The Selection Of Polypropylene And Study On Zeolite Used As The Auxiliary Nucleating Agent Of Polypropylene

Polypropylene (PP) has good mechanical property, nonposonous, lower relative density and higher heat and chemical reagents resistance, and it is easy to be processed. It is one of polymorphic material, The study on crystallization behaviour and crystal structure in PP has received considerable attention in recent years. Modification of the morphology by using nucleating agents is a simple route to improve the properties such as tensile strength and impact resistance of PP. In the present there are many kinds of a-nucleating agents, but little kinds of P-nucleating agent exist.In this paper, there is a kind of a-nucleating agent 15# and a kind of β-nucleating agent 30# selected from more than thirty kinds of organic compounds. The result indicated that the a nucleating agents made the peak crystallization temperature of PPincreased by 10℃, and the relative crystallization degree was improved by 5 percent. The crystal structure of PP was changedobviously by adding the B-nucleating agent, and the relative crystallization degree was improved by more than 4 percent.In addition, there are many reports on the study on the inorganic particles used in polypropylene to improve the impact strength, especially the nano-particles. n-CaCO3 is one of the most conventional filler used in PP to improve the mechanical characteristics. Numerous paper reported that n-CaCO3 fillers can induce PP to form B-type crystals and others reported that n-CaCO3 used in PP acted as an auxiliary nucleating agents. Zeolite is a kind of aluminosilicate with a special pore structure different from other inorganic particles, and its surface character is changeable. There isn't any report on the zeolite used as the auxiliary nucleating agent in PP read in recent years.In this paper, different types of zeolites and n-CaCO3 with different surface character were first chosen to act as auxiliary nucleating agents in different PP/nucleating agents system, and their effect on auxiliary nucleation in different PP/nucleator system were investigated. The crystal structure, crystal morphology and crystal behavior were characterized by WAXD, PLM and DSC.The results indicated that in PP/13 nucleating agent system, zeolite 5A with moderate surface acidity obviously induced the formation of 13-type PP. In PP/TMB-5 system, not only the sphemlites size of PP was made smaller and uniform, but also therelative content of the (3-type (KP) was increased from 79.65% to97.97% by addition of zeolite 5A. It also appeared the sameeffect on the auxiliary nucleating in PP/30# nucleating agent system. The peak crystallization temperature was increased and the crystallization process was accelerated.In polypropylene copolymer, zeolite 5A can also induce the formation of the P-type PP and improve the impact strength more obviously than other zeolites. By analysing, the surface character of the inorganic particles is one of the important factor that effect the auxiliary nucleating in PP/p-nucleating agent system.n-CaCO3 was used as the auxiliary nucleating agent in PP/TMB-5 and PP/30# nucleating agent system, strong promoting effect on the auxiliary nucleating was observed because their surface was modified by steric-coating.