Poly(vinylidene fluoride), PVDF, as one of essential polymeric components with extensively

Poly(vinylidene fluoride), PVDF, as one of essential polymeric components with extensively scientific passions and technological applications, displays five crystalline polymorphs with , , , and phases obtained by different processing strategies. 4.90 ?, and = 2.56 ? [12]. Three characterization methods, specifically X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) are accustomed to research the development and contribution of different crystalline phases of PVDF. Open up in another window Figure 1 Diagrams of the chain conformation for , and crystalline phases of PVDF [13]. The XRD and FTIR can put into action the qualitative identification and quantitative evaluation of the stage (Shape 2a,b). DSC can be a thermo-analytical technique that is complementary to the additional identification ways to determine the crystalline stage of PVDF. The XRD spectra (Shape 2a) concur that the peaks at 17.7, 18.3 and 19.9 characteristic of the phase of PVDF, and the peaks at 18.5, 19.2, 20.0, characteristic of the phase. The peak at 2 = 20.26 is related to the diffraction of phase at (110) and (200) [14,15,16]. FTIR spectra of these three PVDF polymorphs have been investigated thoroughly and extensively [5,17,18,19]. Vibrational bands of phase are at 530 cm?1, 615 cm?1 and 765 cm?1 and 795 cm?1, while vibrational bands exclusively of phase are at 510 cm?1 TGFB4 and 840 cm?1, and the bands correspond to the phase are at 431 cm?1, 776 cm?1, 812 cm?1, 833 cm?1 and 1233 cm?1, as shown in (Figure 2b). The melting temperatures of the crystallites and phase PVDF are similar at 167C172 C (Figure 2c), so DSC is used to calculate the crystalline percentage, but not to distinguish these three phases [15,20]. As a result, two of the above three measurement techniques are needed to identify a specific phase at least. Open in a separate window Figure 2 Synopsis of main experimental features of the different experimental techniques for correct identification of the PVDF phase: (a) XRD (K1, = 1.5405600 ?); (b) FTIR; and (c) DSC [16]. Though the IR spectrum of the , and phases includes many of the peaks due to overlapping absorptions, several unique peaks for different phases can be used for identification and quantification of the , and phases, such as their relative amounts. The IR absorption bands, characteristic of the and phases in each sample are at 766 cm?1 and 840 cm?1, respectively. The fraction of phase, F(), can be calculated using Equation (1) explained by Gregorio, and the formula is as follows: and purchase Actinomycin D in Equation (1) are representative for the mass fraction of and phases, absorption bands at 763 cm?1 and 840 cm?1 are represented by the and and the absorption coefficients are expressed by and purchase Actinomycin D at the particular wavenumber, respectively. This equation was used to quantify the FTIR results [5]. It is known that the peaks may be assigned to the different crystal phases. One issue is the overlapping of various peaks. The overlapping peaks could be deconvoluted using OMNIC software [21,22]. The aforementioned method can be used to calculate the crystalline phase content of PVDF when just two phases are present in the material ( and , and or and ). 3. Processing Techniques of Phase PVDF The phase PVDF obtained by phase transitions, solvent casting, by the addition of nucleating fillers, or the development of PVDF copolymers have been researched extensively. 3.1. Phase Transition Methods Phase transitions to obtain phase PVDF can be divided into four methods depending on the processing conditions [23], as shown in Figure 3. Open in a separate window Figure 3 Four transition lines from different conformations to obtain phase PVDF. The phase obtained from melt needs high pressure, high temperature, epitaxial growth on Kbr or other specific circumstances [23,24], as shown line 1 in Figure 3. The high-pressure-crystallized PVDF purchase Actinomycin D which includes both low-melting and high-melting stage was indicated in an in depth research [25,26]. purchase Actinomycin D Quenching and annealing of the PVDF movies can induce the crystallization of stage straight from the melt in purchase Actinomycin D the early research of Yang et al. [26]. The phase PVDF offers been obtained straight from.