Reticulation of aqueous polyurethane systems controlled by DSC method

The DSC method has been employed to monitor the kinetics of reticulation of aqueous polyurethane systems without catalysts, and with the commercial catalyst of zirconium (CAT(R) XC- 6212) and the highly selective manganese catalyst, the complex Mn(III)diacetylacetonemaleinate (MAM). Among the polyol components, the acrylic emulsions were used for reticulation in this research, and as suitable reticulation agents the water emulsible aliphatic polyisocyanates based on hexamethylendoisocyanate with the different contents of NCO-groups were employed. On the basis of DSC analysis, applying the methods of Kissinger, Freeman-Carroll and Crane-Ellerstein the pseudo kinetic parameters of the reticulation reaction of aqueous systems were determined. The temperature of the examination ranged from 50 degrees C to 450 degrees C with the heat rate of 0.5 degrees C/min. The reduction of the activation energy and the increase of the standard deviation indicate the catalytic action of the selective catalysts of zirconium and manganese. The impact of the catalysts on the reduction of the activation energy is the strongest when using the catalysts of manganese and applying all the three afore-said methods. The least aberrations among the stated methods in defining the kinetic parameters were obtained by using the manganese catalyst

Spectroscopic characteristics of highly selective manganese catalysis in acqueous polyurethane systems

The latest investigations on producing more efficient catalytic aqueous polyurethane systems are in the domain of metal complexes with mixed ligands. In our previous research works, the high selectivity for the isocyanate-hydroxyl reaction in aqueous polyurethane systems has been shown by the manganese(III) mixed-ligand complexes. The two new complexes have been prepared with two acetylacetonate (acac) ligands and one maleate ligand and its hydroxylamine derivative of the general formula [Mn(C5H7O2)(2)L]. Their structures have been established by using the fundamental analyses, the FTIR and UV/VIS spectroscopic methods, as well as the magnetic measurements. In order to explain the different selectivity of the manganese(III) mixed-ligand complexes, the UV and ESR spectroscopy have been employed to determine the kinetics of the complexes' decomposition. The thermal stability of the complexes has been determined by way of the dynamic TG method at the heating rate of 5 degrees C.min(-1) and at the temperature ranged 20-550 degrees C. It suggests the decomposition of the complexes by loss of acid ligand. The main factor in the selective catalysis control in the aqueous polyurethane systems is the nature of the acid ligands and their impact on the manganese(II)/manganese(III) equilibrium

Thermal stability of aqueous polyurethanes depending on the applied catalysts

The thermal stability of aqueous polyurethanes has been measured applying the thermogravimetric analysis. The aqueous polyurethanes (aqPUR) with catalysts of different selectivity have been studied by use of the dynamic method. To obtain degradations of 0.025, 0.05, and 0.10, employing the dynamic method, the heating rates of 0.5, 1, 2, 5, and 10 degrees C min(-1) have been used in the range of 30-500 degrees C. Using the more selective catalysts in the aqueous polyurethanes, the total resulting time of the decompositon has been on the increase at all degrees of the degradation and at the particular starting temperature. This paper shows that the dynamic method based on the thermogravimetric analysis can be used to assess the thermal stability of the aqueous polyurethanes using the catalysts of different selectivity

Proučavanje mogućnosti mikrotalasne polimerizacije monomera na osnovu obnovljivih sirovina

Polylactide belongs to the biodegradable and biocompatible polymers, and degrade to harmless component, lactic acid, which allows their use in various areas. The development of new methods for the synthesis of polylactide can further extend the application of this polymer and makes its use more economical. The use of microwaves in the synthesis of the polymer can reduce the polymerization time of only 10 to 30 minutes and save a large amount of energy. In this paper, polylactide is synthesized in a microwave reactor, using a frequency of 2,45 GHz and a power of 150 W. FITR analysis confirmed the structure of the resulting polylactide and the thermal properties were studied using differential scanning calorimetry.Polilaktid spada u grupu biorazgradivih i biokompatibilnih polimera i može se razložiti na neškodljivu komponentu, mlečnu kiselinu, što omogućava njegovu primenu u najrazličitijim oblastima. Razvoj novih metoda sinteze polilaktida može proširiti područje primene ovog polimera i učiniti njegovu upotrebu ekonomičnijom. Upotreba mikrotalasa u sintezi polimera može skratiti vreme polimerizacije na svega 10 do 30 minuta štedeći veliku količinu energiju. U ovom radu polilaktid je sintetisan u mikrotalasnom reaktoru, koristeći frekvenciju od 2.45 GHz i snagu od 150 W. FTIC analiza je potvrdila strukturu dobijenog polilaktida, a toplotna svojstva su proučavana metodom diferencijalne skenirajuće kalorimetrije.Vrednost temperatura prelaska u staklasto stanje i temperatura kristalizacije dobijenog polimera zavise od molskog odnosa monomera (L-laktida) i katalizatora (kalaj-oktoata)

Reticulation of Aqueous Polyurethane Systems Controlled by DSC Method

The DSC method has been employed to monitor the kinetics of reticulation ofaqueous polyurethane systems without catalysts, and with the commercial catalyst of zirconium(CAT®XC-6212) and the highly selective manganese catalyst, the complex Mn(III)-diacetylacetonemaleinate (MAM). Among the polyol components, the acrylic emulsions wereused for reticulation in this research, and as suitable reticulation agents the water emulsiblealiphatic polyisocyanates based on hexamethylendoisocyanate with the different contents ofNCO-groups were employed. On the basis of DSC analysis, applying the methods of Kissinger,Freeman-Carroll and Crane-Ellerstein the pseudo kinetic parameters of the reticulation reactionof aqueous systems were determined. The temperature of the examination ranged from 50oC to450oC with the heat rate of 0.5oC/min. The reduction of the activation energy and the increaseof the standard deviation indicate the catalytic action of the selective catalysts of zirconium andmanganese. The impact of the catalysts on the reduction of the activation energy is thestrongest when using the catalysts of manganese and applying all the three afore-said methods.The least aberrations among the stated methods in defining the kinetic parameters wereobtained by using the manganese catalyst

Thermal Stability of Aqueous Polyurethanes Depending on the Applied Catalysts

The thermal stability of aqueous polyurethanes has been measured applying thethermogravimetric analysis. The aqueous polyurethanes (aqPUR) with catalysts of differentselectivity have been studied by use of the dynamic method. To obtain degradations of 0.025,0.05, and 0.10, employing the dynamic method, the heating rates of 0.5, 1, 2, 5, and 10 °Cmin-1 have been used in the range of 30-500 ºC. Using the more selective catalysts in theaqueous polyurethanes, the total resulting time of the decompositon has been on the increaseat all degrees of the degradation and at the particular starting temperature. This paper showsthat the dynamic method based on the thermogravimetric analysis can be used to assess thethermal stability of the aqueous polyurethanes using the catalysts of different selectivity

Spectroscopic Characteristics of Highly Selective Manganese Catalysis in Acqueous Polyurethane Systems

The latest investigations on producing more efficient catalytic aqueouspolyurethane systems are in the domain of metal complexes with mixed ligands. In ourprevious research works, the high selectivity for the isocyanate-hydroxyl reaction inaqueous polyurethane systems has been shown by the manganese(III) mixed-ligandcomplexes. The two new complexes have been prepared with two acetylacetonate (acac)ligands and one maleate ligand and its hydroxylamine derivative of the general formula[Mn(C5H7O2)2L]. Their structures have been established by using the fundamental analyses,the FTIR and UV/VIS spectroscopic methods, as well as the magnetic measurements. Inorder to explain the different selectivity of the manganese(III) mixed-ligand complexes, theUV and ESR spectroscopy have been employed to determine the kinetics of the complexes’decomposition. The thermal stability of the complexes has been determined by way of thedynamic TG method at the heating rate of 5°C⋅min-1 and at the temperature ranged 20-550°C. It suggests the decomposition of the complexes by loss of acid ligand. The main factor in the selective catalysis control in theaqueous polyurethane systems is the nature of the acid ligands and their impact on themanganese(II)/manganese(III) equilibrium

Effects of the Acrylic Polyol Structure and the Selectivity of the Employed Catalyst on the Performance of Two-component Aqueous Polyurethane Coatings

Two kinds of aqueous acrylic polyols (single step and multi step synthesis type)have been investigated for their performance in the two-component aqueous polyurethaneapplication, by using more selective catalysts. The aliphatic polyfunctional isocyanatesbased on hexamethylen diisocyanates have been employed as suitable hardeners. Thecomplex of zirconium, commercially known as K-KAT®XC-6212, and manganese (III)complexes with mixed ligands based on the derivative of maleic acid have been used ascatalysts in this study. Both of the aqueous polyols give good results, in terms of applicationand hardness, when elevated temperatures and more selective catalysts are applied. A moreselective catalyst promotes the reaction between the isocyanate and polyol component. Thisincreases the percentage of urethane bonds and the degree of hardness in the films formedfrom the two components of aqueous polyurethane lacquers. The polyol based on the singlestep synthesis route is favourable concerning potlife and hardness. The obtained resultsshow that the performance of the two-component aqueous polyurethane coatings depends onthe polymer structure of the polyols as well as on the selectivity of the employed catalyst

FTIR analysis and the effects of alkyd/melamine resin ratio on the properties of the coatings

Alkyd/melamine resin mixtures are mainly used in industrial baking enamels. The effects of the alkyd/butylated melamine resin ratio (from 90/10 to 50/50) and curing temperature (from 110 to 180°C) on the crosslinking and properties of the coating are presented in this paper. The curing reactions through functional groups of resins were monitored by FT-IR spectroscopy. The hardness, elasticity, degree of adherence and gloss were also determined. Optimal coating properties could be achieved with an alkyd/melamine resin ratio of 80/20, a curing temperature of 150°C and a curing time of 20 min