ANOMALOUS VISCOSITY OF SOME WATERBORNE FILM FORMING COMPOSITIONS
I. Iliev, P. Petrenko, P. Novakov
ELECTROVISCOSITY OF THE POLYZWITTERIONIC AQUEOUS SOLUTIONS
G. Georgiev, A. Tzoneva, V. Spasov
HEOLOGICAL PROPERTIES OF MIXTURES BASED ON POLY(N-ISOPROPYLACRYLAMIDE)
; INFLUENCE OF FLUOROCARBON MODIFIED POLY(ETHYLENE GLYCOLS)
V. Samichkov, Ya. Ivanov, I. Berlinova, A. Nedelcheva
PIPERAZINE-N-DITHIOCARBAMIC ACID - RUBBER VULCANIZATION ACCELERATOR
E. Djagarova, L. Natova
EXTRUDERS AS CHEMICAL REACTORS
M. Natov, V. Mitova, S. Vassileva
INVESTIGATION OF BLOWING AGENT SYSTEMS BASED ON SODIUM BICARBONATE
G. Kotzev, S. Djoumaliisky, N. Touleshkov
ANOMALOUS VISCOSITY OF SOME WATERBORNE
FILM FORMING COMPOSITIONS
I. Iliev, P. Petrenko, P. Novakov
|
University of
Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: ilia_iliev@hotmail.com
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Sometimes during the dilution of waterborne
film forming compositions by water an anomalous viscosity appears. Very often
it represents a maximum in the dependence of viscosity versus dry content
of film forming material. In this study the same phenomenon at the waterborne
compositions on the base of oligoesters both of epoxy resin with maleinised
tall acids and trimellitic anhydride with diethylene glycol was investigated.
The viscosity changes with maximum at definite dry content correlate with
the changes of the electrical conductivity of the same compositions. The way
to avoid the appearance of this undesirable in technological aspect maximum
was established by the introducing of aminoformaldehyde resin in the paint
compositions.
Keywords: waterborne film forming compositions, anomalous viscosity,
epoxy esters, oligoesters of trimellitic anhydride and diethylene glycol
ELECTROVISCOSITY OF THE POLYZWITTERIONIC
AQUEOUS SOLUTIONS
G. Georgiev, A. Tzoneva, V. Spasov
|
University of
Sofia, Faculty of Chemistry (*Faculty of Physics),
Laboratory of "Water-Soluble Polymers, Polyelectrolytes and Biopolymers"
1, James Bourchier Avenue, 1164 Sofia, Bulgaria.
e-mail: annaalex2002@yahoo.com
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It is established that the polyzwitterionic
aqueous solution electroviscosity effect is more considerable and in an opposite
direction in comparison with that of polyelectrolyte aqueous solution. Temperature
and electric field strength influence on the polyzwitterionic aqueous solution
electroviscosity in parallel, though the reasons for these effects are quite
different. The unusual electroviscosity behaviour of the polyzwitterionic
solution is explained by the "core-shell" model for structure macromolecular
organisation of the polyzwitterion macromolecules, suggesting the cluster
formation because of the intensive dipole-dipole interaction between monomer
units of the same or different macromolecules.
Keywords: electroviscosity, electrorheological fluids, dipole-dipole
cluster, conformation state.
RHEOLOGICAL PROPERTIES OF MIXTURES BASED
ON POLY(N-ISOPROPYLACRYLAMIDE) ; INFLUENCE OF FLUOROCARBON MODIFIED POLY(ETHYLENE
GLYCOLS)
V. Samichkov, Ya. Ivanov, I. Berlinova, A. Nedelcheva
|
Central Laboratory
of Physico-Chemical Mechanics
* Institute of Polymers,
Bulgarian Academy of Sciences, "Acad. G.Bonchev" Str., 1113
Sofia, Bulgaria E-mail: samipolymer@yahoo.com
|
|
The present work relates to the investigation
of rheological properties of poly(N-isopropylacrylamide), as well its mixtures
with poly(ethylene glycol) containing fluoroalkyl end groups. It has been
studied the influence of chain length and structure of hydrophobic modified
poly(ethylene glycol) on the thermoassociative process between both polymers.
It is found, that the addition of hydrophobic modified poly(ethylene glycol)
leads to the appearance of significant elastic properties of the mixture,
a result of transition from a viscous sol to an elastic gel, and hinder the
phase-separation of poly(N-isopropylacrylamide).
Keywords: rheology, association, poly(N-isopropylacrylamide), visco-elastic
properties.
PIPERAZINE-N-DITHIOCARBAMIC ACID - RUBBER
VULCANIZATION ACCELERATOR
E. Djagarova, L. Natova
|
University of
Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail djagar@uctm.edu
|
|
A method for the preparing without waste
of piperazine-N-dithiocarbamic acid (PDTA) was created and patented, where
the solvent which is the reaction medium, can be used repeatedly with no regenerating.
On the basis of the investigations on SBR-model compounds and on industrial
compounds designated to the tyres production, it was stated that the PDTA
behaviour is as an accelerator of the sulphur vulcanization of rubber. An
attempt to determine the specific activity of the new accelerator was made,
and the supposed mechanism of its effect was proposed. It was settled out,
that the new accelerator has no toxicity influence in concentration up to
10 phr. 50 pneumatic tyres of the type 11,00P20PH16, among which 94% are the
first quality, were produced without any technological problems using the
new accelerator.
Keywords: piperazine-N-dithiocarbamic acid, accelerator, sulphur vulcanization
EXTRUDERS AS CHEMICAL REACTORS
M. Natov, V. Mitova, S. Vassileva
|
University of
Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail natov@uctm.edu
|
|
It is developed a methodology for calculation
of circle extruder's dies. Due to selecting appropriate dies and regulating
the extruder's flow rate, the thermodynamic parameters can be regulated the
extruders as new chemical reactors.
Keywords: reactive extrusion, polycaproamide, poly butadiene acrylonitrile
INVESTIGATION OF BLOWING AGENT SYSTEMS
BASED ON SODIUM BICARBONATE
G. Kotzev, S. Djoumaliisky, N. Touleshkov
|
Institute of
Metal Science, Bulgarian Academy of Sciences
67 Shipchenski Prohod St., 1574 Sofia; E-mail: touleshkov@ims.bas.bg
|
|
Thermoplastic foams are heterogeneous materials
consisting of gas phase dispersed in a solid plastic phase. The source of
gas phase are blowing agents, among which sodium bicarbonate (SB) attracts
much attention with its accessibility, harmlessness, as well as the endothermic
effect of decomposition. The main disadvantages of SB are a broad temperature
range of decomposition, the relatively low gas yield, the resulting poor cell
structure of the articles, as well as the bad dispersion with polymers by
mixing. The present investigation is an attempt at modification of SB with
activators (organic acids) and nucleating agents (natural zeolite) to increase
the gas evolution ability and to improve the structure of the finished part.
The decomposition kinetics characteristics of various blowings agent systems
(BAS) were investigated. The efficiency of studied BAS was estimated by extrusion
of foamed LDPE and PVC plasticate. The results were put into practice by elaboration
of granular blowing agent concentrates based on SB.
Keywords: blowing agent system, sodium bicarbonate, organic acids,
decomposition kinetic, foam extrusion, cell morphology.
