Branched Polyaspartic Acid Esters and Their Preparation

Abstract

Disclosed herein is a branched polyester formed by an acid component, a diol component and a polyol component. The acid component includes an amino dicarboxylic acid of formula (I)

##STR00001##

where R.sup.1 is hydrogen or a hydrocarbon having 1 to 20 carbon atoms. One or more carbon atoms can be replaced by oxygen, provided that the replaced carbon is not a primary carbon atom and, if more than one oxygen replaces carbon atoms, at least two carbon atoms are between adjacent oxygen atoms. The diol component includes a diol, the polyol component includes a polyol, and the acid component forms carboxylic acid ester groups with the diol and the polyol. The molar ratio of diol and polyol is between 2:1 and 1:2. Further disclosed are a process for preparing the branched polyester, a reaction product of the branched polyester with a polyisocyanate, and a method of using the reaction product.

Claims

1. A branched polyester formed by an acid component, a diol component and a polyol component, wherein the acid component comprises an amino dicarboxylic acid of formula (I) ##STR00005## wherein R.sup.1 is hydrogen or a hydrocarbon having 1 to 20 carbon atoms, wherein in the hydrocarbon one or more carbon atoms can be replaced by an oxygen, provided that the replaced carbon is not a primary carbon atom and in case of more than one oxygen replacing carbon atoms, at least two carbon atoms are between adjacent oxygen atoms, wherein the diol component comprises a diol, wherein the polyol component comprises a polyol having at least three hydroxyl groups, and wherein the acid component forms carboxylic acid ester groups with the diol component and the polyol component and the dashed lines indicate the bondage to the diol or the polyol via the commonly shared oxygen, characterized in that the molar ratio of diol component and polyol component is in the range from 2:1 to 1:2.

2. The branched polyester of claim 1, wherein the acid component consists of one amino dicarboxylic acid.

3. The branched polyester of claim 1, wherein R.sup.1 is a hydrocarbon having 1 to 20 carbon atoms, wherein in the hydrocarbon one or more carbon atoms can be replaced by an oxygen, provided that the replaced carbon is not a primary carbon atom and in case of more than one oxygen replacing carbon atoms, at least two carbon atoms are between adjacent oxygen atoms, and wherein one or two carbon atoms can be replaced by an oxygen atom.

4. The branched polyester of claim 1, wherein R.sup.1 is selected from the group consisting of n-butyl, tert.-butyl, n-pentyl, n-octyl, 2-ethyl-1-hexyl, cyclohexyl, 2-methylcyclohexyl and 3-methoxypropyl.

5. The branched polyester of claim 1, wherein the diol component consists of one diol.

6. The branched polyester of claim 1, wherein the diol is selected from the group consisting of triethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexandiol, neopentylglycol, 2,5-dimethyl-2,5-hexandiol, and 2-ethyl-1,3-hexandiol.

7. The branched polyester of claim 1, wherein the polyol component consists of one polyol.

8. The branched polyester of claim 1, wherein the polyol is selected from the group consisting of glycerol, butane-1,2,4-triol, n-pentane-1,2,5-triol, n-pentane-1,3,5-triol, n-hexane-1,2,6-triol, n-hexane-1,2,5-triol, n-hexane-1,3,6-triol, trimethylolbutane, trimethylolpropane, trimethylolethane, trimethylolmethane, mixtures of the above trifunctional alcohols, and alkoxylates thereof.

9. The branched polyester of claim 1, wherein the molar ratio of diol component and polyol component is in the range from 1.5:1 to 1:1.5.

10. The branched polyester of claim 1, wherein the molar ratio of acid component to the sum of diol component and polyol component is in the range from 1:2 to 2:1.

11. A process for preparing the branched polyester of claim 1, comprising the steps (a) reacting an acid component with a mixture of a diol component and a polyol component, wherein the acid component comprises an activated maleic acid or activated fumaric acid, wherein the diol component comprises a diol, wherein the polyol component comprises a polyol, and wherein the acid component forms carboxylic acid ester groups with the diol component and the polyol component, characterized in that the molar ratio of diol component and polyol component is in the range from 2:1 to 1:2; and (b) reacting the resulting product from step (a) with R.sup.1—NH.sub.2 in an aza-Michael addition reaction, resulting in the branched polyester.

12. The process of claim 11, wherein the acid component consists of one activated maleic acid or one activated fumaric acid.

13. The process of claim 11, wherein the activated maleic acid is selected from the group consisting of maleic anhydride, a diester of maleic acid with a C.sub.1-4 alkyl alcohol, and a dihalide of maleic acid.

14. A reaction product of the branched polyester of claim 1 with an isocyanate with a functionality of 2 or higher than 2.

15. A method of using the reaction product of claim 14 in adhesives, printing inks, coatings, foams, coverings and paints.

16. The branched polyester of claim 1, wherein the polyol component comprises a polyol having a triol.

17. The branched polyester of claim 1, wherein the polyol component comprises a polyol having a tetrol.

18. The branched polyester of claim 1, wherein R.sup.1 is a hydrocarbon having 3 to 10 carbon atoms, wherein in the hydrocarbon one or more carbon atoms can be replaced by an oxygen, provided that the replaced carbon is not a primary carbon atom and in case of more than one oxygen replacing carbon atoms, at least two carbon atoms are between adjacent oxygen atoms, wherein one or two carbon atoms can be replaced by an oxygen atom.

Description

EXAMPLES

1. Methods

[0083] Hydroxyl Number (HN)

[0084] Hydroxyl numbers (HN) of linear and branched unsaturated polyesters were determined according to ASTM E222 standard using perchloric acid catalyzed method.

[0085] Total Acid Number (AN)

[0086] Total acid numbers (AN) of linear and branched unsaturated polyesters were determined according to ISO 2114:2000 standard.

[0087] Gel Permeation Chromatography (GPC)

[0088] GPC measurements of unsaturated polyesters and polyaspartic acid esters were performed in THF or DMAc (with 0.5% LiBr) at RT by PSS Agilent 1200 Series. The nominal solvent flow rate was 1 mL/min. Three SEC columns with a pore size of 100, 1000, and 10000 Å for THF and 30 and 2×1000 Å for DMAc from PSS Polymer Standards were used for fractionation. The refractive index detector G136A and UV/Vis detector G1314B from Agilent Technologies were used. The calibration was carried out with polystyrene as standard for samples in THF and poly(methyl methacrylate) for samples in DMAc. The results were evaluated using WinGPC UniChrom V 8.20 software from Polymer Standards Service GmbH.

[0089] Viscosity Measurement

[0090] Viscosities of 65 wt % solutions of unsaturated polyesters and polyaspartic acid esters in butyl acetate were measured using Brookfield DV-Ill Ultra Programmable Rheometer (Brookfield Engineering Laboratories, Inc., 11 Commerce Boulevard, Middleboro, MA 02346 USA). The samples (v=400 mL) were placed in 600 mL beaker with an inside diameter of d=8.6 cm. The measurements were done using spindle model HA02, at 100 rpm and 21-22° C.

[0091] Thermogravimetric Analysis (TGA)

[0092] A PerkinElmer Pyris TGA 4000 was used for determination of onset temperatures of decomposition. The samples were heated under air from 50 up to 650° C. with a heating rate of 10 K/min.

[0093] Differential Scanning Calorimetry (DSC)

[0094] A Netzsch DSC 200 F3 (Erich Netzsch GmbH & Co. Holding KG, Selb, Germany) was used to determine the glass transition temperatures of samples. Samples were heated from −150° C. to 150° C. at a rate of 10° C./min under a nitrogen atmosphere. Two cooling-heating runs were performed for each sample and the data from the second heating curve was used. The data was analyzed using the Netzsch Proteus Thermal Analysis (Version 4.8.1) software.

2. Materials

[0095] Maleic anhydride (MAn, ≥99%), diethyl maleate (DEM, ≥96%), triethylene glycol (TEG, 99%), 1,4-butanediol (BD, 99%), 1,6-hexanediol (HD, 99%), neopentylglycol (NPG, 99%), 2,5-dimethyl-2,5-hexanediol (DMHD, 97%), 2-ethyl-1,3-hexanediol (EHD, 97%), glycerol (≥99.5%), trimethylolpropane (TMP, ≥98%), cyclohexylamine (CHA, ≥99.9%), 2-methylcyclohexylamine (MCHA, mixture of cis and trans isomers, 98%), n-butylamine (nBA, 99.5%), tert-butylamine (tBA, 98%), octylamine (OC, 99%), 3-methoxypropylamine (MPA, 99%), 2-ethyl-1-hexylamine (EHA, 98%), n-butyl acetate (99.5%), dibutyltin dilaurate (DBTDL, 95%) and 4-methoxyphenol (MeHQ, 99%) were purchased from Sigma-Aldrich and used as received. Basonat HI 100 (hexamethylene diisocyanate trimer, 88%) was provided by BASF SE and used as received. 1-Pentylamine (PA, 98%) was purchased from Alfa Aesar and used as received. Diethylene glycol (DEG, ≥99.5%) was purchased from Merck and used as received.

3. Synthesis Protocols

[0096] 3.1. Branched Unsaturated Polyesters from Maleic Anhydride (Unsaturated Polyester I=UPE I)

[0097] A series of branched unsaturated polyesters was synthesized from maleic anhydride (MAn), different diols (diethylene glycol (DEG), triethylene glycol (TEG), 1,4-butanediol (BD), 1,6-hexanediol (HD), neopentylglycol (NPG) and 2-ethyl-1,3-hexanediol (EHD)) and two branching reagents (glycerol, trimethylolpropane (TMP)) via polycondensation method. The molar ratio between anhydride, diol and triol was 1:0.5:0.5.

[0098] The experimental procedure for the synthesis of all branched unsaturated polyesters was always the same, an example is described below.

[0099] Maleic anhydride (11.40 g, 116.3 mmol), neopentylglycol (6.05 g, 58.1 mmol) and trimethylolpropane (7.80 g, 58.1 mmol) were placed in a 100 mL round-bottom flask equipped with a magnetic stirrer bar. The flask was attached to a Liebig condenser with Claisen head and a slow flow of dry N.sub.2 through the head was applied to keep the reaction under inert atmosphere and to improve the removal of water vapors. The reaction system was placed in an oil bath at 140° C. for 20 hours. After 20 hours a small amount of MeHQ was dissolved in the polyester and the content of the reaction flask was transferred to a vial.

[0100] The following Table summarizes prepared unsaturated polyesters according to the above protocol:

TABLE-US-00001 TABLE 1 The list of synthesized branched unsaturated polyesters I(reaction conditions: 20 h, 140° C., N.sub.2 atmosphere) Molar No. Polyester ratio Comments 1 MAn + neopentylglycol + TMP 1:0.5:0.5 transparent solid 2 MAn + 2-ethyl-1,3-hexanediol + 1:0.5:0.5 transparent solid TMP 3 MAn + butanediol + TMP 1:0.5:0.5 transparent solid 4 MAn + butanediol + glycerol 1:0.5:0.5 transparent solid 5 MAn + hexanediol + TMP 1:0.5:0.5 transparent solid 6 MAn + diethyleneglycol + 1:0.5:0.5 transparent solid TMP 7 MAn + triethyleneglycol + 1:0.5:0.5 transparent solid TMP

[0101] The branched unsaturated polyesters were used for investigations without further purification. The molar masses, viscosities, total acid numbers, hydroxyl numbers and glass transition temperatures of chosen polyesters were determined.

TABLE-US-00002 TABLE 2a Properties of branched unsaturated polyesters I. GPC in DMAc GPC in THF M.sub.n M.sub.n No. Polyester [g/mol] Ð [g/mol] Ð 1 MAn + neopentylglycol + 1920 2.63 1060 1.45 TMP 2 MAn + 2-ethyl-1,3- 1220 1.75 — — hexanediol + TMP 3 MAn + butanediol + 1910 2.69  980 1.38 TPM 4 MAn + butanediol + 1230 1.76 — — glycerol 5 MAn + hexanediol + 2200 2.97 1370 1.59 TMP 6 MAn + diethyleneglycol + 860 1.42 — — TMP 7 MAn + triethyleneglycol + 1210 1.51  880 1.32 TMP

TABLE-US-00003 TABLE 2b Properties of linear and branched unsaturated polyesters. Solubility in butyl AN [mg HN [mg f or M.sub.nth acetate Viscosity KOH/g KOH/g calculated T.sub.g No. (65 wt %) [mPa .Math. s] sample] sample] from HN [° C.] % cis* 1 S1 1030  55.0 201.8 6.9 30 83 2 S1 348 96.7 203.7 4.4 19 79 3 S1 915 51.7 192.2 6.5 16 86 4 I2 — — — — — — 5 S1 659 39.9 190.9 7.5 −5 84 6 I1 — 103.7  258.3 4.0 14 87 7 I1 — 67.6 221.7 4.8 −2 79 AN—total acid number; HN—hydroxyl number; S1—soluble, transparent, very viscous; S2—soluble, transparent, viscous; I1—2 phases, milky dispersion when shaken; I2—insoluble, 2 phases; f—functionalization degree, number of hydroxyl and carboxyl groups per chain; * % of cis double bonds (maleate units) in comparison with all double bonds (maleate and fumarate double bonds signals in .sup.1H NMR spectra of samples);

[0102] 3.2. Aza-Michael Addition of Primary Monoamines to Branched Unsaturated Polyesters I

[0103] The Aza-Michael reactions between chosen branched unsaturated polyester and eight primary monoamines (cyclohexylamine (CHA), 2-methylcyclohexylamine (2-MCHA), n-butylamine (BA), tert-butylamine (t-BA), pentylamine (PA), octylamine (OC), 3-methoxypropylamine (MPA) and 2-ethyl-1-hexylamine (EHA)) were carried out in n-butyl acetate at 65 wt % concentration of the polyaspartic acid ester.

[0104] The experimental procedure for the synthesis of all polyaspartic acid esters was always the same, an example is described below.

[0105] Branched unsaturated polyester of maleic anhydride, neopentylglycol and trimethylolpropane (1.21 g, 6.08 mmol of double bonds) was placed in 5 mL vial with a screw cap and a magnetic stirring bar. Then 1.22 mL (1.08 g) of n-butyl acetate was added to the vial, the vial was tightly closed and placed on a magnetic stirrer for 24 h at RT (complete dissolution of polyester). After 24 h the 2-ethyl-1-hexylamine (0.996 mL, 0.786 g, 6.08 mmol) was added to the vial, the vial was tightly closed and placed on a magnetic stirrer for 48 h at RT. The photos of samples after 24 h, 48 h and two weeks were taken.

[0106] The synthesized polyaspartic acid esters were used for investigations without further purification (the n-butyl acetate was evaporated for some analyses). The molar masses, viscosities, glass transition temperatures and onset temperatures of decomposition of chosen polyaspartic acid esters were determined.

TABLE-US-00004 TABLE 3a Properties of branched polyaspartic acid esters PAE synthesized from respective UPE and 2-ethyl-1-hexylamine Viscosity of The polyester used for the PAE after 48 h M.sub.n of PAE-I No. synthesis of PAE [mPa .Math. s] [g/mol] A1 MAn + Neopentylglycol + 875 3720 TMP (D = 2.35) A2 MAn + 2-ethyl-1,3-hexanediol + 737 1680 TMP (D = 1.69) A3 MAn + Butanediol + TPM 842 4230 (D = 2.41) A5 MAn + Hexanediol + TMP 475 3480 (D = 2.66) A6 MAn + Diethyleneglycol + 668 2430 TMP (D = 1.47) A7 MAn + Triethyleneglycol + 348 2800 TMP (D = 1.77)

TABLE-US-00005 TABLE 3b T.sub.g T.sub.o.sup.# The polyester used for the [° C] [° C.] Comments No. synthesis of PAE-I (DSC) (TGA) after 48 h A1 MAn + Neopentylglycol + −25 189 clear, viscous TMP solution A2 MAn + 2-ethyl-1,3- −23 184 clear, viscous hexanediol + TMP solution A3 MAn + Butanediol + TPM −35 197 clear, viscous solution* A5 MAn + Hexanediol + TMP −24 204 clear, viscous solution A6 MAn + Diethyleneglycol + −26 178 clear, viscous TMP solution A7 MAn + Triethyleneglycol + −34 199 clear, viscous TMP solution *a bit yellowish after 1 week; .sup.#T.sub.o—onset temperature of decomposition

[0107] 3.3. Aza-Michael Addition of 2-Ethyl-1-Hexylamine to Branched Unsaturated Polyester of Maleic Anhydride, 2-Ethyl-1,3-Hexanediol and TMP in Bulk

[0108] The branched unsaturated polyester of maleic anhydride, 2-ethyl-1,3-hexanediol and trimethylolpropane was synthesized according to the procedure described in chapter 3.4 (instead of the one-neck flask a three-neck flask was used and the magnetic stirrer was replaced with a mechanical stirrer). The standard 1:0.5:0.5 anhydride, diol and triol molar ratio was used, the synthesis was carried out for 11.40 g of maleic anhydride (116.3 mmol).

[0109] After 20 h of the polycondensation reaction, a dropping funnel with 2-ethyl-1-hexylamine (19.04 mL, 15.02 g, 116.3 mmol) and reflux condenser were attached to the flask with polyester under nitrogen flow. The amine was added dropwise to the stirred polyester at 140° C. over a 1 h period. The Aza-Michael reaction was continued for next 23 h at 140° C. Next day the flask was cooled to RT and the content was transferred to a vial. The molar mass and glass transition temperature of the branched polyaspartic acid ester I were determined.

[0110] 3.4. Synthesis of Branched Unsaturated Polyesters with Diethyl Maleate (DEM) (Unsaturated Polyester II=UPE II)

[0111] The branched unsaturated polyesters were synthesized from diethyl maleate, trimethylolpropane and two different diols: 1,6-hexanediol and triethyleneglycol via polycondensation method. The molar ratio between maleate, diols and triol were 1:0.5:0.5 or 1.1:0.5:0.5. An example of an experimental procedure for the synthesis of branched unsaturated polyesters is described below.

[0112] Diethyl maleate (385 g, 2.24 mol), hexanediol (120.10 g, 1.02 mol), trimethylolpropane (136.37 g, 1.02 mol) and dibutyltin dilaurate (1.41 g, 1.32 mL, 2.23 mmol) were placed in a 1 L two-neck round-bottom flask equipped with a mechanical stirrer with PTFE blade. The flask was attached to a Liebig condenser with a Claisen head and a slow flow of dry N.sub.2 through the head was applied to keep the reaction under an inert atmosphere. The reaction system was placed in an oil bath at 160° C. for 10 hours. During the first 2 h, the reaction mixture was kept under N.sub.2 flow than the pressure in the system was gradually reduced to 50 mbar using a vacuum pump. After 10 hours a 660 mg of MeHQ was dissolved in the polyester and the content of the reaction flask was transferred to a bottle.

[0113] The branched unsaturated polyesters were used for further investigations without purification. The molar masses, viscosities, total acid numbers, hydroxyl numbers and glass transition temperatures of polyesters were determined.

TABLE-US-00006 TABLE 8a Reaction conditions and properties of branched unsaturated polyesters UPE-II. Molar Time under GPC in DMAc UPE ratio of Temp. Reaction reduced pressure, M.sub.n II No. Polyester reagents [° C.] time [h] final pressure [g/mol] Ð 01 DEM + Hexanediol + TMP 1:0.5:0.5 140-160 72 2 h, 200 mbar 1300 2.38 02 DEM + Triethyleneglycol + TMP 1:0.5:0.5 150-160 28 4 h, 200 mbar  930 1.96 03 DEM + Hexanediol + TMP 1:0.5:0.5 140 10 8 h, 50 mbar — — −04 DEM + Hexanediol + TMP 1:0.5:0.5 160 10 8 h, 50 mbar 1120 1.69 05 DEM + Hexanediol + TMP 1.1:0.5:0.5   160 10 8 h, 50 mbar 1750 2.59 06 DEM + Triethyleneglycol + TMP 1.1:0.5:0.5   160 10 8 h, 50 mbar 1090 1.82

TABLE-US-00007 TABLE 8b Reaction conditions and properties of linear and branched unsaturated polyesters UPE-I. AN [mg HN [mg f or M.sub.nth UPE Viscosity KOH/g KOH/g calculated T.sub.g % II No. Polyester [mPa .Math. s] sample] sample] from HN [° C.] cis* 01 DEM + Hexanediol + TMP 178 1.1 212.1 4.9 −38 95 02 DEM + Triethyleneglycol + TMP 136 2.0 228.4 3.8 −40 96 03 DEM + Hexanediol + TMP 72 1.4 286.1 — −62 98 04 DEM + Hexanediol + TMP 128 2.1 251.5 5.0 −45 97 05 DEM + Hexanediol + TMP 200 1.0 153.0 4.8 −33 96 06 DEM + Triethyleneglycol + TMP 119 2.1 193.9 3.8 −41 97

[0114] 3.5. Aza-Michael Addition of 2-Ethyl-1-Hexylamine to Branched Unsaturated Polyester II

[0115] The Aza-Michael reactions between chosen linear/branched unsaturated polyester and 2-ethyl-1-hexylamine were carried out in n-butyl acetate at 65 wt % concentration of the polyaspartic acid ester.

[0116] The experimental procedure for the synthesis of all polyaspartic acid esters was always the same, an example is described below.

[0117] Branched unsaturated polyester of diethyl maleate, hexanediol and trimethylolpropane (357.50 g, 1.74 mol of double bonds) was placed in 1 L bottle with a magnetic stirring bar. Then 355.18 mL (313.27 g) of n-butyl acetate was added to the bottle, the bottle was tightly closed and placed on a stirrer for 24 h at RT (complete dissolution of polyester). After 24 h 284.27 mL of 2-ethyl-1-hexylamine (224.29 g, 1.74 mol) was added to the stirred solution from a dropping funnel (during the 2 h period), then the bottle was tightly closed and stirred for 48 h at RT.

[0118] The synthesized polyaspartic acid esters were used for investigations without further purification (the n-butyl acetate was evaporated for some analyses). The molar masses, viscosities and glass transition temperatures of chosen polyaspartic acid esters were determined.

TABLE-US-00008 TABLE 9 Properties of branched polyaspartic acid esters PAE-II synthesized from respective UPE-II and 2-ethyl-1-hexylamine in ~0.5 kg scale. The polyester used Viscosity of M.sub.n of PAE for the synthesis of PAE-I after PAE-I T.sub.g Comments II No. PAE-I 48 h [mPa .Math. s] [g/mol] [° C.] after 48 h 01 UPE-I-01 (DEM + 126 1530 −53 clear, orange Hexanediol + TMP) (D = 2.11) colored, viscous solution 02 UPE-I-02 (DEM + 88 1250 −53 clear, orange Triethyleneglycol + (D = 1.81) colored, viscous TMP) solution

[0119] 3.6. Reactivity of Branched Polyaspartic Esters in Reaction with HDI Isocyanurate Trimer

[0120] The reactivity of chosen polyasparticesters was investigated in reaction with Basonat HI 100 (HDI isocyanurate). The molar ratio between ester and Basonat HI 100 was always equal in terms of reactive groups content —OH/NH groups in polyester vs NCO groups in Basonat HI 100. The experimental procedure was always the same, two examples are described below.

[0121] For the Reaction of PAE-II-1 and Basonat HI 100:

[0122] 2 g of 65 wt % solution of PAE-I-1 (3.87 mmol of NH groups) was placed in 10 mL vial equipped with a magnetic stirrer. Then 0.74 g of Basonat HI 100 (3.87 mmol of NCO groups) was added to the stirred solution and the pot life of the mixture was measured with a stopwatch.

[0123] For the Reaction of UPE-II-1 and Basonat HI 100:

[0124] 3 g of 65 wt % solution of UPE-II-1 (7.37 mmol of OH groups) was placed in 10 mL vial equipped with a magnetic stirrer. Then 1.41 g of Basonat HI 100 (7.37 mmol of NCO groups) was added to the stirred solution and the pot life of the mixture was measured with a stopwatch.

TABLE-US-00009 TABLE 10 Comparison of the reactivity of unsaturated polyesters (UPE- I-01 and UPE-I-02), polyaspartic acid esters (PAE-I-01, 02, 03 and 05) and Jeffamine in reaction with Basonat HI 100. mmole PAE-II, UPE-II or mmole NH/g amine (65 wt % in OH/g PAE- PAE- Pot life No butyl acetate) II/UPE II I/amine [min] Comments 1 PAE-II-01 (UPE II 2.32 2.98 0:30 exothermic reaction, 01 + 2-ethyl-1- clear, poorly mixed, hexylamine) very brittle 2 UPE II 01 (DEM + 3.78 — 9:30 clear, well mixed, Hexanediol + TMP) brittle 3 PAE-II 02 (UPE II 2.57 2.85 0:50 exothermic reaction, 02 + 2-ethyl-1- clear, poorly mixed, hexylamine) very brittle 4 UPE II 02 (DEM + 4.07 — 17:00  milky during first Triethyleneglycol + 2:30 min then clear, TMP) well mixed, brittle 5 PAE-II-01 (UPE II 2.32 2.98 0:33 exothermic reaction, 01 + 2-ethyl-1- clear, poorly mixed, hexylamine) brittle 6 PAE-II-02 (UPE II 2.57 2.85 0:42 exothermic reaction, 02 + 2-ethyl-1- clear, poorly mixed, hexylamine) brittle