Ethylene Adipate Research Articles

Modification and characterisation of terpolymer maleic anhydride–styrene–vinyl acetate by poly(ethylene adipate) copolymer

In the present paper, poly(ethylene adipate) (PEA) copolymer of ethylene glycol/adipic acid was synthesised by the polycondensation in the status without an initiator at 180°C for 5 h. It reacted with the PEA copolymer with maleic anhydride–styrene–vinyl acetate (MA–St–VA) terpolymer without using an initiator at 150°C for 6 h. Thus, MA–St–VA terpolymer was modified by the ring opening method. The original MA–St–VA terpolymer and the modified terpolymer were characterised by Fourier transform infrared spectroscopy (FTIR), thermomechanical analysis (TMA) and the viscosimetric method. It was observed that the modified terpolymer was more elastic than the original terpolymer.

Enhancement of bio‐compatibility via specific interactions in polyesters modified with a bio‐resourceful macromolecular ester containing polyphenol groups

Specific interactions and miscibility are demonstrated in a series of binary miscible blend comprising of bio-compatible/biodegradable polyesters, such as poly(epsilon-caprolactone) (PCL), poly(ethylene adipate) (PEA), or poly (butylene adipate) (PBA), and a macromolecular ester with polyphenol groups, tannic acid (TA). Thermal analysis and infrared spectroscopy were used for proving existence of favorable interactions, and polarized-light optical microscopy was used for characterizing the changes in crystal growth. The appearance of a single composition-dependent glass transition temperature (T(g)) observed by differential scanning calorimetry (DSC) indicated that TA is miscible with PCL, PBA, and PEA, respectively, over the entire range of compositions. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of specific intermolecular hydrogen bonding interactions between the carbonyl groups of polyesters and the phenolic hydroxyl groups of TA. The blend T(g)'s generally exhibited various extents of positive-then-negative deviation from linearity with the compositions. The T(g)-composition relationships for three blend systems could all be fitted by the Kwei equation with large negative q values of -80 to -110 for different polyesters. Significant effects by TA on the spherulitic crystallization growth in the polyester/TA blends were also discussed to support the miscibility and strong interactions. Overall, the behavior of blends of polyesters with TA is similar to that of blends of polyesters with poly(vinyl p-phenol) (PVPh) that have been more widely studied and reported. However, TA is naturally bio-resourceful, bio-compatible, and bio-degradable but PVPh is not. Synergism of miscibility, natural bio-compatibility, and biodegradability in these blends by introducing naturally biodegradable macromolecules such as TA may offer greater potential in intended applications.

Infrared Dichroic Studies of Phase Separation and Orientation of Dibenzyl Hard Segments in Polyurethane

Polyurethanes (PUs) based on diethylene glycol (DEG) and a new isocyanate of variable geometry, 4,4'-dibenzyl diisocyanate (DBDI), were synthesized by the standard two-step procedure. A macro-diol, hydroxyl-terminated poly(ethylene adipate) (PEA) MW = 2000 50 (PEA2000 ) was also used in the PU synthesis. The ability of the two benzene rings in the DBDI unit to rotate in two discrete “sin” and “anti” positions around the —CH2CH2— ethylene bridge enables a specific coplanar packing structure of the hard domains dibenzyl-based polymers. Molecular orientation of the DBDI-based hard segments and soft segments was monitored by means of infrared dichroic experiments. The effect of the strain history on the orientation of macromolecular chains was studied under uniaxial extension and in cyclical deformation experiments. The high modulus domains derived from the DBDI unit containing the aromatic urethane blocks served to reinforce the rubbery prepolymer phase. Since the two (soft and hard) phases are interpenetrating, both were deformed by the applied stress. When the load was removed, the soft domains relaxed to a nearly isotropic state, while the rigid phase remained plastically deformed.

Crystallization and Properties of Novel Polyurethanes Based on the Chain Extender Ethylene Glycol and Aromatic Diisocyanates of Variable Flexibility

AbstractSummary: Novel polyurethane elastomers (PUs) were synthesized with ethylene glycol (EG) as a chain extender. The macrodiol was poly(ethylene adipate) (PEA), MW = 2000 ± 50. Two isocyanates were employed: 4,4′‐methylene bis(phenyl isocyanate) (MDI) and 4,4′‐dibenzyl diisocyanate (DBDI). The conformational mobility of DBDI causes an unusually wide range of mechanical, physical and chemical properties, associated with the possibility of pronounced phase separation into a domain – matrix morphology, and with a higher tendency to crystallization and self‐association by hydrogen bonding. Materials were characterized by wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), dynamic mechanical analyses (DMA), and mechanical measurements. Results were discussed in terms of the effect of PUs crystallinity. In the case where the chain extender–diisocyanate couple was EG‐DBDI, the hard segments were observed to crystallize. The DBDI based PUs displayed higher flow stress in the hard phase caused by stronger phase segregation.

Synthesis of poly(ethylene adipate) and poly(ethylene adipate- co-terephthalate) via ring-opening polymerization

Syntheses of poly(ethylene adipate) (ROP-PEA) and poly(ethylene adipate- co-terephthalate) (ROP-PEA- co-PET) were achieved via ring-opening polymerization of corresponding cyclic oligoesters. In case of ROP-PEA, cyclic oligo(ethylene adipate) (C-OEA) was equilibrated in the presence of di- n-butyltin oxide as a catalyst under high-concentration conditions at 180 and 200 °C for 1–24 h. The polymer products were obtained in yields up to 100% with the M ¯ n and M ¯ w in the ranges of 3000–23 000 g/mol and 5000–60 000 g/mol, respectively. The ROP-PEA- co-PET was prepared by equilibrating an equimolar amount of C-OEA and cyclic oligo(ethylene terephthalate) (C-OET) using di- n-butyltin oxide catalyst under high-concentration conditions at 250 °C for 24 h. The copolyester produced was obtained in yield of 97% with the M ¯ n and M ¯ w of 18 000 and 46 000 g/mol, respectively. 1H NMR spectrum of ROP-PEA- co-PET showed two new proton signals of ethylene unit representing the existence of heterolinkage with different chemical environment in the copolymer. This indicated the random transesterification of C-OEA and C-OET resulting in random structure in copolyester. In addition, the result of ROP-PEA- co-PET from DSC showed the glass transition temperature in the values of −8 °C with no melting temperature indicating thermoplastic elastomeric behavior.

Synthesis and characterization of polyurethane urea acrylates: Effects of the hard segments structure

AbstractA series of poly(ester‐urethane‐urea) acrylates were synthesized using poly(ethylene adipate) diol (PEA), 4,4′‐diphenyl methane diisocyanate (MDI), different diamines and acrylic acid. On the basis of IR, stress–strain, thermogravimetric, and differential scanning calorimetry measurements of their cured materials, relations between their structure and physical properties were investigated systematically. The properties were compared with a polyurethane acrylate (PUA) elastomer in which the variable was the diamine modification. The mechanical analysis indicated that, when the short chain of diamine was used, the strength and strain at break of the polymer was enhanced. The thermal stability and the glass transition of PUA increased with increased of diamine chain. The crosslinking process depresses crystallization of the soft segments and can be used to obtain protective films and finishing materials for the leather industry. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Dispersion of carbon nanotubes in polyurethane matrix

A high intensity ultrasound has been applied to fabricate polyurethanes/carbon nanotubes (MWCNT) composites. Mixtures of MWCNTs and poly(ethylene adipate) (PEA) were prepared in a two-step process. In the first step, MWCNTs were dispersed with acetone, in the second PEA and acetone. The mixture of PEA and MWCNTs was used to produce polyurethane (PUR) nanocomposites under the agitation of ultrasounds. The effect of ultrasound intensity has been studied by HRSEM and AFM investigation of the microstructure. The mechanical properties of polyurethane nanocomposites were also evaluated.

Effects of polymerization method on structure and properties of thermoplastic polyurethanes

AbstractThe effects of the dynamic polymerization method and temperature on the molecular aggregation structure and the mechanical and melting properties of thermoplastic polyurethanes (TPUs) were successfully clarified. TPUs were prepared from poly (ethylene adipate) glycol (Mn = 2074), 4,4′‐diphenylmethane diisocyanate and 1,4‐butanediol by the one‐shot (OS) and the prepolymer (PP) methods in bulk at dynamic polymerization temperatures ranging from 140 to 230 °C. Glass‐transition temperatures (Tgs) of the soft segment and melting points (Tms) of the hard segment domains of OS‐TPUs increased and decreased, respectively, with increasing polymerization temperatures, but those of PP‐TPUs were almost independent of the polymerization temperature. Tgs of the soft segment and Tms of the hard segment domains of these TPUs polymerized above 190 °C were almost the same regardless of the polymerization method. Solid‐state nuclear magnetic resonance spectroscopy (NMR) analyses of OS‐ and PP‐TPUs showed that the relative proton content of fast decay components, which corresponds to the hard segment domains, in these TPUs decreased with increasing polymerization temperatures. These results clearly show that the degree of microphase separation becomes weaker with increasing polymerization temperatures. The temperature dependence of dynamic storage modulus and loss tangent of OS‐TPUs coincided with those of PP‐TPUs at polymerization temperature above 190 °C. The apparent shear viscosity for OS‐ and PP‐TPUs polymerized above 190 °C approached a Newtonian behavior at low shear rates regardless of the polymerization method. These results indicate that TPUs polymerized at higher temperatures form almost the same molecular aggregation structures irrespective of the dynamic polymerization method. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 800–814, 2007

Structural features of inclusion complexes of γ-cyclodextrin with various polymers

The crystalline structures of inclusion complexes of γ-cyclodextrin (γ-CD) with poly(ethylene glycol), poly(ethylene adipate), poly(propylene glycol) and poly(isobutylene) were studied by electron microscopy, in combination with X-ray diffraction works and measurements of thermal properties by DSC and TGA. The crystalline structure of as-prepared complexes was tetragonal and its cell dimensions were a = b = 2.380 nm and c = 1.48 nm. When an as-prepared sample was dried in a vacuum at room temperature, the tetragonal modification was transformed into the monoclinic one with the projected cell dimensions of a = 1.75, b = 1.36 nm and γ = 110°. The transformation occurred by progressive ‘shifting’ of rows of polymer necklaces in the [110] direction along the (110) plane in an original tetragonal lamellar crystal. Complexes lost weight by 10–15% in the process of heating up to 140 °C. The tetragonal crystalline modification was transformed into the hexagonal one, and concurrently, the X-ray diffraction profiles of annealed complexes were broadened. When a sample was dried in a vacuum at room temperature or annealed at high temperatures, followed by exposure to water vapor, the original tetragonal crystalline structure was recovered, restoring the original degree of orientation of crystallites in the sample. When water molecules were removed, the lateral stacking order of γ-CD–polymer complexes was destroyed, but the basic necklace structure in which polymer chains threaded through the cavity of γ-CD rings' structure could be retained.

Quick Molecular Weight Determination of Polyester-Polyurethane Soft Blocks with Phenylisocyanate Using High-Frequency Heating Technique

The chemical degradation method of polyester-polyurethanes using a high-frequency heating technique was investigated. Model polyester-polyurethanes were prepared from 4,4'-dicyclohexylmethane diisocyanate (H12MDI), poly(butylene adipate) or poly(ethylene adipate)-polyols and isophoronediamine as a chain extender. The number-average molecular weights of their polyesterpolyols were 3500 Da. Phenylisocyanate was an effective reagent to decompose the urethane bond selectively without cleaving the ester bond. After 30 mg of a polyurethane sample was heated at 255°C in a mixture of phenylisocyanate in a sealed glass tube, the urethane bond was decomposed after 30 minutes under this condition. After the reaction, the molecular weight and the composition of the polyesterpolyols were determined by MALDI TOF-MS and SEC. The separation between the peaks of the main series consisted with repeated polyesterpolyols units. The ions consisted of a polyester chain with N -phenylurethane terminal groups from MALDI spectra. SEC chromatograms of degraded samples were consistent with the model N -phenylurethane-terminated polyester. The combination of selective degradation with SEC, MALDI and a high-frequency heating technique, using phenylisocyanate, is a viable method for easy and quick polyurethane polyol characterization.

Synthesis, characterization and thermal degradation mechanism of three poly(alkylene adipate)s: Comparative study

Three high molecular weight aliphatic polyesters derived from adipic acid and the appropriate diol – poly(ethylene adipate) (PEAd), poly(propylene adipate) (PPAd) and poly(butylene adipate) (PBAd) – were prepared by two-stage melt polycondensation method (esterification and polycondensation) in a glass batch reactor. Intrinsic viscosities, GPC, DSC, NMR and carboxylic end-group measurements were used for their characterization. Mechanical properties of the prepared polyesters showed that PPAd has similar tensile strength to low-density polyethylene while PEAd and PBAd are much higher. From TGA analysis it was found that PEAd and PPAd have lower thermal stability than poly(butylene adipate) (PBAd). The decomposition kinetic parameters of all polyesters were calculated while the activation energies were estimated using the Ozawa, Flynn and Wall (OFW) and Friedman methods. Thermal degradation of PEAd was found to be satisfactorily described by one mechanism, with activation energy 153 kJ/mol, while that of PPAd and PBAd by two mechanisms having different activation energies: the first corresponding to a small mass loss with activation energies 121 and 185 kJ/mol for PPAd and PBAd, respectively, while the second is attributed to the main decomposition mechanism, where substantial mass loss takes place, with activation energies 157 and 217 kJ/mol, respectively.

New Heterocyclic Polyurethane-ureas Based on 4,4'-dibenzyl diisocyanate. 2. Influence of Pyridine Units on the Mechanical Properties

Heterocyclic polyurethane-ureas containing pyridine units on the main chain have been prepared by a two-step polyadition reaction. First, an urethane prepolymer was prepared in bulk starting from a macrodiol, which was a polyester-diol such as poly(ethylene adipate) (PEA) or a polyether-diol such as poly(tetramethylene glycol) (PTMG), and a diisocyanate such as 4,4'-dibenzyl diisocyanate (DBDI) or 4,4'-methylene-bis(phenyl-isocyanate) (MDI). The resulting urethane prepolymer containing NCO end groups was polymerized afterwards in DMF solution by using 2,6-diamino pyridine (DAPy) as chain extender, leading to polyurethane-ureas containing pyridine units The hard segments contents varied between 1.458–1.967 mol NHCOO/1000 g polymer. The resulting polymers were characterized by IR spectra, elemental and thermogravimetric analyses, differential scanning calorimetry, gel permeation chromatography, inherent viscosity, water retention measurements and mechanical properties. The study of the relationship between structure and properties reveals the influence of the nature of starting materials, macrodiols, the heterocyclic diamine and diisocyanates on the mechanical properties of the polymers. The large number of hydrogen bondings that formed between urea and urethane groups and the presence of pyridine rings in the polymer chain induced an improved thermal stability and good mechanical properties. The influence of the hard segment length was also studied. A greater length of the hard segments led to higher values of some mechanical tests such as: 100 and 300% moduli, strength stress and elongation at break. The mechanical behavior of these polymers is discussed and compared with that of earlier reported linear polyurethane-ureas based on MDI or with that of related polyurethanes chain-extended with diols.

Thermal Behavior of Ring‐Band versus Maltese‐Cross Spherulites: Case of Monomorphic Poly(ethylene adipate)

AbstractSummary: Two types of spherulites, extinction‐ring and Maltese‐cross, in poly(ethylene adipate) (PEA) were identified, isolated, and separately characterized using DSC and polarized‐light optical microscopy (POM). Ring‐band spherulites in PEA occurred only in a very narrow temperature range roughly between 25 and 30 °C, while Maltese‐cross spherulites at 35 °C and above or at 20 °C and below. Thermal behavior of ring‐spherulites is interpreted, analyzed, and compared to that of Maltese‐cross spherulites. The thermal behavior, like the morphology, was found to be significantly different between these two types of spherulites. Among the three multiple melting peaks in PEA, the highest P3 is proven to be related to melting of lamellae in the ring‐band spherulites; P1 and P2, whose relative extent of overlapping is dependent on the temperature of crystallization, are related to melting of lamellae in the regular ringless spherulites. This study has provided urgent and timely evidence for one major step further in the interpretation of relationships between the thermal behavior, melting, and extinction‐ring versus Maltese‐cross spherulites in semi‐crystalline polymers.DSC curves (10 °C · min−1, scanned from where the trace begins) for: (a) ring‐spherulites in PEA crystallized at 30 °C for 90 min, (b) sample‐(a) heated to 50 °C for 1 min, and (c) sample‐(a) heated to 50 °C, then quenched to 20 °C.magnified imageDSC curves (10 °C · min−1, scanned from where the trace begins) for: (a) ring‐spherulites in PEA crystallized at 30 °C for 90 min, (b) sample‐(a) heated to 50 °C for 1 min, and (c) sample‐(a) heated to 50 °C, then quenched to 20 °C.

The modification and characterization of maleic anhydride-styrene-methyl metacrylate terpolymer by poly(ethylene adipate)

In this study, the functionality of maleic anhydride was utilized in the maleic anhydride-styrene-methyl metacrylate (MAStMMA) terpolymer. First, the polyester of poly(ethylene adipate), PEA, polycondensation copolymer was synthesized from ethylene glycol and adipic acid monomers. PEA was then modified on its maleic anhydride units in the MAStMMA terpolymer which has been synthesized previously. This modified copolymer was characterized by FTIR (Fourier Transform Infrared spectroscopy). The viscosimetric and thermomechanical characterization of MAStMMA terpolymer and its modified copolymer were also performed and the results were compared. The modified copolymer obtained was found to be more elastic and more soluble, and had lower viscosity and density.

Correlation between interactions, miscibility, and spherulite growth in crystalline/crystalline blends of poly(ethylene oxide) and polyesters

Crystalline/crystalline blend systems of poly(ethylene oxide) (PEO) and a homologous series of polyesters, from poly(ethylene adipate) to poly(hexamethylene sebacate), of different CH 2/CO ratios (from 3.0 to 7.0) were examined. Correlation between interactions, miscibility, and spherulite growth rate was discussed. Owing to proximity of blend constituents' T g's, the miscibility in the crystalline/crystalline blends was mainly justified by thermodynamic and kinetic evidence extracted from characterization of the PEO crystals grown from mixtures of PEO and polyesters at melt state. By overcoming experimental difficulty in assessing the phase behavior of two crystalline polymers with closely spaced T g's, this work has further extended the range of polyesters that can be miscible with PEO. The interaction parameters ( χ 12) for miscible blends of PEO with polyesters [poly(ethylene adipate), poly(propylene adipate), poly(butylene adipate), and poly(ethylene azelate) with CH 2/CO = 3.0–4.5] are all negative but the values vary with the polyester structures, with a maximum for the blend of PEO/poly(propylene adipate) (CH 2/CO = 3.5). The values of interactions are apparently dependent on the structures of the polyester constituent in the blends; interaction strength for the miscible PEO/polyester systems correlate in the same trend with the PEO crystal growth rates in the blends.

Synthesis and properties of readily recyclable polymers from bisfuranic terminated poly(ethylene adipate) and multi-maleimide linkers

Polymers that can repeatedly polymerize and depolymerize at moderate conditions was designed and synthesized. Furyl-telechelic poly(ethylene adipate) [PEA2F] was prepared and copolymerized with bis- and tris-maleimides by Diels–Alder [DA] reaction at 60°C. Though the reaction with bismaleimide proceeded partially to give a polymer whose molecular weight was only twice as large as PEA2F, the reaction with trismaleimide gave a product with a 3D-network structure. The latter product shows elasticity at room temperature. By keeping at 145°C, these DA products were easily disconnected by retro-Diels–Alder [rDA] reaction to reproduce the starting macromonomer, PEA2F. The repetition of the cycle of the DA and rDA reactions induce the reduction of neither the mechanical properties of the DA products nor the molecular weight of the rDA products. Therefore, we have successfully obtained readily recyclable polymers.

Preparation of Aqueous Polyurethane Dispersions Using Aromatic Diisocyanate

AbstractAqueous polyurethane dispersions were prepared by the reaction of hydroxyl‐terminated poly(ethylene adipate), ethylene glycol, dimethylol propionic acid and aromaic diisocyante, 4,4′‐diphenylmethane diisocyanate. The influence of molecular weight of oligoester and molar ratio between isocyanate and hydroxyl groups (NCO/OH) in the prepolymerization step were investigated. Molecular weight, particle size and particle size distribution were measured and compared. It was verified that the molecular weight increases with increasing in NCO/OH molar ratio. The results suggest that the hard segment content plays an important role in particle size and particle size distribution of the dispersions.

New Heterocyclic Polyurethane-ureas based on 4,4′-dibenzyl diisocyanate, Part 1: Influence of Oxadiazole Structure on Mechanical Properties

A series of polyurethane-ureas was synthesized by solution polyaddition reaction of the following components: a polyester-diol, such as poly(ethylene adipate) (PEA), a polyetherdiol, such as poly(tetramethylene glycol) (PTMG) and a diisocyanate, such as 4,4′-dibenzyl diisocyanate (DBDI) or 4,4′-methylene-bis(phenyl-isocyanate) (MDI). In addition, 2,5-bis-(4-amino-phenylene)-1,3,4-oxadiazole (DAPO) was used as a chain extender. The hard segment content ranges between 1.384 and 1.819 mol NHCOO/1000 g polymer. For comparative studies, similar polyurethane-ureas were prepared by the same way but using 4,4′-methylene dianiline (MDA) and 4,4′-diamino-dibenzyl (DAB) as chain extenders. The resulting linear polymers were characterized by IR spectra, elemental and thermogravimetric analyses, differential scanning calorimetry, gel permeation chromatography, inherent viscosity measurements, wideangle X-ray scattering and mechanical properties. The study of the relationships between structure and properties reveals the influence of the nature of starting materials, macrodiols, the heterocyclic diamine and diisocyanates on the mechanical properties of the polymers. The great number of hydrogen bonding that formed between urea and urethane groups and the presence of oxadiazole rings in the polymer chain induced an improved thermal stability and good mechanical properties. The mechanical behavior of these polymers was discussed and compared with that of earlier reported linear polyurethane-ureas based on MDI or with that of related polyurethanes chain-extended with diols.

Multiple order light scattering by ringed spherulites

The transmittivity [Point JJ. Bull Clas Sci Acad Roy Belg 1953;39:455; 1955;41:982. [1]] of light intensity through spherulitic films of poly(ethylene adipate) (PEA) is not uniform. These films may actually be used as multiple diffraction gratings. The intensity of the first order scattering depends reversibly on the temperature T of the film (between 10 and 59 °C). For sufficient film thickness (e.g. 30 μm), this intensity is an increasing function of T. It is, however, a decreasing function of T when the films are sufficiently thin (e.g. 2 μm). These, and other effects are explained by geometrical optics and by the electromagnetic theory of light. Evidently, these effects are not specific to PEA but are characteristic properties of ringed spherulites of polymers and other materials.

A Novel PHB Depolymerase from a Thermophilic Streptomyces Sp.

A novel PHB depolymerase from a thermophilic Streptomyces sp. MG was purified to homogeneity by hydrophobic interaction chromatography and gel filtration. The molecular mass of the purified enzyme was 43 kDa as determined by size exclusion chromatography and 41 kDa by SDS-PAGE. The optimum pH and temperature were 8.5 and 60 degrees C respectively. The enzyme was stable at 50 degrees C and from pH 6.5-8.5. The enzyme hydrolyzed not only bacterial polyesters, i.e. poly(3-hydroxybutyric acid and poly(3-hydroxybutyrate-co-3-hydroxyvalerate), but also synthetic, aliphatic polyesters such as polypropiolactone, poly(ethylene adipate) and poly(ethylene succinate).