Lie detector

Novel, semicrystalline polyamides and copolyamides were synthesized from a new carbohydrate-based diamine, namely isoidide-2,5-dimethyleneamine (IIDMA). In combination with 1,6-hexamethylene diamine (1,6-HDA) as well as the biobased sebacic acid (SA) or brassylic acid (BrA), the desired copolyamides were obtained via melt polymerization of the nylon salts followed by a solid-state polycondensation (SSPC) process. Depending on the chemical compositions, the number average molecular weights (Mn) of the polyamides were in the range of 4000–49000 g/mol. With increasing IIDMA content in the synthesized copolyamides, their corresponding glass transition temperatures (Tg) increased from 50 °C to approximately 60–67 °C while the melting temperatures (Tm) decreased from 220 to 160 °C. The chemical structures of the polyamides were analyzed by NMR and FT-IR spectroscopy. Both differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) analyses revealed the semicrystalline character of these novel copolyamides. Variable-temperature (VT) 13C{1H} cross-polarization/magic-angle spinning (CP/MAS) NMR and FT-IR techniques were employed to study the crystal structures as well as the distribution of IIDMA moieties over the crystalline and amorphous phases of the copolyamides. The performed ab initio calculations reveal that the stability of the IIDMA moieties is due to a pronounced boat conformation of the bicyclic rings. The incorporation of methylene segments in between the isohexide group and the amide groups enables the hydrogen bonds formation and organization of the polymer chain fragments. Given the sufficiently high Tm values (200 °C) of the copolyamides containing less than 50% of IIDMA, these biobased semicrystalline copolyamides can be useful for engineering plastic applications

Chemistry and technology of polyamides

This chapter presents a comprehensive overview of the chemistry, process technology, and thermal and mechanical properties of hydrolytically prepared fully aliphatic and semiaromatic commercial polyamides (PAs). In addition, commercially available block copolyetheramides and the most important PA blends are discussed. A few molecular characterization methods, typically used for the characterization of PAs, are briefly discussed, as well as some physical phenomena very characteristic of PAs, such as the Brill transition and the odd–even effect in the melting points of a series of PAs. The applications of the wide variety of commercial PAs are discussed in terms of their propertie

Conductive polymer composition

The present invention relates to a process for the preparation of a conductive polymer composition comprising graphene and the articles obtained by this process. The process comprises the following steps: A) contacting graphite oxide in an aqueous medium with a water-soluble or dispersible component, comprising either a water-soluble or dispersible first polymer or a water-soluble or dispersible (conductive) surfactant and subsequently adding a reducing agent to the aqueous medium; B) mixing the resulting product from step A) with either an aqueous latex of a second polymer, or with (a) water-soluble precursor(s) of a second polymer; C) removing water from the so obtained mixture; D) heating the product from step C) to a temperature at which the second polymer flows or where the second polymer is formed from out of its precursor(s); and E) processing and/or solidifying the product of step D) into a desired form

Unsaturated biobased polyesters and their cross-linking via radical copolymerization

Biobased, unsaturated polyesters derived from isosorbide, maleic anhydride, and succinic acid were synthesized and characterized. The presence of maleic anhydride units in the structure of the polyesters allowed converting them into cured coatings by radical copolymerization with crosslinking agents such as 2-hydroxyethyl methacrylate, N-vinyl-2-pyrrolidinone, acrylic acid or methacrylamide. The investigated polyesters were obtained via bulk polycondensation, catalyzed by titanium(IV) n-butoxide. 2D NMR and MALDI-Tof-MS spectroscopy proved that this polymerization resulted in isomerization of maleic acid units into fumaric ones and in the formation of slightly branched structures by the reaction of isosorbide (end) groups with main chain unsaturated bonds. Moreover, some double bonds proved to have reacted with the condensation by-product water. The resulting polyesters displayed the expected correlation between variables such as molecular weight and content of unsaturated bonds and their Tg values. Since the thermal properties of the obtained polyesters were appropriate for coating applications, the polymers were crosslinked with unsaturated monomers by radical copolymerization. The crosslinking process was studied using FTIR spectroscopy and by measurements of the soluble part of the cured coating

The plastic deformation of ultra-high molecular weight polyethylene

Gel-spun filaments of different initial morphologies have been subjected to controlled drawing at elevated temperatures. The drawn samples have been examined by high-resolution scanning electron microscopy. The deformation mechanism at temperatures up to 120° C is very similar to crazing, especially in the case of unoriented gel-spun filaments. Filaments exhibiting a shish-kebab morphology offer the opportunity of examining the deformation of elementary fibrils in a quantitative way. The transformation of individual lamellae into fibrils is the initial deformation mode, which is followed by slip of fibrils at a later stage. This is concluded from a comparison of experimental data and model calculations of the maximum draw ratio. Drawing at 144° C results in the formation of globular aggregates of lamellae, with a characteristic long period of 40 nm. This long period persists until all the globules have been converted, by micronecking, into aggregate fibrils of extended-chain character. On a molecular scale, the various processes can be described as the temperature-dependent flow behaviour of an entanglement network

Process for the preparation of polycarbonates

The invention relates to a process for the preparation of polycarbonates from oxiranes and CO2 characterized in that the polymerization is carried out in a single step in the presence of a chain transfer agent. Preferred chain transfer agents are polyols. The invention also relates to branched polycarbonates that have functional hydroxyl endgroups

Synthesis and characterization of novel renewable polyesters based on 2,5-furandicarboxylic acid and 2,3-butanediol

Novel polyesters from 2,5-furandicarboxylic acid or 2,5-dimethyl-furandicarboxylate and 2,3-butanediol have been synthesized via bulk polycondensation catalyzed by titanium (IV) n-butoxide, tin (IV) ethylhexanoate, or zirconium (IV) butoxide. The polymers were analyzed by size exclusion chromatography, nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy (FTIR), matrix-assisted laser ionization-desorption time-of-flight mass spectrometry, electrospray ionization time-of-flight mass spectrometry, electrospray ionization quadruple time-of-flight mass spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. Fully bio-based polyesters with number average molecular weights ranging from 2 to 7 kg/mol were obtained which can be suitable for coating applications. The analysis of their thermal properties proved that these polyesters are thermally stable up to 270–300 °C, whereas their glass transition temperature (Tg) values were found between 70 and 110 °C. Furthermore, a material was prepared with a molecular weight of 13 kg/mol, with a Tg of 113 °C. This high Tg would make this material possibly suitable for hot-fill applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 201