Properties of waterborne polyurethane‐fluorinated marine coatings: The effect of different types of diisocyanates and tetrafluorobutanediol chain extender content

Three series of waterborne polyurethane‐ (WBPU) fluorinated coatings were prepared with single aliphatic (4,4′‐dicyclohexylmethane diisocyanate, H₁₂MDI), aromatic (4,4′‐diphenylmethane, MDI) and a mixture of aliphatic and aromatic diisocyanates (1 : 1). Different contents of 2,2,3,3‐tetrafluoro1,4‐butanediol (TFBD) as a chain extender were used in the WBPU coatings. The fluoro‐enriched surface of the WBPU coatings was obtained with a combination of a high TFBD content (8.77 mol %) as well as the aliphatic or mixed diisocyanates. The tensile strength, Young's modulus, elongation at break (%) and adhesive strength were characterized with respect to the TFBD contents. The mechanical strength and adhesive strength increased with increasing TFBD content in the three series. In artificial salt water, the maximum adhesive strength of WBPU was observed for this coating, which was achieved by TFBD bonded H₁₂MDI of mixed diisocyanates with a higher TFBD content (8.77 mol %). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39905.     

Synthesis and properties of waterborne polyurethane adhesives: effect of chain extender of ethylene diamine,butanediol, and fluoro-butanediol

Waterborne polyurethane (WBPU) adhesives were prepared using poly(tetramethylene oxide glycol), 4,4’-dicyclohexylmethane diisocyanate (H₁₂MDI), hydrophilic agent dimethylol propionic acid and chain extender of 2,2,3,3-tetrafluoro-1,4-butanediol (TFBD), ethylene diamine (EDA), and 1,4-butanediol. All three chain extenders have been used as single and mixed (different ratio) content during synthesis, and the effect of chain extender and their content to the properties of tensile strength, Young’s modulus, water swelling (%), and adhesive strength was investigated. The adhesive strength value was higher using EDA as a single-chain extender; however, the potentiality of adhesive strength under water was improved using mixed-chain extenders of EDA and TFBD in WBPU adhesives. The maxima potentiality was observed with 6.31 mole% TFBD and 2.10 mole% EDA in WBPU adhesives.     

Preparation and properties of MDI/H12MDI‐based water‐borne poly(urethane‐urea)s—Effects of MDI content and radiant exposure

Water‐borne poly(urethane‐urea)s (WBPUs) were prepared by a prepolymer mixing process using aromatic diisocyanate (MDI, 4,4′‐diphenylmethane diisocyanate)/aliphatic diisocyanate (H₁₂MDI, 4,4′‐methylenebis cyclohexyl isocyanate), polypropylene glycol (PPG, M_n = 1000), dimethylol propionic acid, and ethylene diamine as a chain extender, and triethylamine as a neutralizing agent. The effect of MDI on the molecular weight, chemical structure, dynamic thermo, and tensile properties of WBPUs was investigated. The yellowness index (YI, photo‐oxidation behavior) change of WBPUs under accelerated weathering exposure was also investigated. The WBPUs containing higher MDI content showed lower molecular weight, which verified the participation of some high reactive isocyanate groups of MDI into side reaction instead of chain growing reaction. As the MDI content increased, the storage modulus and tensile modulus/strength of WBPUs film increased, and their glass transitions of soft segments (T_gs) and hard segments (T_gh) were shifted to higher temperature. The intensity of tan δ peak of all three samples increased with increasing radiant exposure. The YI of H₁₂MDI‐based WBPU sample (WBPU‐0) was not occurred. The YI of WBPUs containing MDI increased with increasing MDI content and radiant exposure. However, the YI of sample WBPU‐25 containing 25 mol % of MDI at 11.3 MJ/m² (radiant exposure) was 6.6 which is a permissible level for exterior applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Properties of Waterborne Polyurethane Adhesives: Effect of Chain Extender and Polyol Content

A series of waterborne polyurethane (WBPU) adhesives were prepared with various ratios of polyol, poly(tetramethylene oxide glycol) (PTMG), and chain extender, ethylene diamine (EDA), at a fixed content of diisocyanate, 4,4-dicyclohexylmethane diisocyanate (H₁₂MDI) and hydrophilic agent, 2,2-dimethylol propionic acid (DMPA). WBPU adhesives were characterized by IR and ¹H-NMR spectroscopies, X-ray diffraction (XRD) and gel permeation chromatography (GPC). It was found that the extent of hydrogen bonds between hard–hard segment (i.e., hydrogen bonds between the NH and carbonyl groups) increased with increasing chain extender content (decreasing polyol content). Moreover, the disordered hydrogen bond of carbonyl group (hydrogen bond of urethane groups in the interfacial region) increased with increasing chain extender content (decreasing polyol content). The cyclic urea and allophanate group, which are attributed to the side reaction and cross-linking reaction, respectively, were found above a molar ratio 0.17 of chain extender to diisocyanate. The adhesive strength was maximum with 0.95 wt% and 63.10 wt% chain extender and soft segment (PTMG), respectively (H2 sample) at room temperature for the WBPU adhesive. However, with increasing application temperature the adhesive strength decreased for all samples.     

Effect of Poly(dimethylsiloxane) Content on the Properties of Water-Borne Poly(urethane-urea)s Containing MDI

Low photo- and water-resistance is often cited as the problem of MDI-based WBPU. This study addressed this problem. Water-borne poly(urethane-urea)s (WBPUs) were synthesized using a pre-polymer mixing process from 4,4'-methylenebis(phenyl isocyanate)(MDI)/4,4-dicyclohexylmethyl diisocyanate (H₁₂MDI) (15/85 mole %)/dimethylol propionic acid (DMPA)/ethylene diamine (EDA)/triethylamine (TEA) with different poly(propylene glycol) (PPG, M _n = 2000)/hydroxyl terminated poly(dimethylsiloxane) (PDMS, M _n = ～550) molar ratios. This study highlights the effect of PDMS content on the inherent viscosity, hydrogen-bonding, storage modulus, tan δ peak intensity, tensile modulus/strength, elongation (%) at break, water swelling (%), contact angle, and the yellowness index of WBPUs containing MDI. The mechanical properties (strength/modulus), water-resistance and photo-resistance of WBPUs containing MDI increased significantly in proportion to the PDMS content. These results indicate the potential for using multi-performance WBPU with PDPS for WBPU coatings.     

Properties of segmented polyurethanes derived from different diisocyanates

Various segmented polyurethane materials with a polyurethane hard segment (HS) content of 40 wt % were prepared by bulk polymerization of a poly(tetramethylene ether) glycol with M_n of 2000, 1,4‐butanediol, and various diisocyanates. The diisocyanates used were pure 4,4′‐diphenylmethane diisocyanate (MDI), 2,4‐toluene diisocyanate (T100), toluene diisocyanate containing 80% 2,4‐isomer and 20% 2,6‐isomer (T80), isophorone diisocyanate (IPDI), hydrogenated 4,4′‐diphenylmethane diisocyanate (HMDI), and 1,6‐hexane diisocyanate (HDI). The segmented polyurethane materials were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile properties, tear strength, and Shore A hardness. The DSC and DMA data show that the thermal transitions are influenced significantly by the diisocyanate structure. In the segmented polyurethane materials with aliphatic HS, the polyether soft segment (SS) is immiscible with the HS. However, in the segmented polyurethane materials with aromatic HS, the SS is partially miscible with the HS. The diisocyanate structure also influences the mechanical properties significantly and is described as the effect of symmetry and chemical structure of the HS. Various solution polymerized polyurethane resins with solid content of 30 wt % were also prepared and their thickness retention, water resistance, and yellowing resistance were determined for the evaluation of their usage as wet process polyurethane leather. The polyurethane resin with aliphatic HS show poorer thickness retention but better yellowing resistance. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 167–174, 2000     

Synthesis,characterization and thermal dissociation of 2‐butoxyethanol‐blocked diisocyanates and their use in the synthesis of isocyanate‐terminated prepolymers

A series of blocked diisocyanates has been synthesized from toluene diisocyante (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), 4,4′‐diphenylmethane diisocyanate (MDI) and 2‐butoxyethanol. The synthesis of blocked diisocyanate adducts was confirmed by Fourier transform infrared, ¹H NMR, electron impact mass spectrometry and nitrogen analysis. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and carbon dioxide evolution were used to determine the minimum de‐blocking temperatures. De‐blocking temperatures determined by these three techniques were found to be in the order DSC > TGA > CO₂ evolution. The effect of different metal catalysts on thermal de‐blocking reaction of the blocked diisocyanates was studied, using the carbon dioxide evolution method. It was found that iron(III) oxide has the maximum catalytic activity on de‐blocking. The solubility of the blocked diisocyanate adducts was determined in different solvents. The study revealed that at 30 °C blocked IPDI and HDI adducts show better solubility than adducts based on TDI and MDI. Isocyanate‐terminated prepolymers of blocked diisocyanates and hydroxyl‐terminated polybutadiene (HTPB) were prepared. The storage stability and gelation times of the prepolymers were studied. Results showed that all the diisocyanate‐HTPB compositions are stable at 50 °C for more than three months. However, aliphatic diisocyanate‐HTPB compositions require greater gelation time than aromatic diisocyanate‐HTPB compositions at their respective de‐blocking temperatures. Copyright © 2007 Society of Chemical Industry     

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     

Effects of NCO:OH ratio on the mechanical properties and chemical structure of Kraft lignin–based polyurethane adhesive

ABSTRACT

This work aimed to evaluate the influence of the aliphatic and aromatic hydroxyl level on the polyurethane adhesive property and chemical structure. This adhesive was obtained through the reaction of technical Kraft lignin (TKL) as polyol with diphenylmethane diisocyanate (MDI). Thus, lignopolyurethane adhesives were obtained with NCO:OH ratios of 0.8:1.0, 0.9:1.0, 1.0:1.0, 1.1:1.0, and 1.2:1.0. Initially only the TKL aliphatic hydroxyl level was taken into consideration in the stoichiometry in order to define the mass ratio between MDI and polyol. Subsequently, lignopolyurethane adhesive was obtained using the same NCO:OH ratios considering TKL total hydroxyls’ level, and aromatic and aliphatic hydroxyls. The chemical structures of the synthesized adhesives were analyzed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (¹³C NMR). The mechanical property of the adhesively bonded joints, comprising wood substrates and synthesized adhesives, was measured using single lap shear tests. Results illustrated that by increasing the NCO:OH ratio, there is an increase in the free isocyanate content leading to higher shear strength values. Higher free isocyanate content leads to MDI dimer formation in the lignopolyurethane structure.     

Synthesis,characterization, and acoustic properties of new soluble polyurethanes based on 2,2′‐[1,4‐phenylenebis(nitrilomethylylidene)diphenol and 2,2′‐[4,4′‐methylene‐di‐2‐methylphenylene‐1,1′‐bis(nitrilomethylylidene)]diphenol

Eight novel polyurethanes based on 2,2′‐[1,4‐phenylenebis(nitrilomethylylidene)]diphenol and 2,2′‐[4,4′‐methylene‐di‐2‐methylphenylene‐1,1′‐bis(nitrilomethylylidene)]diphenol acting as hard segments with two aromatic and two aliphatic diisocyanates (4,4′‐diphenylmethane diisocyanate, toluene 2,4‐diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate) were prepared and characterized with Fourier transform infrared, UV spectrophotometry, fluorescence spectroscopy, ¹H‐NMR and ¹³C‐NMR spectroscopy, thermogravimetric analysis, and differential thermal analysis. All the polyurethanes contained domains of semicrystalline and amorphous structures, as indicated by X‐ray diffraction. The acoustic properties and solubility parameters were calculated with the group contribution method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis,characterization of novel dihydrazide containing polyurethanes based on N1,N2‐bis[(4‐hydroxyphenyl)methylene]ethanedihydrazide and various diisocyanates

Four novel types of polyurethanes (PUs) were prepared from N¹,N²‐bis[(4‐hydroxyphenyl)methylene]ethanedihydrazide with two aromatic diisocyanates (4,4′‐diphenylmethane diisocyanate and tolylene 2,4‐diisocyanate) and two aliphatic diisocyanates (isophorone diisocyanate and hexamethylene diisocyanate). The chemical structure of both diol and PUs was confirmed by UV–vis, fluoroscence, FTIR, ¹H NMR, and ¹³C NMR spectral data. DSC data show that PUs have multiple endotherm peak. X‐ray diffraction revealed that the PUs contained semicrystalline and amorphous regions that varied with the nature of the backbone structures. PUs were soluble in polar aprotic solvents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of novel polyurethanes based on N1,N4‐bis[(4‐hydroxyphenyl)methylene]succinohydrazide hard segment

This article deals with the synthesis and characterization of novel polyurethanes (PUs) by the reaction between two aromatic diisocyanates (4,4′‐diphenylmethane diisocyanate and tolylene 2,4‐diisocyanate) and two aliphatic diisocyanates (isophorone diisocyanate and hexamethylene diisocyanate) with N¹,N⁴‐bis[(4‐hydroxyphenyl)methylene]succinohydrazide, which acted as hard segment. UV–vis, FTIR, ¹H NMR, ¹³C NMR, and DSC/TGA analytical technique has been used to determine the structural characterization and thermal properties of the hard segmented PUs. X‐ray diffraction revealed that PUs contained semicrystalline and amorphous regions that varied depending upon the nature of the backbone structures. PUs were soluble in polar aprotic solvents. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of polyisocyanate hardener on adhesive force of waterborne polyurethane adhesives

A series of waterborne polyurethane (WBPU)/hardener adhesives were obtained from mixing of WBPU containing different types of polyol as a soft segment with aliphatic and aromatic polyisocyanates hardeners. By characterization of allophanate and biuret bonds formed from the reaction of hardener NCO with urethane/urea groups of WBPU using ¹HNMR spectroscopy. It was found that the optimum number ratio (molar ratio) of NCO group of hardener to urethane/urea group of WBPU that shows the highest adhesion force was depended on the type of hardener (aliphatic/aromatic polyisocyanate) and dimethylol propionic acid (DMPA) content (total content of urethane/urea groups); however independent of the type of soft segment (polyol) of WBPU. The optimum number ratio (molar ratio) of NCO group of aromatic polyisocyanate hardener to urethane/urea was higher than that of aliphatic hardener to achieve the highest adhesion force of WBPU. The adhesive force increased with increasing hardener content up to the optimum point and then decreased. Poly(tetramethylene adipate glycol) (PTAd) based WBPUs with aliphatic hardener show higher adhesive force than Poly(tetramethylene oxide glycol) (PTMG) and aliphatic hardener‐based WBPUs at the optimum number ratio (molar ratio) of NCO group of hardener to urethane/urea group of WBPU. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3663–3669, 2007     

Kinetic investigations of trimethylolpropane–diisocyanate reactions

Trimethylolpropane (TMP) is frequently used as a trifunctional branching and chain‐extending agent in polyurethane production. This article deals with the analysis of the reactivities of the three primary hydroxyl groups of TMP during reactions with two exemplary diisocyanates: aromatic diphenylmethane‐4,4′‐diisocyanate and aliphatic m‐tetramethylxylylene diisocyanate. The method of examination is online attenuated total reflection/Fourier transform infrared spectroscopy. With this method, reactions in progress can be monitored simultaneously. It is shown that the addition of an isocyanate (here phenyl isocyanate) to the alcohol affects the rate of subsequent reactions. The higher the substitution degree is, the smaller the rate constant is of the reaction between the remaining free hydroxyl groups and the diisocyanates. This effect is largely determined by the type of diisocyanate. For reactions with very reactive aromatic diisocyanates, steric hindrance plays a significant role. For aliphatic diisocyanates, the substitution shows only minor effects because of the slowly reacting isocyanate groups. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4090–4097, 2006     

Thermally stable polyurethane‐ureas and copolyurethane‐ureas containing zinc and nickel dihydroxysaltrien complexes

New 4,4′‐dihydroxysaltrien metal complexes, (MOHSal₂trien, where M = Zn and Ni) were synthesized and used for the synthesis of metal‐containing polyurethane‐ureas and copolyurethane‐ureas. MOHSal₂trien underwent polymerization reaction with two diisocyanates, namely 4,4′‐diphenylmethane diisocyanate (MDI) and isophorone diisocyanate (IPDI) to yield polyurethane‐ureas. Copolyurethane‐ureas were synthesized by the reaction between MOHSal₂trien, MDI, and diamines or dialcohols. The diamines or dialcohols employed were 4,4′‐methylenedianiline (MDA), hexamethylenediamine (HMA), bisphenol A (BPO), and hexamethylene glycol (HMO). The polymers were characterized by IR, NMR, elemental analysis, XRD, solubility, and viscosity. Thermal stability and flammability of polymers were studied by thermogravimetric analysis (TGA) in air and by measuring limiting oxygen index (LOI) values, respectively. It was found that the resulting metal‐containing polyurethane‐ureas and copolyurethane‐ureas exhibited good thermal stability. Among all metal‐containing polyurethane‐ureas, NiOHSal₂trien‐MDI was the most thermally stable polymer with char yield of 55% at 600°C. Solubility in DMSO of zinc‐containing copolyurethane‐ureas based on dialcohols was greatly improved when compared with those of zinc‐ and nickel‐containing polyurethane‐ureas. ZnOHSal₂trien‐MDI‐BPO and ZnOHSal₂trien‐MDI‐HMO gave high char yield of 46% at 600°C, which is almost comparable with that of NiOHSal₂trien‐MDI. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Aliphatic polyurethane elastomers with high performance properties

A new diisocyanate, 1,4-eyclohexane diisocyanate (CHDI), has been used in a series of polyether-based polyurethane elastomers. The slightly opaque samples are semicrystalline in nature with high performance properties, including high softening temperature, very good thermal stability, high tensile and tear strengths, excellent solvent resistance, and low hysteresis in compressive fatigue. Polymer properties are in part due to the small, compact, symmetrical structure of the aliphatic CHDI. Comparison of the physical, mechanical, and thermal properties of polyurethanes prepared from the aliphatic diisocyanate 4,4′-dicyclohexylmethane dilsocyanate (H₁₂MDI) reveal the H₁₂MDI polymers to be more flexible and transparent elastomers with lower softening temperatures and tensile moduli and higher hysteretic heat build up. They are generally soluble in organic solvents.     

Synthesis and characterization of novel polyureas based on benzimidazoline‐2‐one and benzimidazoline‐2‐thione hard segments

Six novel polyureas were prepared from benzimidazolin‐2‐one and benzimidazolin‐2‐thione, which acted as hard segments, with two aromatic diisocyanates (4,4′‐diphenylmethane diisocyanate and toluene 2,4‐diisocyanate) and one aliphatic diisocyanate (hexamethylene diisocyanate). The polymers that formed were fully characterized with Fourier transform infrared spectroscopy, ¹³C‐NMR cross‐polarization/magic‐angle spinning, differential scanning calorimetry, and thermogravimetry. X‐ray diffraction revealed that the polymers contained crystalline and amorphous regions that varied with the nature of the backbone structures. All the polyureas were insoluble in common organic solvents, and this made it difficult to investigate their solution properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 576–583, 2006     

无溶剂型双组分有机硅改性PU胶粘剂的制备与性能研究

以聚醚二元醇(DL-1000)、4,4′-二苯基甲烷二异氰酸酯(MDI)为主要原料合成端-NCO基PU(聚氨酯)预聚体;然后以γ-氨丙基三乙氧基硅烷(KH-550)对其进行嵌段共聚改性,并以3,3′-二氯-4,4′-二氨基二苯基甲烷(MOCA)/蓖麻油作为复合固化剂,制备出无溶剂型双组分有机硅改性PU胶粘剂。研究结果表明:硅烷键已引入PU胶粘剂中;随着KH-550含量的不断增加,胶粘剂的黏度增大、固化时间缩短、室温剪切强度下降且耐热性增强;通过调节不同KH-550含量,可制备出不同性能要求的胶粘剂;该胶粘剂的玻璃化转变温度(-45.9℃)相对较低,说明其耐寒性相对较好。     

Preparation and characterization of novel polyurethanes containing 4,4′‐{oxy‐1,4‐diphenyl bis(nitromethylidine)}diphenol schiff base diol

Four novel segmented polyurethanes (PUs) based on4,4′‐{oxy‐1,4‐diphenyl bis(nitromethylidine)}diphenol (ODBNMD) diol with different diisocyanates such as 4,4′‐diphenylmethane diisocyanate, toluene 2,4‐diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate have been prepared by solution method. The structures of ODBNMD and PUs have been confirmed by Fourier transform infrared (FTIR), nuclear magnetic resonance (¹H‐NMR and ¹³C‐NMR), UV‐visible, and fluorescence spectroscopies. The segmented PUs were further characterized by thermogravimetry (TGA), differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction. FTIR confirmed hydrogen bonding interactions, whereas TGA and DSC suggested that introduction of aromatic/phenyl ring in the main chain considerably increased the thermal stability. POLYM. ENG. SCI., 54:24–32, 2014. © 2013 Society of Plastics Engineers     

Effect of diisocyanate structures on the properties of liquid crystalline polyurethanes

Thermotropic liquid crystalline polyurethanes (LCPUs) were synthesized through the polyaddition reaction of 2,4‐toluene diisocyanate (2,4‐TDI), 4,4′‐diphenylmethane diisocyanate (MDI), or o‐toluidine diisocyanate (ODI) with 4,4′‐bis(6‐hydroxyhexoxy)biphenyl, and the effect of the structures of the diisocyanates on the properties of LCPUs were investigated. Intrinsic viscosities of the polymers were in the range of 0.23–0.30 dL/g. Mesomorphic behavior of the polyurethanes were investigated by differential scanning calorimetry, polarized optical microscopy, and wide‐angle X‐ray scattering. Different mesomorphic behaviors were observed according to the different structural characteristics of diisocyanates. Polyurethanes employing 2,4‐TDI and MDI exhibited monotropic behaviors, while that with ODI showed enantiotropic behavior. POLYM. ENG. SCI., 47:439–446, 2007. © 2007 Society of Plastics Engineers.