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MDI Prepolymers Extended with Amines – A Reality! DR. ASHOK M. SARPESHKAR

Bayer MaterialScience, LLC Pittsburgh, PA 15205 JAMES-MICHAEL BARNES, DR. JENS KRAUSE,

DR. HARTMUT NEFZGER & DR. MANFRED SCHMIDT,

Bayer MaterialScience AG Leverkusen, Germany

Abstract

The production of cast polyurethane elastomers from diphenylmethanediisocyanate (MDI) prepolymers and cast polyurethaneurea elastomers from toluenediisocyanate (TDI) prepolymers is well documented. The slower reactivity of TDI prepolymers with aromatic diamines offers a formulator the ability to produce polyurethaneurea elastomers with superior physical properties. In contrast, the reaction of a MDI prepolymer with either an aliphatic or aromatic amine is too fast to be of any practical utility. TDI exposure in the workplace has long been a concern of cast elastomer processors. This concern has been mitigated with the commercialization of low free-TDI prepolymers. Nonetheless, the development of amine extendable prepolymers based on lower vapor pressure MDI has been a long term goal of industry suppliers. This paper describes a new Baytec® MAX (MDI amine crosslinked) prepolymer product line, consisting of novel polyester and polyether prepolymers produced from diphenylmethanediisocyanate. These prepolymers demonstrate reactivities similar to that of corresponding, free-monomer stripped 2,4-TDI prepolymers when extended with diamine co-reactants such as MbOCA and MCDEA, and produce polyurethaneurea elastomers with comparable physical properties. The paper will highlight processing benefits and reactivity profiles with amine extenders. Physical properties of elastomers derived from these prepolymers will be compared to those from low free-monomer TDI prepolymers. The development of these prepolymers represents a breakthrough in MDI cast elastomer technology. For the first time, formulators can produce MDI based polyurethaneurea cast elastomers with superior mechanical properties and performance. Introduction

Cast elastomers produced by the reaction of difunctional prepolymers from MDI, TDI, NDI, PPDI and low molecular weight diols and diamines represent ideal structures on which the morphological concept of hard segment-soft segment was developed. The superior mechanical properties of these cast elastomers is attributed to the high degree of phase segregation of microcrystalline hard segments from the soft segment as depicted in the frequently cited morphological diagram1 (Figure 1). The configuration of chains in the hard segment portion of a MDI-Butane diol adduct1 is shown in Figure 2. In MDI prepolymers, the symmetric structure and linearity of the 4,4’-MDI molecule is largely responsible for the excellent phase segregation and ensuing superior dynamic properties of elastomers produced when 4,4’-MDI prepolymers are cured with low molecular weight hydroxy co-reactants such

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as 1,4-butane diol. When naphthalene-1,5-diisocyanate is employed, this phase segregation is further enhanced in the elastomer. TDI prepolymers cured with diamine curatives produce hard blocks with increased hydrogen bonding, but they are not as well-defined due to the non-linear structure of the TDI molecule. Hence phase segregation in elastomers based on TDI is less well defined. A scholarly evaluation of the microstructure of TDI based polyurethaneurea elastomers has been published2 . However, TDI brings other attributes such as its ability to react with diamines at a reasonable reaction rate, thus enabling a formulator to produce polyurethaneurea cast elastomers that cannot be achieved via existing 4,4’-MDI based prepolymer chemistry.

Figure 1: Polyurethane Domain Morphology

Figure 2: Secondary Structure of Hard Segments

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Another concern with TDI based prepolymers has been the long standing issue of volatile monomer that is left behind in the product during manufacture. Manufacturers have addressed this issue by developing prepolymers with very low monomer contents employing techniques such as wiped-film evaporation3 and other chemical techniques4,5. Results and Discussion

Polyurethaneurea cast elastomers based on MDI chemistry are now a reality! The object of this paper is to introduce to the cast elastomer industry, a new Baytec® MAX (MDI amine crosslinked) prepolymer product line consisting of both polyester- and polyether based prepolymers. Based on a specialty MDI, these prepolymers can be reacted with diamine curatives to produce polyurethaneureas. The work addresses the long standing concern of the health and safety aspects of free-TDI monomer in TDI prepolymers. Prepolymers currently available are listed in Table-1. These prepolymers are cured with diamine chain extenders such as MbOCA, Lonzacure MCDEA, Baytec XL-1604, Ethacure 100 and Ethacure 300, extenders typically used to cure TDI prepolymers. Additionally, blends of these prepolymers may be employed to produce intermediate physical properties. Lower processing temperatures are employed and reactivities of the new MDI/polyester and MDI/polyether prepolymers are suitable for production of medium to large parts. Mechanical properties of elastomers produced from these new prepolymers are generally superior, especially in regards to tear and abrasion. Table 1: New Desmodur MDI Polyester & Polyether Prepolymers

Bayer Prepolymer

Polyol Component

%NCO Viscosity @90°C (mPa.s)

Desmodur VP.PU MS 40TF01 Polyester 4.0 1450 Desmodur VP.PU MS 40TF03 Polyester 4.0 1070 Desmodur VP.PU MS 58TF02 Polyester 5.8 880 Desmodur VP.PU MS 78TF03 Polyester 7.8 365 Desmodur VP.PU ME 40TF04 Polyether 4.0 1000 Desmodur VP.PU ME 60TF04 Polyether 6.0 450 Desmodur VP.PU ME 80TF04 Polyether 8.0 600

Experimental

Prepolymers based on polyesters and polyethers were prepared according to standard methods of MDI prepolymer manufacture. Prepolymers described in Table 1 are in the EPA Registration process and are currently available for R & D purposes only. Casting conditions were similar to those used for TDI prepolymer processing. Curatives employed were Baytec XL-1604, Lonzacure MCDEA and MbOCA. Hand castings were made using a Hauschild High Speed Mixer DAC 400 FV and gel times measured on a Gardner Gel Tester at 110°C. Experiments with MbOCA were run on a low pressure meter-mix machine using standard MbOCA conditions. All experiments were run at an index of 1.05 with postcure conditions of 110°C for 24 hrs. The preferred index for Lonzacure MCDEA is 1.07 while an index of 1.14 is recommended for Baytec XL-1604.

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Effect of Free Monomer on Elastomer Properties

In order to highlight the benefits of residual MDI monomer on the physical properties of the elastomer, a comparison of elastomers obtained from Desmodur VP.PU MS 40TF01, Desmodur TEC 41 (unstripped) and Desmodur TS-35 (monomer content <0.5%), and Baytec XL-1604 curative was made. Results are shown in Table 2. Table 2: Comparison of MS 40TF01, TEC-41 & TS-35 Extended with Baytec XL-1604*

Property Test Method Units MS40TF01 TEC-41 TS-35

Shore Hardness DIN 53505 A/D 93/36 90/36 86/34 Comp. Set 70h/23°C DIN 53517 % 22 18 28 Comp. Set 24h/70°C DIN 53517 % 42 36 47 Resilience DIN 53512 % 44 43 46 Graves Tear DIN 53515 pli 480 314 228 Tensile Strength DIN 53504 psi 6667 7975 7975 100% Modulus DIN 53504 psi 1058 870 870 300% Modulus DIN 53504 psi 1623 1595 1160 Elongation DIN 53504 % 770 610 630 Abrasion DIN 53516 mm3 54 (6.7mg) 50 (6.15 mg) 50 (6.15 mg) Density DIN 53479 g/ml 1.24 1.23 1.23 *Data presented as general information only. They are not part of the product specifications. As is evident from the above results, stripping monomer from TDI prepolymers results in a lowering of physical properties. Thus Desmodur TS-35 has a lower hardness, and a much reduced tear strength. In contrast, the beneficial effect of the MDI monomer in Desmodur MS 40TF01 may be clearly noticed in an overall improvement of physical properties. From a morphology point of view, lowering monomer levels in a TDI prepolymer results in a lower concentration of reinforcing hard segment domains6 which can compromise elastomer physical properties.

MDI/Polyester Prepolymers cured with MbOCA

Polyester based MDI prepolymers were extended with MbOCA on a low pressure machine. For purposes of comparison, a TDI/polyester prepolymer with an NCO content of 4.0% and a free-TDI monomer content of <0.1% was chosen. Processing conditions are shown in Table 3 and physical properties of elastomers produced are shown in Table 4.

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Table 3: Processing Parameters for Desmodur MS Prepolymers with MbOCA*

Prepolymer/

Parameter

MS 40TF01 MS 40TF03 MS 58TF02 TDI/Polyester

% NCO 4.0 4.0 5.8 4.0 Index 1.05 1.05 1.05 1.05 Prepol Temp. 90°C 90°C 90°C 90°C Extender Temp. 120°C 120°C 120°C 120°C Gel Time 3min:20secs 4:30 1:15 6:00 Demold Time 25:00 25:00 25:00 25:00 Postcure Conditions

110°C/24 hr. 110°C/24 hr. 110°C/24 hr. 110°C/24 hr.

*Data presented is for general information only. They are not part of the product specifications

Table 4: Desmodur MS Prepolymers cured with MbOCA Properties* ASTM

Method

Unit MS40TF01 MS40TF03 MS58TF02 TDI

Prepolymer

Durometer Hardness D-2240 Shore Scale 92A 42D

91A 40D

98A 55D

90A 42D

Taber Abrasion H-18 Wheel, 1000g load, 1000 cycles

D-3489-06 mg loss 1.8 1.3 13 9

Bayshore Resilience D-3574 % 33 36 41 27 Tensile Strength D-412 psi 5609 5154 6208 5948 100% Elongation psi 967 1006 1563 942 200% Elongation psi 1232 1287 1999 1190 300% Elongation psi 1711 1618 2719 1593 Ultimate Elongation D-412 % 645 683 580 613 Die C Tear D-624 pli 562 492 627 503 Split Tear D-3489 pli 440 331 535 331 Compression Set: 22 hrs @ 70°C

D-395B % 30 33 35 34

Compression Deflection D-575A psi 2% 185 153 318 145 5% 389 328 853 315 10% 627 560 1374 574 15% 751 707 1562 754 20% 872 844 1745 905 25% 1010 995 1970 1066 50% 2207 2295 4092 2357

*Data presented as general information only. They are not part of the product specifications. As shown in Table 3, reactivities of the Desmodur MS prepolymers with MbOCA are faster compared to the reactivity of the low free-TDI prepolymer. However, the reactivities are suitable for producing medium to large parts. As expected, the higher NCO prepolymers have a shorter gel time, a trend also observed with TDI prepolymers. Compared to the 4% NCO prepolymers, a drop in abrasion is observed. Elastomers from the MDI/polyester prepolymers, however, show very good abrasion resistance and enhanced tear resistance, highlighting the beneficial effect of free-MDI monomer. Due to a very small amount of free monomer, the TDI prepolymer does not provide a similar property profile.

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MDI/Polyether Prepolymers Cured with MbOCA

The Desmodur ME series of prepolymers were also cured with MbOCA. Processing parameters are shown in Table 5 and physical properties of elastomers shown in Table 6. Table 5: Processing Parameters for Desmodur ME Prepolymers with MbOCA*

Prepolymer/

Parameter

ME 40TF04 ME 60TF04 ME 80TF04

% NCO 4.0 6.0 8.0 Index 1.05 1.05 1.05 Prepol Temp. 90°C 90°C 90°C Extender Temp. 120°C 120°C 120°C Gel Time 6min:40secs 2:30 1:00 Demold Time 15:00 15:00 15:00 Postcure Conditions

100°C/16 hr. 100°C/16 hr. 100°C/16 hr.

*Data presented is for general information only. They are not part of the product specifications

Table 6: Desmodur ME Prepolymers cured with MbOCA*

Property Test

Method

Units ME40TF04 ME 60TF04 ME 80TF04

Shore Hardness DIN 53505 A/D 95A 98/55 65D Comp. Set 24h/70°C DIN 53517 % 29 32 37 Resilience DIN 53512 % 43 48 42 Graves Tear DIN 53515 pli 662 765 828 Tensile Strength DIN 53504 psi 5652 6957 6232 100% Modulus DIN 53504 psi 1710 2348 3536 300% Modulus DIN 53504 psi 2855 4058 5899 Elongation DIN 53504 % 484 429 325 Abrasion DIN 53516 mm3 40 (4.4mg) 45 (5.1 mg) 62 (7.1 mg) Density DIN 53479 g/ml 1.11 1.14 1.15 *Data presented is for general information only. They are not part of the product specifications

The polyether based prepolymers have processing windows which are similar to TDI/polyether systems. They have outstanding overall mechanical properties, especially tear and abrasion resistance. Evaluation of Amine Curatives other than MbOCA

Polyester Prepolymers

Besides the commonly used MbOCA, other aromatic diamine curatives such as Baytec XL-16047, Ethacure 1008 Ethacure 3009 and Lonzacure MCDEA10 have been employed in TDI prepolymer chemistry. An effort was made to study the utility of these extenders as alternatives to MbOCA. The reactivity of Desmodur MS40TF03 with the three curatives is shown in Table 7.

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Table 7: Processing of Desmodur MS40TF03 with Amine Curatives*

Processing

Parameter

Baytec XL-

1604

Lonzacure

MCDEA

MbOCA

Prepol Temp. 90-95°C 80°C 90°C Extender Temp. 100°C 100°C 120°C Gel Time 14min:52secs 1:50 4:30 Demold Time 30:00 15:00 25:00 Postcure Conditions

110°C/24 hr 110°C/24 hr 110°c/24 hr

*Data presented as general information only. They are not part of the product specifications. The reactivity of curatives studied was found to vary in the following order: Lonzacure MCDEA > MbOCA > Baytec XL-1604

These curatives can be used in place of MbOCA to produce elastomers with mechanical properties comparable to, or in some cases superior to MbOCA cured low-free TDI prepolymers. Table 8 shows the range of physical properties obtained. Table 8: Desmodur MS/Polyesters Cured with MCDEA and XL-1604

Properties ASTM

Method

Unit MS40TF01

(MCDEA)

MS40TF01

(XL-1604)

MS40TF03

(MCDEA)

MS40TF03

(XL-1604)

Durometer Hardness D-2240 Shore Scale 95A/44D 91A/38D 96A/57D 90A/38D Taber Abrasion H-18 Wheel, 1000g load, 1000 cycles

D-3489-

06

mg loss

66

82

40

23

Bayshore Resilience D-3574 % 42 37 46 40 Tensile Strength D-412 psi 7652 6799 6731 6694 100% Modulus psi 1222 1124 1526 1239 200% Modulus psi 1581 1467 1840 1556 300% Modulus psi 2246 2132 2385 2014 Ultimate Elongation D-412 % 692 549 543 543 Die C Tear D-624 pli 627 579 650 507 Split Tear D-3489 pli 456 488 579 400 Compression Set: 22 hrs @ 70°C

D-395B % 30 25 32 30

Compression Deflection D-575A psi 2% 282 190 261 151 5% 651 423 615 332 10% 954 672 936 577 15% 1125 806 1140 728 20% 1296 942 1350 880 25% 1490 1097 1588 1055 50% 3106 2455 3654 2595 *Data presented as general information only. They are not part of the product specifications.

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Polyether Prepolymers

The polyether based Desmodur ME prepolymers were extended with both Baytec XL-1604 and Lonzacure MCDEA. Processing parameters are provided in Table 9 and properties of elastomers shown in Tables 10 and 11. Table 9: Processing Parameters for Desmodur ME Prepolymers

Prepolymer/

Parameter

ME 40TF04 ME 60TF04 ME 80TF04

% NCO 4.0 6.0 8.0

Index 1.05 1.05 1.05

Prepol Temp. 90°C 90°C 90°C Extender Temp. 100°C 100°C 100°C

Gel Time XL-1604 6min:20secs 4:30 2:30

Gel Time MCDEA 1:40 0:35 0:15 Demold Time XL-1604 11:00 8:00 4:30

Demold Time MCDEA 2:30 1:30 1:00

Postcure Conditions 110°C/24 hr. 110°C/24 hr. 110°C/24 hr.

*Data presented as general information only. They are not part of the product specifications. Table 10: Elastomers from Desmodur ME Prepolymers and Curative Baytec XL-1604

Property Test

Method

Units ME40TF04 ME 60TF04 ME 80TF04

Shore Hardness DIN 53505 A/D 91/34 97/45 99/54 Comp. Set 70h/23°C DIN 53517 % 26 30 38 Comp. Set 24h/70°C DIN 53517 % 44 61 63 Resilience DIN 53512 % 52 46 49 Graves Tear DIN 53515 pli 343 508 680 Tensile Strength DIN 53504 psi 4203 5797 5507 100% Modulus DIN 53504 psi 1159 1739 2464 300% Modulus DIN 53504 psi 1594 2899 4058 Elongation DIN 53504 % 600 480 400 Abrasion DIN 53516 mm3 46 (5.1mg) 49 (5.5mg) 56 (6.4 mg) Density DIN 53479 g/ml 1.10 1.12 1.14 *Data presented as general information only. They are not part of the product specifications.

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Table 11: Elastomers from Desmodur ME Prepolymers and Curative Lonzacure MCDEA

Property Test

Method

Units ME40TF04 ME 60TF04 ME 80TF04

Shore Hardness DIN 53505 A/D 97/42 99/53 99/60 Comp. Set 70h/23°C DIN 53517 % 26 27 31 Comp. Set 24h/70°C DIN 53517 % 40 55 40 Resilience DIN 53512 % 51 50 53 Graves Tear DIN 53515 pli 560 554 651 Tensile Strength DIN 53504 psi 5362 5652 4638 100% Modulus DIN 53504 psi 1739 2464 3189 300% Modulus DIN 53504 psi 2319 4058 5218 Elongation DIN 53504 % 510 390 250 Abrasion DIN 53516 mm3 37 (4.1 mg) 35 (3.9 mg) 36 (4.1 mg) Density DIN 53479 g/ml 1.11 1.12 1.14 *Data presented as general information only. They are not part of the product specifications. At the same isocyanate content, Lonzacure MCDEA produces a harder elastomer with properties superior to those from Baytec XL-1604. However, MCDEA extended systems have much shorter gel times. A detailed analysis of the mechanical properties of these elastomers and those obtained from MbOCA cured polyether based MDI prepolymers is currently underway.

DMA, TMA & DSC Analysis

Dynamic Mechanical Analysis was performed in the torsion mode on a TA Instruments ARES Rheometer. Subambient Tg’s were measured with a Perkin Elmer DSC7 using liquid nitrogen as coolant. A Perkin Elmer Diamond DSC was used for the high temperature data. Heating rates in both cases was 20°C/min. A Perkin Elmer TMA was used in the penetration mode with liquid nitrogen as coolant. The heating rate was 2°C.min and the force on the probe was 300mN. Dynamic Mechanical Analysis (DMA), Thermomechanical Analysis (TMA) and Differential Scanning Calorimetry (DSC) were used to compare three Desmodur MS prepolymers with a TDI/polyester prepolymer as listed in Table 4. All prepolymers were cured with MbOCA and postcured under identical conditions (see Table 3). Composite TMA curves of all four elastomers are shown in Figure 3 while Figures 4, 5 and 6 show the elastic modulus (G’), the loss modulus (G”) and Tan delta scans of the elastomers. Table 12 provides the consolidated data from the thermal curves.

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Figure 3: TMA Scans of MbOCA Cured Desmodur MS Prepolymers

Figure 4: G’ Scans of MbOCA cured Desmodur MS Prepolymers

-105.0-80.0 -60.0 -40.0 -20.0 0.0 15.0 35.0 55.0 75.0 95.0 115.0 140.0 165.0 190.0

106

107

108

109

1010

Temp [°C]

G' (

) [

Pa]

G'

G' TDI / Polyester MS40TF01 MS40TF03

MS58TF02

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Figure 5: G” Scans of MbOCA cured Desmodur MS Prepolymers

Figure 6: Tan delta Scans of MbOCA cured Desmodur MS Prepolymers

-105.0-80.0 -60.0 -40.0 -20.0 0.0 15.0 35.0 55.0 75.0 95.0 115.0 140.0 165.0 190.0

10-3

10- 2

10- 1

100

Temp [°C]

ta

n(⎯)

()

[

]

Tan Delta

Tan delta TDI / Polyester MS40TF01 MS40TF03 MS58TF02

-105.0-80.0 -60.0 -40.0 -20.0 0.0 15.0 35.0 55.0 75.0 95.0 115.0 140.0 165.0 190.0

105

106

107

108

109

Temp [°C]

G" (

) [

Pa]

G"

G" TDI / Polyester MS40TF01 MS40TF03

MS58TF02

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Table 12: DSC, DMA and TMA Analysis of Desmodur MS Elastomers

DSC DMA TMA

Elastomer Tg

(ϒC)

Cp

(J/gϒC)

Tm

(ϒC)

Hm

(J/g)

Tg**

(ϒC)

G’@20%

(ϒC)

G’@ 25ϒC

(Pa)

Tonset

(ϒC)

MS40TF01 MDI/Polyester

(4%NCO)/MbOCA

-27 (-28)

0.34 (0.42)

187 206

4.11

-28 185 3.0 x 107 -29 193*

MS58TF02 MDI/Polyester

(5.8%NCO)/MbOCA

-21 (-22)

0.29 (0.31)

230 2.21 -22 194 8.5 x 107 -29 204*

MS40TF03 MDI/Polyester

(4%NCO)/MbOCA

-34 (-31)

0.24 (0.39)

189 205

5.97

-33 187 2.6 x 107 -28 194*

TDI/Polyester (4%NCO)/MbOCA

-21 (-21)

0.38 (0.44)

194 211

8.14

-23 185 2.2 x 107 -17 193*

* onset of major softening; **from peak in G” curve; ( ) DSC reheat data

In general, DMA and DSC scans of Desmodur MS prepolymers having an isocyanate content of 4.0% and the TDI prepolymer (4.0% NCO) are similar. MS40TF03 shows the lowest Tg (-34°C) which is considered low for a polyester based polyurethaneurea. Glass Transition Temperature (Tg)

There is good agreement between the soft segment Tg’s determined by DSC and DMA for all the elastomers. Differences in the glass transition temperatures determined by TMA could be attributed to conditions of the test and the nature of the soft segment. The elastomer from MS58TF02 prepolymer shows a higher Tg (-21°C) compared to the other samples. Although the higher NCO of this prepolymer (5.8%) produces a higher concentration of hard segment domains, the low heat of fusion ( Hm = 2.21 J/g) indicates a low level of hard segment crystallinity. As can be seen in the DSC curves, the glass transition event for this elastomer occurs over a 25 degree temperature range compared to a 15–20 degree range for the other elastomers shown in Table 12 which is an indication of phase mixing. High Temperature Performance

Elastomers from MS40TF01, MS40TF03 and the TDI/polyester prepolymer all show a very level rubbery plateau ranging from about 35°C to 140°C with similar modulus values in the plateau region. There is good correlation of the G’ values at 25°C of all elastomers with their material properties as shown in Table 4. Again, MS58TF02 is the exception with higher modulus values due to its higher isocyanate content. As can be seen from the DMA curves, the modulus begins to drop off at temperatures above 140°C. Temperatures at which the modulus is 20% off its rubbery plateau value are shown in Table 12. Although these values correlate well with the softening temperatures measured by TMA, the differences observed, stem from the heating rate and static force used in TMA measurements. Thus, a higher static force would lower the onset of softening. In general, the elastomer from MS58TF02 has the highest softening temperature of all the elastomers.

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Conclusions

With the introduction of the Baytec® MAX prepolymer product line, the hot-cast elastomer industry now has, for the first time, MDI-based prepolymers that may be processed similar to TDI prepolymers. Cured with diamine extenders such as MbOCA, these prepolymers have reactivities similar to those of low free monomer containing TDI prepolymers. Elastomers with mechanical properties similar to, or in some cases, superior to corresponding TDI prepolymers are produced. Acknowledgements

The authors would like to thank their marketing colleagues Peter Barwitzki, Gilbert Ellerbe, Peter Plate and Rich Rogers for continuous support of this work. On the technical front, thanks go out to Marylyn Donaldson, John Hodel, and Frank Muschiol for their meticulous bench work and Tech Service contributions. Marie Urick & John Liddle helped the authors in analyzing the DMA, TMA and DSC work. Biographies:

James-Michael Barnes

Recently retired as a Development Chemist at Bayer MaterialScience AG in Leverkusen, Germany. Michael received his B.Sc. Degree in Organic Chemistry from the University of Bristol in 1968 and started his career at Bayer AG in 1970. He was responsible for the development of elastomers especially Bayer’s Vulkollan and Baytec product lines. Michael holds several patents in the area of polymer synthesis and the application of elastomer raw materials.

Jens Krause

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After receiving his Ph.D Degree in Polymer Chemistry in from the Technical University in Munich, Germany in 2004, Jens started his career in 2005 at Bayer MaterialScience AG, Leverkusen, Germany, in the Marketing and Business Development Unit. He is responsible for the development of the Vulkollan and Baytec cast elastomer product lines.

Hartmut Nefzger

Is currently a Scientist for Polyurethane Innovation at Bayer MaterialScience, AG, Leverkusen, Germany. Hartmut received his Ph.D Degree in Polymer Chemistry in 1987 from the University of Karlsruhe (TH), and after a short tenure as Post Doctoral Fellow at Bayreuth, joined Bayer’s Polyurethane Research Department in Dormagen, Germany in 1990. Hartmut then transferred to the Research Department of Bayer’s U.S. production facility in New Martinsville, WV where he stayed for 4 years. Hartmut is responsible for the development of new applications for elastomer raw materials, in particular those based on polyesters and polycarbonate polyols. He holds several patents in elastomer synthesis and applications of polyols.

Ashok M. Sarpeshkar

Currently a Principal Scientist in the Cast Elastomer Group of the Specialty Systems Group at Bayer MaterialScience LLC., Ashok’s responsibilities include providing technical support for Bayer’s hot-cast, one-shot elastomeric systems, aliphatic isocyanate based elastomers, identifying and developing new applications for Bayer’s cast elastomeric systems. A Ph.D in Organic Chemistry, Dr. Sarpeshkar began his career at Bayer in the Polyurethanes Research Department in 1985 and moved into the Applications and Development area in 1992. He has published technical articles, made presentations at the API, PMA, CUMA and has twenty five U.S. patents covering a broad range of polyurethane applications.

Manfred Schmidt

Presently a Scientist for Polyurethane Innovation at Bayer MaterialScience AG, Leverkusen, Germany, Manfred received his Ph.D Degree n Organic Chemistry from the Justus Liebig University of Giessen in 1979. Manfred started his career as a Chemist in 1979 at Bayer AG’s Polyurethane Research Department. He is responsible for the development of new applications for polyurethane raw materials and in recent years for isocyanate modifications. Manfred has several patents on elastomer synthesis and applications of polyols.

References:

1. Oertel, G., Polyurethane Handbook: Chemistry – Raw materials – Processing-Application-Properties, 2nd edn., Carl Hanser Verlag, Munich, 1993

2. Structure vs. Performance Properties of Cast Elastomers – A comparison of Airthane Prepolymers with Conventional Prepolymers., Musselman S. G., Santosusso, T. M., & Sperling, L. H., Polyurethanes Expo ’98, September 17-20, 1998.

3. U.S. Patent 5,051,152 (A); U.S. Patent 5,202,001(A); U.S. Patent 5,077371; U. S. Patent 5,051,152; U.S. Patent 5,202,001 to Air Products & Chemicals and Uniroyal Chemical Co.

4. U.S. Patent 5,817,734 and U.S. Patent 5,925,781 to Bayer Material Science. 5. U.S. Patent 6,046,297 to Crompton Inc. 6. Musselman, S. G., Santosusso, T. M., Sperling, L. H., Barnes, J. D. Journal of Polymer Science.

Part B: Polymer Physics - January 01, 1999. 7. Isobutyl-(3,5-diamino-4-chloro)benzoate from BUEFA Systems, Inc. 8. Diethyl toluenediamine from Albemarle Inc. 9. Di-(methylthio)-toluenediamine from Albemarle Inc. 10. 4,4’-Methylene-bis(3-chloro-2,6-diethylaniline) from Air Products & Chemicals, Inc.