Performance And Structure Research Of Glass Fiber/Wood Flour/Polypropylene Three Phase Composites

Wood thermo-plastic composite (WPC) is a kind of economical and environmental friendly material. Three types of composites, bamboo flour(BF)/PP composite, wood flour/PP composite, and glass fiber (GF)/ wood flour (WF)/PP composite were prepared by co-rotate twin screw extruder. The paper investigated the effect of malayic grafted polypropylene(MAPP) on WF/PP interface, the respective influence of filler size and filler content on composite performance, and the influence of treatment by stearic acid, titanmium acid silicic couple agent, couple agent respectively on composite interface and performance. The impact of content of glass fiber and wood flour on the GF/WF/PP composite were also discussed respectively. The XRD spectrums were fitted by Gaussian deconvolution method to characterize the differences of crystallnity, crystal type and crystallite dimension. DMTA was used to analysis the interface adhesion and compatibility. The main conclusions list below: 1. Wood flour can increase material's flexible module and strength with drop in tensile strength, elongation and impact strength. 2. MAPP can help improve WF/PP composite's flexible strength, tensile strength, elongation and impact strength. 3. For WF/PP composite, mechanical properties, the flexible module, flexible strength, tensile strength, elongation and impact strength, increase when using smaller size of wood flour, and then decrease after reaching top value at 80 mesh wood flour. The melt index increase straight with smaller WF size. For BF/PP composite, the smaller BF causes lower flexible module and strength, tensile strength and hardness.40 mesh appears the better mechanical properties. 4. The increase of WF content results in the increases of WF/PP composite rigidity but the decrease of composite tenacity. The composite flexible module increases notably with WF content increase, for an instance, the flexible module improves 22% when using 30% wt WF. The increase of WF content obviously decreases the elongation and impact strength, but influences little on tensile strength. 5. The mechanical properties of WF/PP composites were investigated after treatments by stearic acid, KH550, NDZ105 and NDZ201 respectively besides using MAPP. KH550 improves composite flexible module. stearic acid, NDZ105 and NDZ201 improve composite elongation.NDZ105 improves the material impact strength. 6. According to the experiments, the composite shows more balanced mechanical properties (ASTM) below, when using 5% wt MAPP and 30% wt, 80 mesh WF, flexible module 2801 MPa, flexible strength 71 MPa, elongation 21%, impact strength (no gap) 258 J/m, HR (R) 107, melt index 1.8 g/10 min. 7. For GF/WF/PP three phase composite, appropriate GF content can increase the flexible module, flexible strength and tensile strength. But after the GF content reaching 15% wt, the above mechanical properties decrease. The elongation and impact strength decrease straight with GF content increases. When GF content is given, the increase of WF content still improves the flexible module but decreases all other mechanical properties. 8. The tensile fracture SEM photos show that the break of wood fiber is the main destroy mechanism of WF/PP composite, while the root cause of GF/WF/PP composite destroy is the draw and break of glass fiber. 9. XRD investigation shows that MAPP treatment causes lower crystallnity of WF/PP composite, reducing the size difference among surfaces. WF increases the βcrystal of PP, while GF decreases it. Both WF and GF can improve αcrystal of PP. In WF/PP composite, wood flour combines with PP, producing many inhomogenous crystals. In GF/WF/PP composite, most inhomogenous crystals are composed of glass fiber and PP. 10. DMTA analysis shows that MAPP improves wood flour / PP interface adhesion. The interface adhesion gets better when using stearic acid, KH550 and NDZ105 treatment respectively. Among these agents, stearic acid provides best wood flour / PP interface adhesion.