Preparation And Properties Of Glass Fiber/Calcium Carbonate/POE/PP Quadruple Composites

Polypropylene(PP) is an excellent thermoplastic with versatile application. However, it has limited impact strength and large mold shrinkage, which greatly limit its application. In order to get PP composites with low mold shrinkage and high strength and toughness, multi-components were adopted in this work to co-modify PP. First of all, the nano-CaCO₃/POE/PP and micro-CaCO₃/POE/PP ternary composites were prepared respectively by melt-extrusion with fixing the weight ratio (100:15) of PP and POE. Based on the ternary composites, glass fiber (GF)/nano-CaCO₃/POE/PP and GF/micro-CaCO₃/POE/PP quadruple composites were fabricated by adding different content of GF into the ternary composites with the aid of a two-screw extruder. Then the mold shrinkage, mechanical properties and crystallization features of the composites were investigated comparably.The results showed that the addition of nano-CaCO₃ caused an increase in the crystallization rate of PP in the ternary composites. The Charpy unnotched impact strength considerably increased in the presence of nano-CaCO₃, with a maximum for 10phr, but the tensile strength slightly decreased. And the nano-CaCO₃/POE/PP composites exhibited better performances than micro-CaCO₃/POE/PP composites. After adding the glass fiber, the quadruple composites possessed better performances than the corresponding ternary composites. Similar to the ternary composites, the quadruple composites containing nano-CaCO₃ also showed better properties than those containing micro-CaCO₃. When the weight ratio of GF, nano-CaCO₃, POE and PP is about 15:3:3:20, the composites possess optimal comprehensive properties that the mold shrinkage S_L1, S_L2 and S_L3 are 0.5%, 0.3% and 0.14%, with the tensile strength of 43.4MPa, 40.5% greater than PP. Moreover, the composites have about four times the Izod notched impact strength (5.7KJ/m2) of PP.