The effect of thermal annealing on the abrasion resistance of a segmented block copolymer urethane elastomers

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The effect of thermal annealing on the abrasion resistance of a segmented block copolymer urethane elastomers Małgorzata Nachman, Konrad Kwiatkowski

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S0043-1648(13)00444-4 http://dx.doi.org/10.1016/j.wear.2013.07.014 WEA100795

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Wear

Received date: 5 April 2013 Revised date: 11 July 2013 Accepted date: 20 July 2013 Cite this article as: Małgorzata Nachman, Konrad Kwiatkowski, The effect of thermal annealing on the abrasion resistance of a segmented block copolymer urethane elastomers, Wear, http://dx.doi.org/10.1016/j.wear.2013.07.014 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

The effect of thermal annealing on the abrasion resistance of a segmented block copolymer urethane elastomers Małgorzata Nachman*, Konrad Kwiatkowski Institute of Materials Science and Engineering, West Pomeranian University of Technology Szczecin, Piastów Av. 19, 70-310 Szczecin, Poland *Corresponding author. Tel: +48 91 4494774; fax: +48 91 4494356. Email address: [email protected]

Abstract The influence of thermal annealing on two-body abrasion resistance, molecular mass and phase separation of segmented block copolymer (multiblock) urethane elastomers is reported. The materials studied contained 50, 55, 60 and 65 wt. % of soft segment based on poly(tetramethyleneoxide) of molecular mass 1000, and hard segment consisting of 4,4’methylenebis(phenyl isocyanate) and 1,4-butanodiol. Multiblock urethane elastomers (PUR) were synthesized with an annealing step at one of the temperatures: 60, 100 or 120 °C. Abrasion resistance was determined using a rotating cylindrical roller device. Phase separation was characterized by Fourier transformed infrared (FT-IR) spectroscopy. Intrinsic viscosities were measured to estimate the molecular mass of the PUR. On the basis of the results it was determined, that an increase of annealing temperature of PUR, in the applied temperature range, increases their phase separation and molecular mass, which in turn affects an improvement of abrasion resistance. However it was shown, that for PUR materials with high content of polyether flexible segments (eg. 65 wt. %) annealing in 120 °C causes degradation and significant decrease in abrasion resistance.

Keywords two-body abrasion, thermal annealing, urethane elastomers, phase separation, molecular mass

1

1. Introduction Multiblock urethane elastomers (PUR) possess a unique combination of properties: excellent rubber elasticity, good mechanical properties and enhanced abrasion resistance. PUR are the most abrasion-resistant of all elastomeric materials. They are commonly used in tribological systems, where high abrasion resistance is required. For example: conveyor belts elements, sieve for debris, wheels for industrial trucks, sealing rings or soles, etc. [1,2,3]. The specific structural feature of PUR elastomers is their segmented structure. The PUR chain is composed of rigid segments and flexible segments arranged alternately. The rigid segments aggregate giving rise to a separated micro-phase are dispersed in the soft phase. Hard phase is hardly miscible with the soft phase, which has been formed with the use of much less polar soft segments. The rigid segments can interact with each other through hydrogen bonds. These strong bonds and high cohesion energy in urethane groups are responsible for good mechanical properties and enhanced abrasion resistance of PUR elastomers. The -NH- group in the urethane structure is a proton - donor, the acceptor function can be provided by the oxygen atom within the urethane C=O group or within the ester group in case of poly(esterurethanes), or by the ether oxygen atom in case of poly(ether - urethanes) [4]. Infrared spectroscopy is well established for measuring changes in hydrogen bonding in polyurethanes. The carbonyl hydrogen-bonding index (R) can be determined by analyzing the intensities of the carbonyl stretching vibrations of free and hydrogen-bonded groups whose overlapping bands are located at 1730 cm-1 and 1700 cm-1. Significant changes in carbonyl hydrogen-bonding index allow to observe differences in phase separation and phase mixing [6,7]. Mechanical properties of the commercial PUR materials, e.g. their abrasion and scratch resistance, depend on the phase separation process and also content of rigid segments, their chemical constitution and molecular mass [8,9,10,11,12]. Thermal annealing of PUR to improve their morphological structure and mechanical properties is often used in industrial practice. Therefore the effect of annealing in different temperatures on changes in phase separation and molecular mass and in consequence on the abrasive wear of PUR is a very interesting subject to study. In literature the influence of thermal annealing time and temperature on the interdomain mixing, molecular mass, and thermal properties has been examined for crystallizable segmented block copolyurethane [13]. The temperature treatment 2

dependence of hydrogen bonding and degree of structural organization evidenced by differential scanning calorimetry (DSC) in the hard-segment units in polyurethane elastomers was also investigated [14]. Moreover, we can find a lot of research results describing the wear properties of polyurethanes [1,2,3,10,11,15,16,17]. However, in the literature, there is a lack of information on the influence of thermal annealing on the wear properties of segmented block copolymer urethane elastomers. The aim of our study was to investigate the effect of annealing temperature on the degree of PUR phase separation and molecular mass and to evaluate the effect of these factors on the abrasion resistance. The impact of the soft segments content in PUR on the abrasion resistance was also investigate. Therefore, it is important to establish the interrelation between segmented structure of PUR and wear resistance as well as the correlation with other physicmechanical characteristics of materials.

2. Materials and experimental methods

2.1. Materials and synthesis Segmented block copolymer urethane elastomers containing 50, 55, 60 and 65 wt. % of soft segments were synthesized and analyzed in this study. The soft segment was poly(tetramethyleneoxide) (PTMO, DuPont) with molecular mass of 1000, whilst the hard segment consisted of 4,4’-methylene bis (phenyl isocyanate) 98 wt. % (m-MDI, SigmaAldrich) and 1,4-butanodiol (1,4-BD, DuPont). PTMO and 1,4-butanodiol were dried under vacuum at 110–130 ºC for 3 h before use. A series of poly(ether-urethane)s was synthesized using a two-step polymerization method. Prepolymer was obtained by mixing polyol and MDI (with 6 wt. % excess) in a 1000 ml glass flask under vacuum at 120 ºC for 1 h. The free isocyanate content in the prepolymer was determined by titration with N,N’-dibutylamine [18]. To inhibit the process, before starting the second step, prepolymer was cooled down to 50 ºC. After that prepolymer was intensively mixed with 1,4-butanodiol and the polymeric reaction takes place under vacuum conditions 30 s. The resulting material filled into a mold and left to cure at room temperature for 24 h. Before annealing all samples were heated at 60 ºC for 3 h in order to complete curing. Urethane elastomers were then annealed for 2h at one of the temperature range: 60, 100 and 120 ºC. Usually, in practice, the PUR products based on MDI and BD are annealed in the 3

temperature of about 120 °C, what is well known and described in literature on polyurethanes technology [19], however irrespectively of the flexible segments content. The motivation for our investigation was to evaluate the abrasion resistance of PUR as a function of annealing temperature and material composition. The glass transition temperature of MDI and BD based pure hard phase is about 108 – 109 ºC [20, 21]. In urethane – ether copolymer the Tg of hard phase is lower than 109 °C and depends on the content of flexible segments and phase separation [22]. Therefore, the annealing temperature of 120 °C was treated as intermediate between theoretical glass transition of hard phase made by rigid segments (to be sure of their mobility) and the melt temperature of hard phase (ca. 150 – 180 °C) (fig.1) in order to prevent the sample deformation and thermal degradation. Annealing temperature of 60 °C was performed as normalization process and these samples were treated as reference in our investigations. The polymerization of urethanes is exothermal and depending on sample shape as well as the material of mold, in PUR samples the temperature gradient becomes during polymerization. Thus the additional annealing in 60 °C is needed to uniform the structure. The temperature of 100 °C was intermediate between 120 °C and 60 °C, and was chosen in order to check if the lowering of annealing temperature of 20 °C would cause significant difference in wear resistance.

PUR 50

PUR 55

PUR 60

PUR 65

Tg

Heat flow, W/g

a nnealing temp.: 60, 100,120  OC

0,1

Tm

60

-75

-45

-15

15

45

100 120

75 105 Temperature, OC

135

165

195

225

4

 

Figure 1. DSC analysis of urethane – ether elastomers with different PTMO 1000 content (Table 1). Tg – glass transition temperature of soft phase, Tm – melting temperature. After that all samples were cooled to room temperature and conditioned for two weeks. Compositions of the prepared poly(ether-urethane)s samples with different concentration of polyether soft segments are given in Table 1. Table 1. Composition and weight content of urethane elastomers segments Mass composition for 100g of PUR Sample

Soft segment, g

Hard segment, g

6 wt. % excess of m-MDI, g

Molar ratio: polyol/ isocyanate/ butanodiol

PTMO, M=1000

1,4-BD

m-MDI

PUR50

50.00

9.93

40.07

2.40

1.00/3.40/2.21

PUR55

55.00

8.27

36.73

2.20

1.00/2.83/1.67

PUR60

60.00

6.62

33.38

2.00

1.00/2.36/1.23

PUR65

65.00

4.96

30.04

1.80

1.00/1.96/0.85

2.2. Characterization methods Differential scanning calorimetry (DSC): The thermal analysis of urethane elastomers was performed using DSC Q100 (TA Instruments). Samples were heated to melt with the rate 10 °C in the temperature range: -90 to 240 °C. Fourier transform infrared (FT-IR) spectroscopy: The urethane elastomers were characterized using an FT-IR spectrophotometer (Bruker Optik GmbH model Tensor 27). Measurements were carried out using the attenuated total reflectance (ATR) technique. Each sample was scanned 32 times at the resolution of 2 cm −1 over the frequency range of 4000— 400 cm −1 . The carbonyl hydrogen-bonding index (R) was determined by analyzing the intensities of the carbonyl stretching vibrations of free (Afree) and hydrogen-bonded (Abonded) groups, whose bands were located at 1730 cm −1 and 1700 cm −1 . From the intensities of the characteristic absorbances A, the carbonyl hydrogen-bonding index R was calculated as given in Eq. (1) [6,7]. 5

R=

Abonded A free

(1)

The degree of phase separation (DPS) and the degree of phase mixing (DPM) were obtained through Eq. (2) and (3) [6,7,10,23].

DPS =

R (2) R +1

DPM = 1 − DPS

(3)

Intrinsic viscosity [η]: PUR intrinsic viscosities were measured using Ubbelohde capillary viscometer in a thermostatic water bath held at 30 ± 0.05 °C. The Ubbelohde capillary type I c (K = 0,03294) was used for PU solutions in 0.05 M LiBr/DMF and the concentration of the poly(ether-urethane)s in LiBr/DMF was 0.5 g/dl [24,25]. Dried samples were dissolved in 0.05 M LiBr/DMF at room temperature. Prior to each flow-time measurement the temperature of solution was equilibrated for approx. 15 min. For each samples the measurements were repeated, until the relative error of five successive measurements was less than 0.1 % and an average value of flow times was recorded. Detailed measurement procedure is described in ISO 1628-1:2009 standard. The relative (ηr ) and specific ( η sp ) viscosities were calculated for a single concentration and the intrinsic viscosity ([η]) was determined using the Solomon–Ciuta equation (4) [26,27]:

[η ] =

2(η sp − lnη r ) c

(4)

where c is the concentration of the polymer solution.

Abrasion resistance: The resistance to wear by mechanical action upon a surface of test samples was measured using a rotating cylindrical roller device and the procedure complied with ISO 4649:2010 standards. The abrasion resistance was expressed as relative volume loss ( ΔVrel ) of sample compared to an abrasive sheet calibrated using a standard reference, which was standard rubber from Federal Institute for Materials Research and Testing (Berlin, Germany) (ISO 4649:2010, standard reference compound No 1). Cylindrical 6

elastomer test specimen (16 ± 0,2 in diameter and 2 mm high) was fixed to slide over an abrasive sheet at a 10 N ± 0,2 N contact pressure in the distance of 40 m and it was rotating during the test. The abrasive sheet was attached to the surface of a rotating cylindrical roller, against which the test specimen was held and across which it was traversed (see Figure 2).

Figure 2. Rotating cylindrical roller device. Abrasive sheet was made of aluminum oxide with grain size 60 and it was calibrated to a standard reference compound mass loss of between 180 mg and 200 mg for an abrasion distance of 40 m. The loss in mass of the test specimen was determined and the volume was calculated from the density of the material used. The volume loss of the test specimen was compared to that of reference compound tested under the same conditions. Relative volume loss ( ΔVrel ) was calculated with the following relation (5):

ΔVrel =

Δmt * Δmconst Δmr * ρt

(5)

where: Δmt is the mass loss of the analyzed sample, mg; Δmconst is the defined value of the mass loss of the standard rubber sample (defined as 200 mg); Δmr — the arithmetic mean of the mass loss of three standard rubber samples, mg; ρt - the density of the analyzed material, mg/mm³. The abrasive wear resistance is expressed as inverse of relative volume loss ( ΔVrel ) with the unite mm-3. 7

Determination of the density was performed according to ISO 2781:2008.

3. Results and Discussion 3.1. Fourier transform infrared (FT-IR) spectroscopy

0,35

0,3

hydrogen bonded ‐C=O 

Absorbance

0,25

0,2

hydrogen bonded -NH

0,15

free ‐C=O 

0,1

0,05

0 3500

3000

2500

2000 Wavenumber, cm-1

1500

1000

500

Figure 3. FT-IR spectra of PUR containing 55 wt. % contents of soft segment, annealed at 100 °C. Fourier transform infrared spectroscopy (FT-IR) was used to follow structural changes in the multiblock urethane elastomers caused by annealing in different temperature. The influence of soft segments content on the structural changes has been also observed. The effect of the temperature annealing on the degree of phase separation in polyurethane can be determined from the extent of hydrogen bonding in the hard segments. The detailed description of IR bands in polyurethane can be found elsewhere [28], and only the relevant ones are discussed here. Important bands are located at 3320 cm-1 (N–H hydrogen bonded stretching), 3480 cm-1 (free N–H stretching) and two overlapping bands are present in the carbonyl stretching region – one peak apparently centered at 1730 cm-1 and broad shoulder at 1700 cm-1. These signals are ascribed to the stretching vibrations of free (non-hydrogenbonded) and hydrogen-bonded carbonyl, respectively [6,28,29]. In the transmission IR spectra there was a band located at 3320 cm-1, and no band appeared at 3480 cm-1 indicating, that the N-H groups in the PUR were nearly completely hydrogen-bonded. Bands from the stretching vibrations of carbonyl groups present in urethane bonds were used to analyze the phase 8

separation degree. Representative FT-IR spectra of the multiblock urethane elastomers are shown in Fig. 3. Table 2. The carbonyl hydrogen bonding index (R), the degree of phase separation (DPS) and the degree of phase mixing (DPM) in multiblock urethane elastomers annealed at three different temperatures: 60, 100 and 120 °C. Temperature annealing, °C

Sample

A1730*

A1700**

R***

DPS

DPM

PUR 50 0,34 0,66 1,92 0,1303 0,0678 PUR 55 0,36 0,64 1,75 0,1082 0,0618 60 PUR 60 0,41 0,59 1,46 0,1122 0,0770 PUR 65 0,43 0,57 1,32 0,1765 0,1341 PUR 50 0,0929 0,1963 2,11 0,67 0,32 PUR 55 0,0919 0,1683 1,83 0,65 0,35 100 PUR 60 0,0880 0,1324 1,50 0,60 0,40 PUR 65 0,0991 0,1365 1,38 0,58 0,42 PUR 50 0,29 0,71 2,43 0,2383 0,0979 PUR 55 0,35 0,65 1,85 0,1930 0,1042 PUR 60 120 0,40 0,60 1,51 0,1048 0,0693 PUR 65 0,42 0,58 1,39 0,1835 0,1321 * A1730, absorption intensity of free carbonyl; **A1700, absorption intensity of hydrogen-bonded carbonyl. *** R=A1700/A1730, carbonyl hydrogen bonding index.

The calculated values of R, DPS and DPM for polyurethane elastomers are given in Table 2. The degree of hydrogen bonding of carbonyl groups and the DPS increases with the decreased soft segment ratios. It seems to be obvious as carbonyl groups are located in rigid segments. The hydrogen bonding index and thereby DPS in polyurethanes increased with the increasing temperature of annealing regardless of soft segment ratios. Observed increase is more significant for higher content of rigid segments in polymer chains. The degree of phase separation for PUR 50 sample rises with annealing temperature from 66 % up to 71 % (5 % of increase), whilst for other samples (PUR55, PUR 60, PUR 65) only 1 % of DPM increase is observed in the same annealing conditions.

3.2. Intrinsic viscosity Values of [η] for multiblock urethane elastomers containing 50, 55, 60 and 65 wt. % of soft segments are presented on Fig. 4 and are getting higher for copolymers containing more flexible segments. One can observe, that the intrinsic viscosity, which is related to molecular 9

mass, is increasing along with annealing temperature. It means that additional annealing process enables further reactions between components i.e. polymerization. What is surprising, the sample containing the highest content of PTMO segments (PUR65) after annealing in 120 °C revealed a decrease in [η] values (molecular mass) compared to the sample annealed in 100 °C. It is an evidence, that for materials with significant content of polyether in structure the degradation reactions take place under such annealing conditions. That is because the ether group –O– in flexible PTMO segments is particularly susceptible to thermal oxidation in higher temperature, what leads to a drop in molecular mass [30].

0.75

PUR65 PUR60 PUR55

Intrinsic viscosity, dl/g

0.65

PUR50

0.55

0.45

0.35

0.25 50

60

70

80

90 100 Annealing temperature, °C

110

120

130

Figure 4. The effect of temperature annealing on the intrinsic viscosity [η] of urethane elastomers with different content of soft segments.

10

3.3. Density 1,15

PUR50 PUR55

1,14

Density, g/cm3

PUR60

1,13

PUR65

1,12 1,11 1,1 1,09 1,08 50

60

70

80 90 100 110 Annealing temperature, °C

120

130

Figure 5. Density of urethane elastomers with different contents of soft segments, annealed at three different temperatures: 60, 100 and 120 °C. The 95 % - confidence interval is indicated with ISO 2602:1980.

All samples revealed statistically significant increase of density after annealing in 120 °C (Fig. 5), what suggests better molecular packing of rigid segments in hard phase.

3.4. Abrasion resistance The results obtained from abrasion tests indicate, that the wear resistance of urethane elastomers increases along with the content of flexible ether segments and increase in annealing temperature (Fig. 6). The one exception is the sample containing 65 % wt. of PTMO. The thermal treatment in 120 °C leads to decrease of abrasion resistance and it was not observed after annealing in 100 °C. This phenomena can be explained as a consequence of lower molecular mass of the material due to degradation processes proceeding during heating (see Fig. 4 and Fig. 6). The correlation between intrinsic viscosity and abrasive wear resistance of PUR proves above thesis (Fig 7). According to Mark–Houwink equation the

11

intrinsic viscosity is exponential function of molecular mass and for linear polymers the

Abrasive wear resistance, mm -³

intrinsic viscosity cannot change without changes in molecular mass. 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

PUR50 PUR55 PUR60 PUR65

50

60

70

80

90 100 Annealing temperature, °C

110

120

130

Figure 6. Abrasive wear resistance of urethane elastomers with different contents of soft segments, annealed at three different temperatures: 60, 100 and 120 °C. The 95 % - confidence interval is indicated with ISO 2602:1980 16.000 PUR50 Abrasive wear resistance, mm-3

14.000

PUR55

12.000

PUR60

10.000

PUR65

8.000 6.000 4.000 2.000 0.000 0.2

0.3

0.4

0.5

0.6

0.7

0.8

Intrinsic viscosity, dl/g

Figure 7. Abrasive wear resistance versus intrinsic viscosity of urethane elastomers with different contents of soft segment, annealed at three different temperatures: 60, 100 and 120 °C. The 95 % confidence interval is indicated with ISO 2602:1980

5. Conclusions 12

The aim of this study was to investigate the influence of annealing temperature on the abrasion resistance of a segmented ether-urethane elastomers. An increase of thermal treatment temperature leads to higher molecular mass of samples and improvement in phase separation degree. In consequence the wear resistance of materials is improved. It was proved that this PUR feature is strongly influenced by molecular mass and less by phase separation degree. The choice of optimum annealing temperature should be correlated with the content of flexible ether segments in PUR elastomers, as for materials with relatively high PTMO segments ratio the thermal treatment can lead to undesirable degradation processes due to low thermo oxidative resistance of ether groups. In turn degradation - induced drop in molecular mass has negative impact on wear resistance of ether-urethane elastomers. Acknowledgements The research was financed by the Polish Ministry of Science and Higher Education from the resources for the years of 2009-2011 as a research project. Małgorzata Nachman also thank for financial support from West Pomeranian University of Technology Szczecin. We thank Dr. M. Kwiatkowska for providing language help and proof reading the article.

References [1] R. A. Beck, R.W. Truss, Effect of chemical structure on the wear behaviour of polyurethane-urea elastomers, Wear, 218 (1998) 145-152. [2] A.N. Trofimovich, V.N. Anisimov, V.N. Kurachenkov, V.V. Strakhov, M.P. Letunovskii, S.F. Egorov, Role of structure factor in evaluating polyurethane wear resistance, Sov. Journal Friction Wear, 8 (1987) 87-92. [3] V. N. Anisimov, A. A. Semenets, M. P. Letunovskii, V. V. Strakhov, Effect of Rigid Blocks on the Mechanical Characteristics and Abrasive Resistance of Polyurethanes, Materials Science, 38 (2002) 95-98. [4] Król P., Synthesis methods, chemical structures and phase structures of linear polyurethanes. Properties and applications of linear polyurethanes in polyurethane elastomers, copolymers and ionomers, Progress in Materials Science, 52 (2007) 915–1015. [6] T. Pretsch, I. Jakob, W. Muller, Hydrolytic degradation and functional stability of a segmented shape memory poly(ester urethane), Polymer Degradation and Stability, 94 (2009) 61–73. 13

[7] Y.I. Tien, K.H. Wei, Hydrogen bonding and mechanical properties in segmented montmorillonite/polyurethane nanocomposites of different hard segment ratios, Polymer 42 (2001) 3213–3221. [8] B. Pilch-Pitera, Synthesis of urethane oligomers as intermediates for the production of polyurethanes with controlled molecular weight distribution. Doctor’s Thesis, Rzeszow Technical University, 2003. [9] D.G. Thompson, J.C. Osborn, E.M. Kober, J.R. Schoonover, Effects of hydrolysisinduced molecular weight changes on the phase separation of a polyester polyurethane, Polymer Degradation and Stability, 91 (2006) 3360-3370. [10] J. Ryszkowska, Supermolecular structure, morphology and physical properties of ureaurethane elastomers, Polymers, 57 (2012) 777-785. [11] P. Michalski, M. Nachman, K. Kwiatkowski, Abrasive wear of urethane elastomers based on monomeric or polymeric diisocyanate MDI, Polymers, 57 (2012) 839-845. [12] M. P. Letunovskii, “Application of percolation theory for the description of the critical viscoelastic behavior and structure formation of heterogeneous polymeric systems,” in: Int. Conf. on Caoutchouc and Rubber (Preprints of Papers), Part A-2, Moscow (1984), pap. A-69. [13] Wenchun Hu, J.T. Koberstein, Effect of thermal annealing on the thermal properties and molecular weight of a segmented polyurethane copolymer, Polym. Sci. Part B, 32 (1994) 437446. [14] C.M. Brunette, S.L. Hsu, W.J. Mac Knight, Hydrogen-bonding properties of hardsegment model compounds in polyurethane block copolymers, Macromolecules, 15 (1982) 71-77. [15] Y.M. Xu1, B.G. Mellor, A comparative study of the wear resistance of thermoplastic and thermoset coatings, Wear, 255 (2003) 722–733. [16] C.J. Schwartz, S. Bahadur, Development and testing of a novel joint wear simulator and investigation of the viability of an elastomeric polyurethane for total-joint arthroplasty devices, Wear, 262 (2007) 331–339. [17] D.J.T. Hill, M.I. Killeen, J.H. O'Donnell, P.J. Pomery, D. St. John, A.K. Whittaker, Laboratory wear testing of polyurethane elastomers, Wear, 208 (1997) 155-160. [18] D.J. David, H.B. Staley, Analytical chemistry of polyurethanes, New York, 1969. [19] Z. Wirpsza, Polyurethanes: Chemistry, Technology, and Applications, Horwood, Ellis Limited, 1993 [20] W. J., Macknight, M., Yang, T. Kajiyama, Polym. Prepr., 9 (1968) 860

14

[21] K. C. Chen, J. Y. Chui, T. S. Shieh, Glass Transition Behaviors of a Polyurethane Hard Segment based on 4,4-Diisocyanatodiphenylmethane and 1,4-Butanediol and the Calculation of Microdomain Composition, Macromolecules 30 (1997) 5068 [22] R.W. Seymour, S.L. Cooper S.L., Thermal analysis of Polyurethane Block Polymers, Macromolecules, 6 (1972) 48-53 [23] C.W. Meuse, X. Yang, D. Yang, S.L. Hsu, Spectroscopic analysis of ordering and phaseseparation behavior of model polyurethanes in a restricted geometry, Macromolecules, 25 (1992) 925-932. [24] E. Žagar, M. Žigon, Solution properties of carboxylated polyurethanes and related ionomers in polar solvents (DMF and LiBr/DMF), Polymer 41 (2000) 3513–3521. [25] S. Paszkiewicz, A. Szymczyk, Z. Špitalský, M. Soccio, J. Mosnáček, T. A. Ezquerra, Z. Rosłaniec, Electrical conductivity of poly(ethylene terephthalate)/expanded graphite nanocomposites prepared by in situ polymerization, Journal of Polymer Science, Part B: Polymer Physics, 50 (2012) 1645–1652 [26] R. Pamies, J.G. Hernández Cifre, M. del Carmen López Martínez, J. García de la Torre, Determination of intrinsic viscosities of macromolecules and nanoparticles. Comparison of single-point and dilution procedures, Colloid Polym Sci, 286 (2008) 1223–1231. [27] O.F. Solomon, B.S. Gottesman, Correct determination of intrinsic viscosity, Journal of Applied Polymer Science, 12 (1968) 971–972. [28] R.W. Seymour, G.M. Estes, S.L. Cooper, Infrared Studies of Segmented Polyurethane Elastomers. I. Hydrogen Bonding., Macromolecules, 3 (1970) 579–583. [29] H.S. Lee, Y.K. Wang, S.L. Hsu, Spectroscopic Analysis of Phase Separation Behaviour of Model Polyurethanes., Macromolecules, 20 (1987) 2089–2095. [30] A. Szymczyk, Z. Roslaniec, Degradation and stabilization of thermoplastic ether-ester elastomers (TPE-E), Polymers, 51 (2006) 627-642.

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Highlights

•

The effect of annealing temperature on abrasion resistance of urethane elastomers (PUR) has been analyzed.

•

The thermal treatment of ether containing linear PURs induces increase in both molecular mass and the number of hydrogen bonds in hard phase.

•

The abrasion resistance level of urethane elastomers is determined by molecular mass.

•

The choice of annealing temperature of elastomers should be always correlated with the content of rigid and flexible segments in copolymer and thermal characteristic.

16