Rozana Mohd Dahan

Effect of Annealing Temperature on the Crystallinity, Morphology and Ferroelectric of Polyvinylidenefluoride- Trifluoroethylene (PVDF-TrFE) Thin Film

The annealing temperature for 250 nm PVDF-TrFE (70:30 mol %) spin coated thin films were varied at solvent evaporation (Ts = 79 °C), Curies transition (Tc= 113 °C), till melting temperature (Tm = 154 °C). XRD measurement showed that, there was an improvement in the crystallinity of the annealed films, consistent with the increased in the annealing temperatures. Morphological studies of the annealed PVDF-TrFE thin films as observed with Field Emission Scanning Electron Microscope (FESEM) (100k magnification), showed enhanced development of elongated crystallite structures known as ferroelectric crystal. However, thin film annealed at 160 °C (AN160) showed fibrous-like structure with appearance of nanoscale separations, which suggested high possibility of defects. Ferroelectric characterization indicated an improvement in the remnant polarization of annealed PVDF-TrFE thin films with the exception to AN160 in which leakage of current was inevitable due to the presence of cracks on the film surface.

Effect of Fiber Treatment on the Fiber Strength of Kenaf Bast Fiber as Reinforcing Material in Polymer Composite

The use of natural fibers at high percentages of loading in thermoplastic composites for the production of sustainable and green materials in consumer goods, furniture, automotive industry and construction industry is emerging. Several studies have been conducted by many researchers to improve the mechanical properties of the fibers and the fiber-matrix interface for better bonding and load transfer especially when high fiber loading is used. The natural fiber hydrophilic properties make the poor interface and poor resistance to moisture absorption when used to reinforce hydrophobic matrices. Therefore, this study investigates the effects of different surface treatment namely magnesium chloride (MgCl2) and sodium hydroxide (NaOH) on the properties of kenaf fiber for different molarities. Morphology using scanning electron microscopy (SEM) and fourier transform infrared (FTIR) spectroscopy and tensile properties of kenaf fibers after different surface treatment are evaluated. Results showed that the treatment on kenaf fibers has removed the hydroxyl group in cellulose and increase the surface roughness which resulted in the improvement of the tensile properties of kenaf fibers as compared to untreated kenaf fibers.

Different surface morphology of annealed PVDF-TrFE thin films and the effect on its ferroelectric properties

The different morphology of 250 nm PVDF-TrFE (70:30 mol%) thin films were observed in relation to its ferroelectricity. The annealing temperatures were varied from solvent evaporation (Ts), Curies transition (Tc), up to melting temperature (Tm). It was found that the annealing process promoted the development of elongated crystallite structure also known as ferroelectric crystal, which significantly improved the ferroelectric properties of PVDF-TrFE (70:30 mol%) thin films. However, the presence of nanoscale separations on the thin film annealed over Tm (AN160) suggested high possibility of defects, and hence a reduction in ferroelectric properties of thin films.

Surface Modification of Polyvinylidenefluoride-Trifluoroethylene Film Using Argon Gas Plasma

This study investigates the surface properties of plasma surface modified spin coated PVDF-TrFE (70/30) film using Atomic Force Microscopy (AFM), Water Contact Angle (WCA) and X-ray Photoelectron Spectroscopy (XPS). The surfaces of the spin coated PVDF-TrFE film were modified using 13.56 MHz rf Argon plasma. The exposure time of the charged particle PVDF-TrFE films were varied for 1, 3 and 5mins. Prior to modification, the average surface roughness obtained was 8.615nm, but upon modification, the surface roughness was found to increase to 12.466nm. The value of the contact angle of the modified film was reduced from 90o to 43o and the XPS analysis showed dehydrofluorination of PVDF-TrFE films surfaces. The improved in surface roughness and the increased in wettability of the modified film, resulted in good biocompatibility of the modified PVDF-TrFE thin films. This phenomenon has created interest in researchers for developing functional polymer used for applications in areas such are biomedical, bio-analytical assays, textile and even food industry.

The Study of the Surface Morphology of PVDF/MgO Nanocomposites Thin Films

This study investigates the effect of varying loading percentages of MgO on the topography and morphology of Poly (vinylideneflouride)/Magnesium Oxide (PVDF/MgO) nanocomposites thin films. PVDF/MgO nanocomposites spin coated thin films with thicknesses ranging from 200nm to 456nm were successfully characterized. The nanocomposite solutions were spin coated on Al-glass substrates at 1500rpm. The topography and surface roughness of PVDF/MgO nanocomposites were characterized by using AFM. FE-SEM was used to investigate the surface morphology of the nanocomposites thin films and ATR-FTIR was used to determine the chemical bonding of PVDF/MgO nanocomposites. MgO (7%) was found to be the optimum loading percentage for PVDF/MgO nanocomposite film with favorable distribution of MgO particles, minimum defects and high content of β-phase as evident by FESEM and FTIR.

Ferroelectric characteristics of ZnO/MgO-based organic capacitor

Magnesium oxide, MgO with nanometre dimension particles size (36 to 73 nm) was successfully deposited on cleaned glass substrate. The drying temperatures were varied from 100 to 300°C and the dielectrics behaviour was investigated. From the results, it was revealed that variation of nano-MgO films properties obtained by changing the drying temperature. Nano-MgO film dried at 200°C was found to be a good dielectric layer due to it structural properties that resulted in the enhancement of relative permittivity value. The electrical properties shows better in dielectric layer characteristic where the resistivity was found to be 12.8 × 104 Ω.cm with leakage current density of 10−9 A.cm−2. The ZnO/MgO-based organic capacitor was fabricated and the remnant polarisation obtained was in range of 59 to 69 mC/m2 with capacitance value of 40 pF.

Mechanical, morphological and thermal properties of linear low density polyethylene/poly(lactic acid) blends

Melt blending of linear low density polyethylene (LLDPE) and polylactic Acid (PLA) were performed in a twin screw extruder. The blend compositions were prepared in the ratios of 0/100; 15/85; 25/75; 35/65 and 50/50 of PLA/LLDPE. The objective of this work is to study the effect of different content of the PLA on the properties of the blends. The phase morphology and mechanical properties of the thermoplastic blend samples were examined. The blend compositions were optimized by tensile and Izod impact tests. The thermal properties were examined by TGA and DSC. The tensile strength result of the blend with the addition of 50 wt.% PLA decreased by 57% as compared to the neat LLDPE. Examination of images from fracture surface of tensile specimen using scanning electron microscope (SEM) showed the presence of fibrous surface (ductile fracture) for sample with higher content of LLDPE. The TGA results for the PLA/LLDPE blends samples shows two degradation steps of mass loss during heating. DSC results for all po...

Structural and electrical properties of PVDF-TrFE/ZnO bilayer and filled PVDF-TrFE /ZnO single layer nanocomposite films

Abstract This study investigates the effect of ZnO nanofillers loading ratios on Polyvinylideneflouride-Triflouroethylene/Zinc Oxide (PVDF-TrFE/ZnO) nanocomposites thin films; filled single layer and bilayer film. Both films were produced using a spin coater with ZnO nanofillers of weight percentages 1, 3, 5 and 7%. These films were characterized for their crystal phase change via ATR-FTIR and electrical properties using I-V measurement. The ATR-FTIR for both single layer and bilayer nanocomposites films showed three distinguished peaks at absorption bands of 1400, 1290 and 848 cm−1, evident of the β-phase PVDF-TrFE crystals. The resistivity value recorded for the bilayer PVDF-TrFE/ZnO nanocomposites thin films were significantly higher in comparison to the filled single layer PVDF-TrFE/ZnO nanocomposites film. At 1 wt%, the resistivity value for PVDF-TrFE/ZnO bilayer thin film was 4.34 × 105 Ω cm, relative to 1.50 × 105 Ω cm resistivity value, for the single layer film. Therefore, it is established in this study that PVDF-TrFE/ZnO bilayer film showed enhanced resistivity property at small loading percentage of ZnO nanofillers, suggests that the bilayer film is suitable to be utilized as a dielectric film for storage devices.

Effect of Exposure Time on Plasma Modified Polyvinylidenefluoride-Trifluoroethylene (PVDF-TrFE) Film Surfaces

This study investigates the plasma surface modified spin coated PVDF-TrFE (70/30) film of 200nm thick using Atomic Force Microscopy (AFM), Water Contact Angle (WCA) and Fourier Transform Infrared Spectroscopy (FTIR). The surface of the spin coated PVDF-TrFE film were modified using 13.56 MHz rf Argon plasma. The exposure time of the charged particle on PVDF-TrFE films were varied for 1, 3, 5, 7 and 9mins. Prior to modification, the average surface roughness observed was 3.5nm. However upon modification, the surface roughness was increased to 9.5nm. The contact angle of the surface modified film was reduced from 89° to 58°. The increase in surface roughness and wettability of the modified film provided good biocompatibility. This finding created great interest in developing functional polymer suitable for applications in areas such are biomedical, bio-analytical assays, textile and even food industry.

Ferroelectric Properties of Polyvinylidenefluoride-Trifluoroethylene (PVDF-TrFE) Annealed Thin Film

The annealing temperature for 250nm PVDF-TrFE (70:30 mol %) spin coated thin films were varied at solvent evaporation (Ts = 79°C), Curies transition (Tc= 113°C) till melting temperature (Tm = 154°C). From the XRD measurement, there was an improvement in the crystallinity of the annealed films, consistent with the increased in the annealing temperatures. Morphological studies of the annealed PVDF-TrFE thin films as observed with Field Emission Scanning Electron Microscope (FESEM) (100k magnification), showed enhanced development of elongated crystallite structures better known as ferroelectric crystal. However, the AN160 thin film showed fibrous-like structure with appearance of nanoscale separations, which suggested to posed high possibility of defects. Ferroelectric characterization indicated an improvement in the remnant polarization of annealed PVDF-TrFE thin films with the exception to AN160 in which leakage of current was inevitable due to the presence of cracks on the film surface.