Studies For The Effect Of Nucleating Agent On The Crystallization Behaviors Of PP/POE Blends

Modification of PP by adding nucleating agents is an important way to improve the performance of PP resin. It can significantly improve the properties of crystallization and mechanical properties. Many studies demonstrated that there is significant synergy effect about nucleating agents consisting of inorganic, organic or other different structure substance. In order to make use of the advantages of a variety of nucleating agent, development of multi-component composite nucleating agent is an important trend for the modification of PP.A series of NF composite nucleating agent was prepared based on low molecular weight PA6 powder in this paper. The effect of NF composite nucleating agent on the crystallization properties and morphology of polypropylene ethylene-octene copolymer blends was investigated by means of differential scanning calorimetry, polarizing optical microscope, ARES advanced rheometer etc. We discussed crystallization kinetics of the modification of PP using NF composite nucleating agent by Avrami equation and LH theory.The results show that NF series nucleating agent have certain nucleation effect on PP/POE blends, they have varying degrees of impact on the crystallization rate, crystallization temperature, half peak width and crystallinity. Three of the NF series nucleating agents (NF-6, NF-9, and NF-10) have remarkable improved integrated effect. The effect of the amount of nucleating agent on the crystallization behavior of PP/POE blends: when the amount of nucleating agent is gradually increased from 0% to 0.6%, the crystallization properties of polypropylene blends improved significantly and the trend is very clear, while the amount of nucleating agent is more than 0.6%, crystallization temperature and crystallization rate changed slightly.Adding nucleating agents into PP/POE blends improved the crystallization properties. After adding NF-14, the crystallization temperature of PP/POE blends increased from 117℃to 131℃, elevating 14℃, and the crystallization temperature of start crystal also increased significantly. Adding NF-10, the crystallinity of PP/POE blends was about 50%, which is the most effective nucleating agent on elevating the crystallinity within NF series nucleating agent. When adding NF-9, it can lead to the fastest crystallization rate.The results of crystallization kinetics show that all the two systems of PP/POE and PP/POE/NF exist homogeneous nucleation and heterogeneous nucleation simultaneity. The crystallization half-time t1/2 remarkably decreased and the crystallization rate G significantly enhanced after adding nucleating agent. Adding the nucleating agent had an impact on the crystallization morphology of PP/POE. The spherulites size of PP/POE is large, when spherulites grows they collides with each other and forms a clear interface. Adding the nucleating agent interfere the formation of complete crystal ball and the spherulites interface becomes blurred, it also reduces spherulites size significantly, increases nucleation density, improves the crystallization rate.ARES advanced rheometer scan results show that the storage modulus, loss modulus and torque of PP/POE are increased by adding NF series nucleating agent. While after adding NF-6 and NF-10, tan d is smaller than that of PP/POE. This shows that after the addition of nucleating agent the viscoelastic proportion of the material is changed, and change the material properties. ARES advanced rheometer scan results are consistent with the dynamics, which show that the crystallization behavior of blends is in accordance with Avrami equation and the LH theory after adding NF series nucleating agent.