An ESR and NMR study of the gamma radiolysis of a bisphenol-A based polycarbonate and a phthalic acid ester

A study of the gamma-radiolysis of the commercial polymers U-polymer, UP (Unitake) and polycarbonate, PC, (Aldrich) has been undertaken using ESR spectroscopy. The G-value of radical formation at 77 K has been found to be 0.31 +/- 0.01 for UP and 0.5 +/- 0.02 for PC. By using thermal annealing and spectral subtraction, the paramagnetic species formed on irradiation has been assigned. The effect of radiation on the chemical structure of UP and PC has been investigated at ambient temperature and at 423 K. The NMR results show that a new phenol type chain end is formed in the polymers on exposure to gamma-radiation. The G-value of formation of the new phenol ends was estimated to be 0.7 for PC (423 K) and 0.4 for UP (300 K). (C) 1998 John Wiley & Sons, Ltd.

Free-radical bulk polymerization of styrene: ESR and near-infrared spectroscopic study of the entire conversion range

The free radical polymerization of styrene in bulk was monitored by ESR and FT near-infrared spectroscopy at 70°C for a series of concentrations of the initiator, dimethyl 2,2′-azobis(isobutyrate). In order to obtain detailed kinetic information over the intire conversion range, and the gel effect range in particular, conversion and free radical concentration data points were accumulated with exceptionally short time intervals. The polystyrene radical concentration ([St•]) went through a sharp maximum at the gel effect, a feature that has hitherto escaped observation due to the rapid concentration changes in the gel effect range relative to the data point time intervals of previous studies. Temperature measurements throughout the polymerization were employed to calculate that a temperature increase was not the cause of the [St•] maximum, which thus appeares to be a genuine feature of the gel effect of this system under isothermal conditions. The propagation rate constant (kp) as a function of monomer conversion exhibited a marked dependence on initiator concentration at high monomer conversion; the sharp decrease in kp with increasing conversion was shifted to higher conversions with increasing initiator concentration.

An ESR study of the gamma radiolysis of aromatic polyesters containing isomeric naphthalene links

Six polyesters were synthesised from 4,4 ' -oxy-bis(benzoyl chloride) and 1,4-, 1,5-, 1,6-, 2,3-, 2,6-, and 2,7-naphthalenediol isomers. The structures of the polyesters were characterised by means of IR, inherent viscosities in tetrachloroethane (TCE), solutions at 303 K and thermal analysis. The glass transition temperatures were in the range of 425-494 K by DSC thermal analysis. All of the polyesters were irradiated in an AECL Gammacell 220 unit at a dose rate of approximately 6.7 kGy/h to doses in the range of 0-15 kGy at 77 and 300 K. ESR spectroscopy was used to examine the radicals formed during radiolysis and to measure their yields. The G-values for radical formation in the polyesters were found to be in the range 0.18-1.41 at 77 K and 0.19-0.78 at 300 K. At 77 K, up to 15% of the radicals formed on radiolysis were found to be photo-bleachable anion radicals. Annealing experiments were carried out in order to identify the neutral radicals, which were assigned to naphthyl- or phenyl- and phenoxyl-type radicals. (C) 2001 Elsevier Science Ltd. All rights reserved.

An ESR study on gamma-irradiated poly(vinyl alcohol)

The formation of radicals in poly(vinyl alcohol), PVA, powder irradiated at 77 K by gamma -rays and the transformations of these radicals during photolysis with visible wavelengths and on thermal annealing have been studied. After irradiation a four-line ESR spectrum was observed. It was assigned to a triplet of the C-alpha-radical (38%), with a splitting of 3.27 mT, superimposed on a doublet (62%) with a splitting of 2.7 mT. The doublet appears to be composed of two radicals, one of which is photo-bleachable (58%) and the other which is not photo-bleachable (42%). This suggests that the latter radical is a neutral radical. The photo-bleachable component of the doublet has been assigned to a carbonyl anion radical. but the second doublet due to a neutral radical is unassigned. The total G-value for formation of radicals at 77 K was found to be 2.41 +/- 0.03. Upon illumination with visible light, the anion radicals were removed and the doublet components or the spectrum diminished in intensity, while the three-line spectrum of the C-alpha-radical became more clearly visible. This transition was due to the photo-detachment of electrons from traps which were proposed to be located on carbonyl groups in the polymer resulting from incomplete hydrolysis of the vinyl acetate. The photo-decay of the anion radicals could be satisfactorily described by a two-stage process. The first stage comprised the decay of approximately 80% of the anion radicals present, while the second stage was associated with the decay of the remaining 20%. Subsequent thermal annealing of a photolysed sample to 290 K led to a change in the shape of the spectrum to form a more clearly defined triplet, As the doublet of the neutral radical decays on thermal annealing between 150 and 250K, the C-alpha-radical is formed. (C) 2001 Elsevier Science Ltd. All rights reserved.

An ESR study of irradiated poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (PFA)

Poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (PFA) with 2 mol% perfluoropropyl vinyl ether (PPVE) was exposed to gamma -irradiation in vacuum at both 77 K and room temperature and the ESR spectra recorded. Both the main chain, similar to CF2-(CF)-F-.-CF(2)similar to, and end chain, similar to (CF2CF2)-F-. radicals were identified at both temperatures and their thermal stabilities measured, No radicals unique to the radiolytic cleavage at the PPVE units were observed at room temperature, either due to the low concentration of the comonomer or beta -scission to form a chain end radical and a nonradical species. G-values for radical formation at room temperature and 77 K were found to be 0.93 and 0.16, respectively. (C) 2001 Elsevier Science Ltd. All rights reserved.

The radiation chemistry of ultem at 77 K as revealed by ESR spectroscopy

Radical formation in ultem following gamma-radiolysis has been reassessed, and the G(R*) values at different temperatures have been determined by ESR spectroscopy. The radical assignment and radical reactivity have been re-examined by photobleaching and thermal annealing studies. Photobleachable radical anions were found to comprise approximate to40% of the total number of radicals formed on radiolysis at 77 K. Spectral subtraction methods, ESR spectral simulations, measurement of g-values and the hyperfine splitting constants were used to identify the other radical intermediates. The principal chain scission radicals are formed due to scission of the main-chain at (i) the ether linkage, (ii) the isopropylidene group and (iii) the imide ring in the main chain. The side chain methyl groups of the isopropylidine units also lose hydrogen to form methylene radicals. The five-line spectrum observed to decay in the temperature range 370-430 K, which has not been assigned previously, has been identified as being characteristic of a di-substituted benzyl radical. (C) 2002 Elsevier Science Ltd. All rights reserved.

Simultaneous FT-NIR and ESR analyses to yield propagation rate coefficients for polymerization of methyl methacrylate based monomers

A hyphenated instrumental approach has been used to obtain reliable values for the propagation rate coefficients as a function of conversion for polymerizations of methyl methacrylate (MMA) and a mixture of MMA and ethyleneglycol dimethacrylate (EGDMA) with a 1:1 concentration of double bonds, from near the onset of the Trommsdorf region into the glass region. ESR spectroscopy was used to measure the radical concentration while FT-NIR fibre-optic spectroscopy was employed to measure instantaneously the double-bond concentration within the temperature-controlled cavity of the ESR instrument during polymerization. The advantage of this approach to the measurement of the rate coefficient is that it is equally applicable to branching and linear polymerizations. For the polymerization of methyl methacrylate, the values of the rate coefficient at the lowest conversions at which reliable values could be obtained were in agreement with recently reported values obtained by the PLP-SEC method. For the lowest conversions, the values obtained were 403 1 mol(-1) s(-1) at 306 K for MMA and 5201 mol(-1) s(-1) at 310 K for a 1:1 mixture of MMA and EGDMA. (C) 2003 Society of Chemical Industry.

A study of the radiation chemistry of poly(chlorotrifluoroethylene) by ESR spectroscopy

The ESR spectra of poly(chlorotrifluoroethylene) were recorded following gamma-radiolysis under vacuum at room temperature and 77 K. The very broad spectrum at 77 K revealed little fine structure with which to identity the radicals formed upon irradiation, but subsequent photobleaching and annealing studies, together with radiolytic studies at higher temperatures, afforded scope for making radical assignments. Both main-chain radicals and a range of chain-end radicals have been identified. The G-values for radical formation were 1.55, 0.36 and 0.32 at 77 K, 273 K and room temperature, respectively. (C) 2003 Elsevier Science Ltd. All rights reserved.

Kokemuksia ESR-rahoitteisen hankkeen hallinnoinnista

Virtuaaliammattikorkeakoulu, VirtuaaliAMK

Sivuraiteilta uralle! : Koulutuksen keskeyttämisen ehkäisemiseen suunnatut ESR-projektit Kaakkois-Suomessa ja malleja muualta Suomesta

Tämä julkaisu on yhteenveto Kaakkois-Suomen elinkeino-, liikenne- ja ympäristökeskuksen valvonnassa käynnistyneistä, Euroopan sosiaalirahaston rahoittamista koulutuksen keskeyttämisen ehkäisyyn pyrkivistä projekteista vuosina 2007–2012 (tilanne 23.02.2012). Lisäksi selvitykseen on koottu vastaavissa projekteissa kehitettyjä malleja muualta Manner-Suomesta. Projekteista esitetään lyhyesti hankkeen keskeiset tiedot; hallinnoijan yhteystiedot, projektin kohdealue, tavoitteet ja tulokset. Lisäksi projekteista esitetään tarkempia esimerkkejä niissä kehitetyistä malleista ja välineistä. Tarkasteltavissa hankkeissa on pyritty ehkäisemään koulutuksen keskeyttämistä ammattioppilaitosten ja erilaisten työpajojen välisellä yhteistyöllä, erilaisilla opetusmenetelmillä, erityisopettajuudella, moniammatillisten verkostojen tuella sekä erilaisilla sähköisillä arviointivälineillä. Selvityksessä on käytetty lähteenä hankkeiden Eura2007-järjestelmään kirjattuja loppu- ja väliraportteja sekä projektisuunnitelmia ja näissä esitettyjä tietoja. Näitä tietoja täydennettiin projektien yhteyshenkilöille lähetetyllä kyselyllä ja kyselystä saaduilla vastauksilla ja materiaalilla. Lisäksi apuna käytettiin hankkeiden omia julkaisuja. Selvityksen on laatinut ELY-keskuksen korkeakouluharjoittelija, hum. kand. Teemu Räihä.

Tavoitteena tutkinto – unelmana ura : Hyviä käytäntöjä ESR-rahoitteisista maahanmuuttajahankkeista ohjelmakaudella 2007–2013

Tämä raportti esittelee ESR-rahoitteisia maahanmuuttajahankkeita ja niistä saatuja hyviä käytäntöjä. Raportissa esitellään hankkeet, joita on toteutettu Kaakkois-Suomen alueella rakennerahastokaudella 2007–2013. Lisäksi esitellään muutama muualla Suomessa toteutettu hanke, joista on saatu hyviä tuloksia. Hankkeista esitellään lyhyesti niiden keskeiset toimenpiteet ja saadut tulokset sekä kehitetyt toimintamallit. Lisäksi kerrotaan, mistä on mahdollista saada lisätietoa hankkeista ja niissä kehitetyistä malleista. Tarkasteltavissa hankkeissa on pyritty rakentamaan maahanmuuttajien koulutus- ja urapolkuja, kehittämään maahanmuuttajille suunnattua ohjausta ja neuvontaa sekä edistämään heidän kotoutumistaan ja työllistymistään. Selvityksessä lähteinä ovat toimineet hankkeiden EURA2007-järjestelmään kirjatut loppuraportit ja projektisuunnitelmat sekä näissä esitetyt tiedot. Lisäksi lähteinä on käytetty hankkeiden omia loppujulkaisuja ja Internet-materiaaleja. Näitä tietoja on täydennetty kysymällä lisätietoja suoraan projektien yhteyshenkilöiltä.