492 resultados para POLYESTER-TONER
Resumo:
v. 1. Ungdomsdikter. Italienska bilder. España. Intermezzo. Sonetter.--v. 2. Tankar och toner. I Afrika. Firenze och Sorrento. Fantasier och verkligheter.--v. 3. Svenska bilder.--v. 4. Berättelser och sägner. Hemlandstoner. Minnessånger och tillfällighetsdikter.--v. 5. Goethe, Visor och dikter. Goethe, Ballader. Sju engelska dikter. Béranger, Tio sånger. Sully P̊rudhomme, Fyra dikter. François Coppee. För kronan.
Resumo:
"Order of exercises at the Old South Church, commemorative of the death of James Monroe, on Thursday, Aug. 25, 1831": p. [97]-100.
Resumo:
Indexes to this work were published by J.M. Toner, Washington, 1898, and by J.C. Wise, Richmond, 1910.
Resumo:
Pforzheimer Bruce Rogers Collection: Vol. 6, no. 1 (Nov. 1896).
Resumo:
Top Row: Maura P. Boran, Michelle M. Bernier, Pamela S. Reed, Catherine G. Dollries, Dorinda K. Nance, Sheila M. Raftery, Sandra J. Toner, Nancy E. Naeckel, Jill M. Cornell, Amy C. Wikol, Valerie A. Quaderer, Debra A. Davis, Beth I. Craigie, Lynne L. Stallworth, Elizabeth Foote
Row 2: Jill A. Stockwell, Katherine A. Allen-Bridson, Elizabeth J. Henry, Yvonne M. Levernois, Kristen Ligness, Karen Riffel, Carol Hayes, Lori Follmer, Laura Risto, Lisa Crouch, Kelli J. Chandler, Debra L. Browning, Cassandra L. Milne, Venus M. Varner
Row 3: Tamara D. Haas, Betsy A. Mahlke, Linda D. Dillard, Rebecca A. Miller, Julie A. Hatch, Kimberly E. Kinning, Elizabeth A. Bole, Sharon Szetela
Row 4: Jill Y. Frye, C. Holly Trentacoste, Hristine S. Cavanaugh, Shari W. Goldstein
Row 5: Lisa A. Danto, Laura L. Greig, Kristen L. Jacobus, Mary E. Zukowski, Tracy L. Park, Alicia L. Hempstead
Row 6: Catherine A. Mehall, Leigh A. Baguley, Heide Milbrandt-Godke, Tina Vasher, Cindy L. Bishop, Jayne C. Grun
Row 7: Paula M. Daoust, Cindy T. Cassidy, Sally J. Williams, Theresa Harris, Cheryl E. Easley, Janice B. Lindberg, Rhetaugh G. Dumas, Sally A. Sample, Shake Ketefian, Lori S. Smith, Teresa L. O'Brien, Lauren A. Christoff, Susan R. Stein
Row 8: Amy L. Manley, Jennifer L. Elie, Linda L. Grabowski, Cheryl L. Pavlik, Dana S. Berry, Kriste L. Fedon, Lynn M. Shute, Kathleen J. Burns, Suzanne L. Farhat, Kathryn E. Grant, Catharina M. Ojert, Laurie A. Klemczak, Caroline E. Broida, Mary M. Heikkinen
Row 9: Shelley A. Howington, Rita A. Mclemore, Shirley A. Stratton, Laura A. Sweeney, Bonnie L. Woods, Mary D. Wheatley, Colleen M. Brown, Ilze E. Sturis, Karen A. Gilbert, Amy L. Mayne, Jennifer L. Borucki, Connie L. Passon, Caryn A. Spielman, Judy L. Buhler
Resumo:
The chemical structure, synthesis, morphology, and properties of polyurethane elastomers are briefly discussed. The current understanding of the effect of chemical structure and the associated morphology on the stability of polyurethanes in the biological environments is reviewed. The degradation of conventional polyurethanes appears as surface or deep cracking, stiffening, and deterioration of mechanical properties, such as flex-fatigue resistance. Polyester and poly( tetramethylene oxide) based polyurethanes degrade by hydrolytic and oxidative degradation of ester and ether functional groups, respectively. The recent approaches to develop polyurethanes with improved long-term biostability are based on developing novel polyether, hydrocarbon, polycarbonate, and siloxane macrodiols to replace degradation-prone polyester and polyether macrodiols in polyurethane formulations. The new approaches are discussed with respect to synthesis, properties and biostability based on reported in vivo studies. Among the newly developed materials, siloxane-based polyurethanes have exhibited excellent biostability and are expected to find many applications in biomedical implants.
Resumo:
Thermosetting blends of a biodegradable poly(ethylene glycol)-type epoxy resin (PEG-ER) and poly(epsilon-caprolactone) (PCL) were prepared via an in situ curing reaction of poly(ethylene glycol) diglycidyl ether (PEGDGE) and maleic anhydride (MAH) in the presence of PCL. The miscibility, phase behavior, crystallization, and morphology of these blends were investigated. The uncured PCL/PEGDGE blends were miscible, mainly because of the entropic contribution, as the molecular weight of PEGDGE was very low. The crystallization and melting behavior of both PCL and the poly(ethylene glycol) (PEG) segment of PEGDGE were less affected in the uncured PCL/PEGDGE blends because of the very close glass-transition temperatures of PCL and PEGDGE. However, the cured PCL/PEG-ER blends were immiscible and exhibited two separate glass transitions, as revealed by differential scanning calorimetry and dynamic mechanical analysis. There existed two phases in the cured PCL/PEG-ER blends, that is, a PCL-rich phase and a PEG-ER crosslinked phase composed of an MAH-cured PEGDGE network. The crystallization of PCL was slightly enhanced in the cured blends because of the phase-separated nature; meanwhile, the PEG segment was highly restricted in the crosslinked network and was noncrystallizable in the cured blends. The phase structure and morphology of the cured PCL/PEG-ER blends were examined with scanning electron microscopy; a variety of phase morphologies were observed that depended on the blend composition. (C) 2004 Wiley Periodicals, Inc.
Resumo:
The effects of modified atmosphere (MA) conditions on the quality of minimally processed pineapple slices were determined. Commercial pineapple slice packs sealed with 40 pm thick polyester film were kept at 4.5 degrees C for 14 d. The oxygen transmission rate of the film was 23 ml m(-2) day(-1) atm(-1) (at 25 degrees C, 75% RH). In-built atmospheres and the quality of the products were determined. O-2 concentrations within the packs stabilised at 2%, while CO2 concentrations increased to 70% by day 14. The high CO2 level suggested an inappropriate lidding film permeability for the product, and hence affected its quality. Three batches of pineapple slices were packed in the laboratory using lidding films with oxygen transmission rate of 75, 2790 or 5000 ml m(-2) day(-1) atm(-1) (at 23 degrees C, 0% RH). Headspace atmospheres from laboratory-packed pineapple slices suggested an optimum equilibrium modified atmosphere of ca. 2% O-2 and 15% CO2. Respiration data from the laboratory-prepared packs were pooled together and used to develop a correlation model relating respiration rates to O-2 and CO2 concentrations. The model showed a decrease in respiration rate with decreasing O-2 and increasing CO2 concentrations. Respiration rate stabilised at 2% 02 and 10% CO2. The high concentrations of CO2 observed in the commercial packs did not fit the range in the respiration model. The model could aid in selection of MA conditions for minimally processed pineapple fruit.
Resumo:
Purpose: To determine the activity and tolerability of SAM496A, an inhibitor of S-adenosylmethionine decarboxylase (SAMDC), in patients with metastatic melanoma who had not received prior chemotherapy. Selected patients were offered participation in two sub-studies examining early changes in tumor metabolism with FDG-PET and changes in tumor polyamine content. Patients and methods: Fifteen patients with measurable metastatic melanoma, normal cardiac function, and no known CNS metastases were eligible and received SAM486A by 1-hour IV infusion daily for 5 days every 3 weeks. Response was assessed by SWOG criteria. Results: No patient had a confirmed partial response. Fatigue/lethargy, myalgia and neutropenia were the main toxicities but no febrile neutropenia or grade 4 non-hematological toxicity occurred. Five patients had PET scans pre-treatment and on days 8-12 of cycle 1. No patient had reduction of tumor metabolism. Serial biopsy in one patient showed alterations in polyamines consistent with SAMDC inhibition. Conclusions: Using the present dose and schedule of administration, SAM486A does not have significant therapeutic potential in patients with metastatic melanoma.
Resumo:
This paper reviews the recent research and development of clay-based polymer nanocomposites. Clay minerals, due to their unique layered structure, rich intercalation chemistry and availability at low cost, are promising nanoparticle reinforcements for polymers to manufacture low-cost, lightweight and high performance nanocomposites. We introduce briefly the structure, properties and surface modification of clay minerals, followed by the processing and characterization techniques of polymer nanocomposites. The enhanced and novel properties of such nanocomposites are then discussed, including mechanical, thermal, barrier, electrical conductivity, biodegradability among others. In addition, their available commercial and potential applications in automotive, packaging, coating and pigment, electrical materials, and in particular biomedical fields are highlighted. Finally, the challenges for the future are discussed in terms of processing, characterization and the mechanisms governing the behaviour of these advanced materials.
Resumo:
This article reports thermoset blends of bisphenol A-type epoxy resin (ER) and two amphiphilic four-arm star-shaped diblock copolymers based on hydrophilic poly(ethylene oxide) (PEO) and hydrophobic poly(propylene oxide) (PPO). 4,4'-Methylenedianiline (MDA) was used as a curing agent. The first star-shaped diblock copolymer with 70 wt% ethylene oxide (EO), denoted as (PPO-PEO)(4), consists of four PPO-PEO diblock arms with PPO blocks attached on an ethylenediamine core; the second one with 40 wt% EO, denoted as (PEO-PPO)(4), contains four PEO-PPO diblock arms with PEO blocks attached on an ethylenediamine core. The phase behavior, crystallization, and nanoscale structures were investigated by differential scanning calorimetry, transmission electron microscopy, and small-angle X-ray scattering. It was found that the MDA-cured ER/(PPO-PEO)(4) blends are not macroscopically phase-separated over the entire blend composition range. There exist, however, two microphases in the ER/(PPO-PEO)(4) blends. The PPO blocks form a separated microphase, whereas the ER and the PEO blocks, which are miscible, form another microphase. The ER/(PPO-PEO)(4) blends show composition-dependent nanostructures on the order of 10-30 nm. The 80/20 ER/(PPO-PEO)(4) blend displays spherical PPO micelles uniformly dispersed in a continuous ER-rich matrix. The 60/40 ER/(PPO-PEO)(4) blend displays a combined morphology of worm-like micelles and spherical micelles with characteristic of a bicontinuous microphase structure. Macroscopic phase separation took place in the MDA-cured ER/(PEO-PPO)(4) blends. The MDA-cured ER/(PEO-PPO)(4) blends with (PEO-PPO)(4) content up to 50 wt% exhibit phase-separated structures on the order of 0.5-1 mu m. This can be considered to be due to the different EO content and block sequence of the (PEO-PPO)(4) copolymer. (c) 2006 Wiley Periodicals, Inc.
Resumo:
This thesis is concerned with the effect of polymer structure on miscibility of the three component blends based on poly(lactic acid) (PLA) with using blending techniques. The examination of novel PLA homologues (pre-synthesised poly(a-esters)), including a range of aliphatic and aromatic poly(a-esters) is an important aspect of the work. Because of their structural simplicity and similarity to PLA, they provide an ideal system to study the effect of polyester structures on the miscibility of PLA polymer blends. The miscibility behaviour of the PLA homologues is compared with other aliphatic polyesters (e.g. poly(e-caprolactone) (PCL), poly(hydroxybutyrate hydroxyvalerate) (P(HB-HV)), together with a series of cellulose-based polymers (e.g. cellulose acetate butyrate (CAB)). The work started with the exploration the technique used for preliminary observation of the miscibility of blends referred to as “a rapid screening method” and then the miscibility of binary blends was observed and characterised by percent transmittance together with the Coleman and Painter miscibility approach. However, it was observed that symmetrical structures (e.g. a1(dimethyl), a2(diethyl)) promote the well-packing which restrict their chains from intermingling into poly(L-lactide) (PLLA) chains and leads the blends to be immiscible, whereas, asymmetrical structures (e.g. a4(cyclohexyl)) behave to the contrary. a6(chloromethyl-methyl) should interact well with PLLA because of the polar group of chloride to form interactions, but it does not. It is difficult to disrupt the helical structure of PLLA. PLA were immiscible with PCL, P(HB-HV), or compatibiliser (e.g. G40, LLA-co-PCL), but miscible with CAB which is a hydrogen-bonded polymer. However, these binary blends provided a useful indication for the exploration the novel three component blends. In summary, the miscibility of the three-component blends are miscible even if only two polymers are miscible. This is the benefit for doing the three components blend in this thesis, which is not an attempt to produce a theoretical explanation for the miscibility of three components blend system.
Resumo:
The enzyme catalysed polytransesterification of diesters with diols was investigated under various conditions. The most consistent results were obtained using crude porcine pancreatic lipase (PPL) suspended in anhydrous diethyl ether. Addition of molecular sieve to the above system gave higher molecular weight products. The PPL catalysed reaction of bis(2,2,2-trichlorethyl) adipate and glutarate with butane-1,4-diol in anhydrous ether with and without molecular sieve was investigated over a range of times from 8 to 240 hours. The 72 hour adipate reaction with molecular sieve gave the highest molecular weight polymer (Mn 6,500 and Mw 9,400). The glutarate gave the maximum molecular weight polyester after 24 hours (Mn 5,700 and Mw 9,500). Occasionally the glutarate reaction produced very high molecular weight polyester-enzyme complexes. Toluene generally gave lower molecular weight products than diethyl ether. Dichloromethane and tetrahydrofuran gave mainly dimers and trimers. Alternative enzyme and diol systems were also investigated. These yielded no polymeric products. The molecular weights of the polyesters were determined by 1H NMR end-group analysis and by GPC. The molecular weights determined by NMR were on average about twice as great as those determined by GPC. The synthesis of the following diesters is described: i)Bis(2,2,2-trichloroethyl) succinate, glutarate, adipate, trans-3-hexenedioate, and trans-3,4-epoxyadipate. ii) Diphenyl glutarate and adipate.iii)Bis(2,2,2-fluoroethyl) glutarate and trans-3-hexendioate.iv) Divinyl glutarate. v) N,N'Glutaryl dicyclohexanone oxime.The polytransesterification of all the above esters with diols was investigated. The easily synthesised bis(2,2,2-trichloroethyl) glutarate and adipate gave the best results and the work was concentrated on these two esters.
Resumo:
The interaction of microorganisms with glass-reinforced polyester resins(GRP), both under laboratory and simulated operating conditions, has been examined following reports of severl! fungal biodeterioration. Although GRP was not previously associated with substantial microbial growth, small amounts of microbial activity would pose problems for products associated with comestible materials. The microbiology of the raw materials was investigated, two ingredients were supportive to microbial populations whilst five materials were biostatic or inhibitory in their action. Production laminate was not susceptible to microbial deterioration or inhibitory to microbes. Incorporation of zinc stearate, one of the supportive ingredients, at 300% manufacturing level or drastic undercuring produced laminate capable of supporting microbial growth but only after a non-biotic stage of degradation. Study of the long-term population dynamics of cisterns of GRP and competitive materials under conditions simulating in-service conditions, monitoring microbial numbers within the experimental vessels and comparing with the populations of the supply water, suggests that the performance of GRP cisterns is slightly superior to conventional competitive materials. An investigation of the biological performance of GRP cisterns in an isolated area of known microbiological hazard was conducted. Severe biodeterioration had been experienced with Preform GRP articles moulded using different production techniques, but substitution of current GRP articles resulted in no recurrence of the problem. All attempts to establish the fungal isolate responsible for the phenomena in cisterns under controlled conditions failed. Scanning Electron Microscopy of GRP surfaces showed that although differences exist between current and Preform laminates, these could not satisfactorily explain the differences in service behaviour. These results and the results of the British Plastics Federation Expert Working Group interlaboratory study are discussed in relation to the original report of gross fungal biodeterioration and, to the design of future testing programmes for the products of industrial concerns.
Influence of pretreatment on corrosion behaviour of duplex zinc/polymer coatings on steel substrates
Resumo:
An investigation has been undertaken to determine the major factors influencing the corrosion resistance of duplex-zinc coatings on steel substrates.Premature failure of these systems has been attributed to the presence of defects such as craters and pinholes in the polymer film and debonding of the polymer film from the zinc substrate.Defects found on commercially produced samples have been carefully characterised using metallographic and scanning electron microscopy techniques. The influence of zinc substrate surface roughness, polymer film thickness and degassing of conversion coatings films on the incidence of defects has been determined.Pretreatments of the chromate, chromate-phosphate, non chromate, and alkali-oxide types were applied and the conversion coatings produced characterised with respect to their nature and composition. The effect of degassing on the properties of the films was also investigated. Electrochemical investigations were carried out to determine the effect of the presence of the eta or zeta phase as the outermost layer of the galvanized coating.Flow characteristics of polyester on zinc electroplated hot-dip continuous and batch galvanized and zinc sprayed samples were investigated using hot-stage microscopy. The effects of different pretreatments and degassing after conversion coating formation on flow characteristics were determined.Duplex coatings were subjected to the acetic acid salt spray test. The effect on adhesion was determined using an indentation debonding test and the results compared with those obtained using cross-cut/peel and pull-off tests. The locus of failure was determined using scanning electron microscopy and X-ray photoelectron spectroscopy techniques.