The effects of particle size and concentration of Vietnam calcium carbonate fillers on the critical oxygen index, and the evolution of hydrogen chloride during pyrolysis of PVC have been examined. Both retention of hydrogen chloride in the condensed phase and critical oxygen index chloride in the condensed phase, and critical oxygen index depend not only on concentration but also on particle size of the calcium carbonate. Efficiency of retention of hydrogen chloride increases with decreasing particle size and approaches 100% at particle sizes below 0.1 micron. Critical oxygen index is not appreciably affected by calcium carbonates of particle size around one micron. Coarser calcium carbonates increase critical oxygen index, while finer calcium carbonates decrease it up to concentrations at which all the hydrogen chloride is retained in the condensed phase, after which it is steadily increased with increasing concentration.
Calcium carbonate in PVC might affect burning behaviour in a number of ways including direct modification of degradation reactions, indirect modification of degradai tion reactions by ‘furing’ hydrogen chloride, dilution of organic feedstock, modification of mechanical behaviour and char formation, reduction or prevention of hydrogen chloride evolution into the flame and dilution of flammable organic vapours by inert carbon dioxide and water vapour. The hydrogen chloride itself might modify degradation reactions in the ‘condensed’ phase, inhibit burning by chemical reaction in the vapour phase, and physically dilute flammable organic vapours. Work is continuing with the objective of quantifying the contributions from each of these various mechanisms, but some tentative conclusions may be suggested on the basis of the results presented here.
It seems obvious that inorganic additives must act by dilution of organic feedstock, and it is apparent that the coarsest calcium carbonate examined acts mainly in this way. It is reasonable to suppose that finer calcium carbonates would exert a similar influence at least as efficiently, and that the magnitude of this effect is directly related to concentration. At any concentration then the differences in effects on COI of calcium carbonates of different particle sizes are presumably attributable to differences in effectiveness in retaining hydrogen chloride and releasing equivalent amounts of carbon dioxide and water. At a particle size around one micron any effect arising from furation of hydrogen chloride appears to be balanced by dilution of organic feedstock by the calcium carbonate and flammable vapours by carbon dioxide and water. If the effect of dilution of flammable vapours is independent of the chemical nature of the diluent it should not be affected by retention of hydrogen chloride by the calcium carbonate since in this process equivalent volumes of carbon dioxide and water are liberated. The fact that the finer calcium carbonates cause a reduction in COI suggests that the hydrogen chloride is exerting a chemical effect in either the vapour phase or the condensed phase.
We offers a wide range of Vietnam Calcium Carbonate of different particle size assuring that our different clients will receive suitable quality material with cost-efficiency. We have the purest and brightest source of calcium carbonate and exploit the high standard of sustainability with uncoated and coated Calcium Carbonate (Stearic acid coating Calcite Powder). Raw materials are chosen carefully and the production process is conducted in ISO standard factories to ensure the most consistent quality for end-users.
Uncoated calcium carbonate is natural calcium carbonate obtained from high purity Vietnam lime stone. It is used in many industries as filler to reduce production cost. We can provide a wide range of particle size from 5 to 450 microns.
Coated calcium carbonate is made from uncoated calcium carbonate with 1% stearic acid. It is used for replacing some expensive polymers and additives to reduce production cost with particle size ranging from 5 to 45 microns.
We offers a wide range of calcium carbonate of various particle size, Uncoated and Coated Calcium Carbonate (Stearic acid coating Calcite Powder).
Buy Vietnam Calcium Carbonate from Vietnam.
We would like to send all of you our warmest greetings. Our company is very pleased to introduce you to our uncoated calcium carbonate powder as follows:
– Commodity: Uncoated calcium carbonate powder with particle sizes from 5–100 microns.
– Materials: The materials are mined from quarries in Tan Ky District and Quy Hop District with high quality.
We are looking forward to receiving your attention and long-term cooperation.
Thank you very much!
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