Short glass fiber reinforced polypropylene composite material with high electromagnetic shielding performance and high weld mark strength retention rate and preparation method thereof

The invention discloses a short glass fiber reinforced polypropylene composite material with high electromagnetic shielding performance and high weld mark strength retention rate and a preparation method thereof, and the polypropylene composite material comprises the following raw materials by weight: 26-86% of polypropylene, 1-20% of linear low density polyethylene, 10-30% of short glass fiber, 1-12% of expanded graphite, 1-4% of a coupling agent, 1-5% of a compatilizer and 0.1-1% of an antioxidant. And 0-2 parts of other auxiliary agents. The mold stripping expansion effect of a high polymer material is fully utilized, and in the twin-screw extrusion or injection molding process, linear low-density polyethylene with a high melt flow rate flows towards the outer side of a melt to drive expanded graphite to be uniformly dispersed and enriched on the surface layer of the material, so that a conductive path is formed; meanwhile, part of the expanded graphite sheet layer is adsorbed on the surface of the short g