Effect of sodium dodecyl sulfate surface⁃modified hydrotalcite on thermal stability of PVC

doi:10.19491/j.issn.1001-9278.2024.02.013

Abstract

Abstract:

Sodium dodecyl sulfate （SDS） was used to modify magnesium⁃aluminum⁃lanthanum carbonate hydrotalcite （LDHs）， and the effect of different modification conditions on the static thermal stability of poly（vinyl⁃chloride）（PVC） was investigated.The molecular structures of modified PVC samples were characterized by using X⁃ray diffractometry， scanning electron microscopy， and infrared spectroscopy. The thermal stabilities of the PVC samples with modified and unmodified LDHs were evaluated by means of Congo red test paper method， thermal aging oven method， torque rheometer， and thermogravimetric analysis. The results indicated the modification effect was best at a constant pH value of 7 and a mass ratio of SDS to LDHs of 1/10 in a water bath at 80 ℃ for 3 h. SDS did not change the crystal structure of hydrotalcite but was only adsorbed on the surface of LDHs， which enhanced its compatibility with PVC. The static and dynamic thermal stability times of the PVC/LDHs samples using the LDHs modified SDS for 65 and 28.5 min， respectively. Meanwhile， the later coloring of PVC samples was improved to make plasticize and form more easily. The temperature corresponding to the maximum weight loss rate of the modified PVC sample was 346 ℃， which increased by 55 ℃ compared to pure PVC. This could effectively inhibit the thermal degradation of PVC.

Key words: poly（vinyl chloride）, hydrotalcite?like, surface modification

CLC Number:

TQ325.3

LI Xianming, ZHANG Ning, LI Gaihua, LIU Shuang, LIU Zhengyuan. Effect of sodium dodecyl sulfate surface⁃modified hydrotalcite on thermal stability of PVC[J]. China Plastics, 2024, 38(2): 82-86.

Figures/Tables 10

Fig.1. Static thermal stability time of PVC/modified LDHs at different stirring temperature

Fig.2. Static thermal stability time of PVC/modified LDHs under different stirring time

Fig.3. Static thermal stability time of PVC/modified LDHs at different pH value

Fig.4. Static thermal stability time of PVC with different modifier dosages

Fig.5. XRD patterns of LDHs before and after modification

Fig.6. SEM images of LDHs before and after modification

Fig.7. FTIR spectra of LDHs before and after modification

样品	热稳定时间/min	试样随加热时间的颜色变化
样品	热稳定时间/min	10 min	20 min	30 min	40 min	50 min	60 min	80 min	100 min	120 min
PVC/LDHs	27
PVC/SDS⁃LDHs	65

Tab.1. Static thermal stability of LDHs before and after modification

Fig.8. Torque rheological curve of LDHs before and after modification

Fig.9. TG and DTG curves of pure PVC and LDHs before and after modification

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