Preparation And Properties Of PP / Inorganic Particles / Co - Dispersant Composites

PP is one of the most important commodity polymers. Because of its relatively high mechanical strength, good processability, low cost, and great recyclability, PP has found a wide range of applications in construction, packaging, automobiles and household goods. However, owing to its low modulus, high touch sensitivity, and good impact resistance, especially under extreme conditions such as low temperature or high strain rates, the usefulness of PP as an engineering thermoplastic is still limited. And then, the challenge of increasing the impact strength and modulus of PP has provoked considerable interest.Addition of inorganic fillers into PP not only could decrease the cost, but also it is one of the most important modification methods of PP. However, if the interface interaction between the inorganic fillers and polymer matrix is not strong or the dispersion of inorganic fillers in the polymer matrix is poor, the mechanical properties of PP composites would not be unreinforced, and even be decreased, such as the yield strength and impact strength. The challenge how to reinforce and toughen PP through mixing with inorganic fillers is an important issue. Magnetic Fe3O4particles and inorganic fillers have a more similar polarity, so there would be strong interaction between them. Due to the magnetic property of Fe3O4particles, magnetic interaction exists between the magnetic particles and the metal components of processing machine such as screws, and then this magnetic interaction would help inorganic filler disperse well in the PP matrix with the mechanical shear.In order to study the effect of magnetic particles on the mechanical properties of PP/inorganic fillers composites, four kinds of inorganic fillers including talcum, calcium carbonate, titanium dioxide, silicon dioxide, and magnetic Fe3O4particles were used. And the mixtures of PP and fillers in different proportion were processed into composites samples. After testing, the results showed magnetic Fe3O4particles damaged the tensile and flexural properties of PP. After adding magnetic Fe3O4particles, the mechnical propeties of PP/Talc composites had been improved, and when the content of talc was20wt%, the flexural strength of PP composites was improved about6%; when the content of talc was30wt%, the impact strength reached a maximum, and was improved20%; when the content of talc was10wt%～20wt%, MFR was improved about10%. Magnetic Fe3O4particles harmed the mechanical properties of PP/CaCO3, PP/TiO2, and PP SiO2.composites. Besides, The influence of different contents of Fe3O4particles on the mechanical properties of PP/Talc composites was also studied, and the results showed, when the magnetic Fe3O4particles content was5wt%, the better mechanical performance of PP/Talc composites behaviored. Compared to surface modification of inorganic fillers by coupling agent, when the content of talc was higher than20wt%, magnetic Fe3O4particles had a better performance than coupling agent.The crystallization and morphology properties of PP and PP/Talc composites with magnetic Fe3O4particles were analyzed by DSC,XRD and SEM, the results showed, the crystallization behavior of PP has no obviously changed after adding magnetic Fe3O4particles; Different contents of magnetic Fe3O4particles also have no significant effect on the crystallization behavior of PP/Talc composites. Non-isothermal crystallization kinetic study found that, magnetic Fe3O4particles increased the crystallization activation energy of PP/Talc composites weakly, but the parameter F(T), and a had non-significant changes. To conclude, magnetic particles had no obvious effect on the crystallization properties of PP/Talc composite, and the improvement mechanical properties of PP/Talc composite by adding magnetic particles was caused by improving the dispersion of talc in the PP matrix, while SEM photos had confirmed this conclusion. The influence of magnetic Fe3O4particles on rheological properties of PP/Talc was analyzed by Rheometer. It indicated that, under a steady-state, with the increment of the content of Fe3O4particles, the zero shear viscosity of PP composites was decreasing, non-Newtonian index n was firstly increased and then decreased, the yield stress was firstly decreased and then increased. Under a dynamic condition, magnetic particles improved the relative complex viscosity of PP/Talc composites; With the increment of content of Fe3O4particles, the relative complex viscosity, dynamic viscosity and storage modulus of the PP composites was firstly decreased and then increased and then decreased, tanδ was firstly increased and then decreased and then increased; Magnetic Fe3O4particles could improved the numbers of slow motor units.