Pyridine terminated polyurethane dendrimer/chlorinated butyl rubber nanocomposites with excellent mechanical and damping properties

摘要

Due to the special viscoelastic property,traditional rubber with high performance has been widely used in human life and production.However,it is challenging to improve the damping property without sacrificing the extensibility.In this work,a novel type of second-generation polyurethane dendrimer terminated with pyridine(G2-Py)was synthesized by using thiolactone chemistry and subsequently complexed with Zn ions.The structure and morphology of G2-Py were characterized.G2-Py-Zn2+was then mixed with chlorinated butyl rubber(CIIR)by a two-roll mill.A series of CIIR/G2-Py-Zn2+elastomers were obtained through vulcanization.CIIR/G2-Py-Zn2+elastomers could achieve high stretchability(a strain of
1035%),high mechanical strength(a tensile stress of 7.64 MPa).This was benefitted from the friction between G2-Py and CIIR as well as variety of non-covalent bonds provided by G2-Py-Zn2+,which can dissipate energy to further improve the strength and extensibility.The coordination of Zn2+-pyridine was confirmed by Fourier transform infrared spectroscopy,stress relaxation and cycle tensile test.To further investigate the morphology and damping properties of the elastomers,scanning electron microscopy and dynamic mechanical analysis were performed.CIIR-5 showed the best damping performance with higher tandmax and wider effective damping temperatures.Therefore,this dendrimer modification technology provides wider applications for CIIR elastomers in daily life.