Preparation Of NBR/PP Thermoplastic Elastomers And Their Morphology, Structure And Properties

In this work, functionalized polypropylene (PP) with glycidyl methacrylate (GMA) was prepared through reactive extrusion by using dicumyl peroxide (DCP) as an initiator. The effects of the grafting monomer content, initiator content and the addition of styrene on grafting degree, grafting efficiency and melt flow rate of grafting copolymers were studied systematically. The crystallization behavior of PP-g-GMA was studied too.The obtained main results were as follows: At a fixed DCP content, the grafting degree appeared a peak value with increasing the content of monomers; At a fixed content of GMA, the grafting degree and grafting efficiency were increased with increasing the DCP content; The grafting degree and grafting efficiency were increased remarkably by the addition of styrene.The crystallization behavior of functionalized polypropylene was characterized through differential scanning calorimetry (DSC). The experimental results were showed as following. Fistly, the crystal temperature and melt temperature changed remarkably after grafting, the crystal temperature heightened 13-15℃, the melt temperature heightened 11-13℃, and the crystal enthalpy and melt enthalpy increased obviously. Secondly, conclusions could be drew from the kinetic parameter calculated by Avrami equation, the crystal rate increased obviously after grafting and GMA groups grafted onto PP chain acted as a kind of nuclear agent.The NBR/PP thermoplastic elastomers were prepared through reactive blending by using PP-g-GMA or PP-g-MAH as a compatibilizer. And the morphology, structure and properties of the thermoplastic elastomers were studied systemically. The results could be summed up as following. In the first place, the reaction between PP-g-GMA and amine terminated liquid nitrile rubber (ATBN) was confirmed by FTIR. Secondly, TEM Images of NBR/PP blends revealed that there was not only rubber particle with 100nm, but also rubber particles with several microns. But the content of compatibilizer and reactive time did not influence the morphology evidently. Thirdly, the mechanical properties such as the tensile strength, the stress at 100% strain and elongation at break of NBR/PP blends were greatly improved by the addition of compatibilizer. However, the mechanical properties of the NBR/PP blends did not increase with the increase of reactive time. Next, the DSC results showed: (1) There was no obvious effect on crystallization behavior by increase the content of compatibilizer and reactive time. (2) And the isothermal crystallization behavior of NBR/PP-g-MAH and NBR/PP-g-GMA blends was described commendably by Avrami equation. Finally, the dynamic thermal and mechanical properties of functionalized polypropylene and corresponding blends were studied by DMA, the results showed: NBR/PP blending system in this study was typically partially miscible system by the compatibilized effect of grafted PP. In addition, the modules of blends were lower than PP because of the degradation of PP during the reactive process.