Preparation And Properties Of Composite Polyurethane Damping Materials With Wide Temperature Range

To single polyurethane damping material, the temperature range of internal friction peak is generally narrow. In order to obtain a kind of PU damping material with wide effective damping temperature range and a high damping loss factor, blended PU was derived from prepolymer of polyester polyurethane(PESP) and prepolymer of polyether polyurethane(PETP) which have a certain extent, while, millable PU was prepared with PU and chlorobutyl rubbrer(CIIR). Furthermore, the material’s application performance was investigated.Different structures of polyester diol were prepared with succinic acid(SA), adipic acid(AA), neopentyl glycol monoester hydropivalicate(HPHP) and neopentyl glycol(NPG),then mixed in different proportions with PESP and PETP which prepared separately with polyester diol, polypropylene oxide glycol(PPG) and diisocyanate, finally extended the chain with 4,4’-Methylene-bis-(2-chloroaniline)(MOCA) to achieve blended polyurethane damping materials. The effect of the moleculer weight of polyester diol and polyether diol,the type of polyester diols and diisocyanate, PESP/PETP and the content of-NCO on the damping performance of blended polyurethane damping materials were studied. The results show that PESP and PETP form erratic "block" structure; The value of tanδ is the highest and the effective damping temperature range is wide when the blended polyurethane is synthesized with PPG-2000, TDI-100 and PHPS which number average molecular weight is 2300; The blended polyurethane can receive the best damping properties when-NCO% is3.4%.PU raw rubber was prepared with diphenyl methane diisocyanate(MDI-50) and two polyester diols with different structures which synthesized with SA, maleic anhydride(MA)and HPHP, then mixed with CIIR and various additives, finally, vulcanized at 160℃ for 20 minutes to obtain samples of vulcanized rubber. The effect of the species and proportion of filler, PU/CIIR, the molecular weight and structure of polyester diol on the damping and mechanical properties of the vulcanized rubber were discussed. The results showed that 40 parts of graphite can improve the damping property but decrease the mechanical property.The damping property is best when PU/CIIR = 30/70, and along with the reduction of the component of CIIR, the tensile strength and elongation at break decrease, while the effective damping temperature range decreases too. The vulcanized rubber prepared with PU containing no double bonds has better damping property, but the effective damping temperature range is narrow; The vulcanized rubber prepared with PU containing double bonds has higher tensile strength and elongation at break.PU material was synthesized with PHPS which number average molecular weight is2418, TDI-100 and MOCA with the chain extender, then laminated with steel material to form constrained damping structure. Its shear performance and the effect of loading frequency and strain amplitude on the equivalent stiffness and damping ratio at room temperature were tested. The results show that, the constrained damping structure formed with metal plate and PU which prepared with AA and HPHP has a larger equivalent damping ratio and a smaller equivalent horizontal stiffness at a lower frequency. When the excitation amplitude increases, the equivalent horizontal stiffness is gradually reduced, and the damping property at lower excitation amplitudes is good.