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The effect of Zn-Al-hydrotalcites composited with calcium stearate and β-diketone on the thermal stability of PVC.

Tong M, Chen H, Yang Z, Wen R - Int J Mol Sci (2011)

Bottom Line: The results showed that the Zn-Al-hydrotalcites can be successfully synthesized at three different Zn/Al ratios of 3:1, 2:1 and 1:1.The results showed that Zn-Al-LDHs can not only enhance the stability of PVC significantly due to the improved capacity of HCl-adsorption but also increase the initial stability and ensure good-initial coloring due to the presence of the Zn element.The effects of various amounts of Zn-Al-LDHs, CaSt(2) and β-diketone on the thermal stability of PVC were discussed.

View Article: PubMed Central - PubMed

Affiliation: Hunan Chemical Vocational and Technical College, Zhuzhou 412004, China; E-Mail: 13973327103@163.com.

ABSTRACT
A clean-route synthesis of Zn-Al-hydrotalcites (Zn-Al-LDHs) using zinc oxide and sodium aluminate solution has been developed. The as-obtained materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The effects of metal ions at different molar ratios on the performance of hydrotalcites were discussed. The results showed that the Zn-Al-hydrotalcites can be successfully synthesized at three different Zn/Al ratios of 3:1, 2:1 and 1:1. Thermal aging tests of polyvinyl chloride (PVC) mixed with Zn-Al-LDHs, calcium stearate (CaSt(2)) and β-diketone were carried out in a thermal aging test box by observing the color change. The results showed that Zn-Al-LDHs can not only enhance the stability of PVC significantly due to the improved capacity of HCl-adsorption but also increase the initial stability and ensure good-initial coloring due to the presence of the Zn element. The effects of various amounts of Zn-Al-LDHs, CaSt(2) and β-diketone on the thermal stability of PVC were discussed. The optimum composition was determined to be 0.1 g Zn-Al-LDHs, 0.15 g CaSt(2) and 0.25 g β-diketone in 5 g PVC.

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Fourier transform infrared spectroscopy (FT-IR) spectra of Zn-Al-LDHs with Zn/Al molar ratios of (a) 1:1; (b) 2:1; and (c) 3:1.
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f2-ijms-12-01756: Fourier transform infrared spectroscopy (FT-IR) spectra of Zn-Al-LDHs with Zn/Al molar ratios of (a) 1:1; (b) 2:1; and (c) 3:1.

Mentions: FT-IR spectra of the LDHs samples are shown in Figure 2. As shown in Figure 2, a band near 3,420 cm−1 corresponds to the vibration bands of hydroxyls (νOH). The peak moves to a higher wavenumber with increasing Zn/Al ratio. The possible reason is that the ionic radius of Al3+ is smaller than that of Zn2+ and the charge number of Al3+ is greater than that of Zn2+, the electrostatic force between Al3+ and OH− is stronger than that of Zn2+ and OH− with increasing the Zn/Al ratio. The bending mode of water molecules appears at 1,620 cm−1 and the intensity increases slightly with increasing Zn/Al ratio. The sharp intense band at 1,364 cm−1 is the antisymmetric stretching of interlayer carbonate with high values of Zn/Al ratio. Compared with the peak of CO32− in CaCO3 (1,430 cm−1), a large shift toward a lower wavenumber indicates that the CO32− intercalating into the interlayer is not free, and is interlayered with water molecules between with hydrogen bonds are formed [16]. The interlayer charge density and the coulomb repulsion between interlayer anions increases with decreasing Zn/Al ratio, which results in a stronger peak of interlayer CO32− and a lower wave number (1,357 cm−1). The band at 794 cm−1 is the flexural vibration of CO32−. The bands at 430 cm−1 and 560 cm−1 can be attributed to the lattice vibration modes, M-O and O-M-O vibration, respectively. The structural parameters of FT-IR are listed in Table 1.


The effect of Zn-Al-hydrotalcites composited with calcium stearate and β-diketone on the thermal stability of PVC.

Tong M, Chen H, Yang Z, Wen R - Int J Mol Sci (2011)

Fourier transform infrared spectroscopy (FT-IR) spectra of Zn-Al-LDHs with Zn/Al molar ratios of (a) 1:1; (b) 2:1; and (c) 3:1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3111632&req=5

f2-ijms-12-01756: Fourier transform infrared spectroscopy (FT-IR) spectra of Zn-Al-LDHs with Zn/Al molar ratios of (a) 1:1; (b) 2:1; and (c) 3:1.
Mentions: FT-IR spectra of the LDHs samples are shown in Figure 2. As shown in Figure 2, a band near 3,420 cm−1 corresponds to the vibration bands of hydroxyls (νOH). The peak moves to a higher wavenumber with increasing Zn/Al ratio. The possible reason is that the ionic radius of Al3+ is smaller than that of Zn2+ and the charge number of Al3+ is greater than that of Zn2+, the electrostatic force between Al3+ and OH− is stronger than that of Zn2+ and OH− with increasing the Zn/Al ratio. The bending mode of water molecules appears at 1,620 cm−1 and the intensity increases slightly with increasing Zn/Al ratio. The sharp intense band at 1,364 cm−1 is the antisymmetric stretching of interlayer carbonate with high values of Zn/Al ratio. Compared with the peak of CO32− in CaCO3 (1,430 cm−1), a large shift toward a lower wavenumber indicates that the CO32− intercalating into the interlayer is not free, and is interlayered with water molecules between with hydrogen bonds are formed [16]. The interlayer charge density and the coulomb repulsion between interlayer anions increases with decreasing Zn/Al ratio, which results in a stronger peak of interlayer CO32− and a lower wave number (1,357 cm−1). The band at 794 cm−1 is the flexural vibration of CO32−. The bands at 430 cm−1 and 560 cm−1 can be attributed to the lattice vibration modes, M-O and O-M-O vibration, respectively. The structural parameters of FT-IR are listed in Table 1.

Bottom Line: The results showed that the Zn-Al-hydrotalcites can be successfully synthesized at three different Zn/Al ratios of 3:1, 2:1 and 1:1.The results showed that Zn-Al-LDHs can not only enhance the stability of PVC significantly due to the improved capacity of HCl-adsorption but also increase the initial stability and ensure good-initial coloring due to the presence of the Zn element.The effects of various amounts of Zn-Al-LDHs, CaSt(2) and β-diketone on the thermal stability of PVC were discussed.

View Article: PubMed Central - PubMed

Affiliation: Hunan Chemical Vocational and Technical College, Zhuzhou 412004, China; E-Mail: 13973327103@163.com.

ABSTRACT
A clean-route synthesis of Zn-Al-hydrotalcites (Zn-Al-LDHs) using zinc oxide and sodium aluminate solution has been developed. The as-obtained materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The effects of metal ions at different molar ratios on the performance of hydrotalcites were discussed. The results showed that the Zn-Al-hydrotalcites can be successfully synthesized at three different Zn/Al ratios of 3:1, 2:1 and 1:1. Thermal aging tests of polyvinyl chloride (PVC) mixed with Zn-Al-LDHs, calcium stearate (CaSt(2)) and β-diketone were carried out in a thermal aging test box by observing the color change. The results showed that Zn-Al-LDHs can not only enhance the stability of PVC significantly due to the improved capacity of HCl-adsorption but also increase the initial stability and ensure good-initial coloring due to the presence of the Zn element. The effects of various amounts of Zn-Al-LDHs, CaSt(2) and β-diketone on the thermal stability of PVC were discussed. The optimum composition was determined to be 0.1 g Zn-Al-LDHs, 0.15 g CaSt(2) and 0.25 g β-diketone in 5 g PVC.

Show MeSH