“…As revealed by Figure (a), there is only a diffused peak for PEEK films with different stretching ratios at 135°C, indicating that the lower stretching temperature promotes the formation of the amorphous PEEK films. As demonstrated by Figure (b), there are the three sharp peaks indexed as 110, 200, and 020 for PEEK films with different stretching ratios at 210°C, hinting that the higher stretching temperature induces the formation of the crystalline PEEK films. Therefore, the improvement in the tensile strength of PEEK films stretched at the lower temperature (below and close to the glass transition temperature of PEEK, T ≤ 155°C, T g = 143°C) origins from the single effect of orientation, whereas the enhancement in the tensile strength of PEEK films stretched at the higher temperature (above the glass transition temperature of PEEK, T ≥ 190°C, T g = 143°C) result from the synergistic effect of orientation and crystallization.…”
Section: Resultsmentioning
confidence: 88%
“…When the stretching temperature is greater than or equal to 190°C ( T ≥ 190°C), the obtained PEEK films is crystalline, as proven by Figure (b). As revealed by Figure (b), there are the three sharp peaks indexed as 110, 200, and 020 for PEEK films ( T ≥ 190°C). Hence, the change of the tensile strength depends on two aspects of orientation and crystallization.…”
High-strength poly(ether ether ketone) (PEEK) films were prepared through melt extrusion followed by stretching. The tensile strength, orientation, and crystallization behaviors of PEEK films were characterized by universal testing machine, thermomechanical analysis, wide-angle X-ray diffraction, and differential scanning calorimetry. The results indicated that the tensile strength of PEEK films mainly depended on the stretching rate (m), stretching temperature (T), and stretching ratio (k L ). Moreover, the tensile strength of the stretched PEEK film (333 MPa) was almost four times higher than that of the unstretched PEEK film (87 MPa) under an optimized condition. This is attributed to a synergistic effect of orientation and crystallization in the stretching process, and the influence of orientation is stronger than that of the crystallization on the improvement of the tensile strength of PEEK films. V C 2013Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40172.
“…As revealed by Figure (a), there is only a diffused peak for PEEK films with different stretching ratios at 135°C, indicating that the lower stretching temperature promotes the formation of the amorphous PEEK films. As demonstrated by Figure (b), there are the three sharp peaks indexed as 110, 200, and 020 for PEEK films with different stretching ratios at 210°C, hinting that the higher stretching temperature induces the formation of the crystalline PEEK films. Therefore, the improvement in the tensile strength of PEEK films stretched at the lower temperature (below and close to the glass transition temperature of PEEK, T ≤ 155°C, T g = 143°C) origins from the single effect of orientation, whereas the enhancement in the tensile strength of PEEK films stretched at the higher temperature (above the glass transition temperature of PEEK, T ≥ 190°C, T g = 143°C) result from the synergistic effect of orientation and crystallization.…”
Section: Resultsmentioning
confidence: 88%
“…When the stretching temperature is greater than or equal to 190°C ( T ≥ 190°C), the obtained PEEK films is crystalline, as proven by Figure (b). As revealed by Figure (b), there are the three sharp peaks indexed as 110, 200, and 020 for PEEK films ( T ≥ 190°C). Hence, the change of the tensile strength depends on two aspects of orientation and crystallization.…”
High-strength poly(ether ether ketone) (PEEK) films were prepared through melt extrusion followed by stretching. The tensile strength, orientation, and crystallization behaviors of PEEK films were characterized by universal testing machine, thermomechanical analysis, wide-angle X-ray diffraction, and differential scanning calorimetry. The results indicated that the tensile strength of PEEK films mainly depended on the stretching rate (m), stretching temperature (T), and stretching ratio (k L ). Moreover, the tensile strength of the stretched PEEK film (333 MPa) was almost four times higher than that of the unstretched PEEK film (87 MPa) under an optimized condition. This is attributed to a synergistic effect of orientation and crystallization in the stretching process, and the influence of orientation is stronger than that of the crystallization on the improvement of the tensile strength of PEEK films. V C 2013Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40172.
“…Our previous study [41] reported the impregnation of PA6 precursor fiber with cupric chloride solution followed by oxidative stabilization in air at 180℃. Figure 1 shows the procedure used during the preparation of PA6-based carbon fiber.…”
Section: Resultsmentioning
confidence: 99%
“…The curve-fitted equatorial X-ray diffraction trace of untreated PA6 fiber presented in Figure 6(a) demonstrates the presence and coexistence of a polymorphic structure containing α and γ-crystalline forms along with an amorphous phase. Qualitative inspection of the equatorial X-ray diffraction trace of PA6 fiber shows three strong and well-defined reflections with d-spacings of 0.436, 0.413 and 0.378 nm which can be indexed as the α-form (200), γ-form (200) and α-form (002/202) reflections (Figure 6) [41]. Figure 6.Equatorial X-ray diffraction traces of untreated PA6 (a), 3% CuCl 2 impregnated PA6 sample oxidatively stabilized in air 180℃ for 12 h (b) and oxidatively stabilized sample pre-carbonized in nitrogen at 250℃ for 4 h (c).…”
Amorphous carbon fiber from polyamide 6 (PA6) precursor was produced using a multi-step procedure consisting of oxidative stabilization in air at 180℃ in the presence of cupric chloride impregnation, pre-carbonization at 250℃ and carbonization at temperatures ranging from 500℃ to 1000℃ in nitrogen. The results obtained from thermal analysis data suggested that cupric chloride impregnation enhanced thermal stability. During the oxidative stabilization process, a polymorphic structure consisting of α- and γ-phases was eliminated due to the decrystallization process. The pre-carbonization step was found to be necessary to enhance the thermal stability of oxidatively stabilized PA6 fiber prior to carbonization. The results suggested that the pre-carbonization step improved the aromatization and crosslinking reactions. The results obtained from the experimental data suggested that the carbonization temperature had an effective role on the molecular structure and properties of the resulting carbon fibers. The carbon fibers obtained from stabilized and pre-carbonized PA6 fibers showed physical and structural changes with rising temperature. They were characterized by a reduction in fiber diameter, linear density, carbon fiber yield, hydrogen and nitrogen content values due to the removal of non-carbon elements together with increases in the values of density, crystallite thickness, carbon content, C/H ratio and electrical conductivity values. The results obtained from X-ray diffraction, IR spectroscopy and elemental analysis suggested that the crystalline structure was totally lost and converted to a carbonized structure at 500℃ and above due to the formation of an amorphous carbon structure during carbonization reactions.
“…DSC is the most direct experimental technique to resolve the energetic of conformational transitions of biological macromolecules [5]. In order to investigate the thermal stability of the employed catalysts, DSC analysis was conducted [6]. The melting point of the semi crystalline material is observed at the temperature around 120°C.…”
In deciding the workable layout of any network an appropriate technology plays a major role and can improve accuracy and flexibility efficiently, if chosen and implemented in best possible way. The growth in the infrared applications has created a need for knowledge of its optical characteristics in the spectral region for the purpose of designing. Very little work is previously reported in natural oil doped PVA membranes. In this work, a simple attempt is made synthesize and characterize the wintergreen oil and basil oil doped PVA membranes. In investigation, basil oil and wintergreen oil doped PVA membranes were prepared and is made to characterize. The resulting membranes were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WXAD), thermo-gravimetric analysis (TGA) and differential scanning Calorimetry (DSC).
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