Process and nanoparticle induced piezoelectric super toughened poly(vinylidene fluoride) (PVDF) nanohybrids have been demonstrated. The nanohybrids have been prepared by incorporating organically modified nanoclay through melt extrusion and solution route. The solution processed nanohybrid exhibit 1100% improvement in toughness as well as adequate stiffness as compared to pure PVDF without any trade-off. The structural and morphological origins of super toughening phenomena have been worked out. The unique crystallization behavior of PVDF on top of the silicate layers (β-phase, planar zigzag chain conformation, and subsequent polar γ-phase and α-phase as layered type) has been revealed to create an island type of structure, which in turn is responsible for greater toughness. The extent of piezoelectric β-phase has been enhanced by controlled stretching of the nanohybrid at moderately high temperature for better disentanglement, and 90% of the piezoelectric phase has been stabilized. The structural change over has been confirmed through XRD, FTIR, and DSC studies. The nanohybrids possess β-phase with a small amount of α-phase and distorted γ-phase (T 3 G-T 6 G) before stretching which convert into predominantly β-phase with increasing the draw ratio, whereas pure PVDF converted directly into β-phase from pure α-phase. The piezoelectric coefficient (d 33 ) exhibits significant increase with draw ratio, and the relative enhancement is more in nanohybrid vis-a-vis pure PVDF arising from the presence of greater β-phase leading to super toughened lightweight piezoelectric material.
Electrodeposited Ni-SiC composite deposits with 10.5 wt % SiC were produced on copper substrate using a non-aqueous organic solvent. N-Methylformamide was found to be the most suitable solvent as it has a high dielectric constant ͑182͒ that allows high tolerance of the electrolyte in the bath, which is ordinarily not obtained in other solvents. The optimum condition arrived for deposition was nickel acetate 200 g/l, boric acid 35 g/l, SiC 10 g/l, current density 2.0 A dm −2 , duration of electrolysis 30 min, and bath temperature 60°C. Satisfactory bright composite deposits were obtained, which were quite adherent to the copper base. Scanning electron microscope, energy-dispersive analysis by x ray, and X-ray diffraction studies have been performed to characterize the composites. Effect of current density on composition and microhardness of the composite deposits was investigated. Also, the effect of annealing on the microhardness of the deposits was studied.
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