| The research and development of damping materials and technology have been widely used in the field of automobile industry, construction, mechanical industrial, aerospace, ships, and so on, since noise pollution and its hazards have been paid more and more attention. Damping material as a kind of materials is to transform solid mechanical vibration energy into heat energy. And polymers damping material is a kind of functional materials that uses polymer as stroma to suppressing vibration and noise reduction. To meet the requirements of practical damping applications, good damping materials should exhibit a high loss factor (tanδ≥0.3) over a temperature range of at least60-80℃。 The glass transition temperature range of homopolymer and random copolymer is relatively narrow generally. so the blends, grafts, blocks, crosslinking and interpenetrating polymer network have been used to modify polymers with different glass transition temperature in order to preparing high-damping properties of materials.Hyperbranched polymers may have good damping properties with special molecular structure, large dispersion, large amounts of branched chain and end groups and multiplicity of molecular motion. The polymers in three-dimensional network structure are prepared with hydroxy terminated polyolefin-based polyhydric alcohols (HTPB, HTBN), chain extending agents and cross-linking agents at room temperature or high temperature, which are able to have good damping properties. Therefore, modifying polyurethane with hyperbranched polymers and hydroxy terminated liquid rubber can increase the damping properties of waterborne polyurethane.In the first chapter, we introduced the damping mechanism, the methods of synthesis and modification, the field of application and the methods of determination in the overview of polymers damping material.Then hyperbranched polymers and polyolefin-based polyurethane were introduced.At last, the current status of the research on polyurethane damping material was summarized.In the second chapter, hydroxy terminated hyperbranched polyurethane(HBPU) was synthesized from Isophorone diisocyanate(IPDI), dimethylolpropionic acid (DMPA), diethanolameine(DEOA) and N, N-dimethylformamide(DMF).Then we used HBPU as cross-linking agent, toluene diisocyanate(TDI), polyether diol(N210) and DMPA to prepare hyperbranched waterborne polyurethane emulsion which the acrylate monomer and initiator were added to for getting the hyperbranched polyurethane/polyacrylate copolymer emulsion. The properties of the emulsion were characterized by thermogravimetric analysis(TGA) and dynamic mechanical analysis(DMA). The results of thermogravimetric analysis and dynamic mechanical analysis showed that the heat resistance of polymers with two different cross-linking agents was little difference, and the damping properties was good when damping factor tanδ was about0.75, the temperature range of tanδ greater than0.3was about60℃. And the damping properties was better with the increasing contents of PA.In the third chapter, hyperbranched prepolymer(network I) was prepared by TDI, N210, DMPA and HBPU.Then vinyl monomer, initiator and crosslinking agent were distributed to the network I to getting hyperbranched polyurethane/polyacrylate latex interpenetrating polymer networks.The impacts on damping properties and heat resistance by the factors of the initiator concentration, the ratio of raw materials, the content of vinyl monomers, the vinyl monomer crosslinker were investigated, which was by particle size analysis, transmission electron microscope(TEM),tensile test, DMA, TGA, and so on. The results revealed that the emulsion has interpenetrating network structure, good damping properties and heat resistance,which can be widely used in the field of automobile industry, construction, and so on. The results of particle size analysis and transmission electron microscope(TEM) showed that the particle size was bigger with the increasing contents of PA.And elongation at break decreased.It is because the intertwining of PA and PU chains make the degree of microphase separation in PU decreasing.In the fourth chapter, a series of polyolefin-based polyurethane/polyacrylate interpenetrating network polymer emulsion was prepared by hydroxyl terminated butadiene acrylonitrile copolymer(HTBN), TDI, DMPA. The impacts on damping properties and heat resistance by the content of HTBNwere investigated, comparing to hydroxyl-terminated polybutadiene-based emulsion.The interpenetrating polymer networks and good damping properties was proved by particle size analysis, TEM, DMA.The TGA showed that the emulsion had good heat resistance. |
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