Vol.1, No 5, 2000 pp. 69 - 79
UDC 678.664:661.8
CORRELATION OF REACTION KINETIC PARAMETERS
IN TWO COMPONENT POLYURETHANE SYSTEMS
Suzana Perošević, Ljiljana Rašković
Tehnološki fakultet Leskovac
Abstract. Two component polyurethane systems are the new materials
that have ever growing application in everyday practice, mainly in the
dye industry, and the corrosion protection. The advantages of these systems
are in lower content of the organic solvents, with the same level of the
film properties. From the research and developing view, one must have the
information's about the mechanism of final structure formation and their
properties. Correlation between the final film structure and their kinetic
parameters, could lead to the formation process optimization. Goal of presented
research was to find time event sequence during two-component polyurethane
water film formation. Experiments were designed in that way that each event,
which takes place during film formation process, could be identified and
quantified. All the factors, which have influence on the identified event,
were also investigated, as well as their influence on final film properties.
Film formation mechanism is presented in the form of the time event sequence
which identified the process interactions such as: particle coalescence,
izocianates-hydroxyl group and water reactions water evaporation and organic
solvent evaporation. For two-component water systems, viscosity changes
is not a valuable measure of system changes, so reologic methods could
not be used for this research. For measuring macro kinetic parameters (activation
energy and reaction order), we used differential scanning calorimetric
(DSC). Mechanical properties, hardness, were measured in order to correlate
the structure with the mechanical properties. All obtained results were
used for defining the time event sequence of two-component water polyurethane
film formation.
Key words: DSC method, two-component system, kinetic of reaction,
organic solvent, polyurethane coatings, water system
KORELACIJA KINETIČKIH PARAMETARA U REAKCIJAMA
DVOKOMPONENTNIH POLIURETANSKIH SISTEMA U ORGANSKIM RASTVARAČIMA I SA VODOM
Dvokomponentni vodeni poliuretanski premazi predstavljaju nove sisteme,
koji se koriste za različite aplikacije u oblasti površinske zaštite. Manji
sadržaj isparljivih organskih rastvarača, uz očuvanje kvaliteta funkcionalnih
svojstava koje imaju sistemi sa organskim rastvaračima, predstavlja njihovu
komparativnu prednost. pri primeni dvokomponentnih poliuretanskih sistema,
reakcija stvaranja filmova je veoma brza pa je neophodno reaktante mešati
neposredno pre primene, jer bi u suprotnom dolazilo do preranog geliranja
sistema. Osnov za razvoj dvokomponentnih poliuretanskih sistema organskih
prevlaka sa visokim radnim svojstvima, predstavlja visoka reaktivnost izocijanatne
grupe, koja lako reaguje sa poliolima i formira stabilnu poliuretansku
strukturu. Tokom istraživanja, za ispitivanje mikrokinetičkih parametara
(energije aktivacije i rada reakcije), korišćena je metoda diferencijalne
skening kalometrije (DSC). Diferencijalna skanirajuća kalorimetrija je
termoanalitička metoda koja se bazira na merenju razlike sadržaja toplote
u uzorku i referenci u funkciji temperature, kada se uzorak i referenca
izlože kontrolisanom temperaturnom programu.
Ključne reči: DSC metoda, dvokomponentni sistemi, kinetika
reakcije, organski rastvarači, poliuretanski premazi, vodeni sistemi
