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实验发现石蜡断面具有良好的超疏水性能,石蜡断面的水滴接触角达到152.4±3°,石蜡外表面水滴接触角为108±3°。利用铜网在石蜡表面复制其断面形貌,可快速制备大面积超疏水石蜡表面,接触角高达162.4±3°,滚动角小于3°。利用此超疏水石蜡表面设计出一种自动油水分离装置,可实现油水连续分离,收集正己烷速率可达0.67mL/s。扫描电子显微镜(SEM)观察发现石蜡断面粗糙度很高且存在较多连续和非连续的晶区,而石蜡外表面较光滑。扫描差示量热仪(DSC)和X射线衍射(XRD)证明石蜡具有一定的熔限和较高的结晶度。偏光显微镜(POM)观察石蜡熔体的冷却过程,发现冷却过程中有大量不同尺寸的结晶产生。实验结果表明:石蜡断面和石蜡外表面的超疏水性差别较大的原因在于断面具有较高的粗糙度,而外表面粗糙度较低,断面的高粗糙度来自于石蜡内部存在大量的连续晶相和非晶相。当石蜡断裂时,晶相一方面充当了应力集中点,导致断面出现不规则的裂纹;另一方面,晶相充当了微纳尺度的“填料”;晶相和非晶相在断裂面的凸起也会导致断面粗糙度高。
The experimental results show that the paraffin section has good superhydrophobic properties. The contact angle of water droplets in the paraffin section reaches 152.4 ± 3 ° and the contact angle of water droplets on the paraffin surface is 108 ± 3 °. Using copper mesh to copy the cross-sectional morphology of the paraffin surface, the surface of large-area superhydrophobic paraffin can be quickly prepared. The contact angle is as high as 162.4 ± 3 ° and the rolling angle is less than 3 °. Using this superhydrophobic paraffin surface design an automatic oil-water separation device, continuous separation of oil and water can be achieved to collect n-hexane rate of up to 0.67mL / s. Scanning electron microscopy (SEM) observation showed that paraffin sections had high roughness and more continuous and discontinuous grain boundaries, while the outer surface of paraffin was smoother. Scanning differential calorimetry (DSC) and X-ray diffraction (XRD) showed that paraffin wax had certain melt limit and high crystallinity. Polarizing microscope (POM) observed the paraffin melt cooling process and found that there are a large number of crystals of different sizes in the cooling process. The experimental results show that the reason for the difference of the superhydrophobicity between the paraffin section and the paraffin surface is that the cross section has higher roughness and the outer surface roughness is lower and the high roughness of the section comes from the presence of a large number of continuous crystals Phase and amorphous phase. On the other hand, the crystalline phase acts as the “filler” of the micro-nano scale; the crystalline phase and the amorphous phase act as a stress concentration point on the one hand and lead to fractures at the fracture surface The bulge will also lead to high profile roughness.