Dynamic mechanical behavior of poly(ether ether ketone)/poly(ether sulfone) block copolymers

Poly(ether ether ketone) (PEEK)/poly(ether sulfone) (PES) block copolymers were synthesized via condensation reaction between fluorine-terminated PEEK oligomers and hydroxyl-terminated PES oligomers. The dynamic mechanical behavior of a composite sample prepared by compression molding of a glass fibre cloth and the copolymer was investigated by means of a dynamic viscoelastometer. The β relaxation peak and the α′ relaxation peak were observed in the logarithmic decrement curve of the amorphous block copolymer of PEEK/PES. The glass transition temperature (β relaxation peak) is shifted to higher temperature and approaches a constant value as annealing time and degree of crystallinity increase. The glass transition temperature of the copolymer rises more slowly upon annealing with increasing PES content. The α′ relaxation peak becomes smaller upon annealing, and eventually disappears. The α′ relaxation peaks are related to the motion of molecules upon transition from the non-crystalline to the crystalline state. The α′ relaxation occurs for the copolymer with a degree of crystallinity of 0 to 3%.     

Thermal properties and crystallization behavior of poly(ether ether ketone ketone)/poly(ether biphenyl ether ketone ketone) copolymers

Thermal properties of poly(ether ether ketone ketone) (PEEKK)/poly(ether biphenyl ether ketone ketone) (PEDEKK) copolymers were investigated by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The glass transition temperature (T_g) increases from 154°C to 183°C as the content of PEDEKK units increases. The melting point (T_m) of the copolymers varied in the range between 314°C and 409°C and showed the behavior of eutectic type copolymer. From the investigation of the crystallization behavior of the copolymers, it was found that the cold-crystallization temperature (T_c′) of the amorphous copolymers assumes a maximum value for the copolymer with a mole fraction of the PEDEKK segment (n_B) of about 0.6, isothermally crystallized PEEKK and the PEEKK/PEDEKK copolymer exhibit double-melting behavior.     

Molecular structure of some model compounds for poly(aryl ether ketone)s

The molecular structure of a series of model compounds for poly(aryl ether ketone)s was investigated by means of ¹³C NMR spectroscopy, quantum chemical calculation, and wide-angle X-ray scattering. The comparison of the chemical shifts for the model compounds dissolved in 98% H₂SO₄ and CDCl₃ (or CDCl₃ + DMSO-d₆) suggested that their carbonyl groups are partially protonated by sulfuric acid and the induced positive charges are delocalized in their aromatic rings. This result was supported by the charge distribution obtained by quantum chemical calculations. The model compounds were also used to characterize the molecular structure of poly(aryl ether ketone)s. The length of the repeating unit of the polymer chain, which was calculated based on the whole chain length or fragment chain length of the model compounds obtained by semiempirical PM3 method, is compared with the c-axis of the crystal unit cell of the polymer. For poly(aryl ether ketone)s containing biphenyl moieties, the length of the c-axis of the unit cell is approximately twice that of the repeating unit of the macromolecule.     

Polyurethane elastomer-LiClO4 complexes as a polymeric solid electrolyte

A polymeric solid electrolyte with high ionic conductivity was prepared by complexing a polyurethane elastomer with LiClO₄. The ionic conductivity of these complexes increases proportional to the increase of the content of poly(tetramethylene oxide) component in the polyurethane elastomer and with increasing LiClO₄ concentration, and reaches a value of 10^?4 S/cm at 80°C for [LiClO₄] = 1,20 mmol/g polymer. The polyurethane elastomer-LiClO₄ complex has good mechanical properties compared with poly(ethylene oxide)-and poly(propylene oxide)-based complexes.     

Electrical properties of an acrylic elastomer-LiClO4 complex as a polymeric solid electrolyte

A polymeric solid electrolyte having a low glass transition temperature, obtained by complexing LuCIO₄ with an acrylic elastomer (AR) containing ester groups in the side chains, shows a conductivity of 2,0 · 10^?4 S/cm (LiCIO₄: 2,1 mmol/g AR, film thickness: ca. 100–300 μm) at 80°C. From the relationship between ionic conductivity and LiCIO₄ concentration, we conclude that LiCI₄ dissociates in the acrylic elastomer to produce carrier ions. We also suggest, in regard to temperature characteristics of ionic conductivity and reciprocal dielectric relaxation time, that the driff of ions is related to the motion of acrylic elastomer chains. The carrier mobility in the acrylic elastomer-LiCIO₄ complex was measured by using the voltage polarity reversing method. The carrier mobility increased with increasing LiCIO₄ concentration and temperature.     

Grafting of styrene onto carbon fibers having pendant thiol groups

Carbon fibers containing thiol groups were produced by reacting carbon fiber oxidized by nitric acid, with excess thiirane. Then, graft polymerization with styrene was carried out in a sealed tube under nitrogen. The following order of initiating ability of the investigated initiators was found: di-tert-butyl peroxide > p-cumenyl hydroperoxide (CHPO) > dodecyl peroxide > benzoyl peroxide > 2,2′-azoisobutyronitrile. When CHPO was used as initiator, the rate of graft polymerization was maximum at [CHPO] = 0,01 mol/1. Chain transfer constant and grafting efficiency, both calculated from the equations of Fox and others, were compared with the experimental results.     

Electric characteristics of polycation perchlorate composites as a solid electrolyte and its application

Polycation perchlorate composites have excellent film-forming properties and high ionic conductivity. The ionic conductivity at 40°C is of the order of 10^?7?10^?5S·cm^?1, depending on the kind of perchlorate. The temperature dependence of the ionic conductivity follows the Williams-Landel-Ferry relationship. Furthermore, the electrochemical polymerization of pyrrole using polycation perchlorate composites as a solid electrolyte produces bilayer composite films.