Effect of sodium dodecyl sulfate surface-modified hydrotalcite on thermal stability of PVC
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 rheome-ter,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 hy-drotalcite but was only adsorbed on the surface of LDHs,which enhanced its compatibility with PVC.The static and dy-namic thermal stability times of the PVC/LDHs samples using the LDHs modified SDS for 65 and 28.5 min,respective-ly.Meanwhile,the later coloring of PVC samples was improved to make plasticize and form more easily.The tempera-ture 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.
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