PAPI型聚氨酯改性沥青性能与微观机理

为了研究聚氨酯(PU)对沥青的改性机理,以多亚甲基多苯基多异氰酸酯(PAPI)与聚己二酸乙二醇酯二元醇(PEA)、聚四氢呋喃(PTMEG)合成两种PU预聚体,并用其制备PU改性沥青。采用针入度、软化点、延度、黏度试验测试改性沥青基本性能,并通过傅里叶变换红外光谱(FTIR)、原子力显微镜(AFM)、热重(TG)分析、差示扫描量热法(DSC)对其微观结构及反应机理进行分析。研究结果表明,PAPI型PU可以通过物理和化学反应协同改善沥青的高低温性能,PU的加入可使沥青针入度降幅超过20%,软化点提升高于35%,延度性能提升超350%,两种PU改性剂均可显著提升沥青的黏度。PU与沥青反应生成PU-沥青枝接物提高了相容性,导致改性沥青的官能团比例发生变化,PU掺入后会增大沥青中蜂形结构的高度,从而提高沥青的高温性能。PAPI-PEA型PU改性沥青热稳定性优于PAPI-PTMEG型PU改性沥青,而PAPI-PTMEG型PU改性沥青具有更低的玻璃化转变温度。

Properties and Microscopic Mechanism of PAPI Type Polyurethane Modified Asphalt

In order to study the modification mechanism of polyurethane (PU) on asphalt, two kinds of PU prepolymers were synthesized from polymethylene polyphenyl polyisocyanate (PAPI), polyglycol adipate diol (PEA) and polytetrahydrofuran (PTMEG), which were used to prepare PU modified asphalt. The basic properties of modified asphalt were tested by penetration test, softening point test, ductility test and viscosity test, and the microstructure and reaction mechanism of modified asphalt were analyzed by fourier transform infrared spectroscopy (FTIR), atomic force microscope (AFM), thermogravimetric (TG) analysis and differential scanning calorimetry (DSC).The results show that PAPI type PU improves the high and low temperature performances of asphalt through physical and chemical reactions. The addition of PU reduces the penetration of asphalt by more than 20%, improves the softening point by more than 35%, and improves the ductility by more than 350%. Both PU modifiers significantly improve the viscosity of asphalt. PU reacts with asphalt to form PU-asphalt grafts to improve compatibility, resulting in a change in the ratio of functional groups of modified asphalt. The incorporation of PU increases the height of the bee-shaped structure in the asphalt, thereby improving the high temperature performance of the asphalt. PAPI-PEA type PU modified asphalt has better thermal stability than PAPI-PTMEG type PU modified asphalt, while PAPI-PTMEG type PU modified asphalt has a lower glass transition temperature.