further increases, The material's specific tensile strength, specific flexural strength, and specific impact strength are all reduced.

Compared with pure PP material, the 5% talc powder PP material foamed, the specific tensile strength and specific bending strength increased, and the specific impact strength decreased slightly; continue to increase the talc powder mass fraction, foamed material The specific tensile strength, specific bending strength, and 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, and the specific weight of the talc powder is continuously increased, but the specific strength of the material is reduced. Therefore, a small amount of talc powder filling is beneficial to improve the mechanical properties of the PP material after foaming.

2.Sample preparation

(1) PP / talc powder masterbatch

Co-rotating twin-screw extruder is used for extrusion granulation. Process parameters: screw rotation speed is 140r / min, feeding rate is 1.2-1.5r / min, and the temperature of the extrusion heating zone is 160-188 ° C.

(2) Micro-foamed PP / talc powder composite material

PP / talc powder masterbatch and 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%, and the injection pressure was 500 kPa.