Polyhydroxyalkylation of Urea with Ethylene Carbonate and Application of Obtained Products As Components of Polyurethane Foams

http://www.e-polymers.org e-Polymers 2008, no. 166 ISSN 1618-7229

Polyhydroxyalkylation of urea with ethylene carbonate and application of obtained products as components of polyurethane foams

Iwona Zarzyka-Niemiec*

*Rzeszów University of Technology, Department of Organic Chemistry, Al. Powstańców Warszawy 6, 35-959 Rzeszów, Poland; e-mail: [email protected]

(Received: 17 March, 2008; published: 27 December, 2008)

Abstract: The reaction between urea and ethylene carbonate occur with partial release of CO2 and partial incorporation of carbonate groups into products. The carbonate groups were found to be attached both to nitrogen of urea and to oxyethylene chain. The most effective catalyst of the synthesis was potassium carbonate. The hydroxyethyl and hydroxyethoxy groups of urea derivatives undergo partial dimerization to form carbamate groups in the products. The products of reaction between urea and ethylene carbonate have good thermal stability, they start to decompose at 200 0C. The obtained products can be used as polyol components for polyurethane foams. Polyurethane foams obtained from hydroxyethoxy derivatives of urea (EC8) are rigid products of low water uptake, good stability of dimensions, low mass loss on 30 days heating at 150 C, enhanced thermal stability and good compressive strength.

Introduction Hydroxyalkyl derivatives of urea can be obtained by reaction of urea with corresponding aminoalcohols (I, y = 1) [1, 2]: O O

2H N CH O H+H N C NH H O CH HN C NH CH O H+2NH (1) 2 2 n y 2 2 2 n y 2 n y 3 (I) where: n = 2-5, y = 1, 2 or 3. Similarly the hydroxyalcoxy derivatives of urea (I, y = 2 or 3) can be obtained using aminoetherol substrates [3, 4]. The synthesis is accompanied by ammonia release, which must be removed to improve the yield of synthesis. Moreover, the competitive formation of carbamates by the reaction between hydroxyl groups with urea takes place. We have experienced that purification of products, especially tetrakis(hydroxyalkyl)- and alcoxy- derivatives of urea was ineffective because they do not precipitate from the reaction mixture and decompose upon distillation even under reduced pressure. Another method of synthesis of hydroxyalkylurea and hydroxyalcoxyurea derivatives is based on the reaction of urea with oxiranes, like ethylene oxide or 2,3-epoxybutane according to the following scheme [5, 6].

1 O O CH CH O H H O CH CH z H N C NH + R CH CH R x N C N 2 2 R R R R (2)

O H O CH CH CH CH O H y w R R R R

where: R = CH3-, H-, x + y +z + w = 2 4. However, oxiranes are toxic and cancerogenic and additionally the synthetic protocol requires high pressure. It seemed reasonable to replace them with alkylene carbonates, which are less ecologically hazardous [7, 8]. They posses higher boiling points and are good solvents for urea. They are expected to react with urea in analogous manner as oxiranes. Here the attempts of such a synthesis are described together with the application of polyol products to obtain polyurethane foams of enhanced thermal stability.

Results and discussion The reactions of urea with EC were performed in presence of potassium carbonate as catalyst at 120-160 C temperature range (Table 1).

Tab. 1. Reaction conditions of urea with EC.

Initial Amount of Time Kind of Temp. Presence of Synth. Molar catalyst of Reaction Catalyst [ C] Carbodiimide Ratio [mole/mole urea] [h]

1. 1 : 1 K2CO3 0.06 120 10 +

2. 1 : 2 K2CO3 0.03 120 18.5 +

3. 1 : 2 K2CO3 0.06 120 11 +

4. 1 : 2 K2CO3 0.03 140 13.5 +

5. 1 : 2 K2CO3 0.06 140 6 + 6. 1 : 2 DABCO 0.06 120 28 + a 7. 1 : 2 ZnCl2 0.06 120 27 +

8. 1 : 3 K2CO3 0.06 140 6.5 +

9. 1 : 4 K2CO3 0.06 120 35 +

10. 1 : 4 K2CO3 0.06 140 8.5 -

11. 1 : 8 K2CO3 0.09 160 10.5 -

12. 1 : 12 K2CO3 0.09 160 16 -

13. 1 : 16 K2CO3 0.09 160 21 - a: EC did not react completely.

The resin-like product was obtained at 1:1 molar ratio of substrates (Table 1, synthesis 1), which has shown the same ratio of oxyethylene to urea. The initial stoichiometry was chosen at the assumption that total elimination of CO2 occurs (reaction 3). However the spectral analysis of product evidenced the presence of carbonate groups in the product by the presence of the primary amide proton resonance at 6.4 ppm in the 1H-NMR spectrum (Figure 1) as well as the resonance at

2 7.5 ppm attributed to imide group proton (H2N-CO-NH-COO-) [9]. Thus the carbonate groups are preserved at product, which can be represented by the formula (III). O O C NH C NH CH CH OH CO O O O 2 2 2 + 2 (II) NH C NH + CH CH 2 2 2 2 O O

NH2 C NH C O CH2 CH2OH (3) (III)

In the spectrum of product (III) the resonance of methylene group proton at -CH2-O-CO was found at 4.15 ppm [10] while those at 5.4 and 6.0 ppm were attributed to primary and secondary amide protons of N-(2-hydroxyethyl)urea (II) [9]. From the integral intensity of the NH2 group resonances in (II) and (III), respectively, it can be concluded that N-(2-hydroxyethyl)urea (II) is the major component in obtained mixture (ca 60%).

Fig. 1. 1H-NMR spectrum of the product of reaction between urea and EC at 1:1 molar ratio in the presence of 0.06 mole K2CO3/mole urea at 120 C.

The IR spectrum (Figure 2) of the product corroborates well with the NMR data. The valence C=O stretching ester and imide group band are present at 1730 cm-1 while I amide bands of primary and secondary amides are observed at 1663 and 1607 cm-1, respectively. The asymmetric and symmetric valence bands of ester -C-O- group occur at 1250 and 1150 cm-1, respectively. The C-OH valence band of primary alcohol is observed at 1059 cm-1. Some minor products were also found in the reaction mixture obtained from 1:1 urea: EC system. Derivative (IV) was tentatively identified by the strong IR band at 2157 cm-1, which was assigned to valence band of carbodiimide fragment N C N. Carbodiimides were found to be formed upon dehydration of N,N’-disubstituted ureas [11].

3 1150 2157 1730 1250 1059 1663 1607

Fig. 2. IR spectrum of the product of reaction between urea and EC at 1 : 1 molar ratio in the presence of 0.06 mole K2CO3/mole urea at 120 C.

The product (V) was identified based on 7.0 ppm resonance at 1H-NMR spectrum of the product which was assigned to secondary amide protons in N-substituted urea with accepting groups [10]. O O C HO CH CH NH C NH CH CH OH + 2CO 2 2 2 2 2 O O O (IV) H N C NH +2CH CH 2 2 2 2 O O O C NH C +CO HO CH2 CH2 NH CH2 CH2 OH 2 (4) (V) In the reaction between urea and EC at 1:2 molar ratio a mixture of products is also found, some with preserved carbonate group (V) and others without it (IV). The 1H- NMR of this product is similar to that obtained from 1:1 system. The presence of the amine proton resonances centered at 5.4 and 6.4 ppm from (II) and (III) indicates the partial decomposition of EC and formation of mono-substituted derivatives and/or N,N’-bis(hydroxyalcoxy) derivatives of urea.

The synthesis at 120 C in presence of 0.03 mole K2CO3/mole of urea lasts too long (18.5 hours), therefore the process was performed at higher concentration of catalyst (0.06 mol; Table 1, syntheses 2 and 3). During this process the ammonium carbamate sublimed into reflux condenser (the product was identified by IR spectrum). It forms in the reaction between urea and water (present in the reaction mixture due to dehydration of N,N’-disubstituted derivatives of urea with formation of carbodimide). This by-product was also formed at higher temperature irrespective of the catalyst concentration (Table 1, syntheses 4 and 5), while it was not observed under less basic conditions (in presence of 0.03 mole K2CO3/mole of urea (Table 1, synthesis 2) at lower temperatures. The percentage of ammonium carbamate did not exceed 10 wt.-%.

4 The reaction is slower in presence of DABCO catalyst instead of K2CO3; the time of reaction was 28 hours at 120 °C (Table 1, synthesis 6). The amount of ammonium carbamate and carbodiimide of by-products remains unaltered. Also the major products are the same as previous, namely (II)‚(V). Therefore the acid catalyst; zinc chloride was also tested (Table 1, synthesis 7), which is known to catalyze the reaction between amines and alkylene carbonates [12]. In the presence of this catalyst the reaction was much slower and although ammonium carbamate was not formed, the carbodiimide by-product was still present. Further studies were performed with potassium carbonate as catalyst. When 3-molar excess of EC related to urea was applied (Table 1, synthesis 8) the percentage of by-products was considerably reduced. When four-fold excess of EC was applied at 120 C (Table 1, synthesis 9) ammonium carbamate was absent. At higher temperature (140 C; Table 1, synthesis 10) also carbodiimide did not form. The resonances at 5.4 and 7.5 ppm in the 1H-NMR of product are absent indicating that all amide and imide group hydrogens were substituted according to the following scheme: O

H O CH CH O C O CH CH O H 2 2 y 2 2 s x N C N

H O CH CH 2 2 z (VI) CH2CH2 O H w where: x + z + s + w ≤ 4; 0 ≤ y 1, At 3-fold and higher excess of EC the carbonate groups can build into product not only next to nitrogen but also to hydroxylic oxygen present in the product of reaction between urea and EC:

O C O O O O O CH CH N C N CH CH OH 2 2 N C N CH CH O C O CH CH OH 2 2 2 2 2 2 (5) (VII)

The resonances from methylene protons in (VII) -CH2-OCO-O-CH2- at 4.15 ppm overlap with methylene proton resonance of methylene group in (VI) N-(CO)-O-CH2-. This precludes the estimation of incorporated carbonate groups by integral integration of corresponding resonances in the 1H-NMR spectra. Moreover the product of condensation of hydroxyethyl derivatives of urea with formation of carbamate groups in (VIII) (see scheme below) shows also the signal at 4.15 ppm from methylene protons in -N-(CO)-O-CH2- [10].

.. O: CH CH O O O 2 2 .. + H N C N O: N C N 2 N C N .. .. CH2 CH2 O CH CH O C N CH2CH2 O.. H 2 2 .. + NH (VIII) 3 (6)

However, the presence of carbonate and carbamate groups in hydroxyalkyl derivatives of urea obtained from urea and EC is evident as follows. The 1H-NMR spectrum of the product obtained from 1:12 system (Table 1, synthesis 12) before and after extra heating at 200 C are presented at Figures 3a-c. Upon 4-hour heating the resonance at 4.15 ppm decreases (Figures 3a and b) and no extra peaks appear.

5 a.

Fig. 3. 1H-NMR spectra of the product of reaction between urea and EC at 1 : 12 molar ratio in the presence of 0.09 mole K2CO3/mole urea at 160 C: a. before heating at 200 C; after heating at 200 C for b. 4 h, c. 10 h.

6 This indicates consumption of carbonate groups at amide fragment (IX, z = 0) and/or in ethoxy chain (IX, z 1):

O O CH CH O C O CH CH O H O 2 2 z 2 2 n CH CH O CH CH O H N C N N C N 2 2 z 2 2 n - CO (7) O H (IX) 2 CH2 CH2 CH CH O H w 2 2 w Prolonged heating of the sample up to 10 hours results in further decrease of the intensity of the resonance at 4.15 ppm and concomitant appearance of the signal at 2.6 ppm belonging to methylene group protons from amine CH2-N (Figure 3c). This observation indicates that carbamate groups formed initially upon condensation, decompose with formation of tertiary amine according to the following scheme: O O O N C N CH2 CH2 O CH CH O C N N C N CH CH O 2 2 CH CH N 2 2 CH CH O 2 2 + CO2 (8) 2 2 CH CH O 2 2 The products were analyzed by MALDI ToF spectrometry. Product analysis have shown that in the systems with 8- and 12-fold EC excess the self condensation of hydroxyethoxy derivatives of ureas is restricted only to partial dimerization; only one carbamate group is present in oligomer (Figures 4 and 5). The product obtained in the presence of 8-fold excess of EC is composed of oligomers containing 3 to 16 oxyethylene units per urea molecule and 5 to 10 units of EC per dimer. The product obtained at presence 12-fold EC excess contains oligomers built out of 3-17 oxyethylene units and similar dimers as before. (see Figures 4 and 5).

Fig. 4. MALDI ToF spectrum of product from urea:EC 1:8 in the presence of 0.09 o mole K2CO3/mole urea at 160 C

Fig. 5. MALDI ToF spectrum of product from urea:EC 1:12 in the presence of 0.09 o mole K2CO3/mole urea at 160 C.

Products were also analyzed chromatographically. It was found that hydroxyalkylation of urea with EC was not accompanied by the by-products formed from EC and water, i.e. ethylene glycol and the products of its consecutive reaction with EC, as it was in case melamine:EC system [13]. Only products obtained from 1:8 and and higher systems (Table 1, syntheses 11-13) are accompanied by small amount of TETRAEG (less than 4 wt.-%).

Tab. 2. Thermal stability of products.

Temperature of Initial Molar T T T Max. Entry Ratio T [ C] 10% 20% 50% 5% [ C] [ C] [ C] Decomposition OA : EC [ C] 1 1 : 4 180 210 230 280 380 2 1 : 8 210 230 250 330 360 3 1 : 12 210 230 250 330 360 4a 1 : 12 220 250 290 350 360 5 1 : 16 210 230 260 330 350 6 1 : 8b 170 200 240 470 240 a: after heating of the product at 200 C for 10 hours b: the foam obtained from EC8 was analyzed (comp. 1, Table 3) Tx% - temperature at which the weight loss is x%

Derivatographic measurements indicated higher thermal stability of products of reaction between urea and EC (Table 2). Two peaks were observed on DTG curve of product obtained at 12-fold EC excess (Figure 6a). The first one centered at 220 C

8 originate from carbonate and carbamate decomposition, and is not present when the sample of product was extensively worked-up thermally at 200 C (see Figures 6a and b). The second peak observed at 380 C is characteristic for decomposition of urea group. For the products obtained from the systems with higher EC excess, the peaks tend to coalesce and for the product obtained from the mixture at 16-fold EC excess eventually only one peak centered at 350 C is observed (Figures 7 a and b). These observations lead to conclusion that upon increase of excess of EC in the reaction systems with the percentage of carbonate groups drops down. On the other hand, the examination of MALDI ToF spectra of products evidenced that percentage of carbamate groups remains practically unchanged upon use of larger excess of EC (Figures 4 and 5).

o . T [ C] 1000 a. b.

m [wt.-%.] m [wt.-%.]

0 10 20 30 40 50 60 70 80 90 100

time [min] time [min]

Fig. 6. Thermal analysis of products of reaction urea : EC 1 : 12 molar ratio in the presence of 0.09 mole K2CO3 / mole urea at 160 C a. before heating at 200 C; after heating at 200 C for 10 hours.

Relevant physical properties of urea derivatives obtained at 8-, 12- and 16-molar EC excess were studied, i.e.: the density, surface tension, refraction index, and viscosity in function of temperature (Figure 8) within the 20-80 C temperature range. It has been observed that density, surface tension and refraction index decrease nearly linear with temperature, while the viscosity decreases exponentially (Figure 8d). These trends are typical for polyols traditionally used for polyurethane foams preparation [14]. Therefore the products of hydroxyalkylation of urea were subjected to formation of polyurethane foams in order to characterize their properties.

9 Hydroxyethoxy derivatives of urea of variable percentage of ethoxy groups were foamed with diphenylmethane diisocyanate (MDI) and water. The optimized water amount was 2 wt.-% related to polyol and ca 0.43 g TEA / 100 g of polyol (Table 3). The best foams were obtained with the use of 0.75-molar excess of isocyante groups in relation to number of hydroxyl groups (Table 3).

T [oC] 1000 T [oC] 1000 a. b. 900 900

800 800

700 700

600 600

500 500

400 400

300 300

200 200

100 100

0 0 m [wt.-%] m wt.-[%]

time [min] time [min]

Fig. 7. Thermal analysis of products of reaction urea:EC: a. 1 : 8, b. 1 : 16 molar ratio in the presence of 0.09 mole K2CO3 / mole urea at 160 C.

Creaming time for the foaming with the use of the product of reaction between urea and 8-molar excess of EC (EC8) was approximately 10 s (Table 3, comp. 1 and 2), while for the products obtained from the systems with larger excess of EC (EC12 and EC16) was shorter, ca 5 s (Table 3, comp. 3-5). The foams obtained from EC8 have short time of growing, namely about 5 s (Table 3, com. 1 and 2), while that for foams obtained from EC12 and EC16 is even shorter (ca 1 s). All foams showed short drying time, about 1 s. (Table 3). The relevant properties of polyurethane foams were studied, namely: apparent density, water uptake, stability of dimension, thermal stability and glass transition temperature. The apparent density of obtained foams falls in 70-83 kg/m3 region (Table 4).

10 a. b.

urea : EC = 1 : 8 urea : EC = 1 : 8 urea : EC = 1 : 12 urea : EC = 1 : 12

urea : EC = 1 : 16 urea : EC = 1 : 16

]

[N / m] / [N

density [g / cm / density [g surfacetension 10*

temperature [oC] temperature [oC]

c. d. urea : EC = 1 : 8 urea : EC = 1 : 8 urea : EC = 1 : 12 urea : EC = 1 : 12

urea : EC = 1 : 16 urea : EC = 1 : 16

[-]

n viscosity [mPa*s]viscosity

temperature [oC] temperature [oC]

Fig. 8. Physical properties of reactions products of urea with EC as a function of temperature.

Water uptake for the foams obtained from EC8 was not more than 5.6 wt.-% after 24- hour exposition. In case of other foams it was considerably higher, especially upon prolonged exposition and reached 16 wt.-% (Table 4). The foams obtained from EC8 have better stability of dimension; the linear distortions are less than 5 % (Table 4). The foams obtained from EC12 and EC16 undergo much larger deformations upon heating (Table 4). Glass transition temperature of foams generally decreased for the foams obtained from the products of increasing EC excess. Thus it was 125, 94 and 75 C for the foams obtained from EC8, EC12 and EC16, respectively. In every case the glass temperature was above ambient temperature. Thus, the products fall into category of rigid foams [14]. Derivatographic analysis confirms the aimed result; the foams obtained here are thermally stable; 5 % weight loss occurs at 170 C, and maximum decomposition temperature is 240 C (Table 2).

Tab. 3. Parameters of Foaming Process.

Initial Composition Foaming Process Molar [g/100 g of polyol] Properties Ratio Composition of Foams Urea : No. Molar Time [s] Just EC in Isocyanatea Water Catalystb Ratio Prepared Polyol OH/NCO Creamingc Expandingd Dryinge

1. 216 2 0.43 1 : 1.67 10 5 1 rigid 1 : 8 2. 214 2 0.22 1 : 1.66 9 5 1 rigid

1 : 12 3. 156 2 0.43 1 : 1.73 6 1 1 rigid

4. 126 2 0.43 1 : 1.81 5 2 1 rigid 1 : 16 5. 126 2 0 1 : 1.81 5 1 1 rigid a: 4,4’-diphenylmethane diisocyanate, b: triethylamine, c: Time of Creaming: the time elapsed from the moment of mixing to the start of volume expansion, d: Time of Expanding: the time from the start of expansion to the moment of reaching the sample final volume, e: Time of Drying: the time from reaching by the sample its final volume to the moment of loosing its surface adhesion to powdered substances.

Tab. 4. Properties of Foams.

Water Uptake Linear Dimension Change after-Heating at 150 C [wt.-%] [%] Comp. Density No.a [kg/m3] length width thickness after 5 after 3 after 24 min hrs hrs after 20 after 40 after 20 after 40 after 20 after 40 hrs hrs hrs hrs hrs hrs 1 75.18 4.31 5.16 5.60 4.34 4.50 4.47 4.61 3.28 4.49

3 69.38 9.23 11.62 14.13 12.73 13.08 15.60 17.84 18.06 19.61

5 83.18 7.51 12.37 15.67 9.23 29.88 22.16 27.46 37.33 38.26 a: Comp. No. according to Table 3.

The prolonged heating test (30 days at 150, 175 or 200 C; Figure 9) indicated that constant mass of samples was achieved after 10-15 days. The lowest mass loss was observed for the foam obtained from EC8. It reached 20, 25 or 30 wt.-% at studied temperatures, respectively. Slight higher mass loss was observed for the foam obtained from EC12, while the unstable were the foams obtained from EC16 (Figure 9) in this test.

The foam samples both freshly prepared and after thermal treatment at 150, 175, and 200 C for 30 days were tested for their compressive strength. The best compressive strength of 0.25 MPa was observed for the ‘fresh’ samples prepared with EC16. The samples after thermal treatment had much better compressive strength than the fresh ones. The compressive strength increases considerably for the samples heated at the lowest temperature of 150ºC (by a figure as high as 120%

12 for samples prepared with EC8 (0.40 MPa)). After heating at 175ºC this strength further slightly increased. Prolonged heating at the highest temperature of 200ºC did not improved compressive strength, but it slightly decreased.

a. comp. 1 100 comp. 3 comp. 5

80 weihgt loss [wt.-%] loss weihgt

0 5 10 15 20 25 30 b. time [day] comp. 1 100 comp. 3 comp. 5

] wt.-%

[ 80 loss

70 weihgt

0 5 10 15 20 25 30

c. time [day] comp. 1 100 comp. 2 comp. 3 90

70 massloss[wt.-%]

0 5 10 15 20 25 30 time [day] Fig. 9. Thermal stability of polyurethane foams expressed as the weight loss after heating at: a. 150, b. 175, c. 200 C for 30 days

Experimental

Synthesis

-Reaction of urea with ethylene carbonate In a 100 cm3 three-necked round bottom flask 3 g of urea (0.05 mole) (pure, POCH, Gliwice, Poland) and the appropriate amount of EC (pure, Fluka, Switzerland), were placed to reach the molar ratio of reagents of 1 1-1 16 and 0.00-0.62 g potassium carbonate (0.00-12.42 g/mole urea, 0.00 0.09 mol/mol urea) or 0.34 g diazabicyclo[2.2.2]octane (DABCO) (6.72 g/ mol urea, 0.06 mol/mol urea), or 0.41 g zinc chloride (8.16 g/mol urea, 0.06 mol/mol urea). The reaction mixture was protected from moisture and stirred mechanically at 120-160 C with monitoring of progress of reaction by determination of unreacted EC [13].

-Foam preparation Attempts of foaming the reactions products of urea with EC were carried out in small 250 cm3 test cups at room temperature. To 5 g of hydroxyethoxy derivatives of urea, 0.1 g of surfactant (Silicon 5340, Houdry Hülls), 0.0-3.0 % wt. of triethylamine (TEA) catalyst (pure, Avocado, Germany), and 2-4 % wt. of water were added. After careful mixing of the components, a pre-weighed amount of 4,4’-diphenylmethane diisocyanate (pure, Merck, Germany) was added, calculated as described in [15]. The amounts of diisocyanate and water were adjusted to give OH:NCO molar ratio varying from of 1:1.66 to 1:1.81. Each composition was vigorously mixed until it started to cream (see Table 3). The samples for testing were cut out from the foams thus obtained after ca. 48 hrs.

Analytical Methods 1H-NMR spectra of products were recorded with BS-586A 80 MHz spectrometer (Tesla, Brno, Czechoslovakia) in d6-DMSO, and HMDS reference. IR spectra were taken for films with PARAGON 1000 FTIR spectrophotometer (Perkin Elmer, Wellesley, MA, US). MALDI ToF spectra of reaction products of urea with EC were obtained on Voyager- Elite Perseptive Biosystems (US) mass spectrometer working at linear mode with delayed ion extraction, equipped with nitrogen laser working at 337 nm. The matrix was α-cyano-4-hydroxycinnamic acid. The samples were diluted with methanol to 1 mg/cm3, followed by addition of 10 mg/cm3 NaI in acetone. Therefore in some cases + + + the molecular ion weights were increased by the mass of Na , H , K and CH3OH. Chromatographic analysis of by-products, i.e. ethylene glycol (EG) and products of its consecutive reactions with EC (diethylene glycol, triethylene glycol and tetraethylene glycol (TETRAEG)) was performed with gas chromatograph HP 4890A (Hewlett Packard, Ringoes, NJ, US) with FID detector and HP1 30 m x 0.53 mm column packed with crosslinked methylsiloxane film of 1.5 m thickness. Initial temperature was 50 C, heating rate: 20 C/min, end temperature: 220 C, time of heating at 220 C: 6 min, loader temperature: 250 C, detector temperature: 300 C. The samples were dissolved in methanol (0.01 M). Internal reference was cyclohexanone. Precentage of diols and polyols were calculated according to calibrtaion curves as described in [16].

14 Thermal analyses (DTA, DTG and TG) of hydroxyethyl derivatives of urea and polyurethane foams were performed with 200 mg samples in ceramic crucible at 20-1000 C temperature range, with 100 min registration time, under air atmosphere with Paulik- Paulik-Erdey derivatograph, MOM, Hungary. The following properties of hydroxyethoxy derivatives of urea have been determined: pycnometer density [17], refractive index (with Abbe’s refractometer), Höppler viscosity [18], and surface tension by ring detach method [19]. All measurements were made in temperature range 20-80 C. The following properties of foams were determined: apparent density [20], water uptake [21], stability of dimension [22], glass transition temperature (by DSC), thermal stability as the weight loss after heating at 150, 175 and 200 C for a month and the compressive strength [23]. The differential scanning calorimetry (DSC) measurements were made using a DSC822e Mettler Toledo instrument, in 20-200 C temperature range and 10 deg/min heating rate under nitrogen atmosphere. The results were recorded as heat flow in [W/g] versus temperature.

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