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采用“先臂后核”的方式合成了超支化聚氨酯(HBPU)。经单因素试验筛选出HBPU与聚氨酯预聚体(PPU)的最佳合成条件:PPU采用先熔化聚酯多元醇(P-3020)后直接加入MDI的加料方式,—NCO∶—OH摩尔比为1.15∶1,反应时间为30min,反应温度80℃。HBPU采用丙三醇(TG)、乙二醇(EG)一次加料、4,4’-二苯基甲烷二异氰酸酯(MDI)逐步加料的方式,控制多元醇(TG、EG)与MDI摩尔比为1∶1.15,MDI分3次加入,每次反应30min,反应温度80℃。用IR、GPC对所合成的HBPU分子结构进行了表征,确定反应按照预期路线进行。与普通线性聚氨酯相比,在相同黏度条件下:HBPU的Mn增幅为22%,Mw增幅为37%,说明HBPU相较于PU有着黏度低、流动性好的优点。
Hyperbranched polyurethane (HBPU) was synthesized using a “forearm nucleus” approach. The optimum synthesis conditions of HBPU and polyurethane prepolymer (PPU) were screened by single factor test: PPU was fed directly to MDI after melting polyester polyol (P-3020), the molar ratio of -NCO: -OH was 1.15: 1, the reaction time is 30min, the reaction temperature is 80 ℃. The molar ratio of polyols (TG, EG) to MDI was controlled by HBPU using glycerol (TG), primary feeding of ethylene glycol (EG) and stepwise feeding of 4,4’-diphenylmethane diisocyanate (MDI) 1: 1.15, MDI was added 3 times, each reaction 30min, the reaction temperature was 80 ℃. The structure of the synthesized HBPU was characterized by IR and GPC, and the reaction was confirmed as expected. Compared with ordinary linear polyurethane, under the same viscosity conditions, the increase of Mn of HBPU is 22% and the increase of Mw is 37%, indicating that HBPU has the advantages of low viscosity and good fluidity compared to PU.