@article{LavrenkoStrelinaOkatovaetal.1996,
  author    = {Lavrenko, Peter N. and Strelina, Irina A. and Okatova, Olga V. and Schulz, Burkhard},
  title     = {Orientation of naphthylene ring in the new poly(naphthylen-1,3,4-oxadiazole)s molecules},
  year      = {1996},
  language  = {en}
}
@article{LavrenkoSchulzStrelinaetal.1997,
  author    = {Lavrenko, Peter N. and Schulz, Burkhard and Strelina, Irina A. and Okatova, Olga V.},
  title     = {Synthesis and molecular properties of new poly(naphthalene-1,3,4-oxadiazole)s},
  year      = {1997},
  abstract  = {Poly[(1,4-naphthalene)-2,5-diyl-1,3,4-oxadiazole] and poly[(2,6-naphthalene)-2,5-diyl-1,3,4-oxadiazole] have been synthesized and investigated in conc. H2S04, by the flow birefringence method in comparison with poly(1,4- phenylene)-2,5-diyl-1,3,4-oxadiazole]. Changes in conformation parameters and optical anisotropy of a chain unit induced by incorporation of the naphthalene groups into the macromolecule backbone have been evaluated.},
  language  = {en}
}
@article{LavrenkoStrelinaSchulz1997,
  author    = {Lavrenko, Peter N. and Strelina, Irina A. and Schulz, Burkhard},
  title     = {Dynamo-optical properties of poly(naphthylene oxadiazole)s in sulfuric acid},
  year      = {1997},
  abstract  = {Flow birefringence induced in dilute solutions of poly[(1,4-naphthylene)-2,5-diyl-1,3,4-oxadiazole] and poly[2,6-naphthylene)-2,5-diyl-1,3,4-oxadiazole] in conc. sulphuric acid has been investigated. The shear optical coefficient was found for these polymers to be approximately double the value of that obtained in the same solvent for poly[(para-phenylene) -2,5-diyl-1,3,4-oxadiazole]. Rigid-chain behaviour of the polymers was characterized by hydrodynamic and dynamo-optical parameters evaluated with application of the worm-like chain model and the "method of similar structures". Change in optical anisotropy of a chain unit induced by incorporation of naphthylene groups into the main chain has been evaluated.},
  language  = {en}
}
@article{LavrenkoOkatovaSchulz1998,
  author    = {Lavrenko, Peter N. and Okatova, Olga V. and Schulz, Burkhard},
  title     = {Stability and degradation of poly(p-pheneylene-1,3,4-oxadiazole) molecules in sulphuric acid},
  year      = {1998},
  abstract  = {The translational diffusion coefficient and intrinsic viscosity of poly(1,4-phenylene-1,3,4-oxadiazole) molecules in 96\% H2S04 have been determined at different stages of degradation of the molecules in acid solution at temperature ranging from 82 to 105 °C. The degradation rate constant, k, has been obtained from the change in the molecular weight, M, of the product degraded in solution with time at high temperature. The activation energy of the hydrolysis process was 103 ± 7 kJmol-1, which is smaller than that of aromatic polyamides in the same solvent. According to our hydrodynamic data, the degree of coiling of the molecules of degraded products does not differ from that of undegraded samples, and our conclusion was that the degradation is not accompanied with a noticeable change in the short- range interactions in the molecular chain and may be understood as a random chain scission.},
  language  = {en}
}
@article{LavrenkoOkatovaSchulz1998,
  author    = {Lavrenko, Peter N. and Okatova, Olga V. and Schulz, Burkhard},
  title     = {Hydrodynamic properties and conformation of the molecules of meta- and para-isomers of polyphenyleneoxadiazole in sulphuric acid},
  year      = {1998},
  abstract  = {Translational diffusion of poly(1,4-phenylene-1,3,4-oxadiazole) in 96\% H2S04 was studied, and the intrinsic viscosity of the polymer solution was measured in various stages of degradation at temperatures from 82 to 105°C. The rate constant of the degradation process was determined from variation of the molecular mass of the degradation products with time at a fixed solution temperature, and the activation energy of the process was calculated using the temperature dependence of the rate constant. The activation energy (E = 103 ± 7 kJ/mol) is lower than that for the hydrolysis of aromatic polyamides in sulfuric acid. According to the hydrodynamic data, the degree of coiling of the degradation products is the saine as that of the intact (non-degraded) macromolecules. This indicates that elements of the chernical structure responsible for the short-range order in the macromolecular chain are retained in the course of degradation.},
  language  = {en}
}
@article{LavrenkoOkatovaCherkasovetal.1998,
  author    = {Lavrenko, Peter N. and Okatova, Olga V. and Cherkasov, Victor A. and Schulz, Burkhard},
  title     = {Hydrodynamic properties of Poly(p-phenylene-oxadiazole) in various stages of hydrolytic thermal degradation in sulfuric acid},
  year      = {1998},
  language  = {en}
}
@article{OkatovaLavrenkoFedotovetal.1995,
  author    = {Okatova, Olga V. and Lavrenko, Peter N. and Fedotov, Y. A. and Schulz, Burkhard},
  title     = {Polyelectrolyte behavior of some new polyheteroarylene derivatives in sulfuric acid},
  year      = {1995},
  language  = {en}
}
@article{OkatovaAndreevaSchulzetal.1999,
  author    = {Okatova, Olga V. and Andreeva, Katharina A. and Schulz, Burkhard and Lavrenko, Peter N.},
  title     = {Degradation of poly(m-phenylene oxadiazole) in concentrated sulfuric acid},
  year      = {1999},
  language  = {en}
}
@article{LavrenkoOkatovaSchulzetal.1999,
  author    = {Lavrenko, Peter N. and Okatova, Olga V. and Schulz, Burkhard and Andreeva, Katharina A. and Strelina, Irina A.},
  title     = {Hydrodynamic and dynamo-optical properties of poly(1,3-phenylene-1,3,4-oxadiazole) molecules in sulphuric acid},
  year      = {1999},
  abstract  = {Translational diffusion of the macromolecules, intrinsic viscosity and flow birefringence induced in dilute solutions of poly(1,3-phenylene-1,3,4-oxadiazole) (PMOD) in conc. sulphuric acid has been investigated. Molecular-weight dependences of hydrodynamic and dynamo-optical properties are established over the M range from 8.1 103 to 87 103. Experimental data agree well with the theories developed for translational friction and intrinsic viscosity of the wormlike chains with the following molecular parameters: mass per chain unit ML = 22.7 Dalton/{\AA}, the Kuhn segment length A = 59 ± 4 {\AA}, the chain diameter d = 4 ± 1.5 {\AA}. Hindrance to intramolecular rotation is characterized by the parameter s = 1.7. The shear optical coefficient was found to be approximately 1.7 times lower the value of that obtained in the same solvent for the para-phenylene isomer of this polymer, being in good agreement with higher equilibrium flexibility of the PMOD molecule chains in solutions as determined herein from the hydrodynamic data.},
  language  = {en}
}
@article{LavrenkoAndreevaStrelinaetal.1999,
  author    = {Lavrenko, Peter N. and Andreeva, Katharina A. and Strelina, Irina A. and Garmonova, Tatjana I. and Schulz, Burkhard},
  title     = {Optical anisotropy and flexibility of poly(m-phenylene oxadiazole) in sulfuric acid},
  year      = {1999},
  language  = {en}
}