- 作者: Wang, Jenn-Hwa; Yu, Jin-Min
- 作者服務機構: Department of Chemical Engineering National Cheng-Kung University, Tainan, Taiwan, R.O.C.
- 中文摘要: --
- 英文摘要:
The effects of metallic stearates on the dehydrochlorination of emulsion
polymerized PVC in the early stages up to about 0.9% conversion are studied
by the pH method at temperatures ranging from 160℃ to 200℃ under the
atomospheres of nitrogen, air and oxygen.
Experimental results indicated that all the metallic stearates somewhat possess
a stabilization effect both on the thermal and thermo-oxidative degradation of
PVC, and the magnitude of this effect depends on the kind and concentration of
stearates and the ambient atomospheres. They act as acid acceptors to retard the
rate of dehydrochlorination to a considerable degree during the earlier period up
to about 0.045% conversion, then the rate of decomposition is catalyzed severely
in the later period (0.045%-0.9% conversion) by the metallic chlorides. However,
the addition of the metallic stearate has no effect on the order of dehydrochlorina-
tion reactions. In the range of this experimental conditions, they are constant
rate zero order reactions except the initial period between zero and 0.0027%
conversions.
The orders of effectiveness of various metallic stearates on the retardation of
dchydrochlorination in the earlier period are:
in N2: Sr>Na>Ca>Mg>Ba>Al>Cd>PR-A>Zn
in Air: Sr>Ba>Ca>Na>Mg>Al>Cd>PR-A>Zn
in O2: Sr>Ba>Ca>Na>Mg>Cd>Al>PR-A>Zn
The effects of metallic stearates on the thermal stability under high--temperature
processing conditions are also investigated. - 中文關鍵字: --
- 英文關鍵字: --