Hard Segment Polyurethane (Effect of Cross-Linking Agent On Thermal and Mechanical Stability of Polyurethanes) 2000 2 1
Hard Segment Polyurethane (Effect of Cross-Linking Agent On Thermal and Mechanical Stability of Polyurethanes) 2000 2 2
2000 2 ( ) ( ) ( ) 3
polyurethane, hard segment. hard segment. polyurethane diisocyanate 4,4`diphenylmethane diisocyanate chain extender 1,4-butanediol hard segment. soft segment polytetramethylene glycol (PTMG MW=1000g/mol). PTMG (MW=1000g/mol) MDI end capping free isocyanate group. allophanate polyurethane 200 ~220 melt blending free isocyanate group hard segment urethane group N-H. polyurethane weight percent 0%, 10%, 15%, 20% 4. stress-strain curves, hysteresis, DSC ATR FT-IR segmental. Small Angle X-ray Scattering (SAXS) domain. mechanical properties hard domain thermal stability. 4
Abstract In this study, chemical cross-linkings between hard segments in thermoplastic elatomers have been introduced to increase the mechanical and thermal stabilities of polyurethanes. The effect of the amount of cross-linking agent on internal structure and mechanical properties have been also investigated. The polyurethane used in this work consists of 4,4 -diphenylmethane diisocyanate(mdi) and 1,4 butanediol as hard segments and polytetramethylene glycol (PTMG MW=1000 g/mol) as soft segments. Cross-linking agent having free isocyanate functional groups at both ends were synthesized by end-capping each mole of PTMG (MW=1000 g/mol) with two moles of MDI. Melt blending of polyurethanes with the cross-linking agent at 200-220C was expected to form allophanate linkage through the chemical reaction between N- H in urethane group and free isocyanate group. Four different samples containing 0, 10, 15, 20% (wt/wt) of cross-linking agent were prepared. The effect of cross-linking agent on mechanical properties of polyurethane were studied through stress-strain curves and hysteresis. Effect on degree of phase separation and segmental thermal stability were also investigated with DSC and FTIR-ATR methods. The themal stability of micro-phase separated domain structure was also analyzed with synchrotron small angle X-ray scattering method. As amount of cross-linking agent content in polyurethane increased, the mechanical properties was improved, while thermal stability was found to be lowered. 5
Abstract Hard segment polyurethane 1. 2. Material 3. Experiment 3.1 Density Measurement 3.2 ATR FT-IR 3.3 Small Angle X-ray Scattering (SAXS) 3.4 Mechanical Properties Test 4. Result and Dicussion 5. Conclusion 6. Reference 6
Hard Segment Polyurethane 1. Segmented polyurethane elastomers T g rigid hard segment T g flexible soft segment. 1 hard domain hard segment van der waals force 2~4. van der waals force. melting point cooling. hard segment van der waals force. polyurethane... polyurethane. polyurethane 7
, polyurethane. g -radiation, ultra-violet radiation polymerization. 5~7 polyurethane urethane isocyanate allophanate chain. diol isocyanate urethane. Allophanae polyurethane,. 8~14 polyurethane soft segment tri multifunctional polyol, tri higher functional chain extender. 15~16 Z. Petrovic et al 17 soft segment diol triol, mechanical properties. hard segment, hard segment crystal thermal stability melting flow. Chang et al. 18 33% hard segment polyester urethane chain extender butane diol trimethylopropane (TMP) hard segment density butane diol trimethylopropane ratio. 8
compression hardness loss resistance. system polytetramethylene oxide polyol diacetylene hard segment irradiation morphology, modulus breaking point elongation. 19 polyurethane triol irradiation. triol irradiation PTMG (MW=1000) MDI isocyanate allophanate group hard segment. Polyurethane hydrogen group isocyanate group urethane linkage,, isocyanate carbamic acid urea group biuret. isocyanate urethane linkage allophanate group, isocyanate isocyanurate.5,6,21 polyurethane, isocyanate polyol molar ratio,,,. Allophanate group 100 ~ 140 without catalyst system.20 polyurethane extruder 200 ~220 polyurethane 9
melt blending vacuum 80. 0%, 10%, 15%, 20% stressstrain curves hysteresis. DSC, ATR FT-IR small angle x-ray scattering (SAXS) hard segment structure. 2. Material polyurethane hard segment MDI BD soft segment PTMG (MW=1000) Table 1. Samples of Designation Cross-Linking Agent Content [wt%] Cpu00% 0% Cpu10% 10% Cpu15% 15% Cpu20% 20% Cpu00% => Hard Segment:Soft Segment = 43 : 57 [wt%] Table 1. Designation of Samples 10
ON HO ON HO [ OCN CH 2 NCO (CH 2 ) 4 OCN CH 2 NCO ] [(CH 2 ) 4 O m Hard Segment (a) Polyurethane Soft Segment OCN CH 2 NC [ OCH 2 ] OCN CH 2 NCO n (b) Cross-linking Agent Urethane group O C N C O H N Cross Linking Agent (c) Allophanate Figure 1. Chemical structure of Polyurethane,Cross-Linking Agent, and Allophanate 11
PTMG(MW=1000) MDI free isocyanate. Polyurethane weight percent 00%, 10%, 15%, 20% 4 200 ~ 220 1.14g/min extruder blending. melt press vacuum 80 annealing. Extruder 3 zone mixer part. zone 190, 220, 220 zone 220 setting blending. Polyurethane, allophanate Figure 1. 3. Experiment 3.1 Density Measurement Density solvent, toluene (0.8669g/cm 3 ) carbon tetrachloride (1.594g/cm 3 ) density gradient column.. sample density 85cm column density 1.10g/cm 3 ~ 1.18g/cm 3 broad solution, column 23. 4 standard bead ( 1.00, 1.05. 1.10, 1.15g/cm 3 ) calibration density linear. 12
3.2 ATR FT-IR Nicolet 520 FT-IR resolution 4cm -1, scan 32 data. FT-IR spectrum 10µm melt press sample ATR. heating cell ATR crystal KBR-5 sample heating segmental. heating rate 10 /min equilibrium time 5, 10 IR spectrum. 3.3 Small Angle X-ray Scattering (SAXS) hard segment structure SAXS white beam line 1B2 (wavelength=1.55ao). sample 1mm 5min equilibrium time. polymer scattering intensity exposure time 3min, sample detector 125.6cm. Detector 2D CCD camera(1242x1152 pixels, 27.5x25.9mm, Princeton Instrument Inc) image analysis PV-Wave 6.21 program. 13
3.4 Mechanical Properties Test hard segment structure SAXS white beam line 1B2 (wavelength=1.55å). sample 1mm 5min equilibrium time. polymer scattering intensity exposure time 3min, sample detector 125.6cm. Detector 2D CCD camera(1242x1152 pixels, 27.5x25.9mm, Princeton Instrument Inc) image analysis PV-Wave 6.21 program. 4. Results and Discussion Urethane group, molar ratio. metal allophanate, allophanate group 100 o C. polyurethane isocyanate allophanate.11 FT-IR isocyanate allophanate. 10,14,23 14
Figure 2 sample polyurethane good solvent tetrahydrofuran (THF) 1, 2 swelling 1. data swelling. 1mm 10mm, 0.3g. Figure 2 sample. swelling allophanate. 100 80 1 hour 2 hours Weight Loss [%] 60 40 20 0 0 5 10 15 20 Cross-Linking Agent Contents Figure 2. Weight loss with cross-linking content in THF 15
4 2 0 Cpu00% Cpu10% Cpu15% Cpu20% mw -2-4 -6-150 -100-50 0 50 100 150 200 250 300 Temperature [ o C] Figure 3. DSC thermograms for cross linking agent content Figure 3 DSC thermogram -100 ~ 200, sample data. 100 peak annealing hard segment short range order peak, 100 broad peak hard domain order disorder.24~26 enthalpy of fusion Figure 4 100 peak enthalpy of fusion plot. enthalpy of fusion.., hard segment 16
J/g 10 9 8 7 6 5 4 3 2 0 5 10 15 20 C.A. Contents Figure 4. Enthalpy of Fusion for Cross-linking agent content. Rigid hard segment hard segment hard segment packing. hard segment hard segment hard domain. hard segment hard domain domain packing density. enthalpy of fusion. Figure 5 density. density. 17
1.148 1.147 1.146 1.145 g/cm 3 1.144 1.143 1.142 1.141 1.140 1.139 0 5 10 15 20 C.A. Contents Figure 5. Density values for cross-linking agent content at room temperature Density DSC enthalpy of fusion. hard segment hard domain soft matrix hard domain packing density. solvent, DSC, density allophanate,. 18
mechanical property stress-strain hysteresis. Figure 6 stress-strain curve. initial modulus. soft segment PTMG, hard segment soft segment content soft segment content, hard segment packing density initial modulus. draw ratio 2.0 stress. hard segment soft segment hard segment. Hard segment draw ratio hard segment rigid hard segment stress draw ratio 2.0 stress hysteresis. Hysteresis plastic deformation energy deformation energy. hysteresis 0 hysteresis. Figure 7 (1) hysteresis A Hysteresis [%] = 100 (1) A+ B draw ratio hysteresis 19
4 3 Cpu00% Cpu10% Cpu15% Cpu20% Stress [kgf/mm 2 ] 2 1 0 1 2 3 4 5 Draw Ratio Figure 6. Stress-Strain Curves for cross linking agent content and initial modulus draw ratio. hysteresis.., creep,. 2. 20
70 60 50 Hysteresis [%] 40 30 20 10 Stress A 0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 B Strain Draw Ratio Cpu00% Cpu10% Cpu15% Cpu20% Figure 7. Hysteresis for cross-linking agent having different draw ratio.. Polyurethane, segment,. segment,,, annealing. 20 polyurethane. 21
ATR FT-IR spectrum. IR spectrum urethane carbonly C=O bond hard segment C=O bond hard segment hard domain soft matrix 1730cm -1 hard domain hard segment wavenumber shift 1700cm -1 2 peak. 27 Urethane (2) absorbance A. A H bond Freebond C=O C=O absorbance. hard segment urethane C=O absorbance C=O absorbance. H bond A A Freebond A SP. IR spectrum C=O absorbance. A SP = A H-bond A + A H-bond Freebond (2) Figure 8 ATR FT-IR spectrum. spectrum 1750cm -1 1670cm -1 baseline, spectrum carbonyl absorbance. Figure 8 1730cm -1 carbonyl peak absorbance 22
1.2 1.0 0.8 Cpu00% Cpu10% Cpu15% Cpu20% Absorbance 0.6 0.4 0.2 0.0 1750 1740 1730 1720 1710 1700 1690 1680 1670 Wavenumber [cm -1 ] Figure 8. ATR FT-IR spectra showing the carbonyl absorbance region for cross-linking agent content,. hard segment hard segment hard segment packing hard domain. Hard domain hard segment soft matrix. Figure 9 Figure 11 ATR FT-IR Heating. 23
Absorbance Ratio 0.70 0.65 0.60 0.55 0.50 0.45 0.40 0.35 H-bond C=O Free C=O -2-3 -4-5 -6 Endo mw 0.30-7 20 40 60 80 100 120 140 160 180 200 Temperature [ o C] Figure 9. Carbonyl stretching peak absorbance ratio of Cpu00% as a function of temperature and solid line is DSC thermogram FT-IR spectrum urethane group carbonyl absorbance phase segmental mixing. carbonyl peak absorbance. hard domain hard segment chain mobility, soft segment. 24
Absorbance Ratio 0.70 0.65 0.60 0.55 0.50 0.45 0.40 0.35 H-bond C=O Free C=O 1 0-1 -2-3 mw Endo 0.30-4 20 40 60 80 100 120 140 160 180 200 Temperature [ o C] Figure 10. Carbonyl stretching peak absorbance ratio of Cpu10% as a function of temperature and solid line is DSC thermogram carbonyl absorbance ratio carbonyl absorbance ratio hard segment order-disorder transition temperature(t ODT ). DSC curve. Figure 9 absorbance ratio carbonyl absorbance ratio. Figure 9 11 ATR FT-IR heating DSC thermogram. 25
Absorbance Ratio 0.70 0.65 0.60 0.55 0.50 0.45 0.40 0.35 H-bond C=O Free C=O 1 0-1 -2-3 Endo mw 0.30-4 20 40 60 80 100 120 140 160 180 200 Temperature [ o C] Figure 11. Carbonyl stretching peak absorbance ratio of Cpu20% as a function of temperature and solid line is DSC thermogram carbonyl absorbance ratio. Figure 9 Figure 10 carbonyl peak absorbance ratio 140 ~150. Figure 11 Cpu20% 100 absorbance ratio. ATR FT-IR Heating segmental mixing Cpu00% T ODT 140, Cpu20% 100 T ODT.. 26
packing density, hard domain. conventional X-ray intensity X-ray scattering data exposure time. intensity synchrotron real time segmented block copolymer domain. 28,29 Small angle x-ray scattering (SAXS) scattering scattering intensity. Two-phase model parameter invariant. Invariant (Q) (2). 1 2 Q = I( q )q dq (2) 2 p 0 invariant. Q 2 Dr (3) Q F F 1 2 ( r 1 2 2 - r ) (4) I (q): X-ray intensity q : Scattering Vector q = 4πsin θ λ Φ i, ρ i : i volume fraction electron density θ: Scattering angle λ: X-ray wavelengh 27
(4) 1, 2 phase volume fraction electron density invariant electron density invariant. invariant domain. 30 Bragg law domain long period. 31 2p d = (5) q m q m: intensity scattering vector SAXS parameter Porod Constant interface thickness. Scattering vector (q) I(q)q 4 Porod constant,. thermal density fluctuation diffuse phase boundary (6). hard segment soft segment Porod (7). 32~34 lim I( q ) = q-> q Kp 4 q (6) lim I( q ) @ q-> Kp (1-4 q 2 E q 12 2 ) (7) 28
E. scattering vector I(q)q 4 q 2, E Porod constant. 35 Figure 12 Cpu10% 2D image profile. Figure 12 scattering ring pattern homogeneous 360 O ring pattern ring pattern scattering vector. soft segment, hard domain long period. hard domain soft matrix mixing scattering. SAXS scatterig pattern 2D image merdian 1D data Figure 13. Figure 12 data intensity scattering vector. domain domain domain long period. long period Cpu10%, 20% Cpu00%. domain Figure 14 long period. Long period y 0.5 data shift. long period, 29
110 o C 200 o C 80 o C 170 o C 60 o C 150 o C 25 o C 130 o C Figure 12. Isointensity plots of the two-dimensional SAXS data of Cpu10% as function of temperature 30
150 125 Intensity 100 75 Temperature Increases 50 25 0 0.00 0.04 0.08 0.12 0.16 Temperature [ o C] Figure 13. Cpu00% SAXS heating Exp t 1D data profiles as function of temperature Cpu00% long period 140 Cpu10%, 15% 100 long period. Cpu20% 80 long period. Figure 14 long period long period hard domain thermal stability. 31
Relative Long Period 5.0 4.5 4.0 3.5 3.0 2.5 2.0 Cpu00% Cpu10% Cpu15% Cpu20% 1.5 1.0 40 60 80 100 120 140 160 180 Temperature [ o C] Figure 14. The change of long period values for cross-linking agent content as function of temperature invariant interface thickness. Figure 15 Figure 16 Cpu00, 20% invariant. Invariant Cpu00% 140 invariant, Cpu20% 100 invariant. Figure 17 interface thickness interface thickness.. Long period, invariant, interface thickness 32
0.020 0.018 0.016 Invariant 0.014 0.012 0.010 0.008 0.006 20 40 60 80 100 120 140 160 180 Temperature [ o C] Figure 15. Invariant of Cpu00% as a function of temperature 33
0.020 0.018 0.016 Invariant 0.014 0.012 0.010 0.008 0.006 20 40 60 80 100 120 140 160 180 Temperature [ o C] Figure 16. Invariant of Cpu20% as a function of temperature 34
Relative Interfacial Thickness 2.2 2.0 1.8 1.6 1.4 1.2 1.0 Cpu20% Cpu10% Cpu00% 40 60 80 100 120 140 160 180 Temperature [ o C] Figure 17. Relative interface thickness as function of temperature order-disorder transition temperature(t ODT ) IR Heating segmental mixing long period, invariant. 35
hard segment hard domain soft matrix hard segment, hard domain packing density. 36
5. Conclusion Polyurethane allophanate group mechanical property. Polyurethane good solvent THF weight loss weight loss. DSC enthalpy of fusion density. stressstrain curve hysteresis. Stress-strain curve initial modulus draw ratio 2.0 stress. hard segment hard segment packing density soft segment initial modulus. soft segment hard segment hard segment hard segment, domain draw ratio hard segment interconnected point hard domain stress. hysteresis. 37
,, creep,. 2.. ATR FT-IR, hard segment hard domain soft matrix. ATR FT-IR heating segmental mixing Cpu00% 140 order-disorder transition(t ODT ) Cpu20% 100 T ODT. domain SAXS heating, long period invariant, interface thickness Cpu00% 140 domain. domain Cpu20% 80 domain. ATR FT- IR Heating segmental mixing SAXS domain, Cpu00%. 38
hard segment packing hard domain soft matrix, hard domain packing density. mechanical properties 39
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