Study On The Morphology, Mechanical And Processing Properties Of PP Nanocomposites

In this paper , PP/POE, PP/nano-CaCO3 and PP/POE/nano-CaCO3 composites are studied systematically. On the basis of study on the regulation of elastomer and nano-CaCOa on PP, we put great emphasis on the discussion of the relation between two kinds of modification procedures.The mechanical properties of PP/nano-CaCOs composite show that PP can be reinforced and toughened simultaneously by nano-CaCOs treated in proper way. The effect of nano-CaCOs on PP is chiefly decided by the circumstance of surface pre-treatment of nano-CaCOs , the particle diameter and distribution of nano-CaCOs , the appearance of PP particles and the processing parameters of PP/nano-CaCOs composites as well. With the addition of 6-8 phr. Surface-treated nano-CaCOj, the composite shows the best mechanical properties and the better processing properties,the Izod impact strength increases about 40-50% compare with pure PP, and the tensile strength increases about 15-20%. The TEM morphology show that the dispersant has better dispering effect on nano-CaCOs in PP.Crystal structure and characteristics of PP/nano-CaCOs composite are observed and studied by polarizing microscope and DSC respectively. Results show that nano-CaCOs acts as a nucleation agent in PP, thus upgrading the crystal temperature and nucleation rate. The spherulites of the crystal become small and even,but basically there is little effect on crystalline degree and melt point. Within the scope of admission, increasing the content or surface-treatment of nano-CaCOs have obvious influence on crystal structure characteristics of the system.The polyolefin elastomer POE and EPDM are used as the impact modifier for PP in the second part of the project. The processability,crystallizing behavior and mechanical properties of PP/POE and PP/EPDM blends are analyzed comparatively by Torque Rheometer,Differential Scanning Calorimetry(DSC) and mechanical test respectively.The results show that POE8200 is better than EPDM on processability and toughening effect. With the addition of 12 phr. POE8200, the Izod impact strength of PP/POE composite increases about 2.8 times compare with pure PP, but the tensilestrength descends about 25%.The reinforcing and toughening effects of PP/POE/CaCOs composite is also studied. By addition of POE ,the Izod impact strength of the system is improved dramatically,while the tensile strength is reduced,however, nano-CaCOs can slow down the descent of the tensile strength on a certain degree. As the blend ratio of PP/POE/nano-CaCOs composite is 100/12/8, the two particles have the best comprehensive mechanical modification effect, the Izod impact strength increases about 1.85 times compare with pure PP, and the tensile strength descends only about 15%.In PP/POE/CaCOs system, when the nano-CaCOs is distributed in different proportion between PP and POE, the system will show different mechanical properties. The result shows that it is beneficial to reinforcing and toughening of the system to improve the dispering effect and increase the concentration of nano-CaCOs in PP continuous phase.