纳米CaCO_3/相容剂/PP中的界面相互作用研究

采用不同相容剂(PP-g-MAH、POE-g-MAH和EVA-g-MAH)制备了不同界面相互作用的纳米CaCO3(CC)/相容剂/PP体系,研究了相容剂/PP和相容剂/CC界面相互作用对PP/CC的结晶形态、结晶行为、熔融特性和力学性能的影响.观察到PP/CC界面相互作用提高PP结晶温度和PP/CC的模量和冲击强度,但降低了屈服强度.相容剂/CC界面相互作用进一步提高了PP/CC的结晶温度.PP/相容剂界面相互作用取决于PP与相容剂相容性.PP/PP-g-MAH相容性高有利于提高PP/CC的异相成核作用和PP/CC屈服强度和模量,但降低冲击强度.PP/POE-g-MAH部分相容对相容剂/CC界面的异相成核作用、PP/CC屈服强度和模量影响不大,可明显提高冲击强度.但PP/EVA-g-MAH不相容导致PP/CC冲击强度明显降低.

INVESTIGATION ON INTERFACIAL INTERACTION IN NANO-CaCO3/COMPATIBILIZER/POLYPROPYLENE COMPOSITES

In order to investigate the interfacial interaction in nano-CaCO3 /compatibilizer /polypropylene composites,three kinds of compatibilizers,polypropylene grafted with maleic anhydride(PP-g-MAH),ethylene-octene copolymer grafted with maleic anhydride(POE-g-MAH) and ethylene-vinyl acetate copolymer grafted with maleic anhydride(EVA-g-MAH) with the same polar groups(MAH) but different backbones were used as compatibilizers.Nano-CaCO3 filled polypropylenes(PP /CC) modified by PP-g-MAH,POE-g-MAH and EVA-g-MAH were prepared by on a twin-screw extruder.In the compatibilized composites,the MAH polar groups of compatibilizers associated with the surface of nano-CaCO3 particles by polarity-polarity interaction,resulting in the formation of the core-shell structure in the composites and two interfaces were obtained: PP /compatibilizer interface and compatibilizer /CC interface.The effect of PP /compatibilizer and CC /compatibilizer interfaces on crystalline morphology,crystallization and melting behavior as well as mechanical properties of PP /CC was investigated by DSC,DMA,POM and WXRD.It was observed that the interfacial interaction between PP and CC in the PP /CC composites increased the crystallization temperature due to the heterogeneous nucleation of nano-CaCO3 particles,tensile modulus and impact strength of PP.In the compatibilized composites,the interfacial interaction between CC and compatibilizer further increased the crystallization temperature of PP.The chemical reaction between polar groups(MAH) of compatibilizer and nano-CaCO3 particles in this interface may lead to the formation of carboxylate salts with more heterogeneous nucleation.The carboxylate salts acted as a more effective nucleating agent further increases the crystallization temperature and crystallization rate of PP and induces the formation of β-crystal of PP.However,the heterogeneous nucleation of carboxylate salts was dependent on the interfacial interaction of PP /compatibilizer interface.The high compatibilization between PP and PP-g-MAH was favor to increase the heterogonous nucleation of carboxylate salts and tensile property of PP composites,but decrease the impact strength of PP / CC.The partial compatibility between PP and POE-g-MAH had little influence on the heterogonous nucleation of carboxylate salts and tensile property,but significantly increased the impact strength of PP /CC.However,poor compatibilization between PP and EVA-g-MAH retarded the heterogeneous nucleation of carboxylate salts and decreased the impact strength of PP /CC.