PVDF matrix

To achieve the goal of required performance, durability, and cost of plate materials, one approach is improvement of the control of the composition and microstructure of materials, particularly the composite, in the material designing and manufacturing process. For example, in the direction of development of thermoplastics-based composite plate, CEA (Le Ripault Center) and Atofina (Total Group) have jointly worked on an irmovative "microcomposite" material [33]. The small powders of the graphite platelet filler and the PVDF matrix were mixed homogeneously by the dispersion method. The filler and matrix had a certain ratio at the microlevel in the powder according to the optimized properties requirements. The microcomposite powders were thermocompressed into the composite plate. 

Figure 7.4 shows the glass transition temperatures of PVDF/PMMA blends as a function of PVDF content after a melt process. The results " show agreement with Gordon-Taylor relation up to about 40 wt %, which is much higher than the 20wt % obtained from the annealed blends. This is certainly a result of the increased content of amorphous PVDF matrix in melt-processed blends compared with annealed blends. 

Discussion/Colncidence of Crystallization Temperatures. Let us first consider the PVDF/PA-6 blend. In view of the nonaltered T of PVDF, we suppose that the PVDF crystallization induces the PA-6 crystallization rather than vice versa. Hence, the just created crystals of the PVDF matrix act as nucleating heterogeneity for the PA-6. The A y-value between PVDF crystals and PA-6 melt, obviously, is smaller than that of all other heterogeneities which are present in PA-6 to a sufficient extent except, possibly, the species "A". Its associated specific undercooling, moreover, must be so small that the PVDF crystals can induce the crystallization of the PA-6 from the instant of their own creation. 

The coincident crystallization of the PVDF matrix and dispersed PBTP particles in the 85/15 blend (z = 4) takes place at (142...148)°C, that is, above the T of pure PVDF. It is not clear whether the PVDF or the PBTp crystallizes first. In either case, the nucleation of the first crystallizing component may be induced either by a species of nucleating heterogeneities or by the molten second blend component. The newly created crystals of the one component, then, act immediately as nuclei for the crystallization of the other in the same manner as already described for the PVDF/PA-6 blends. 

Frensch and Jungnickel [1989, 1991] and Frensch et al. [1989] have investigated the thermal behavior of polyvinylidene fluoride, PVDF, in blends with polyamides, in relation to the blend morphology. PA-6 droplets could be finely dispersed into the PVDF matrix. The crystalhzation temperature of the PVDF matrix did not seem to be affected in the blends. A similar behavior was observed in PVDF/PA-66 blends. 

Erensch and Jungnickel [1989] and French et al. [1989] have investigated PVDF/PBT blends and related their thermal behavior with the blend morphology. Similar to PVDF/PA-6 blends, the PBT droplet crystallization was completely suppressed in a 85/15 blend and finally crystallized coincidentaly with the PVDF matrix. Again this phenomenon could be related to the fine dispersion of PBT droplets, in number exceeding the available nuclei. Shorter melt-mixing cycles caused a coarser dispersion leading only to a... 

A second system investigated by the authors was the PVDF/PBT blend. Similar effects could be observed. However, coincident crystallization in the PVDF/PBT 85/15 blend occurred at a somewhat higher temperature than the bulk Tpyp,p. It could be concluded that in this case, the PBT melt induced the crystallization of the PVDF matrix phase. 

PVDF) matrix followed by solvent casting resulted in composites that showed a Young s modulus, tensile strength and toughness in the polymer composite which were two to three times higher than that without the compatibilizer at only 0.05% of MWNTs content." ... 

Poly methylmethacrylate (PMMA) can interact with graphene sheets by the interaction of delocalized n-bonds of graphene with n-bonds of PMMA. On the other hand, as reported in articles, PVDF/PMMA blend is a miscible system. Consequently, in attempt to achieve a homogenous dispersion of nanographene layers in PVDF matrix, the use of PMMA chains as a compatiblizer can be useful. 

In this chapter, we have summarized three different strategies to use phosphonated copolymers as corrosion inhibitors to protect metals. In the first part, the blends of organophosphorus monomers copolymerized with MMA in a PVDF matrix showed relatively good efficiency. These studies also showed phosphonic acid groups as good adhesion/corrosion promoters, but... 

Frensch and Jungnickel (1989) and Frensch et al. (1989) tried to elucidate the crystallization behavior of the minor phase in the binary PVDF/PA-6 blends, in relation to the final blend morphology. They reported that the crystallization of the PA-6 droplets was fractionated and/or retarded, depending on the number of mixing cycles and dispersion size. The smaller the PA-6 droplets, the more pronounced the retardation of the crystallization peak (AT 40 °C). Nevertheless, the melting endotherm remained unaffected. They concluded that part or all of the PA-6 phase finally coincidentally crystallized with the PVDF matrix due to the specific mutual nucleating efficiency of both components. 

Thermoplastic polymer polyphenylene sulfide (PPS)/BST composites were obtained with various BST contents. Particles were uniformly dispersed in PPS matrix using a twin-screw extruder, and composites with 70 wt% BST had a dielectric constant and dielectric loss of 13.5 and 0.0025, respectively, at 1 GHz [139]. Li et al. [140] embedded Bao.6Sro.4Ti03/silver core-shell nanoparticles into PVDF matrix. The silver-coated Bao.6Sro.4Ti03/PVDF nanocomposites showed 73% higher dielectric constant than composites of bare BST meanwhile, the dielectric loss was still low (less than 0.2) at 55 vol% filler content. 

Zhou et al. [153] investigated the dielectric properties of surface-hydroxylated BaTiOs (h-BaTi03)/PVDF composites. Compared with crude BaTiOs/PVDF composite, the h-BaTi03/PVDF composite showed lower loss tangent, higher dielectric strength, and weaker temperature and frequency dependences. The dielectric properties of the composites were improved due to the strong interaction between h-BaTiOs fillers and PVDF matrix. 

TEM photomicrograph of PVDF added with 5 wt% of hydrophilic MMT prepared by melt-extrusion. A micron-scale dispersion of primary particles aggregates is observed in the PVDF matrix, as a result of the high interfacial tension between the hydrophobic polymers and the hydrophilic montmorillonite clay. (From N. Moussaif and G. Groeninckx, Polymer 44, 7899-7906,2003. With permission.)... 

Gel and solid polymer electrolytes aim to combine the function of the electrolyte and separator into a single component to reduce the number of parts in an ES and increase the potential window through the higher stability offered by a polymer matrix. A gel electrolyte incorporates a liquid electrolyte into a microporous polymer matrix that holds in the liquid electrolyte through capillary forces, creating a solid polymer film. The chosen separator must be insoluble in the desired electrolyte and provide adequate ionic conductivity. Non-polar rigid polymers such as PTFE, PVA, PVdF, and cellulose acetate offer good ion conductivity when used as gel electrolytes [114]. Based on the data in Table 4.9, the ionic conductivity of EtMeIm+Bp4 is 14 mS.cm". Ionic conductivity of the same imidazolium salt used as a gel electrolyte in a PVdF matrix retains 5 mS.cm [115]. 

Lijie et al. reported the fabrication and characterization of BaTiOs/PVDF nanocomposites via the sol-gel method, in which nanosized BaTiOs particles with an average size of 50-100 nm were grown in situ in the PVDF matrix. BaTiOs is a ferroelectric ceramic widely used in capacitors and ultrasonic transducers. It was observed that the relative dielectric constant of nanocomposites increased in the frequency range of 5 x 10" to 3 x 10 Hz with increasing weight fraction of nanosized ceramic in the polymer matrix [214]. 

Flgura 21 PVDF matrix semii platform with maldpkxing and preampUfias mounted inside td grounded box. (Adapted 6om Rid. 27.)... 

The next factor is the filler content in the nanocomposite. Nanosized particles provide materials with percolation thresholds at lower filler fractions than those consisting of microsized particles (Putson et al., 2011). The optimal mechanical properties for energy harvesting were obtained for samples with lower filler contents (Wu et al., 2014). The most ideal energy-harvesting properties were obtained when the content of GO or MWCNT particles was 0.05 or 0.1 wt%, respectively, because these concentrations significantly influence the P-crystalline phase of the PVDF matrix. 

The effect of a polar solvent such as propylene carbonate, is understandable to promote salt dissociation and to construct ionic conduction column in PVdF matrix. 

Recently, there has been progress in the preparation and formation mechanisms of the fetroelectric (P and/or y) phases. For example, the p and/or y phases coirld be epitaxially grown on surfaces of KBr, NaCl, or mica [145]. Electrospinning, using polar solvents, was demonstrated to be a facile route to prepare ferroelectric PVDF phases [146-148]. The ferroelectric phases could be readily induced by the incorporation of organically modified clays [149-154] and mirlti-walled CNTs [155,156] in the PVDF matrix. A nearly pine p phase was observed in electrospun PVDF composite fibers with nanoclays [157], magnetic nanoparticles [158], or even CNTs [159]. A mechanism based on the ion-dipole... 

When a microfiber network is introduced into the macroporous PVDF matrix, an interpenetrating network structure is obtained, and the prepared gel polymer electrolyte is stable during the charging and discharging processes [23]. 

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