MINERAL NANOFILLERS OBTAINED VIA KRYOGENIC DEZAGGREGATION METHOD. Janowska G., Rybinski P., Slusarski L., Institute of Polymers, L/ódz Technical University (Poland). Activity of fillers toward polymers depends mainly on sizes of their particles, a value of specific area and surface energy. During manufacturing of fillers, particularly of high activity their primary particles undergo aggregation, because of very high surface energy. Fillers are usually introduced into polymer matrices during mechanical mixing. However even in field of very high shear stresses complete dezaggregation could not be achieved. In our laboratory a cryogenic method of hydrophilic, mineral fillers dezaggregation has been elaborated. It is based on the following assumptions. During aggregation of primary particles empty voids inside aggregates are formed. They could be disclosed and their sizes calculated on the basis of gas adsorption measurements. Typically they are of an order of a few nanometers. They are accessible to water vapour particles. In the first step of our procedure we introduced water into the nanopores of silica or silicates and after that have frozen all the system. As was expected owing an increase of water volume during freezing dezaggregation of fillers particles occured. However it was detected a reaggregation of a filler primary particles during evaporation of adsorbed water at elevated temperature. To avoid reaggregation it was necessary to apply an appropriate intercalating agent. In such a manner nanoparticles of fillers of the size below 50 nm could be obtained. It was demonstrated their activity toward polymers, much higher as compared to the original fillers. Acknowledgment The work was supported by the State Committee for Scientific Research, Grant No. PBZ/KBN-013/T08/39
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