Modified Silica Filter
MODIFIED SILICA FILTER
AS A POLYMER FILM DEBLOCKER
G. Khomenko, V. Annopolsky
State Research and Design Institute of Basic Chemistry Kharkiv, Ukraine
In order to obtain a silica filter used in manufacture of Poviden food-grade film, to improve its opening ability, the following aspects were studied:
– study of samples of filters obtained by silica dehydration;
– study of samples of filters obtained by silica chemical modification;
– During heat treatment of silica silanol groups begin to condensate and be removed in aqueous form to a substantial degree at 170oC. Above 400-450oC a large number of hydroxyl groups were removed from the surface, and enormous siloxane areas appear which are difficult to be rehydrated.
Tests of samples heat treated at 400-450oC showed that application of SiO2 manufactured by hydrochloric acid process with a large BET specific surface (190 m2/g) substantially improved usable properties of the film.
Dehydration method consumes too much energy, therefore, we studied chemical modification of silica.
Hydrochloric-acid process was taken as a basis for chemical modification of silica. The study showed that the structure of graft layer in modified fillers depends on a number of factors: modifier structure, ability of grafted molecules to interact between themselves or with residual silanol groups at the surface as well as on external conditions – medium temperature and polarity.
Silica slurry was treated with modifiers compatible to polymer-propanediol 1,2 and DBS (dibuthyl sebacate).
Tests of silica samples in the film showed acceptability of this method of SiO2 precipitation with subsequent slurry modification with propanediol 1, 2 and spray drying.
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