Ethylene-tetrafluoroethylene Copolymer Research Articles

Electron irradiation effects on partially fluorinated polymer films: Structure–property relationships

The effects of electron beam irradiation on two partially fluorinated polymer films i.e. poly(vinylidene fluoride) (PVDF) and poly(ethylene-tetrafluoroethylene) copolymer (ETFE) are studied at doses ranging from 100 to 1200 kGy in air at room temperature. Chemical structure, thermal and mechanical properties of irradiated films are investigated. FTIR show that both PVDF and ETFE films undergo similar changes in their chemical structures including the formation of carbonyl groups and double bonding. The changes in melting and crystallisation temperatures ( T m and T c) in both irradiated films are functions of irradiation dose and reflect the disorder in the chemical structure caused by the competition between crosslinking and chain scission. The heat of melting (Δ H m) and the degree of crystallinity ( X c) of PVDF films show no significant changes with the dose increase, whereas those of ETFE films are reduced rapidly after the first 100 kGy. The tensile strength of PVDF films is improved by irradiation compared to its rapid deterioration in ETFE films, which stemmed from the degradation prompted by the presence of radiation sensitive tetrafluoroethylene (TFE) comonomer units. The elongation at break of both films drops gradually with the dose increase indicating the formation of predominant crosslinked structures at high doses. However, the response of each polymer to crosslinking and main chain scission at various irradiation doses varies from PVDF to ETFE films.

Biocompatibility of cardiovascular gene delivery catheters with adenovirus vectors: an important determinant of the efficiency of cardiovascular gene transfer.

Gene therapy approaches hold promise for the treatment of a wide variety of cardiovascular diseases. Many strategies for cardiovascular gene therapy involve catheter-mediated vector delivery via intramyocardial injection, intracoronary infusion, or direct gene transfer into the vessel wall. Several different gene delivery catheters have been developed and utilized in preclinical and clinical studies of cardiovascular gene therapy. However, rigorous studies of the biocompatibility of these catheters with gene therapy vectors have not yet been reported. In this report, we have examined the compatibility of cardiovascular gene therapy catheters and catheter constituents with first-generation E1/E3-deleted adenovirus vectors. We show that (i) currently available catheters rapidly and efficiently inactivate adenovirus vector infectivity; (ii) this inactivation is mediated by a variety of commonly used catheter constituents including stainless steel, nitinol, and polycarbonate; (iii) catheter-mediated inactivation of adenovirus vectors can be prevented by preflushing catheters with solutions of serum albumin; and (iv) it is possible to identify a set of catheter materials that are compatible with current adenovirus vectors. These results underscore the importance of catheter/vector compatibility and suggest methods for increasing the efficiency of catheter-mediated cardiovascular gene therapy.

Melting of Ethylene–Tetrafluoroethylene Copolymer

Melting of Ethylene–Tetrafluoroethylene Copolymer

Some investigations on radiation-grafting of acrylic acid onto poly(tetrafluoroethylene-ethylene) copolymer films and its complex with copper salt solution

A study was made of the graft copolymers obtained by radiation-induced grafting of acrylic acid onto poly(tetrafluoroethylene–ethylene) (ET) films. The conversion of the graft copolymers (60wt%) into metal acrylate copolymer complexes was carried out by treatment with various concentrations of aqueous CuCl2. These graft copolymer–metal complexes were studied by IR, UV spectrometry, X-ray diffraction (XDR), and electron spin resonance (ESR). The effect of temperature on the trunk, untreated grafted and treated grafted copolymer films was investigated by IR and thermogravimetric (TG) analysis. The influence of metal complexes of Cu2+ ions on the thermal properties and electrical conductivity was determined. It is assumed that such materials may be of great interest in the field of semiconducting materials, in addition to their resistance to degradation under high temperature, up to 300°C. © 1998 Society of Chemical Industry

Blends of the alternating ethylene–tetrafluoroethylene copolymer with poly(vinylidene fluoride)

Blends of the alternating ethylene–tetrafluoroethylene copolymer (ETFE) with poly(vinylidene fluoride) (PVF2) were prepared by melt-mixing. Compatibility, morphology, thermal behavior, and mechanical properties of the ETFE/PVF2 blends with various compositions were studied by using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), tensile tests, and scanning electron microscopy (SEM). DMA studies showed that the blends have separate glass transition temperatures (Tg) close to those of the pure polymers. ETFE and PVF2 are incompatible. Marked negative deviations from simple additivity were observed for both the ultimate strength and the elongation at break over the entire composition range. The interfaces between ETFE and PVF2 are weakly bonded with rather poor interaction. SEM observations revealed that the blends have a two-phase structure and the adhesion between the phases is poor. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:295–304, 1997

Blends of the alternating ethylene-tetrafluoroethylene copolymer with poly(vinylidene fluoride)

Blends of the alternating ethylene-tetrafluoroethylene copolymer with poly(vinylidene fluoride)

Phase transition in ethylenetetrafluoroethylene (ETFE) alternating copolymer. A spectroscopic study

The study of temperature dependent infrared (i.r.) and Raman spectra of alternating ethylenetetrafluoroethylene (ETFE) copolymer suggests that the transition from orthorhombic to hexagonal phases may be driven by the generation and propagation of conformational solitons (gentle mobile chain twist).

Compatibility and properties of alternating ethylene-tetrafluoroethylene copolymer and poly(methyl methacrylate) blends

Blends of an alternating ethylene-tetrafluorethylene copolymer (ETFE) and poly(methyl methacrylate) (PMMA) were prepared by melt mixing in a mixer. Compatibility, thermal behaviour and morphology of the blends of various compositions were investigated by using dynamic mechanical analysis (d.m.a.), Fourier transform infra-red spectroscopy ( FTi.r.), solid-state nuclear magnetic resonance (n.m.r.) spectroscopy, differential scanning calorimetry (d.s.c.) and wide-angle X-ray diffraction. D.m.a. and d.s.c. results show that the glass transition temperature ( T g) of the ETFE in the blends increases as the PMMA content increases and the T g of the PMMA moves to low temperatures when the ETFE content increases. In addition, d.s.c. results indicate an additional T g, which is located between the T g of PMMA and that of ETFE. The presence of this additional T g suggests the existence of one semicrystalline phase and two amorphous phases—an ETFE/PMMA phase and a PMMA-rich phase. D.s.c. results also indicate that the melting temperature of ETFE decreases while the crystallinity of ETFE increases slightly as the PMMA content increases. FTi.r. results show that the absorption peak of the carbonyl group of the PMMA in the blends stays almost at the same position as in the pure component. Solid-state n.m.r. results reveal that the changes in chemical shift of the carbonyl group of PMMA in the blends are less than 0.5 ppm. These results confirm that only weak interactions exist between ETFE and PMMA. X-ray diffraction results reveal that no new crystal forms appear in the blends. © 1997 Elsevier Science Ltd.

Synthesis and characterization of polymer film obtained by grafting of acrylic monomer onto radioperoxided poly(ethylene-tetrafluoroethylene) copolymer in the presence of polyfunctional monomers. Stability in basic solutions

Acrylic acid (AA), methacrylic acid (MA), diethyleneglycoldimethacrylate (DEGDM) or N,N′-methylenebisacrylamide (NBA) are grafted onto 100 μm radioperoxided poly(ethylene-te-trafluoroethylene) copolymer (ETFE). The stability of the so-obtained cation-exchange membranes immersed in NaOH solutions is studied by following the mass leakage, the exchange capacity, the swelling ratio, the electrical resistance and the permselectivity towards sodium ions. Among these membranes, only those grafted with AA and crosslinked with NBA exhibit a decrease of selectivity lower than 10%, regardless of the number of treatments in basic solution at 70 °C. The important loss of selectivity of the other membranes is attributed to homopolymer elimination and hydrolysis of ester functions in the case of ETFE films grafted with AA and crosslinked with DEGDM.

Influence of constitutional defects on polymorphic behaviour and properties of alternating ethylene-tetrafluoroethylene copolymer

The influence of constitutional defects (those resulting from variations of the comonomer molar ratio from 50/50 and those due to the introduction of termonomer units) and thermal history on the polymorphic behaviour of ethylene-tetrafluoroethylene (ETFE) copolymer is investigated. At low temperatures, while well developed orthorhombic structures are obtained for copolymers with a C 2F 4 content in the range 50–70 mol%, a content of the perfluoropropylperfluorovinylether termonomer of 1.8 mol% is already sufficient to favour formation of the so-called pseudo-hexagonal mesophase. At high temperatures, the degree of crystallinity as well as the correlation length of the hexagonal domains remain essentially unaltered by an increase of the C 2F 4 molar content from 50 to 80%, while both are strongly reduced by low concentrations (1–3 mol%) of the termonomer units (substantially excluded from the crystalline phase). This is expected to be a determinant factor for the improved ultimate properties typical of commercial terpolymers of ETFE.

Electron Spin Resonance Study on Plasma-Induced Surface Radicals of Ethylene–Tetrafluoroethylene Copolymer

We have undertaken Ar plasma irradiation on ethylene–tetrafluoroethylene (1:1) alternating copolymer (ETFE) powder, and the radicals formed were studied by electron spin resonance (ESR). The room temperature ESR spectrum of plasma-irradiated ETFE shows a six-line spectrum (sextet) similar to that of polyethylene (PE), due to a small difference in hyperfine splitting constant between β-H and β-F atom. Thus, the major radical formed was assigned to the midchain alkyl radical generated by hydrogen elimination. The ESR spectral parameters for a representative sextet deduced from the simulated spectra are as follows: g=2.0029, Nα=2.19 mT (1H), Hβ=2.88 mT (2H), and Fβ=2.80 mT (2F). It was also found that the sextet spectrum gradually turned toward a broad single-line spectrum as the plasma duration increased indicating the successive formation of dangling bond sites (DBS) due to the occurrence of cross-linked surface reaction.

Wavelength Dependence of Excimer Laser Irradiation Effects on Ethylene-Tetrafluoroethylene Copolymer

Irradiation with an ArF laser at wavelength of 193 nm formed diene in a whole ethylene-tetrafluoroethylene copolymer (ETFE) film and irradiation with a KrF and a XeCl laser at 248 and 308 nm induced the carbonization of ETFE. ArF-laser radiation at 193 nm formed diene in the bulk of ETFE via the process of single-photon absorption, and in case of KrF and XeCl-laser irradiation multiphoton absorption brought about the carbonization of ETFE. The surface analysis by X-ray photoelectron spectroscopy showed that excimer laser-induced elimination of fluorine atoms depended on the laser wavelength.

A rheometer to measure the viscoelastic properties of polymer melts at ultrasonic frequencies

A rheometer which uses a piezoelectric ultrasonic composite oscillator has been developed to measure the viscoelastic properties, G′(ω) and G″(ω), of polymer melts at ultrasonic frequencies. The storage and loss moduli of an ethylene–tetrafluoroethylene copolymer melt were measured at six frequencies in the range 0.25×106–1.28×106 rad/s (between 40 and 200 kHz nominal frequency) and at a temperature of 280 °C. This ultrasonic instrument operates at strain amplitudes ranging from about 10−8 to 10−3 and is therefore ideally suited for linear viscoelastic property measurements.

Melting and crystallization of tetrafluoroethylene-ethylene copolymers

The melting and crystallization of copolymers of tetrafluoroethylene with ethylene, synthesized in bulk and in suspension by semi-flow method, were studied by DSC. X-ray diffractions and infrared spectra of the copolymers were measured and new crystalline reflections different from those of the homopolymers were observed. The melting temperature of the copolymers synthesized in bulk depends strongly on the composition and exhibits several maxima. A certain small decrease in the melting temperature within the range of the alternating composition is observed. For alternating copolymers synthesized in suspension, the peaks are monomodal indicating a higher structural and chemical homogeneity of the copolymer. The nonisothermal crystallization kinetics in the temperature interval from 260 to 255°C of the alternating copolymer prepared in suspension can be described by a modified Avrami equation. The mechanism of nucleation and nuclei growth during the nonisothermal crystallization of the tetrafluoroethylene-ethylene copolymer is close to that of polyethylene.

Vibrational Analysis as a Tool for Detecting Electronic Mobility. The Case of the Alternating Ethylene-Tetrafluoroethylene Copolymers

Frequency and intensity spectroscopies have been used in the reanalysis of the vibrational spectrum (IR and Raman) of alternate copolymers of ethylene and tetrafluoroethylene. A new assignment of the CH stretching fundamental is proposed. The seeming anomalies of the infrared spectrum in the CH stretching range are accounted for in terms of equilibrium atomic charges and charge fluxes. In particular, the analysis of the dichroic ratios shows that there exists a relevant mobility of the electronic charge along the C-C bonds

Structure and properties of tetrafluoroethylene-ethylene modified with fibre crystals

New types of engineering materials of tetrafluoroethylene-ethylene copolymers and fibre monocrystals (up to 20 mass %) of alkali titanates were obtained. The structure and physical properties of these materials have been investigated by applying a variety of complementary methods: X-ray analysis, differential thermal analysis, differential scanning calorimetry and rheometry. Fibre monocrystals act as nucleators on the polymer melt crystallization and change the rheological behaviour of the compositions. Modified tetrafluoroethylene-ethylene copolymers possess good mechanical and thermal properties, high chemical resistance and can be used as engineering materials operating at high temperatures and in aggressive media.

Properties of cation‐exchange membranes prepared by radiation grafting of acrylic acid onto tetrafluoroethylene–ethylene copolymers

AbstractSome properties of the ion‐exchange membranes prepared by simultaneous and preirradiation techniques of grafting of acrylic acid onto tetrafluoroethylene–ethylene copolymer films, including porous microfilters, have been studied. The water content, electric resistance, transport number, distribution of grafting, thermal and chemical stability, and mechanical characteristics of the membranes were determined as a function of the grafting degree. Graft polymerization proceeds from both surfaces of the polymer film into the polymeric matrix depth. Cation‐exchange membranes prepared possess good electrochemical and mechanical properties, high thermal and chemical stability at grafting degrees from 30 to 50%, and can be successfully used in electrodialysis processes. © 1993 John Wiley & Sons, Inc.

Radiation initiated grafting of acrylic acid onto tetrafluoroethylene–ethylene copolymers

AbstractHydrophilic carboxyl containing fluoropolymers was obtained by radiation grafting of acrylic acid onto tetrafluoroethylene—ethylene copolymers with different compositions. By using simultaneous (60Co) and preirradiation (electron beam) techniques, the effect of the grafting conditions (monomer concentration, dose rate, dose, film thickness, etc.) on the degree of grafting was studied. A considerable effect of the polymer compositions, especially the CF bonds content, and the batch irradiation on the degree of grafting was found. It was observed by scanning electron microscopy that the grafting took place mainly on the polymeric film surface and developed inward with increasing diffusion of the acrylic acid through the grafted layers. © 1993 John Wiley & Sons, Inc.

Excimer laser irradiation effects on ethylene-tetrafluoroethylene copolymer.

Excimer laser irradiation effects on ethylene-tetrafluoroethylene copolymer.

Electronic mobility in alternating ethylenetetrafluoroethylene copolymers: a spectroscopic study

Vibrational spectra (infrared and Raman) of ethylenetetrafluoroethylene copolymers show peculiar characteristics in the CH stretching region: 1. CH 2 stretching bands (of the regular alternating structure) show appreciable frequency shift to higher energies when compared with CH 2 stretching bands of n-alkanes. 2. the IR intensities of the CH 2 stretching bands are very small if compared with the absorptions in the deformation region. 3. the IR CH 2 symmetric stretching band of a spectrum recorded in polarized light on a highly oriented sample shows a dominant component in the polarization direction parallel to the chain axis. We will show in this communication that the data in 1) and 2) can be rationalized in terms of increased polarity of the CH bonds, due to the inductive effect of the fluorine atoms. Observation 3) seems anomalous: it implies that the dipole moment variation induced by CH 2 symmetric stretching has a direction which significantly deviates from the direction along which the vibration takes place (orthogonal to the chain axis). This behaviour can be accounted for in terms of the existence of very large charge fluxes which take place along the CC backbone during CH stretching. This shows the existence of a large electron mobility along σ-bonded chains with highly polarized CC bonds. These data shed further light on the bonding properties of these kinds of polymers and give important information on the use of infrared dichroism in the study of oriented polymers.