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1.
Based on the lotus effect principle, the superhydrophobic poly(vinylidene fluoride) (PVDF) film was successfully prepared by the method of alkali treatment enhancing chemical bath deposition. The surface of PVDF film prepared in this work was constructed by many smooth and regular microreliefs. Oxygen-containing functional groups were introduced in PVDF film by treatment with aqueous NaOH solution. The nano-scale peaks on the top of the microreliefs were implemented by the reaction between dimethyldichlorosilane/methyltrichlorosilane solution and the oxygen-containing functional groups of PVDF film. The micro- and nano-scale structures, similar to the lotus leaf, was clearly observed on PVDF film surface by scanning electronic microscopy (SEM) and atomic force microscope (AFM). The water contact angle and sliding angle on the fabricated lotus-leaf-like PVDF film surface were 157° and 1°, respectively, exhibiting superhydrophobic property and self-cleaning property.  相似文献
2.
Jian Li 《Applied Surface Science》2006,252(6):2229-2234
A super-hydrophobic surface was obtained on a three-dimensional (3D) polyvinylidene fluoride (PVDF) macroporous film. The porous films were fabricated through self-assembled silica colloidal templates. The apparent water contact angle of the surface can be tuned from 106° to 153° through altering the sintering temperature and the diameter of the colloidal templates. A composite structure of micro-cavities and nanoholes on the PVDF surface was responsible for the super-hydrophobicity. The wettability of the porous surfaces was described by the use of the Cassie-Baxter model and Wenzel's equation.  相似文献
3.
徐任信  陈文  周静 《物理学报》2006,55(8):4292-4297
建立了0-3型压电复合材料的等效电学模型.分析了聚合物电导率对复合材料极化性能的影响,研究了聚苯胺改性0-3型锆钛酸铅/聚偏氟乙烯复合材料极化性能与聚合物电导率之间的关系.理论分析和实验结果均表明,提高聚合物电导率可以提高复合材料的极化性能.  相似文献
4.
Dendrite-shaped PbS has been successfully synthesized using hydrothermal method on a large scale. The formation of dendrite-shaped PbS was confirmed by scanning electron microscopy (SEM). A detailed study of variations in dielectric properties on frequency and temperature shows that composites of PVDF and dendrite-shaped PbS have significantly higher dielectric constant than PVDF/PbS nanoparticles (NP) nanocomposites due to low percolation threshold.  相似文献
5.
 采用PVDF贴片传感器对脉冲激光作用下2024铝合金表面的动态应变进行了测量,分析了动态应变曲线的特性。结果表明,PVDF贴片传感器在动态应变测量中动态响应快,灵敏度高,可有效应用于脉冲激光诱导材料表面动态应变的实时测量。脉冲激光作用过程中,2024铝合金冲击光斑周围材料先受挤压,后压应变减小。脉冲激光作用结束后,2024铝合金冲击光斑周围材料表面粒子在卸载稀疏波和表面稀疏波的作用下不断往复运动,冲击光斑周围材料甚至受到了拉应变的作用。最后随着时间的推移,材料表面粒子的动态响应经反复震荡后逐渐衰弱形成最终的稳定状态。  相似文献
6.
袁玲  孙凯华  崔一平  沈中华  倪晓武 《物理学报》2012,61(1):14210-014210
表面粗糙是材料制造过程中必有的副产物, 粗糙表面会引起其中传播的声表面波的速度发生变化. 在利用激光声表面波对材料性质进行评估时, 常用宽带的激光声表面波速度频散特性对材料性质进行反演. 为了研究表面粗糙度是否能作为反演的特征参数之一, 本文建立了激光在表面粗糙样品中激发声表面波、聚偏氟乙烯换能器宽带接收声表面波的实验装置来研究不同粗糙度表面对声表面波速度的影响; 理论上建立了激光在粗糙表面中激发声表面波的计算模型, 利用有限元法得到声表面波的时域特征, 并进一步得到声表面波的速度色散曲线, 理论结果和实验结果能很好地拟合. 这为利用激光声表面波对表面粗糙的评估提供理论和实验依据.  相似文献
7.
Recent studies have shown that giant flexoelectricity may exist in certain elastomers with bent-core molecular structures, which contradicts the previous theoretical estimation that the flexoelectric coupling is small in those materials. In this Letter, we report an analogous phenomenon, i.e., the giant direct flexoelectric effect, observed in a polyvinylidene fluoride (PVDF) film. Our experimental studies indicate that such an enhanced flexoelectric effect might be induced by the interaction between the energy couplings of the apolar and the polar molecular structures of the polymer film under elastic deformation.  相似文献
8.
Films of polyvinylidene fluoride (PVDF) filled with (X)LiBr(20−X)MnCl2 mixture, where X=0, 1, 2, 8, 16 and 20 wt%, were prepared by casting method and studied by ultraviolet/visible optical absorption (UV), differential scanning calorimetry (DSC), X-ray diffraction (XRD), infrared transmission (IR) and electron spin resonance (ESR). The optical absorption spectra suggested the presence of an optical gap (Eg) which depends on filler concentration (W) and arises due to the variation in crystallinity within the polymer matrix. Melting and degradation temperatures were identified using DSC. XRD implied a semicrystalline structure (containing α- and β-PVDF phases for all films). Conjugated double bonds and the role of dimethylformamide with a PVDF chain were detected by IR spectra. The ESR analysis revealed the existence of both isolated and aggregated Mn2+ ions within the PVDF matrix.  相似文献
9.
This article reports on the magnetoelectric (ME) effect observed in bi- and trilayered polymers consisting of polyvinylidene fluoride (PVDF) and polyurethane (PU) filled with magnetically hard magnetite Fe3O4 or Terfenol-D(TeD) magnetostrictive material. The samples had the following compositions: (PU+2 wt% Fe3O4/PVDF), (PU+2 wt% Fe3O4/PVDF/PU+2 wt% Fe3O4), (PU+50 wt% TeD/PVDF) and (PU+50 wt% TeD/PVDF/PU+50 wt% TeD). A model, based on a driven damped oscillation system, has been developed to evaluate and study the influence of the first and second-order ME coefficients on the dc magnetic field-induced phase switching phenomenon between dynamic ME current and the applied ac magnetic field. A good agreement between the simulated results and experimental data was obtained and it was found that phase switching characteristics are mainly influenced by the ME losses induced by magnetostriction losses.  相似文献
10.
A superhydrophobic surface was obtained by embedding hydrophobically modified fumed silica (HMFS) particles in polyvinylidene fluoride (PVDF) matrix. The water contact angle (WCA) on the PVDF-HMFS hybrid composite coating is influenced by the content and nature of silica particles in the coating. As the silica concentration in PVDF matrix was increased from 33.3% to 71.4%, WCA increased from 117° to 168° and the sliding angle decreased from 90° to <1°. Surface topography of the coating was examined using scanning electron microscopy. An irregular rough surface structure composed of microcavities and nanofilaments was found to be responsible for the superhydrophobicity. The method is simple and cost-effective and can be used for preparing self-cleaning superhydrophobic coating on large areas of different substrates.  相似文献
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