| The foamed wood thermo-plastic composite is a new kind of economical and environmental material, which develops quickly, and has been received extensive attentions. In this paper, microfoamed polypropylene/ wood flour composits and microfoamed glass fiber(GF)/ polypropylene/ wood flour composites were prepared through injection moulding process. Meanwhile, the present paper researched the influences of a maletic anhydride/Polypropylene copolymer (MAH-PP), the nucleation agent—talc, the crosslinking agents—dicumyl peroxide (DCPO)/ divinylbenzene (DVB), the foam agent and the wood flour surface treatment with a coupling agent of the silane on the foaming degree, mechanical properties and polypropylene's crystal. The main conclusions list below:1. Microfoamed PP/ wood flour composites and microfoamed GF/ PP/ wood flour composites have a three-layer structure, contained a middle layer with distributed cells and two compact outer layer. In between the foaming area and the surface layer, there developed a transition zone along the direction of the melt flow. This cells'transtion become more notable with the increase of melt front flow speed.2. With the increase of melt front flow speed, microfoamed PP/ wood flour composites'densities become lower, their void fractions enhance, and mechanical properties decrease. But the synthetical property of foamed composites improves.3. The different melt front flow speeds have no effect on PP's crystallization form. Under different melt front flow speeds, PP's crystallization always haveα-form andβ-form. But the crystallinity of PP increases with the increase of melt front flow speed.4. With the addition of MAH-PP, because of the improvement of the adhesion between wood fiber and PP matrix, the density of microfoamed PP/ wood flour composite decreases, and the void fraction increases significantly. Meanwhile, mechanical properties decrease, but modulus enhances, and the tensile strength-density ratio and the flexural strength-density ratio improve.
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