Ethylene Isophthalate Research Articles

Attainment of Water and Oil Repellency for Engineering Thermoplastics without Long-Chain Perfluoroalkyls: Perfluoropolyether-Based Triblock Polyester Additives.

For decades, water and oil repellency of engineering thermoplastics has been achieved with introduction of long-chain perfluoroalkyl substances and moieties (C nF2 n+1, n ≥ 7). However, their bioaccumulative and toxicological impact is now widely recognized and, consequently, the substances have been phased out of industrial production and applications. To this end, we have synthesized fluorinated oligomeric triblock polyesters (FOPBs), which do not possess the long-chain perfluoroalkyl segments and serve as effective low-surface-energy additives to engineering thermoplastics. More specifically, we obtained original perfluoropolyether (PFPE)-based triblock copolymers, in which two identical fluorinated blocks were separated by a short nonfluorinated polyester block made of poly(ethylene isophthalate) (PEI). It was found that when FOPBs were added to poly(ethylene terephthalate), nylon-6, and poly(methyl methacrylate) films they readily migrate to the film surface and in doing so imparted significant water and oil repellency to the thermoplastic boundary. The water/oil wettability of the films modified with FOPB is considerably lower than the wettability of the films modified with an analogous PFPE-based polyester, which differs from FOPB only by the absence of the short nonfluorinated PEI middle block. We associate the superiority of the triblock copolymers in terms of water and oil repellency with their ability to form brushlike structures on polymer film surfaces.

Crystallization behavior of poly(ethylene terephthalate‐co‐neopentyl terephthalate‐co‐ethylene isophthalate‐co‐neopentyl isophthalate) copolyester and its application in laminated tin‐free steel

ABSTRACTA low crystallinity, the copolyester poly(ethylene terephthalate‐co‐neopentyl terephthalate‐co‐ethylene isophthalate‐co‐neopentyl isophthalate) (PENIT) was synthesized and applied for laminated tin‐free steel. The structures and thermal properties of the copolyester were characterized by 1H‐NMR, thermogravimetry analysis, differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized optical microscopy. Differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized optical microscopy results show that the crystallization ability of the copolyester decreased obviously. Meanwhile, the peel strength, crystallinity, and water‐vapor permeability of the copolyester film were also measured at varied lamination temperatures. The result confirm that an improvement in the lamination temperature led to an increased ratio of amorphous PENIT to crystalline PENIT and decreased structural orientation, and the decrease in the structural orientation sped up the increase in the rate of water‐vapor permeability. On the basis of the purpose of reducing a detrimental effect on the corrosion resistance caused by water permeation, a reasonable lamination temperature was selected. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42308.

Structural changes of poly(ethylene isophthalate) subjected to gamma irradiation

The results of studies of the physico-chemical changes of a polyester, poly(ethylene isophthalate), subjected to gamma irradiation up to 1 MGy, are reported. Viscometric measurements were carried out to monitor variations of the molecular weight. Changes in the amorphous fraction of the polymer were observed by means of differential scanning calorimetry. Positron annihilation lifetime spectroscopy was used to show possible modifications of the free volume as a consequence of irradiation. The results allow us to conclude that the polymer shows a good resistance to radiation damage.

Interplay between amorphous and crystalline domains in semicrystalline polymers by simultaneous SAXS, WAXS and Dielectric Spectroscopy

This work presents an experimental study on the interplay between structure and dynamics during isothermal cold crystallization of a copolymer based on poly(ethylene terephthalate) and poly(ethylene isophthalate) of poly(trimethylene terephthalate). Simultaneous X-ray scattering and dielectric spectroscopy measurements revealed that, during cold crystallization, crystalline lamellae tend form lamellar stacks during primary crystallization. A significant amount of rigid amorphous phase is formed during cold crystallization, and its location is assigned to the intralamellar stacks amorphous regions. The formation of the rigid amorphous phase during cold crystallization is less effective for. The mobile amorphous phase, giving rise to the dielectric α relaxation in the semicrystalline system is mainly located out of the stacks. The segmental dynamics of the amorphous phase is restricted by the growing crystals during secondary crystallization, but to a lesser extent than in the case of the homopolymer PET..

Effects of gamma irradiation on poly(ethylene isophthalate)

Radiation methods are largely used for polymerisation and polymer modification, since irradiation induces transformations in the structure of materials which can be exploited to improve their performance. On the other hand, combined action of ionising radiation and oxygen may lead to degradation of the polymer, with worsening of properties such as mechanical strength or electrical insulation resistance. Therefore, the change of the chemical and physical properties of polymers under irradiation is a dynamic topic of research. In this work there are discussed data on the physical features of a polyester, poly(ethylene isophthalate) (PEI), subjected to gamma irradiation up to 1 MGy. PEI is a semicrystalline polymer with a structure similar to polyethylene terephthalate. Viscosity and differential scanning calorimetry measurements were carried out which allowed the monitoring of changes in the structure in terms of variations in the molecular weight, as well as of the percentage crystallinity depending on the dose. Furthermore, positron annihilation lifetime spectroscopy supplied information on the free volume present in the amorphous phase of the irradiated polymer.

Poly(ethylene terephthalate‐co‐isophthalate) copolyesters obtained from ethylene terephthalate and isophthalate oligomers

AbstractA series of poly(ethylene terephthalate‐co‐isophthalate) copolyesters containing upto 50%‐mole of isophthalic units were prepared by polycondensation from ethylene terephthalate and ethylene isophthalate fractions of linear oligomers containing from 5 to 6 repeating units in average. The polyesters were obtained in good yields and with high‐molecular‐weights. The microstructure of the copolyesters was studied as a function of reaction time by 13C‐NMR showing that a random distribution of the comonomers was achieved since the earlier stages of polycondensation. The melting temperature and enthalpy of the copolyesters decreased with the content of isophthalic units so that copolyesters containing more than 25% of these units were amorphous. Isothermal crystallization studies made on crystalline copolyesters revealed that the crystallization rate of copolyesters decreased with the content in isophthalic units. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Synthesis of poly(ethylene terephthalate-co-isophthalate) via ring-opening polymerization of their cyclic oligomers

Syntheses of poly(ethylene terephthalate-co-isophthalate) (PET-co-PEI) were achieved via ring-opening copolymerization of corresponding cyclic oligoesters. The ring-opening polymerization (ROP)-PET-co-PEI were prepared by equilibrating an equimolar amount of cyclic oligo(ethylene terephthalate) and cyclic oligo(ethylene isophthalate) using di-n-butyltin oxide catalyst under high concentration conditions at 270 and 290 °C for 8 and 12 h. The copolyesters were obtained in yields of up to 91% with the inherent viscosity (ηinh) of up to 2.89 dl/g indicating the drastically high molecular weight compared with the conventional and ROP routes for the synthesis of PEI. The differential scanning calorimetry data of ROP-PET-co-PEI showed the melting temperatures above 400 °C indicated the potential used in high temperature application.

Effect of mixing conditions on the rheological and optical properties of chemically modified poly(ethylene terephthalate‐co‐ethylene isophthalate)

AbstractThe optical properties and rheological properties were studied for binary reactive blends composed of poly(ethylene terephthalate‐co‐ethylene isophthalate) [P(ET–EI)] and a styrene–acrylate based copolymer with glycidyl functionality. The blade rotation speed in the internal mixer greatly affected the structure and properties for the blend system. Intensive mixing at a high rotation speed enhanced the optical transparency because of the reduced particle size of the dispersed phase. The graft copolymer generated by the reaction between P(ET–EI) and the modifier was responsible for the fine morphology. Furthermore, the copolymer also enhanced the elastic nature in the molten state because it acted as a long‐chain branched polymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008

Rheological properties and processability of chemically modified poly(ethylene terephthalate‐co‐ethylene isophthalate)

AbstractRheological properties and extrusion processability have been evaluated for poly(ethylene terephthalate‐co‐ethylene isophthalate) (P(ET‐EI)) modified by a styrene‐acrylate‐based copolymer with glycidyl functionality in an extruder. Adding a small amount of the modifier enhances melt elasticity to a great extent. Consequently, modified P(ET‐EI) exhibits excellent processability without sagging, that is, downward deformation of extrudates by gravitational force. Considering that molecular weight and its distribution hardly change, which is confirmed by GPC measurements, generation of long‐chain branches is responsible for the rheological properties and thus the processability. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 25:236–241, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20078

Reorganization of the chain packing between poly(ethylene isophthalate) chains via coalescence from their inclusion compound formed with γ‐cyclodextrin

AbstractAmorphous poly(ethylene isophthalate) (PEI) was synthesized, and was used for preparing an inclusion compound (IC) with γ‐cyclodextrin (γ‐CD). Coalesced polymer was produced by washing the PEI‐γ‐CD‐IC with hot water. Wide angle X‐ray diffraction, Fourier transform infrared, and differential scanning calorimetry analyses were employed to verify formation of PEI‐γ‐CD‐IC and to compare the as‐synthesized and coalesced PEI samples. These observations suggested that the conformations and morphology/chain‐packing of PEI were changed via coalescence from its γ‐CD inclusion compound. The glass‐transition temperature of the amorphous coalesced PEI is 15–20°C higher than the Tg observed for the as‐synthesized sample, even when observed in the second heat after cooling from well above Tg at 260°C. The amorphous as‐synthesized PEI retains its randomly‐coiling structure, while coalesced PEI has at least partially retained, the highly extended and parallel chains from the narrow channels of the inclusion compound, resulting in better/tighter packing among the PEI chains manifested by a higher Tg. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 6049–6053, 2006

Hydrolytic degradation of carbohydrate-based aromatic homo- and co-polyesters analogous to PET and PEI

The hydrolytic degradation of a series of homo- and co-polyesters analogous to poly(ethylene terephthalate) (PET) and poly(ethylene isophthalate) (PEI), prepared from carbohydrate-based monomers, was studied. The degradation process was carried out at temperatures of approximately 10 °C above the T g of the polymers. All the studied polyesters were found to degrade at significant rates, and degradability showed a clear dependence on the configuration of the sugar units present in the polymer chain. No weight loss was detected upon degradation, apparently due to the non-solubility of the degraded products in the aqueous incubation medium. Hydrolysis of co-polyesters took place preferentially by cleavage of the ester groups of the sugar units.

Molecular dynamics in semifluorinated side-chain polyesters as studied by broadband dielectric spectroscopy

The molecular dynamics in a variety of poly(ethylene isophthalate)s (PEIs) is studied by broadband dielectric spectroscopy (BDS). The materials comprise non-substituted main chain polyesters and polyesters with semifluorinated (oxydecylperfluorodecyl) side chains. Combining temperature-dependent small angle X-ray scattering (T-SAXS), differential scanning calorimetry (DSC) and BDS it can be shown that the microphase separated semifluorinated polymers exhibit independent dynamic glass transition relaxations taking place in the separate microphases. Additionally in the glassy state, the non-substituted polymers show an Arrhenius-type relaxation whose activation energy decreases gradually from 52 to 40 kJ/mol with increasing main chain flexibility. The semifluorinated polymers exhibit a relaxation assigned to fluctuations of the perpendicular component of the fluoroalkyl end group with activation energies between 38 and 40 kJ/mol. With increasing flexibility of the main chain, the dynamics of the backbone becomes faster for the non-substituted polymers while an opposite trend is observed in the oxydecylperfluorodecyl substituted side-chain materials. A detailed explanation of the molecular origin of the relaxations is provided.

Aromatic polyesters from naturally occurring monosaccharides: Poly(ethylene terephthalate) and poly(ethylene isophthalate) analogs derived from D‐mannitol and galactitol

AbstractThe synthesis and characterization of a new series of aromatic polyesters based on D‐mannitol and galactitol are described. These polyesters were obtained by polycondensation reaction of the terephthaloyl chloride or isophthaloyl chloride and 2,3,4,5‐tetra‐O‐methyl‐D‐mannitol or 2,3,4,5‐tetra‐O‐methyl‐galactitol in o‐dichlorobenzene. All the new polyesters were characterized by elemental analyses, GPC, IR, and NMR. They were soluble in chloroform, but insoluble in water and other polar oxygenated solvents. They showed a notable hygroscopicity, lower for those containing isophthalic units. DSC and X‐ray diffraction studies showed that D‐mannitol‐based polyesters were stiffer and less crystalline than those derived from galactitol, which presented a noticeably lower thermal stability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4570–4577, 2005

Improving transparency of stretched PET/MXD6 blends by modifying PET with isophthalate

Compatibilized blends of PET and MXD6 have good transparency because their refractive indices match closely. However, haziness is observed when the blends are stretched because stretching imparts greater refractive index anisotropy to PET than to MXD6. Analysis of the strain-dependent birefringence reveals that different molecular deformation models describe the intrinsic birefringence of PET and MXD6. This study focuses on reducing the intrinsic birefringence of PET by partially replacing terephthalate with isophthalate. Statistical copolymers are prepared by conventional copolymerization of the monomers. Alternatively, blocky copolymers are obtained by melt blending PET with poly(ethylene isophthalate) (PEI). A close refractive index match with stretched MXD6 is achieved with copolymers containing 15–20% isophthalate. Statistical copolymers in this composition range are not satisfactory for blending because they have low molecular weight and are difficult to stretch. However, blocky copolymers containing 15–20% isophthalate form blends that stretch readily. After biaxial stretching, transparency of blends with 10 wt% MXD6 approaches that of PET. Good transparency of the blends is validated with stretch-blown bottle walls. Oxygen transport measurements confirm that partial replacement of terephthalate with isophthalate does not affect the good gas barrier properties of biaxially stretched PET blends.

Synthesis and gas barrier characterization of poly(ethylene isophthalate)

AbstractPoly(ethylene isophthalate) (PEI) was synthesized for this research with essentially a condensation polymerization of isophthalic acid and ethylene glycol catalyzed by zinc acetate and antimony trioxide. Several samples were obtained, and their characteristics were observed and compared with poly(ethylene terephthalate) (PET). The synthesized PEI samples were chemically identified by 1H NMR. Thermal analysis with differential scanning calorimetry (DSC) yielded results that indicate the samples were primarily amorphous, with a glass‐transition temperature of 55–60 °C. Molecular weights of these PEI samples were also obtained through intrinsic viscosity measurements (Mark–Houwink equation). Molecular weights varied with conditions of the polymerization, and the highest molecular weight achieved was 21,000 g/mol. Finally, the diffusion coefficient, solubility, and permeability of CO2 gas in PEI were measured and found to be substantially lower than in PET, as anticipated from their isomeric chemical structures. This is because in PET the phenyl rings are substituted in the para (1,4) positions, which allows for their facile flipping, effectively permitting gases to pass through. However, the meta‐substituted phenyl rings in PEI do not permit such ring flipping, and thus PEI may be more suitable for barrier applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4247–4254, 2004

Cooperativity of the beta-relaxations in aromatic polymers.

The dielectric loss spectra of a series of copolyesters of poly(ethylene terephthalate) and poly(ethylene isophthalate) have been measured as a function of temperature in a broad frequency range (10(-1)-10(9) Hz). By these measurements, the merging of the two relevant relaxations alpha and beta has been studied. The beta processes exhibit a complex temperature dependence, showing a clear Arrhenius dependence at temperatures well below the glass transition temperature, a transition zone where the characteristic relaxation time of this process nearly does not change with temperature, and an Arrhenius behavior with a higher activation energy for temperatures above the glass transition. The analysis of these results indicates that the beta relaxation in these systems presents typical characteristics of a genuine Johari-Goldstein process. This finding has been interpreted as due to the full monomer extension of the molecular motions involved in the beta relaxation in agreement with recent proposals.

Poly(ethylene isophthalate)s: effect of the tert-butyl substituent on structure and properties

A comparative study of the two isophthalic acid deriving homopolyesters poly(ethylene isophthalate) (PEI) and poly(ethylene 5- tert-butyl isophthalate) (PE t BI), including synthesis, crystal structure, and thermal and permeability properties, was carried out. The two polyesters were prepared by condensation polymerization in the melt. In both cases, minor amounts of cyclic dimers were observed to form, which were characterized by nuclear magnetic resonance and mass spectroscopy. PEI and PE t BI were thermally stable up to 400 °C and they appeared to be semicrystalline polyesters, having their melting temperatures between 130 and 135 °C. Their glass-transition temperatures were 62 and 94 °C, respectively. The crystal structure adopted by the two polyesters seemed to consist of a regularly folded conformation, clearly different from the almost extended conformation characteristic of poly(ethylene terephthalate). Gas permeability measurements for N 2, O 2, and CO 2 revealed that PE t BI is more permeable to these gases than PEI, in spite of having a higher T g. Furthermore, water vapor diffusion was found to be increased by the insertion of the tert-butyl group, whereas water absorption diminished. The differences in gas and water vapor transport properties observed for these two polyesters were discussed on the basis of their respective molecular structures.

Synthesis of Poly(ethylene terephthalate-co-isophthalate) by Copolymerization of Ethylene Isophthalate Cyclic Dimer and Bis(2-hydroxyethyl) Terephthalate

Ethylene isophthalate cyclic dimer (EI c-2mer) and bis(2-hydroxyethyl) terephthalate (BHET) were successfully copolymerized in the bulk state by microwave heating to give a polymer with Mw>20000. Terminal functionalities of the copolymers obtained were investigated by the MALDI-TOF mass analysis technique. The first stage of the copolymerization reaction involves homopolymerization of BHET. In the second stage, reactive end-group of poly(ethylene terephthalate) or BHET itself can attack the EI c-2mer and gradually produce an EI-terminated copolymer. In the third stage, the propagation reaction of EI-terminated copolymer occurs through the three types of elementary reaction route.

Detailed Atomistic Simulation of the Segmental Dynamics and Barrier Properties of Amorphous Poly(ethylene terephthalate) and Poly(ethylene isophthalate)

We present results from detailed atomistic simulations concerning the structural, conformational, dynamic, and barrier properties of the amorphous (glassy and melt) phases of two polyisomers, PET [poly(ethylene terephthalate)] and PEI [poly(ethylene isophthalate)]. First, well-relaxed atomistic configurations of the two polyesters are generated following a succession of equilibration stages consisting of energy minimizations, temperature annealings and coolings, and compressions−decompressions, as proposed by Hofmann et al. (Hofmann D.; et al. Macromol. Theory Simul. 2000, 9, 293). This equilibration cycle is significantly extended here by subjecting the resulting configurations to an additional molecular dynamics (MD) simulation at a high temperature for 2 ns, affording extra relaxation at all length scales. With the statistically uncorrelated configurations generated via these extended equilibration runs, isothermal−isobaric (NPT) at P = 1 atm as well as canonical (NVT) (with the densities set at the co...

Microstructure and crystallization of melt‐mixed poly(ethylene terephthalate)/poly(ethylene isophthalate) blends

AbstractPhysical blends of poly(ethylene terephthalate) (PET) and poly(ethylene isophthalate) (PEI), abbreviated PET/PEI (80/20) blends, and of PET and a random poly(ethylene terephthalate‐co‐isophthalate) copolymer containing 40% ethylene isophthalate (PET60I40), abbreviated PET/PET60I40 (50/50) blends, were melt‐mixed at 270°C for different reactive blending times to give a series of copolymers containing 20 mol % of ethylene isophthalic units with different degrees of randomness. 13C‐NMR spectroscopy precisely determined the microstructure of the blends. The thermal and mechanical properties of the blends were evaluated by DSC and tensile assays, and the obtained results were compared with those obtained for PET and a statistically random PETI copolymer with the same composition. The microstructure of the blends gradually changed from a physical blend into a block copolymer, and finally into a random copolymer with the advance of transreaction time. The melting temperature and enthalpy of the blends decreased with the progress of melt‐mixing. Isothermal crystallization studies carried out on molten samples revealed the same trend for the crystallization rate. The effect of reaction time on crystallizability was more pronounced in the case of the PET/PET60I40 (50/50) blends. The Young's modulus of the melt‐mixed blends was comparable to that of PET, whereas the maximum tensile stress decreased with respect to that of PET. All blend samples showed a noticeable brittleness. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3076–3086, 2003