No abstract

SUMMARY:The effect of some additives with low molecular weights upon the effective viscosity and slipping in poly(ethylene), poly(propy1ene) and poly(styrene) flow through circular capillaries is studied as a consequence of previous work done. The capillaries are made from different materials: Iron, alloy of copper and zinc, aluminium and poly(tetrafluor0-ethylene). It is noticed that in cases with capillaries made of poly(tetrafluoroethy1ene) the rate of the flow of pure polymers is increased, compared with the rate of the flow through metal capillaries. This effect increases with the increasing of stress and finally reaches 50 percent.One can observe a profound change in slipping and in viscosity behaviour when adding additives with low molecular weight to polymer melts. This effect is characteristic when silicon oil is added to poly(propy1ene) flowing through a poly(tetrafluoroethy1ene) capillary. The relative change of the flow when the conditions are all the same reaches 400%, whereas change through metal capillaries can be neglected.The results show that additives with low molecular weight change the viscosity of the polymer, and when the polymer flows through a poly(tetrafluoroethy1ene) capillary, those additives also change the slipping.

The regularities of ozonation of indeno (1,2,3-c,d) pyrene as a model substance of 6 -cyclic aromatic hydrocarbons have been investigated. On the basis of the experimental results it may be said that within the temperature range investigated (16-33°C) indeno(1,2,3-c,d) pyrene is oxidized in the presence of ozone. The use of methanol as an intermediate compound during the dissolution of indeno(1,2,3-cd) pyrene in an aqueous solution affects the total process rate. The turbidity of the suspension has been determined by spectrophotometric measurement of the optical density. The mean volume of the aggregates is equal to a sphere with a diameter of 120 nm. The activation energy of the reaction of ozonation is of the order of 10 -25 kJ/mol and increases with the pH value. The rate is of a fractional order of magnitude with respect to the reagents. With increasing medium pH the reaction rate decreases. This is explained assuming that the oxidation of indeno (1,2,3-c,d) pyrene proceeds mainly by direct interaction with ozone. The initial data from the identification of the ozonation products demonstrate the formation of primary and/or secondary ozonides with a molecular weight of 324. 571 Downloaded by [La Trobe University] at 12:21 15 June 2016 572 D. Mehandjiev et al.

No abstract