Different catalytic systems on hydroxyl-terminated GAP and PET with poly-isocyanate: Curing kinetics study using dynamic in situ IR spectroscopy

Reactions of hydroxyl-terminated glycidyl azide polymer (GAP) or poly(ethylene oxide-co-tetrahydrofuran) (PET) polymers with poly-isocyanate (N100) were monitored by dynamic in situ Fourier transform infrared spectroscopy. The influence of catalytic systems on the cure kinetics of polyurethane reaction was investigated. From the comparison between GAP/N100 and PET/N100 systems, it was found that primary and secondary hydroxyl groups were differentiated due to the effects of steric hindrance. Using Arrhenius law and Eyring equation, the activation parameters of polyurethane reaction were calculated at different catalytic systems. The negative value of the activation entropy demonstrated an associative mechanism within the transition state.     

Electrocatalytic Reduction of Nitrogen to Ammonia Using Tiara-like Phenylethanethiolated Nickel Cluster

The fixing of N₂ to NH₃ is challenging due to the inertness of the N≡N bond. Commercially, ammonia production depends on the energy-consuming Haber-Bosch (H−B) process, which emits CO₂ while using fossil fuels as the sources of hydrogen and energy. An alternative method for NH₃ production is the electrochemical nitrogen reduction reaction (NRR) process as it is powered by renewable energy sources. Here, we report a tiara-like nickel-thiolate cluster, [Ni₆(PET)₁₂] (where, PET=2-phenylethanethiol)] as an efficient electro-catalyst for the electrochemical NRR at ambient conditions. Ammonia (NH₃: 16.2±0.8 μg h⁻¹ cm⁻²) was the only nitrogenous product over the potential of −2.3 V vs. F_c⁺/F_c with a Faradaic efficiency of 25%±1.7. Based on theoretical calculations, NRR by [Ni₆(PET)₁₂] proceeds through both the distal and alternating pathways with an onset potential of −1.84 V vs. RHE (i.e., −2.46 V vs. F_c⁺/F_c) which corroborates with the experimental findings.     

Chiral donor photoinduced-electron-transfer (d-PET) boronic acid chemosensors for the selective recognition of tartaric acids, disaccharides, and ginsenosides

A modular approach was proposed for the preparation of chiral fluorescent molecular sensors, in which the fluorophore, scaffold, and chirogenic center can be connected by ethynyl groups, and these modules can easily be changed to other structures to optimize the molecular sensing performance of the sensors. This modular strategy to assembly chiral sensors alleviated the previous restrictions of chiral boronic acid sensors, for which the chirogenic center, fluorophore, and scaffold were integrated, thus it was difficult to optimize the molecular structures by chemical modifications. We demonstrated the potential of our new strategy by the preparation of a sensor with a larger scaffold. The photoinduced electron‐transfer (PET) effect is efficient even with a large distance between the N atom and the fluorophore core. Furthermore, the rarely reported donor‐PET (d‐PET) effect, which was previously limited to carbazole, was extended to phenothiazine fluorophore. The contrast ratio, that is, PET efficiency of the new d‐PET sensor, is increased to 8.0, compared to 2.0 with the previous carbazole d‐PET sensors. Furthermore, the ethynylated phenothiazine shows longer excitation wavelength (centered at 380 nm) and emission wavelength (492 nm), a large Stokes shift (142 nm), and high fluorescence quantum yield in aqueous solution (Φ=0.48 in MeOH/water, 3:1 v/v). Enantioselective recognition of tartaric acid was achieved with the new d‐PET boronic acid sensors. The enantioselectivity is up to 10 (ratio of the binding constants toward D ‐ and L ‐tartaric acid, k_D/k_L). A consecutive fluorescence enhancement/decrease was observed, thus we propose a transition of the binding stoichiometry from 1:1 to 1:2 as the analyte concentration increases, which is supported by mass spectra analysis. The boronic acid sensors were used for selective and sensitive recognition of disaccharides and glycosylated steroids (ginsenosides).     

Surface grafting on poly(ethylene terephthalate) track‐etched microporous membrane by activation with trifluorotriazine: Application to the biofunctionalization with GRGDS peptide

A two‐step wet chemistry protocol has been developed for the surface derivatization of poly(ethylene terephthalate) (PET) track‐etched membrane used as cell culturing support, that is, (a) activation by trifluorotriazine (1 M in acetonitrile (ACN), 30 °C, 3 h); (b) coupling to amine‐terminated molecules, namely 3,5‐bis(trifluoromethyl)benzylamine ((F)Tag), (L)‐4,5‐[³H]‐lysine, and Gly‐Arg‐Gly‐Asp‐Ser (GRGDS) pentapeptide (10^?3 M in PB‐ACN, 1:1 (v/v), 20 °C, 17 h). The grafting rates determined by X‐ray photoelectron spectroscopy, from the F/C and N/C atomic ratios, are in the range of 100–140 pmol/cm² (apparent surface), whereas the liquid scintillation counting assays give higher values (180–230 pmol/cm²) corresponding to the open surface reactivity. PET‐g‐(F)Tag is reasonably stable under two usual sterilization conditions of biomaterials, that is, steam heating at 121 °C and γ‐irradiation at 25 kGy. On the other hand, PET‐g‐GRGDS is found to be stable only under ionization radiation (84% of remaining peptide molecules), but damaged in a large extent by the autoclave treatment (23% of remaining peptide molecules). The surfaces of the sterilized PET and PET‐g‐GRGDS samples have been characterized by water contact angle measurement and by atomic force microscopy analysis in air and under water. Comparatively to the corresponding nonsterilized surfaces, γ‐irradiated surfaces are slightly more hydrophilic and also slightly more rough and jagged. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 195–208, 2010     

Phase separation in semicrystalline blends of poly(phenylene sulfide) and poly(ethylene terephthalate). II. Effect of poly(phenylene sulfide) homopolymer solubilization of PPS‐graft‐PET copolymer on morphology and crystallization behavior

The morphology and crystallization behavior of poly(phenylene sulfide) (PPS) and poly(ethylene terephthalate) (PET) blends compatibilized with graft copolymers were investigated. PPS‐blend‐PET compositions were prepared in which the viscosity of the PPS phase was varied to assess the morphological implications. The dispersed‐phase particle size was influenced by the combined effects of the ratio of dispersed‐phase viscosity to continuous‐phase viscosity and reduced interfacial tension due to the addition of PPS‐graft‐PET copolymers to the blends. In the absence of graft copolymer, the finest dispersion of PET in a continuous phase of PPS was achieved when the viscosity ratio between blend components was nearly equal. As expected, PET particle sizes increased as the viscosity ratio diverged from unity. When graft copolymers were added to the blends, fine dispersions of PET were achieved despite large differences in the viscosities of PPS and PET homopolymers. The interfacial activity of the PPS‐graft‐PET copolymer appeared to be related to the molecular weight ratio of the PPS homopolymer to the PPS segment of the graft copolymer (M_H/M_A). With increasing solubilization of the PPS graft copolymer segment by the PPS homopolymer, the particle size of the PET dispersed phase decreased. In crystallization studies, the presence of the PPS phase increased the crystallization temperature of PET. The magnitude of the increase in the PET crystallization temperature coincided with the viscosity ratio and extent of the PPS homopolymer solubilization in the graft copolymer. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 599–610, 2000     

Poly(ethylene terephthalate) reinforced by N,N′‐diphenyl biphenyl‐3,3′,4,4′‐tetracarboxydiimide moieties

Starting with 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and methyl aminobenzoate, we synthesized a novel rodlike imide‐containing monomer, N,N′‐bis[p‐(methoxy carbonyl) phenyl]‐biphenyl‐3,3′,4,4′‐tetracarboxydiimide (BMBI). The polycondensation of BMBI with dimethyl terephthalate and ethylene glycol yielded a series of copoly(ester imide)s based on the BMBI‐modified poly(ethylene terephthalate) (PET) backbone. Compared with PET, these BMBI‐modified polyesters had higher glass‐transition temperatures and higher stiffness and strength. In particular, the poly(ethylene terephthalate imide) PETI‐5, which contained 5 mol % of the imide moieties, had a glass‐transition temperature of 89.9 °C (11 °C higher than the glass‐transition temperature of PET), a tensile modulus of 869.4 MPa (20.2 % higher than that of PET), and a tensile strength of 80.8 MPa (38.8 % higher than that of PET). Therefore, a significant reinforcing effect was observed in these imide‐modified polyesters, and a new approach to higher property polyesters was suggested. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 852–863, 2002; DOI 10.1002/pola.10169     

Unique morphological and thermal behaviors of reorganized poly(ethylene terephthalates)

Bulk poly(ethylene terephthalate) PET has been reorganized both morphologically and conformationally by processing from its inclusion complex (IC) formed with γ‐cyclodextrin (CD). In the narrow channels of its γ‐CD‐IC crystals the included guest PET chains are isolated from neighboring PET chains and the ethylene glycol (EG) units adopt the highly extended g±tg? kink conformations, whose cross‐sectional diameters are ～80% of the diameter of the fully extended, all‐trans crystalline PET conformer, though they are nearly (～95%) as extended. When the highly extended, unentangled guest PET chains are coalesced from their γ‐CD‐IC crystals by exposure to hot water, host γ‐CDs are removed and the PET chains are presumably consolidated into a bulk sample with a morphology and constituent chain conformations not normally found in PET samples solidified from their randomly coiling, possibly entangled, disordered melts and solutions. Observations by polarized light and atomic force microscopies provide visual evidence for widely different semicrystalline morphologies developed in coalesced and as‐received PETs when crystallized from their melts, with possibly chain extended, small crystals and spherulitic, chain‐folded, large crystals, respectively. DSC observations reveal that coalesced PET is rapidly crystallizable from the melt, while as‐received PET is slow to crystallize and is easily quenched into a totally amorphous sample. Analyses of ¹³C‐NMR data strongly indicate that the PET chains in the noncrystalline regions of the coalesced sample remain predominantly in the highly extended kink conformations, with g±tg? EG units, which are required by their inclusion into PET‐γ‐CD‐IC crystals, while the predominantly amorphous PET chains in the as‐received sample have high concentrations of gauche± ? CH₂? CH₂? and trans ? O? CH₂? ,? CH₂? O? EG bond conformations. ¹³C‐NMR T₁(¹³C) and T_1ρ(¹H) relaxation studies show no evidence of a glass transition for coalesced PET, while the as‐received sample shows abrupt changes in both the MHz [T₁(¹³C)] and kHz [T_1ρ(¹H)] motions at T ～ T_g. Preliminary observations of differences in their macroscopic properties are attributed to the very different morphologies and conformations of the constituent chains in these PET samples. Apparently the kink conformers in the noncrystalline regions of coalesced PET are at least partially retained for extended periods even in the melt and are rapidly crystallized upon cooling. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 386–394, 2004     

Feasibility study of using PET to determine nitrogen concentration after high energy photon irradiation

The technique of photon activation analysis (PAA) is widely employed in many fields as an effective non-invasive tool for measuring elemental compositions and concentrations. In recent years there has been a revival and growing interest of PAA in general and for medical applications in particular. The feasibility of using a PET scanner (Ecat Exact 931) to determine nitrogen concentration in a dead rabbit is described. This method is based on the photon activation of ¹⁴N(γ,n)¹³N (T _1/2 = 9.9 min) using an 18 MV photon beam Medical Linear Accelerator (Varian 2300EX).     

Effect of in situ poly(ethylene terephthalate) (PET) microfibrils on the morphological structure and crystallization behavior of isotactic polypropylene (iPP) under an intensive shear rate

The morphological structure and crystallization behavior of in situ poly(ethylene terephthalate) (PET)/isotactic polypropylene (iPP) microparts prepared through micro‐injection molding are investigated using a polarized light microscope, differential scanning calorimeter, scanning electron microscope, and two‐dimensional wide‐angle X‐ray. Results indicate that both the shear effect and addition of PET fibers greatly influence the morphologies of the iPP matrix. Typical “skin‐core” and oriented crystalline structures (shish‐kebab) may simultaneously be observed in neat iPP and iPP/PET microparts. The presence of PET phases reveals significant nucleation ability for iPP crystallization. High concentrations of PET phases, especially long PET fibers, correspond to rapid crystallization of the iPP matrix. The occurrence of PET microfibrils decreases the content and size of β‐crystals; by contrast, the orientation degree of β‐crystals increases with increasing PET content in the microparts. This result suggests that the existence of the microfibrillar network can retain the ordered clusters and promote the development of oriented crystalline structures to some extent. Copyright © 2015 John Wiley & Sons, Ltd.     

Reorganization of the structures,morphologies, and conformations of bulk polymers via coalescence from polymer–cyclodextrin inclusion compounds

Bulk poly(ethylene terephthalate) (PET) and bisphenol A polycarbonate (PC) samples have been produced by the coalescence of their segregated, extended chains from the narrow channels of the crystalline inclusion compounds (ICs) formed between the γ‐cyclodextrin (CD) host and PET and PC guests, which are reported for the first time. Differential scanning calorimetry, Fourier transform infrared, and X‐ray observations of PET and PC samples coalesced from their crystalline γ‐CD‐ICs suggest structures and morphologies that are different from those of samples obtained by ordinary solution and melt processing techniques. For example, as‐received PC is generally amorphous with a glass‐transition temperature (T_g) of about 150 °C; when cast from tetrahydrofuran solutions, PC is semicrystalline with a melting temperature (T_m) of about 230 °C; and after PC/γ‐CD‐IC is washed with hot water for the removal of the host γ‐CD and for the coalescence of the guest PC chains, it is semicrystalline but has an elevated T_m value of about 245 °C. PC crystals formed upon the coalescence of highly extended and segregated PC chains from the narrow channels in the γ‐CD host lattice are possibly more chain‐extended and certainly more stable than chain‐folded PC crystals grown from solution. Melting the PC crystals formed by coalescence from PC/γ‐CD‐IC produces a normal amorphous PC melt that, upon cooling, results in typical glassy PC. PET coalesced from its γ‐CD‐IC crystals, although also semicrystalline, displays a T_m value only marginally elevated from that of typical bulk or solution‐crystallized PET samples. However, after the melting of γ‐CD‐IC‐coalesced PET crystals, it is difficult to quench the resultant PET melt into the usual amorphous PET glass, characterized by a T_g value of about 80 °C. Instead, the coalesced PET melt rapidly recrystallizes during the attempted quench, and so upon reheating, it displays neither a T_g nor a crystallization exotherm but simply remelts at the as‐coalesced T_m. This behavior is unaffected by the coalesced PET sample being held above T_m for 2 h, indicating that the extended, unentangled nature of the chains in the noncrystalline regions of the coalesced PET are not easily converted into the completely disordered, randomly coiled, entangled melt. Apparently, the highly extended, unentangled characters of the PC and PET chains in their γ‐CD‐ICs are at least partially retained after they are coalesced. Initial differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared, and X‐ray observations are described here. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 992–1012, 2002     

Anthraquinone and Azo Dyes in Dyeing Processes of PET Films and PET Knitted Fabrics Using Supercritical CO2 Medium

Summary: Dyeing processes using supercritical fluid present advantages over the conventional dyeing process using aqueous medium. Previous works from our group on polymeric fibers such as N,N-dimethylacrylamide (DMAAm) modified poly(ethylene terephthalate), PET, showed higher sorption of disperse dyes in supercritical medium. Furthermore, recent studies showed that the association of UV radiation and DMAAm treatment leads to a better incorporation of dyes in modified PET soaked in aqueous medium. In this work, modified and non-modified PET knitted fabrics (KF) were dyed in supercritical CO₂ medium. Azo and anthraquinone dyes were used in order to compare the extent of incorporated dye in PET films and PET KF in supercritical CO₂. The dyeing process variables were studied by factorial design and by a response surface methodology (RSM) technique. The anthraquinone dye presented a better incorporation in PET than the azo dye. The UV light exposure and the dyeing times inputs showed positive main effects in the incorporation of dyes in PET films and PET KF. From the RSM data, DMAAm and UV light modified PET KF presented 7.43 mg of incorporated azo dye by g of PET if the optimized dyeing conditions, time: 135 min and pressure: 212 bar would be used. In the respective optimized dyeing conditions for the anthraquinone dye, time 150 min and pressure 229 bar, the incorporated dye would be 22.9 mg of dye by g of PET.     

The Role of Organomodified Different LDHs on Recycled Poly(ethylene terephthalate) Nanocomposites

Recycled poly(ethylene terephthalate)/organomodified‐layered double hydroxide (PET /organo‐LDH ) nanocomposites were successfully synthesized via a melt‐extrusion method. In an attempt to improve the compatibility with PET , LiAl , MgAl , and ZnAl LDH surfaces were modified with sulfanilic acid (SAS ) via electrostatic interaction with LDH cationic layers. In PET nanocomposites containing SAS ‐modified LDH , the (00l ) X‐ray diffraction (XRD ) peaks originating from organo‐LDH were not observed, indicating that the organomodified LDH layers were fully exfoliated and homogeneously dispersed within the PET matrix, which was also confirmed by transmission electron microscopy analysis. However, PET nanocomposites containing SAS ‐modified LiAl , MgAl , and ZnAl LDH showed broad (00l ) XRD peaks, indicating that the organo‐LDH was partially exfoliated. Thermogravimetric analysis confirmed that the thermal stability of PET/SAS‐modified LDH was significantly improved, depending on the type and loading content of SAS‐modified LDH compared to that of pristine PET . PET nanocomposites containing well‐dispersed SAS‐modified LDH showed substantial enhancement of the storage modulus.     

Biofunctional properties of polyester fibers grafted with chitosan and collagen

Poly(ethylene terephthalate) (PET) fiber was treated with ⁶⁰Co-γ-ray and grafted with acrylic acid (AA). The resulting fibers were further grafted with chitosan (CS) via esterification. Afterward collagen (COL) was immobilized onto CS-grafting fibers. The antibacterial activity of CS against Staphylococus aureus, Escherichia coli, and Pseudomonas aeruginosa was preserved after COL-immobilization. After immobilizing COL, the L929 fibroblasts cell proliferation was promoted than CS-grafting PET fiber. The results indicate that by grafting with CS and immobilizing with COL, PET fibers exhibited both antibacterial activity against four pathological bacteria and improvement in the proliferation of fibroblast. Copyright © 2007 John Wiley & Sons, Ltd.     

Compatibilization effect of TiO2 nanoparticles on the phase structure of PET/PP/TiO2 nanocomposites

Polyethylene terephthalate (PET)/Polypropylene (PP)/TiO₂ nanocomposites were prepared by compounding a PP/TiO₂ nanocomposite premix with PET in absence and presence (up to 6 vol %) of maleic anhydride grafted polypropylene (PP‐g‐MA). In absence of PP‐g‐MA, the TiO₂ nanoparticles were mainly located at the PET/PP interface and to a lesser extent in the dispersed PET droplets. As the TiO₂ nanoparticles were coated by polyalcohol their surface could react with PP‐g‐MA and thus improving the compatibilization with PP. Therefore in presence of PP‐g‐MA the TiO₂ nanoparticles were preferentially located in the PP. The incorporated TiO₂ nanoparticles exerted a compatibilization effect on the PET/PP blend. Depending on the location of TiO₂ three different compatibilization mechanisms were proposed to be at work: (1) Locating at the interface, the TiO₂ nanoparticles decrease the free energy of mixing, and thus increase the thermodynamic stability of the nanocomposites; (2) The TiO₂ nanoparticles at the interface also prevent the coalescence of PET droplets; (3) Preferentially located in the PP matrix, the TiO₂ nanoparticles decreased the viscosity ratio which facilitated the droplet breakup of PET. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1616–1624, 2009     

Preparation,non-isothermal crystallization,and melting behavior of β-nucleated isotactic polypropylene/poly (ethylene terephthalate) blends

β-nucleated PP/PET blends were prepared using nano-CaCO₃ supported β-nucleating agent (β-NA), PP as matrix, and PET as dispersion phase. The effects of preparation methods, PET content, and melting temperature on the non-isothermal crystallization behavior and the melting characteristic and polymorphic composition of PP in the blends were investigated by differential scanning calorimeter (DSC) and wide angle X-ray diffraction (WAXD). The results indicated that the PP crystallized predominantly in β-modification in the presence of β-NA. However, efficiency of β-NA for PP crystallization decreased with addition of PET and increasing PET contents. The β-nucleation of β-NA for PP crystallization in the blends was dependant on the preparation methods. The high β-nucleation and high β-PP content were obtained for PP/PET blend prepared at the temperature of 265 °C and added the β-NA into the blend at the temperature of 180 °C. However, the addition of β-PP or β-NA into blends at 265 °C decreased the β-nucleation, and no β-PP was formed because the β-NA mainly dispersed on the PET dispersion phase or at the interface between PP and PET.     

Organomediated Enantioselective 18F Fluorination for PET Applications

The first organomediated asymmetric ¹⁸F fluorination has been accomplished using a chiral imidazolidinone and [¹⁸F]N‐fluorobenzenesulfonimide. The method provides access to enantioenriched ¹⁸F‐labeled α‐fluoroaldehydes (>90 % ee), which are versatile chiral ¹⁸F synthons for the synthesis of radiotracers. The utility of this process is demonstrated with the synthesis of the PET (positron emission tomography) tracer (2S,4S)‐4‐[¹⁸F]fluoroglutamic acid.     

Chain structure and thermal behavior of reactive blends of PET/LCP with bis(2-oxazoline)

The sequence structure and thermal behavior of reactive blends of poly(ethylene terephthalate) (PET) with the liquid crystalline copolyester 60 PHB/PET containing 60 mol % of p-hydroxybenzoic acid (PHB) with addition of bis(2-oxazoline) (BOZ) were studied in detail. ¹H NMR results indicate that both the number average sequence length of PET and PHB segments (L _PET and L _PHB) decrease with increasing mixing time and temperature via transesterification between PET and LCP. The transesterification is promoted in the presence of BOZ. As a consequence, the sequence structure and in turn the crystallization both from the glassy and the melt state and the melting behavior are markedly affected.     

Miscibility of a polyarylate with a liquid crystalline copolyester

The miscibility has been investigated for binary blends of a polyarylate (PAr) with a liquid crystalline copolyester of p-hydroxybenzoate and ethylene terephthalate units in a 6/4 molar ratio (PET/PHB). The binary blends were prepared by solution precipitation. The transitions of the PET/PHB have been measured with a rheometrics dynamic spectrometer. The phases in blends have been studied with a differential scanning calorimeter, by ther-mogravimetry and with a polarizing optical microscope. The blends exhibit two glass transitions (T_gs) over the composition range 10–90 wt %. The amorphous PET phase from the PET-PHB is found to be partially miscible with PAr, which leads to a decrease of the PAr T_g. The amount of this partially miscible portion of PET has been estimated by the Couch-man equation. On heat treatment of the blends at 250 to 300°C, transesterficiation takes place, as judged by the shift of the higher of the two T_gs. © 1993 John Wiley & Sons, Inc.     

End‐group modification of poly(2,6‐dimethyl‐1,4‐phenylene ether) and in situ synthesis of poly(2,6‐dimethyl‐1,4‐phenylene ether)‐b‐poly(ethylene terephthalate) block copolymer

The preparation of poly(2,6‐dimethyl‐1,4‐phenylene ether)‐b‐poly(ethylene terephthalate) block copolymer was performed by the reaction of the 2‐hydroxyethyl modified poly(2,6‐dimethyl‐1,4‐phenylene ether) (PPE‐EtOH) with poly(ethylene terephthalate) (PET) by an in situ process, during the synthesis of the polyester. The yield of the reaction of the 2‐hydroxyethyl functionalized PPE‐EtOH with PET was close to 100%. A significant proportion of the PET‐b‐PPE‐EtOH block copolymer was found to have short PET block. Nevertheless, the copolymer structured in the shape of micelles (20 nm diameter) and very small domains with 50–200 nm diameter, whereas unmodified PPE formed much larger domains (1.5 μm) containing copolymer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3985–3991, 2008     

Thermal behavior and crystallization kinetics of random poly(ethylene‐Co‐2,2‐Bis[4‐(ethylenoxy)‐1,4‐phenylene]propane terephthalate) copolyesters

The thermal behavior of poly(ethylene‐co‐2,2‐bis[4‐(ethylenoxy)‐1,4‐phenylene]propane terephthalate) (PET/BHEEBT) copolymers was investigated by thermogravimetric analysis and differential scanning calorimetry. A good thermal stability was found for all the samples. The thermal analysis carried out using DSC technique showed that the T_m of the copolymers decreased with increasing BHEEBT unit content, differently from T_g, which on the contrary increased. Wide‐angle X‐ray diffraction measurements permitted identifying the kind of crystalline structure of PET in all the semicrystalline samples. The multiple endotherms similar to PET were also evidenced in the PET/BHEEBT samples, due to melting and recrystallization processes. By applying the Hoffman–Weeks' method, the T_m° of PET and its copolymers was derived. The isothermal crystallization kinetics was analyzed according to Avrami's treatment and values of the exponent n close to 3 were obtained, independently of T_c and composition. Moreover, the introduction of BHEEBT units was found to decrease PET crystallization rate. Lastly, the presence of a crystal‐amorphous interphase was evidenced. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1441–1454, 2005