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.

Poly(vinylidene fluoride) (PVDF) has been made radiation-resistant through a nanocomposite (NC) route. The bombardment of high-energy swift heavy ions (SHI) on PVDF and its NCs with layered silicate has been studied in a range of fluences. The degradation of PVDF after SHI irradiation is suppressed radically in NCs. PVDF forms an intercalated nanostructure in the presence of nanoclay and, further, the ion fluence raises the extent of intercalation. The crystallinity and the heat of fusion of pristine PVDF have drastically been reduced after SHI irradiation, while there are relatively small changes in NCs even at higher fluences. The metastable piezoelectric beta form of PVDF gets stabilized by the presence of layered silicate, and the structure is retained upon SHI irradiation. The clay platelets act as nucleating agents, and SHI irradiation causes two crystallization temperatures for the samples exposed to high fluences. The damages created on the surface and bulk of PVDF and its NC films upon SHI irradiation have been measured quantitatively by using atomic force microscopy. The pitting dimensions and degradation are enhanced significantly beyond 10(11) ions/cm(2) fluence for pristine PVDF, which limits the use of PVDF for any ion irradiation application. The degradation is considerably suppressed in NCs, providing a suitable high-energy radiation-resistant thermoplastic polymer.

Poly(vinylidene fluoride-co-hexafluoropropylene) (HFP) nanocomposites with layered silicate have been synthesized via the melt extrusion route. The intriguing nanostructure, crystalline structure, morphology, and thermal and mechanical properties of the nanocomposites have been studied and compared critically with pristine polymer. HFP forms intercalated or partially exfoliated nanostructure (or both) in the presence of nanoclay, depending on its concentration. The bombardment of high-energy swift, heavy ions (SHI) on HFP and its nanocomposites has been explored in a wide range of fluence. The nanoclay induces the piezoelectric beta-phase in bulk HFP, and the structure remains intact upon SHI irradiation. SHI irradiation degrades pure polymer, but the degradation is suppressed radically in nanocomposites. The heat of fusion of pristine HFP has drastically been reduced upon SHI irradiation, whereas there are relatively minute changes in nanocomposites. The coarsening on the surface and bulk of HFP and its nanocomposite films upon SHI irradiation has been measured quantitatively by using atomic force microscopy. The degradation has been considerably suppressed in nanocomposites through cross-linking of polymer chains, providing a suitable high-energy, radiation-resistant polymeric material. A mechanism for this behavior originating from the swelling test and gel fraction (chemical cross-linking) as a result of SHI irradiation has been illustrated.