摘要
利用小振幅振荡剪切实验和KWW方程研究了生物柴油凝点附近恒温过程中黏弹性参数随时间的变化。以地沟油生物柴油为例,根据实验数据和KWW方程分析了不同历史条件下生物柴油的等温胶凝过程特性。结果表明,恒温过程中,随着时间的延长,生物柴油的储能模量和损耗模量逐渐增大,损耗角不断减小,表现出明显的等温胶凝特性,KWW方程能较好地描述生物柴油的储能模量随时间的变化。测量温度越高,降温速率越大,恒温剪切时剪切速率越大,特征松弛时间越长,恒温静置过程中生物柴油形成的胶凝结构强度越弱,且由于剪切后生物柴油中晶体的结构特点,导致剪切后的胶凝结构具有不可逆的恢复特性。
The change of isothermal yiscoelastic parameters of biodiesels with aging time near pour point was studied by small amplitude oscillatory shear experiment and KWW equation. The isothermal gelling process of waste oil biodiesel with different shear and thermal histories were studied by both experimental data and KWW equation. The experimental results suggested that the storage modulus and loss modulus of biodiesels increased but the loss angle of biodiesels decreased with the increase of aging time under isothermal conditions, meaning that biodiesels exhibited obvious isothermal gelling characteristics. The KWW equation was proved to fit well with the experimental data of several different biodiesels. With the increase of temperature, cooling rate and pre-shear rate, the structural relaxation time increased, resulting in the weaker structural strength for biodiesel systems in the isothermal gelling process. It was also discovered that the structural strength after shearing decreased even if biodiesel systems were gelled after long aging time, due to that the pre-shearing made the efficient distance between crystals larger and the attractive forces weaker.
出处
《石油学报（石油加工）》
EI
CAS
CSCD
北大核心
2016年第1期207-214,共8页
Acta Petrolei Sinica(Petroleum Processing Section)
基金
国家自然科学基金项目(51206188
51474235)
山东省优秀中青年科学家科研奖励基金(BS2013SW032)资助
