Inelastic response of copolyurethane elastomers with varying soft segment molecular weights and preparation procedure

A family of thermoplastic polyurethane elastomers (TPUs) based on the soft segment poly(oxytetramethylene) (PTMO₂₀₀₀ and PTMO₁₀₀₀) were synthesized by the one‐shot and prepolymer methods. Two hard segments were chosen, 4,4′‐methylenebis(phenyl isocyanate) (MDI) (non‐crystallizable) and 4,4′‐dibenzyl diisocyanate (DBDI) (crystallizable). Microphase separation and crystallinity were investigated using small‐angle X‐ray scattering and wide‐angle X‐ray scattering, and dynamic viscoelastic properties were also determined. An increased hard phase degree of crystallinity was primarily achieved by use of DBDI instead of MDI, regardless of the preparation procedure and soft segment molecular weight. An increase of the molecular weight leads to an increase in phase separation and to a decrease in hysteresis. For the DBDI based polymers, a lower soft segment molecular weight resulted in an increase in crystallinity. The DBDI series of TPUs obtained by the one‐shot and prepolymer methods showed higher hysteresis and residual elongations compared with the corresponding materials achieved with MDI. Although the materials varied widely in response to first loading, regardless of the preparation procedure, they displayed remarkable reproducibility and commonality in cyclic responses within the maximum strain envelope. The thermomechanical experiments revealed a better thermal behavior with increase of the soft segment molecular weight from PTMO₁₀₀₀ to PTMO₂₀₀₀.© 2013 Society of Chemical Industry     

Structure,composition, and adhesion properties of thermoplastic polyurethane adhesives

The composition and hard segment content of 13 commercial thermoplastic polyurethane elastomers (TPUs) were obtained using 1H-nuclear magnetic resonance (¹H-NMR). The properties of the TPUs were studied using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), dynamic mechanical thermal analysis (DMTA), and contact angle measurements. Solventbased adhesives were prepared by dissolving the TPUs in 2-butanone. Films of the TPUs were obtained by solvent evaporation, and their properties were studied. Adhesion properties were determined from T-peel tests on solvent-wiped poly(vinyl chloride) (PVC)/polyurethane adhesive joints. The influence of the segmented structure on the properties of the TPUs was assessed. The increase in the hard segment content in TPUs favoured the incompatibility (i.e. reduced phase separation) between hard and soft domains. TPUs with a high hard segment content had a low crystallinity, a low wettability, and a high joint strength. The storage and loss moduli obtained using DMTA decreased as the hard segment content in the TPUs increased. Furthermore, the TPUs prepared using ε-polycaprolactone as the macroglycol had a slower crystallization rate than those prepared using the polyadipate of 1,4-butanediol or the polyadipate of 1,6-hexanediol. The increase in the length of the hydrocarbon chain of the macroglycol improved both the rheological and the thermal properties of the TPUs. Finally, TPUs prepared using MDI as the isocyanate showed a higher crystallinity and a higher degree of crosslinking than those prepared using TDI.     

Characterization of thermoplastic polyurethane adhesives with different hard/soft segment ratios containing rosin as an internal tackifier

Three thermoplastic polyurethanes (TPUs) containing different hard/soft (h/s) segment ratios (1.05-1.4) were prepared using the prepolymer method. MDI (diphenylmethane-4,4′diisocyanate) and polyadipate of 1,4-butanediol (M _w = 2440) were allowed to react to produce the prepolymer. To provide the polyurethanes with high immediate adhesion to different substrates, a rosin + 1,4-butanediol mixture (1 : 1 equivalent%) was used as chain extender (TPU-Rs). These TPU-Rs had two types of hard segments: (i) Urethane hard segments, produced by reaction of the isocyanate and the 1,4-butanediol, and (ii) Urethan-amide hard segments, produced by reaction of the isocyanate and the carboxylic acid functionality of the rosin. The TPUs and TPU-Rs were characterized using FTIR spectroscopy, gel permeation chromatography, differential scanning calorimetry, stress-controlled plate-plate rheology, stress-strain measurements, and Brookfield viscosity. The TPUs and TPU-Rs were used as raw materials to prepare solvent-based polyurethane adhesives, the adhesion properties of which were obtained from T-peel tests on PVC/polyurethane adhesive/PVC joints. The addition of rosin as an internal tackifier increased the average molecular weight, more markedly in the TPU-Rs containing higher hard/soft segment ratios, but the elastic and viscous moduli decreased. An increase in the hard/soft segment ratio of the TPU-Rs retarded the kinetics of crystallization (which was determined by the soft segment content in the polyurethane), and increased the immediate T-peel strength in PVC/polyurethane adhesive/PVC joints (which was determined by the urethan-amide hard segments). Furthermore, addition of rosin to the polyurethanes decreased the final adhesion, although always reasonably high peel strength values were obtained.     

The effect of soft‐segment structure on the properties of novel thermoplastic polyurethane elastomers based on an unconventional chain extender

Thermoplastic polyurethane elastomers (TPUs) are now widely used because of their excellent properties that include high tensile and tear strength, and good abrasion, impact and chemical resistance. TPUs are multiblock copolymers with alternating sequences of hard segments composed of diisocyanates and simple diols (chain extenders) and soft segments formed by polymer diols. Commonly used hard segments for TPUs are derived from 4,4′‐diphenylmethane diisocyanate (MDI) and aliphatic diols. The aim of our research was to examine the possibility of obtaining TPUs with good tensile properties and thermal stability by using an unconventional aliphatic‐aromatic chain extender, containing sulfide linkages. Three series of novel TPUs were synthesized by melt polymerization from poly(oxytetramethylene) diol, poly(ε‐caprolactone) diol or poly(hexane‐1,6‐diyl carbonate) diol of number‐average molecular weight of 2000 g mol^?1 as soft segments, MDI and 3,3′‐[methylenebis(1,4‐phenylenemethylenethio)]dipropan‐1‐ol as a chain extender. The structure and basic properties of the polymers were examined using Fourier transfer infrared spectroscopy, X‐ray diffraction, atomic force microscopy, differential scanning calorimetry, thermogravimetric analysis, Shore hardness and tensile tests. It is possible to synthesize TPUs from the aliphatic‐aromatic chain extender with good tensile properties (strength up to 42.6 MPa and elongation at break up to 750%) and thermal stability. Because the structure of the newly obtained TPUs incorporates sulfur atoms, the TPUs can exhibit improved antibacterial activity and adhesive properties. Copyright © 2011 Society of Chemical Industry     

Synthesis and characterization of new thermoplastic polyurethane adhesives containing rosin resin as an internal tackifier

Three thermoplastic polyurethane elastomers (TPUs) were prepared using the prepolymer method. MDI (diphenylmethane-4,4′-diisocyanate) and the polyadipate of 1,4-butanediol (M_w = 2400) were reacted to produce a prepolymer containing unreacted isocyanate groups; chain extenders were different mixtures of 1,4-butanediol and a rosin resin (0-50%). The specific feature of this procedure was the introduction of a rosin resin as an internal tackifier to provide higher immediate adhesion to the TPUs. The new TPUs were characterized using gel permeation chromatography, wideangle X-ray diffraction, differential scanning calorimetry, stress-controlled rheology, and stress-strain measurements. The TPUs were used as raw materials to prepare solvent-based polyurethane adhesives, the adhesion properties of which were obtained from T-peel tests on PVC/polyurethane adhesive/PVC and leather/polyurethane adhesive/PVC joints. The addition of rosin resin as an internal tackifier contributed to the production of two types of hard segments, which affected the properties of the TPUs. Therefore, rosin resin as an internal tackifier produced an increase in the average molecular weight, an increase in the viscosity, and improved the rheological properties. The glass transtition temperature decreased if the TPUs contained rosin resin, due to a greater degree of incompatibility between the hard and soft segments. Consequently, slower kinetics of crystallization was obtained in the TPUs containing rosin resin. Depending on the amount of rosin resin in the TPU, different structures and properties were obtained. On the other hand, the immediate T-peel strength in all joints was improved if the TPU contained rosin resin.     

Green TPUs from Prepolymer Mixtures Designed by Controlling the Chemical Structure of Flexible Segments

This study concerns green thermoplastic polyurethanes (TPU) obtained by controlling the chemical structure of flexible segments. Two types of bio-based polyether polyols—poly(trimethylene glycol)s—with average molecular weights ca. 1000 and 2700 Da were used (PO3G1000 and PO3G2700, respectively). TPUs were prepared via a two-step method. Hard segments consisted of 4,4′-diphenylmethane diisocyanates and the bio-based 1,4-butanodiol (used as a chain extender and used to control the [NCO]/[OH] molar ratio). The impacts of the structure of flexible segments, the amount of each type of prepolymer, and the [NCO]/[OH] molar ratio on the chemical structure and selected properties of the TPUs were verified. By regulating the number of flexible segments of a given type, different selected properties of TPU materials were obtained. Thermal analysis confirmed the high thermal stability of the prepared materials and revealed that TPUs based on a higher amount of prepolymer synthesized from PO3G2700 have a tendency for cold crystallization. An increase in the amount of PO3G1000 at the flexible segments caused an increase in the tensile strength and decrease in the elongation at break. Melt flow index results demonstrated that the increase in the amount of prepolymer based on PO3G1000 resulted in TPUs favorable in terms of machining.     

高固含量水性聚氨酯的合成及其成膜性能的研究

采用预聚体分散法制备出50%以上固含量的水性聚氨酯,考察了软链段分子链长及硬链段含量对聚氨酯相分离行为、热性能及力学性能等的影响。研究表明:硬链段含量、软链段链长的提高和离子基团的增加均有利于拉伸强度的提高。     

Effect of clay modifiers on the morphology and physical properties of thermoplastic polyurethane/clay nanocomposites

Thermoplastic polyurethanes (TPUs)/clay nanocomposites were prepared via melt processing using the ester type and the ether type TPUs and three differently modified organoclays (denoted as C30B, C25A and C15A) as well as pristine montmorillonite (PM). XRD and TEM results showed that the addition of C30B with hydroxyl group led to the nearly exfoliated structures in both TPUs. In the case of C25A and C15A clays, partially intercalated nanocomposites were obtained in both TPUs, where C25A showed better dispersion than C15A. Natural clay (PM) was not effectively dispersed in both TPUs. The tensile properties of nanocomposites with C30B were better than ones with the other clays. Higher tensile properties were obtained for ester type TPU than ether type TPU nanocomposites with all clays tested. Although the improvement in tensile properties decreased after the second extrusion of the nanocomposites, properties of the nanocomposite after first melt processing were still good enough for practical applications. Morphological changes induced by the addition of clays were analyzed using FTIR, DSC and rheological test results. Some clays were observed to cause demixing of hard and soft segments in the nanocomposites and location of clays in either soft segment or hard segment domains was also studied.     

Syntheses and characterization of novel biostable polyisobutylene based thermoplastic polyurethanes

The synthesis of polyisobutylene (PIB) based thermoplastic polyurethanes (TPU) with enhanced mechanical properties have been accomplished using poly(tetramethylene oxide) (PTMO) as a compatibilizer. PIB TPUs with Shore 60-100 A hardness were prepared by employing PIB diols (hydroxyallyl telechelic PIBs) for the soft segment and 4,4′-methylenebis(phenylisocyanate) (MDI) and 1,4-butanediol (BDO) for the hard segment. The TPUs exhibited number average molecular weight (M_n) in the range of 83,000-110,000 g/mol with polydispersity indices (PDIs) = 1.8-3.1. These TPUs, however, were inferior compared to commercial TPUs such as Pellethane™ (Dow Chemical Co.) as they exhibited low tensile strength (6-15 MPa) and/or ultimate elongation (30-400%). Processing of the harder compositions was also difficult and some could not be compression molded into flat sheets for testing. Differential Scanning Calorimetry (DSC) showed the presence of high melting (≥200 °C) crystalline hard segments suggesting longer - MDI-BDO - sequences than expected based on the stoichiometry. Easily processable TPUs with excellent mechanical properties (tensile strength up to 40 MPa, ultimate elongation up to 740%) were obtained by incorporating PTMO in the soft segment. Examination of PIB-PTMO TPUs with varying hard: soft compositions (20:80, 35:65 and 40:60 wt:wt) and Shore hardness (60 A, 80 A and 95 A) indicated that substituting 10-30 wt% of PIB diol with PTMO diol is sufficient to reach mechanical properties similar to Pellethanes.     

Morphology and conductivity changes in a thermoplastic polyurethane‐based copolymer consisting of different soft segments

Three different segmented thermoplastic polyurethanes (TPUs) were synthesized with 4,4′‐methylenebis(phenyl isocyanate) as a hard segment and poly(ethylene glycol) (PEG) or poly(propylene glycol) (PPG) or an equal mixture of PEG and PPG with molecular 2000 as soft segments. The soft‐segment component of TPU was changed to monitor modifications in chemical and physical properties among the three TPUs. Differential scanning calorimetry (DSC) and thermogravimetric analysis were used to monitor changes in thermal characteristics. Fourier transform infrared spectroscopy (FTIR) was employed to predict the interaction between the lithium cation and the hard or soft segment in the presence of added LiClO₄. The deconvolution results of spectral bands associated with the N? H groups of these TPUs were used to obtain such information. Impedance spectroscopy was used to inspect the changes in the bulk conductivity of these TPUs caused by alteration of the soft‐segment component. The conductivity changes were explained through combined DSC and FTIR results. The electrochemical stability of the TPU systems was studied by linear sweep voltammetry. The results showed that the copolymer system had better thermal and electrochemical stability than the other systems. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1462–1473, 2001     

Preparation and properties of transparent thermoplastic segmented polyurethanes derived from different polyols

Various segmented polyurethanes of different soft segment structure with hard segment content of about 50 wt% were prepared from 4,4′‐diphenylmethane diisocyanate (MDI), 1,4‐butanediol and different polyols with a M_n of 2000 by a one‐shot, hand‐cast bulk polymerization method. The polyols used were a poly(tetramethylene ether)glycol, a poly(tetramethylene adipate)glycol, a polycaprolactonediol and two polycarbonatediols. The segmented polyurethanes were characterized by gel permeation chromatography (GPC), UV‐visible spectrometry, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X‐ray diffraction, and their tensile properties and Shore A hardness were determined. The DSC and DMA data indicate that the miscibility between the soft segments and the hard segments of the segmented polyurethanes is dependent on the type of the soft segment, and follows the order: polycarbonate segments > polyester segments > polyether segments. The miscibility between the soft segments and the hard segments plays an important role in determining the transparency of the segmented polyurethanes. As the miscibility increases, the transparency of the segmented polyurethanes increases accordingly. The segmented polyurethanes exhibit high elongation and show ductile behavior. The tensile properties are also affected by the type of the soft segment to some extent. POLYM. ENG. SCI., 47:695–701, 2007. © 2007 Society of Plastics Engineers.     

Segmented block copolymers of natural rubber and bisphenol A–toluene diisocyanate oligomers

Segmented block copolymers were synthesized from hydroxyl‐terminated liquid natural rubber and polyurethane oligomers based on Bisphenol A and toluene diisocyanate by one‐shot and two‐shot processes in solution. Structural features were characterized by infrared and nuclear magnetic resonance spectroscopic analysis. The spectra of the one‐shot materials were identical with those of the two‐shot materials, indicating their chemical identity. The soft segment T_g was well defined and almost invariant around −64°C, but the hard segment T_g varied from 75 to 105°C as the hard segment content increased from 30 to 60 wt %. Two relaxation temperatures were observed for each sample in dynamic mechanical analysis (DMA). These observations and the two‐stage thermal decomposition by random nucleation mechanism, as investigated in thermogravimetric analysis unambiguously confirmed complete phase segregation in these materials. The scanning electron microscopy and optical micrographs showed well‐defined domains dispersed in a matrix, indicating the two‐phase morphology. Systematic changes in hardness and tensile properties with hard segment content were also observed. The samples behaved like soft elastomers at lower hard segment content, toughened plastics at high hard segment content, and rigid elastomers at intermediate compositions. Variations in hardness and tear strength were consistent with this behavior. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 706–721, 1999     

蓖麻油作交联剂的聚氨酯弹性体的合成及性能

以不同摩尔比的四氢呋喃均聚醚（PTMG）和1,6-亚己基二异氰酸酯（HDI）合成聚氨酯（PU）预聚体,再分别用丁二醇（BD）、蓖麻油（CO）以及BD和CO混合物进行扩链交联,合成了一系列不同CO含量的PU.通过FTIR、AFM、拉伸实验和TGA,对不同硬段含量和CO含量PU的氢键化程度、相形态结构、力学性能和热性能进行了比较。结果表明,二异氰酸酯和扩链剂的种类及用量对PU的性能均有很大的影响。随着PU中二异氰酸酯用量的增加,其力学性能和热稳定性能提高。随着扩链剂中CO用量的增加,PU氨酯键的氢键化程度降低,其软、硬段的微相分离程度降低,导致其力学性能降低。但CO用量的增加会提高PU分子链的交联和支化,因而其热稳定性能得到提高。     

MECHANICAL AND THERMAL PROPERTIES OF NANO-AL2O3/NYLON 6 COMPOSITES

Nano-Al₂O₃-reinforced monomer casting nylon (NA/MCN) composites were prepared by using in situ polymerization. The average molecular weight of the matrix nylon was measured using gel permeation chromatography. The thermal-mechanical properties of the NA/MCN composites were characterized by thermo-dynamic mechanical analysis, and the results were compared with micro-Al₂O₃-reinforced nylon (MA/MCN) composites. A tensile property test was conducted to investigate the mechanical properties of neat nylon and composites. Experimental results showed that the average molecular weight of the matrix nylon filled with nano-alumina had little change and was higher than that with micro-alumina. The glass transition temperature (T_g) and storage moduli of NA/MCN composites were higher than that of neat nylon. During the experiment, it was also found that the tensile strength increased up to 52% when 3 wt.% of nano-Al₂O₃ particles were added. The thermal and tensile properties of NA/MCN composites were better than those of the MA/MCN composites when the same weight percentage of Al₂O₃ particles was used.     

Effects of aggregation structure on rheological properties of thermoplastic polyurethanes

The effects of the molecular aggregation structure on the rheological properties of thermoplastic polyurethane (TPU) were investigated. The TPU was composed of poly{(tetramethylene adipate)-co-(hexamethylene adipate)} glycol as the soft segments, 4,4′-diphenylmethane diisocyanate and 1,4-butanediol as the hard segments. The TPU sheets prepared by injection molding were annealed at various temperatures from 23 to 120 °C to vary the molecular aggregation structure. Glass transition temperature of the soft segment and melting points of the hard segment domains of the TPUs decreased and increased, respectively, with increasing annealing temperature. The results of DSC, solid-state NMR spectroscopy and dynamic viscoelastic measurements revealed that the degree of micro-phase separation of the TPUs becomes stronger with increasing annealing temperature due to the progress of formation of well-organized hard segment domains. The dynamic temperature sweep experiments for molten TPUs revealed that the temperature at critical gel point, which is defined as the temperature at which the dynamic storage modulus coincides with the loss storage modulus, in the cooling process increased with the progress of aggregation of the hard segments in the TPUs observed in the solid state. The uniaxial elongational viscosity measurements showed that TPUs exhibited an obvious strain hardening behavior with strain rate owing to residual hard segment domains at an operating temperature. It was revealed that the formation of well-organized hard segment domains had a profound effect on the rheological properties of TPUs, in particular on their elongational viscosity.     

Microphase-separated structure and mechanical properties of norbornane diisocyanate-based polyurethanes

Norbornane diisocyanate (NBDI: 2,5(2,6)-bis(isocyanatomethyl)bicyclo[2.2.1]heptane) is a new commercialized diisocyanate. NBDI-based polyurethane elastomers (PUEs) were prepared from poly(oxytetramethylene) glycol (PTMG), NBDI and 1,4-butanediol (BD) by a prepolymer method. Microphase-separated structure and mechanical properties of the NBDI-based PUEs were compared with general aliphatic and cycloaliphatic diisocyanate-based PUEs. The diisocyanates used were isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (HMDI) and 1,6-hexamethylene diisocyanate (HDI). Regular polyurethanes were also prepared as hard segment models from each isocyanate and BD to understand the feature of each hard segment chain. The HDI-based PUE showed the largest Young's modulus and tensile strength in the four PUEs due to the ability of crystallization of the hard segment component and the strongest microphase separation. HMDI has both properties of aliphatic and cycloaliphatic diisocyanates because of its high symmetrical chemical structure compared with NBDI and IPDI. On the other hand, the NBDI- and IPDI-based PUEs have an inclination to phase mixing, leading to decreased Young's modulus and tensile strength. The NBDI-based PUE exhibited better thermal properties at high temperatures due to stiff structure of NBDI.     

Thermal and mechanical properties of polyisobutylene‐based thermoplastic polyurethanes

We investigated thermal and mechanical properties of thermoplastic polyurethanes (TPUs) with the soft segment comprising of both polyisobutylene (PIB) and poly(tetramethylene)oxide (PTMO) diols. Thermal analysis reveals that the hard segment in all the TPUs investigated is completely amorphous. Significant mixing between the hard and soft segments was also observed. By adjusting the ratio between the hard and soft segments, the mechanical properties of these TPUs were tuned over a wide range, which are comparable to conventional polyether‐based TPUs. Constant stress creep and cyclic stress hysteresis analysis suggested a strong dependence of permanent deformation on hard segment content. The melt viscosity correlation with shear rate and shear stress follows a typical non‐Newtonian behavior, showing decrease in shear viscosity with increase in shear rate. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 891‐897, 2013     

Polyurethane elastomers based on molecular weight advanced poly(ethylene ether carbonate) polyols. III. Effects of diisocyanate modified diols

A series of diisocyanate-modified, molecular weight advanced poly(ethylene ether carbonate) diols has been prepared, characterized, and formulated into polyurethane elastomers using a prepolymer process. Properties were compared to a polyurethane elastomer control in which the only variable was the diisocyanate modification. The diisocyanate modification produces polymers with increased modulus (445–730% at 25°C), improved tensile strength and hardness properties and reduced (improved) coefficients of linear thermal expansion, while still passing the notched Izod impact test. The tensile strength at break increases with increasing number of urethane moieties in the soft segment and the elongation at break also increases. The plaques studied appear to have a three-phase morphology—a soft segment continuous phase containing amorphous hard segment, an amorphous hard segment phase plasticized by about 11% of the soft segment material, and a crystalline hard segment. The polymers based on the diisocyanate modified polyols are significantly more phase mixed than the control due to the increased amount of hard segment-soft segment interactions taking place. The improved properties of the polymers made with the modified polyols are due to their higher hydrogen bonding protential which gives more physically crosslinked polymers.     

Effect of Chain Length for Dicarboxylic Monomeric Units of Polyester Polyols on the Morphology,Thermal and Mechanical Properties of Thermoplastic Urethanes

Polyester polyols of 2000 g mol⁻¹ M mass were synthesized via polyesterification reaction of butane-1,4-diol (1,4-BDO) with linear dicarboxylic acids (DCAs) of odd and even carbon numbers, ranging from C₄ to C₁₀. Melt transition temperatures and crystallization enthalpies of polyester polyols demonstrated differing trends between odd and even chain lengths of their DCA monomeric units, with the latter possessing higher melt transition temperatures and melting enthalpies. The underlying cause of this difference may be attributable to the formation of a crystalline phase between the polyols' alkyl groups, which leads to proper alignment of ester bonds to allow for formation of dipoles that effectively cancel the local polarization. Thermoplastic urethanes (TPUs) were prepared by reacting the polyester polyols with 4,4′-methylene bis(phenyl isocyanate) (4,4′-MDI) and 1,4-BDO chain extender at mole ratio of 1:2:1, respectively. Morphology, thermal and mechanical properties of TPUs were measured. Mechanical properties of TPUs also differ according to even vs. odd chain length of DCA monomeric units: higher hardness, tensile strength, hysteresis and tensile set for the former. The difference in properties is likely related to differences in phase segregation between hard and soft segments as a result of formation of hydrogen bonds as well as dipole–dipole interactions. Therefore, these findings have practical significance in the selection of polyester polyols to design TPUs for their specific applications.     

Oscillatory structure–property correlation in azelate polyols and thermoplastic polyurethanes

Azelate polyols of 2000 g mol^?1 have been successfully prepared via esterification of renewable azelaic acid with linear diols containing different number of CH₂ repeating units. Structure–property correlation of the azelate polyols had been evaluated in thermoplastic polyurethanes (TPUs). TPUs based on azelate polyols of longer chained linear diols with >4 CH₂ repeat units retained higher degrees of crystallinity associated with the polyol soft segment. The ratio of hydrogen bonded urethane in the hard segment to free urethane phase mixed with the soft segment in the TPUs showed a complex oscillating dependence with increased number of CH₂ repeating unit in the linear diols of azelate polyols. Correspondingly, static and dynamic properties of TPUs also showed the oscillatory dependence, whereby dynamic properties maximized with odd number of CH₂ repeating unit and material strength maximized with even number of CH₂ repeating unit. The results therefore can be used as guide to select appropriate azelate polyols to target specific TPU performance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46258.