The photodegradation of 36 μm thick poly(ethylene terephthalate) film under artificial weathering conditions has been investigated. A weatherometer was used to expose samples to a broad wavelength range of light in an oxidative environment, replicating outdoor exposure. Irradiations were also performed using UV lamps of wavelengths 302 and 365 nm light, in an oxidative environment. After exposure, the extent of degradation was determined using attenuated total reflectance Fourier transform infrared spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, UV-visible spectroscopy, fluorescence spectroscopy, differential scanning calorimetry, contact angle measurements, and scanning electron microscopy. Results show the production of a series of degradation products, including carboxylic acid end groups, anhydrides, aldehydes, quinones, and monohydroxy terephthalate groups.
Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Reactive and Functional Polymers. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reected in this document. Changes may have been made to this work since it was submitted for publication. A denitive version was subsequently published in Reactive and Functional Polymers, 89, April 2015, 10.1016/j.reactfunctpolym.2015 Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractSurface modification of amorphous PET in incompatible blends is demonstrated using fluorocarbon end-functional polystyrenes. Contact angles with water and decane were consistent with high levels of surface fluorocarbon, even for spin-cast films with no further processing required. Hydrophobicity and lipophobicity were further increased by annealing above the glass transition temperature. High resolution depth profiling using complementary ion beam analysis and specular neutron reflectometry has enabled accurate characterisation of the composition profile of the additive including the minimum in additive concentration found just below the surface enriched layer. This analysis quantified the very low compatibility between the modifying polymer and the amorphous PET and was consistent with the highly segregated nature of the adsorbing species and its sharp interface with the subphase. For these incompatible polymer blends, surfaces enriched with the surface active polymer could coexist at equilibrium with extremely low (~0.4 %) bulk subphase "amPET" surface active additive Film profiles Annealing sharpens interfaceSpin cast films of incompatible polymers consistently yield a macromolecular monolayer of the surface active component.loadings of the additive. This suggests that for thicker films at even lower additive concentrations than the minimum 1% that we studied, it may be possible to achieve efficient surface modification. However, at this concentration, the efficiency of surface modification is limited by the processing conditions. Finally we note that in higher loadings of surface active additive there is clear evidence for lateral phase separation into patterned domains of differing composition. The enhancement in surface properties is due to local reorganisation rather than bulk redistribution of the components within the film, as the composition versus depth distributions of the polymer blend compone...
Copolycondensation of N,N′-bis(2-hydroxyethyl)-biphenyl-3,4,3′,4′-tetracarboxylic diimide (5–25 mol %) with bis(2-hydroxyethyl)-2,6-naphthalate affords a series of cocrystalline, poly(ethylene 2,6-naphthalate) (PEN)-based poly(ester imide)s. The glass transition temperature rises with the level of comonomer, from 118 °C for PEN itself to 148 °C for the 25% diimide copolymer. X-ray powder and fiber diffraction studies show that, when 5 mol % or more of diimide is present, the α-PEN crystal structure is replaced by a new crystalline phase arising from isomorphic substitution of biphenyldiimide for PEN residues in the polymer crystal lattice. This new phase is provisionally identified as monoclinic, C2/m, with two chains per unit cell, a = 10.56, b = 6.74, c = 13.25 Å, and β = 143.0°.
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