Search results for "Polyester"

Polymer stain resistance: Prediction versus experiment

2013

Strukturuntersuchung von polyestern durch direkten abbau im massenspektrometer, 2. Aliphatische polyester

1976

Die Abbaureaktionen von Polyestern aus Adipinsaure und Athylenglykol 1a, Tetradeuteroathylenglykol 1b, 1,3-Propandiol 1c und 2,2′-Oxydiathanol 1d sowie aus Bernsteinsaure und Athylenglykol 2a, 1,4-Butandiol 2b und 2,2-Dimethyl-1,3-propandiol 2c wurden im Massenspektrometer untersucht. Die Polymeren wurden direkt in der Ionenquelle des Massenspektrometers pyrolysiert und die entstehenden thermischen Bruchstukke durch Elektronenstos ionisiert und fragmentiert. Die Pyrolyse- und Fragmentierungsreaktionen lassen sich nebeneinander nachweisen. Die Kenntnis der Mechanismen beider Abbauschritte ermoglicht es, strukturisomere Polyester zu unterscheiden. The degradation reactions of polyesters of ad…

Lineare polyester mit carboxylendgruppen und deren bestimmung

1955

Durch Umsetzung von „alkoholischen” Bernsteinsaure-1,6-Hexandiol-Polyestern mit Bernsteinsaureanhydrid in Benzol werden kettenanaloge Polyester mit endstandigen Carboxylgruppen hergestellt. Die Titration dieser Carboxylgruppen ergibt Molgewichte bis ∼ 7 · 103. Mit Phenylisocyanat in indifferenten Losungsmitteln reagieren Polyesterdicarbonsauren unter Kettenverlangerung und Bildung von kettenstandigen Carbonsaureanhydridgruppen. Die Umsetzung der Polyester-dicarbonsauren in Phenylisocyanat ohne Verdunnungsmittel erfolgt kettenanalog unter Bildung von Carboxanilidendgruppen. Durch photometrische Anilinbestimmung nach der Hydrolyse konnen diese Endgruppen quantitativ bestimmt und Molgewichte b…

1983

The synthesis and the phase behaviour of liquid crystalline main chain polymers are described. In these poly- and copolyesters the mesogenic units are linked by highly flexible oligodimethylsiloxane spacers. The comparison of their phase behaviour with that of polyesters known from the literature shows that dimethylsiloxane spacers as a replacement for alkyl spacers are leading to a drastic decrease of the transition temperatures. Depending on the length of the spacer glass transitions as low as −111°C can be achieved. The widths of the liquid crystalline phases thereby are retained up to a spacerlength of 13 oxydimethylsilanediyl (dimethylsiloxane) units. The homopolyesters mainly show sme…

Quercetin as natural stabilizing agent for bio-polymer

2014

The introduction of antioxidants in polymers is the main way to prevent or delay the degradation process. In particular natural antioxidants receive attention in the food industry also because of their presumed safety. In this work bio-polymers, i.e. a commercial starch-based polymer (Mater-Bi®) and a bio-polyester (PLA), and a bio-polyether (PEO) were additivated with quercetin, a natural flavonoid antioxidants, in order to formulate bio-based films for ecosustainable packaging and outdoor applications. The photo-oxidation behavior of unstabilized and quercetin stabilized films was analyzed and compared with the behavior of films additivated with a commercial synthetic light stabilizer. Th…

Polysarcosine-containing copolymers: Synthesis, characterization, self-assembly, and applications

2018

Although the first polysarcosine (pSar) synthesis by Wesseley et al. was reported almost a century ago, it was only recently that pSar gained broader attention and is considered a potential alternative of poly(ethylene glycol) (PEG). In contrast to polyethers, such as PEG, pSar is a polypeptoid based on the amino acid sarcosine, i.e. N-methylated glycine. As a polymer, pSar combines PEG-like properties, e.g., excellent solubility in water, protein resistance, low cellular toxicity and a non-immunogenic character, while being based on endogenous material. Sarcosine can be obtained in a simple one-step reaction of bromoacetic acid and methylamine, easily transferred into the sarcosine N-(thio…

Thermomechanical Properties of Radiation-Modified Polyethylene/Ethylene-Propylene-Diene Copolymer/Liquid-Crystalline Copolyester Blends

1999

Radiation-modified blends of high-density polyethylene (PE) with ethylene-propylene-diene copolymer (EPDM; 10-65 wt.%) and thermotropic liquid-crystalline polymer (LCP; 10 wt.%) were investigated. The LCP was a liquid-crystalline copolyester of 40% poly(ethylene terephthalate) with 60% 4-hydroxybenzoic acid. The constituents were blended using a circular extruder, the specimens were prepared by compression molding and irradiated by 60Co γ-radiation up to 200 kGy. Mechanical, thermal, and morphological properties in wide temperature range were investigated for the irradiated and non-irradiated specimens. The effects of irradiation on the thermomechanical behaviour of the PE matrix are discus…

Vapor–liquid equilibria in dendrimer and hyperbranched polymer solutions: experimental data and modeling using UNIFAC-FV

2004

Abstract This work evaluates the potential of the group contribution method universal functional activity coefficients-free-volume (UNIFAC-FV) to predict vapor–liquid equilibria (VLE) in dendrimer-solvent and hyperbranched polymer-solvent systems. The VLE of hydroxyl-functional dendritic polymers (polyethers, polyesters, polyamidoamine), dissolved in polar solvents (ethanol and/or water) are studied both experimentally and theoretically. A new approach is suggested to account for the contribution of selected types of polymer structural units (i.e. linear, dendritic and terminal units) to the solvent residual activity. The results of calculations are in a good agreement with experiment. Furt…

Liquid Crystalline Copolyester Made from Recycled Polyethylene Terephthalate and p-Acetoxybenzoic Acid: Synthesis, Characterization and Blending with…

2013

Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies

2017

International audience; Ultrathin layers (<20 nm) of pBR322 plasmid DNA were deposited onto 2.5 μm thick polyester films and exposed to proton Bragg-peak energies (90–3000 keV) at various fluences. A quantitative analysis of radio-induced DNA damage is reported here in terms of single- and double-strand breaks (SSB and DSB, respectively). The corresponding yields as well as G-values and the cross sections exhibit fairly good agreement with the rare available data, stemming from close experimental conditions, namely, based on α particle irradiation. SSB/DSB rates appear to be linear when plotted against linear energy transfer (LET) in the whole energy range studied. All the data present a ma…