Abstract

A magnetic fluid has been synthesized on the basis of magnetite particles stabilized with poly(dimethylsiloxane) (PDMS) having a molecular weight of 4670. PDMS-stabilized particles retain their mobility after the twofold dilution of this fluid with n-pentane and cooling to a temperature of –95°C. A concentrated sample of the magnetic fluid containing only particles with stabilizing shells has been obtained by centrifugation. Despite the absence of a base carrier liquid, this sample retains its fluidity. Thus, a new type of so-called “solvent-free nanofluids” has been synthesized, with these nanofluids being promising components of various technical devices. The concentrated sample of the magnetic fluid shows the rheological properties characteristic of pseudoplastic fluids. The fluid pseudoplasticity exponent is close to unity and nonmonotonically varies with temperature. The temperature dependence of the concentrated sample viscosity at high shear rates in fact reproduces the temperature dependence of the viscosity of the PDMS stabilizer. When the concentrated sample is diluted with a low-viscosity liquid, oligo(diethylsiloxane), the logarithmic relative viscosity of the sample decreases linearly with an increase in the volume fraction of the oligomer.

中文翻译：

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在没有载体介质的情况下，聚二甲基硅氧烷稳定的磁性流体仍可流动

摘要

已经基于用分子量为4670的聚（二甲基硅氧烷）（PDMS）稳定的磁铁矿颗粒合成了磁性流体。PDMS稳定的颗粒在将该流体用n稀释两倍后仍保持其迁移率。戊烷并冷却至–95°C。通过离心获得了仅包含具有稳定壳的颗粒的磁性流体的浓缩样品。尽管没有基础载液，该样品仍保持其流动性。因此，已经合成了新型的所谓的“无溶剂的纳米流体”，这些纳米流体是各种技术装置的有希望的成分。浓缩的磁性流体样品显示出假塑性流体的流变特性。流体的假塑性指数接近于1，并且随温度非单调变化。实际上，在高剪切速率下浓缩样品粘度的温度依赖性再现了PDMS稳定剂粘度的温度依赖性。