Synthesis, Characterization and USW Sensor of PEO/PMMA/PVP Doped with Zirconium Dioxide Nanoparticles

Piezoelectric phenomena is very important for various applications such as ultrasound waves (USW) sensor and pressure sensors. The raw materials from polyethylene oxide (PEO), Poly(methyl methacrylate)(PMMA) and poly(N-vinyl pyrrolidone) (PVP) polymer blends were doped with 0.02,0.04 and 0.06 wt% from zirconium dioxide (ZrO 2 ) nanoparticles (NPs) as a nanocomposites (NCs). The resultant lms were prepared by dry casting method. The optical microscope (OM) and scanning electron microscopy (SEM) were used to satised from the SiO 2 NPs diffusion in the blend. The SiO 2 NPs were good diffused inside the blend with some weak aggregation happened in the high content of NPs. The composite lms were diagnosed by FTIR. The USW properties were measured for k1 spaceman with various frequencies (25,30,…,45) MHz. The USW coecients were clearly effected by the frequency varied. The resulted composite lm was succeeded to be used as USW sensor, also these ndings could help to realize these new NCs as promising materials for wide applications, such as backlight, car glass and UV lters.


Introduction
The piezoelectric effect or US sensor, known as the direct piezoelectric effect, is an electrical generating phenomena which occurs when a material is exposed to external pressure, mechanical stress or applied force. PEO is a one type of polymers that synthesis from polyether polymer (PE) [1]. PEO has a many important applications in treatment of water, papers industries, physical, medical and engineering [2]. PMMA is a tough and strong, lightweight polymer. It has a density of (1.17-1.20 g/cm 3 ), that is less than half that of glass [3]. PMMA has good impact strength, higher than both polystyrene and glass [3]. PVP is a one kind of vinyl polymers, PVP powder has white color, stable in different temperature ranges, hygroscopic, and good solubility in water. It has a good ability to complexes form with various materials [4]. Zirconium dioxide (ZrO 2 ) has distinguished physical and chemical properties such as heat and chemical resistance, high hardness and strength and catalytic activity characterization, furthermore its mostly used in catalysts industrializations, piezoelectricity, solid fuel batteries [5]. ZrO 2 properties change by very small amounts [5]. ZrO 2 have highly conditioned on the diameters of NPs [6]. The smallest ZrO 2 NPs diameter usually absorbs the photon and have peaks near to UV region, but largest domain cause scattering increases and have broaden and shift to longer IR shifting wavelengths [7,8] 2.2 Synthesis of NCs: Polymers NCs lms were prepared by mixing of the raw materials in (50 mL) deionized water (DI) in a glass beaker at (60 o C) hot plate magnetic stirrer. The process continued for (1 hrs.) to getting on homogenous mixture. The NPs were respectively added as (0.02, 0.04 and 0.6) wt.% as shown in Table (1), for (3 hrs.) then the mixture casted in (5 cm Petri dish) and leaved for two weeks to dry. By digital micrometer, the samples thickness were in the range between (80-95) µm.

The Usw Characterization
The morphological propertied were carried out using Nikon, Olympus model 73346 camera. The spaceman was characterized using FTIR (Vertex 701,Bruker) in the spectral range (4000 -400) cm -1 .
The USW measurements were practically made using (SV-DH-7A/SVX-7) at various frequencies. The USW were applied for testing in the region between the sender and receiver. The receiver converts US pulses to the electrical pulses then received by oscilloscope. The apparent signal in 1 st . channel contains positive peak represent incident USW or initial amplitude (A o ) and the negative part in the 2 nd . channel refers to receiver amplitude (A).

Results And Discussion
The density of PEO/PMMA/PVP composite gels and lms were measured for k1 spaceman at room temperature. Figure (4) represents the densities of all aqueous solutions increased by the increasing of the ration of SiO 2 NPs, because of the gels formed across linked among the molecules of PEO/PMMA/PVP and ZrO 2 NPs that occupied the spaces between PEO/PMMA/PVP molecules, furthermore, the density increased with increasing of doping materials [9].
The US transmittance waves (T) have been computed by [10]: From Figure (6) we notice that, the USW velocity of (PEO/PMMA/PVP) decreased with the increasing of frequencies, and computed by [11]: V= X / t …….……..…… (2) This behavior return to structural relaxation that happens in the associated PEO/PMMA/PVP and ZrO 2 NPs composite with various frequency values. A collide at rest has internal characteristics similar to solid, but when the waves propagate resulted different periodic causes molecules ow between spaces in the lattice during compressing and nally return to the original position. The USW velocity has been directly proportion with ZrO 2 NPs added, but inversely proportional with frequency, because USW causes various physical interaction between PEO/PMMA/PVP and ZrO 2 NPs molecules, lead to increase the velocity, but the increasing of frequencies led to decrease the velocities [12]. Figures (6 and 7) show that, the relaxation time and relaxation amplitude also decrease against the frequencies according to theoretical equation [13]: The increasing of PEO/PMMA/PVP doped with ZrO 2 NPs chains led to increase the fraction between the composition layers that examined by moment of inertia [14].
The compressibility of PEO/PMMA/PVP doped with ZrO 2 NPs were theoretically calculated by Laplacian equation [15], so the values increased by the increasing of frequency: The Young modulus (K) was calculated by [16]: The results in Figure (8) show that the compressibility of PEO/PMMA/PVP were increased with the increasing of frequencies, this is because the propagation of USW made a random polymer chain conformation, in addition of the USW make a compression lead to reduce the elasticity of composition [17]. Furthermore, the velocity of USW is inversely proportional with compressibility. Figure (9

Conclusions
PEO/PMMA/PVP/ZrO 2 NPs novel composite lms were successfully prepared by casting method at thickness of (80-95) µm. The OM and SEM images show a strong diffusion of NPs in the mixtures, furthermore FTIR peaks refers to good interactions between the raw material and NPs. The results also refer to NCs suitable for using in the many coating purposes. The new composite lms can be used as resistant materials versus environment. The NCs havehuman skin harmless property. The obtained results show that most of physical properties were affected by the increasing of ZrO 2 NPs. Most of the results were enhanced after doping and presented higher values than original. When, the ZrO 2 NPs increased the density, viscosity, USW velocity and USW absorption coe cient of the polymer doped ZrO 2 NPs were also increased. In addition, ZrO 2 NPs led to increase the compressibility of USW and thus became more tolerable to environmental conditions and can be used in the modern external environment, and many industrial applications. In this study, it was found that the best frequency value is (25 MHz), which showed the best mechanical USW results. The mechanical properties enhanced after frequency varied such as, ultrasonic velocity and bulk modules. The dielectric constant of the k1 spaceman was (85%) increased with increasing of applied load. As a result, USW sensors can be made from (PEO/PMMA/PVP)/ZrO 2 NCs lm.        Relaxation amplitude vs. frequency  Bulk modulus vs. frequency    Dielectric constant vs. applied load of k2 spaceman.