Controlling thermomechanical behavior of semicrystalline hydrogenated polynorbornene through the cis- to trans-cyclopentylene ratio

Though polynorbornene synthesized by ring-opening metathesis polymerization has an intrinsically all-cis configuration of the cyclopentylene backbone rings, a fraction of these rings can be epimerized to the trans configuration during hydrogenation over suitable catalysts. By varying the method of hydrogenation, semicrystalline hydrogenated polynorbornenes (hPNs) with trans levels between 0 and 36% were obtained. With increasing trans content, the glass transition temperature, melting point, and enthalpy of melting decrease modestly. By contrast, the temperature at which the hPN crystal transitions into a rotationally disordered polymorph varies strongly with trans content, ranging from 126 °C (all-cis) to 71 °C at 27% trans; at trans contents of 34% and above, no rotationally-ordered phase is observed at any temperature. The room-temperature Young's modulus shows no dependence on trans content, while the yield stress drops by 20% at 1% trans content and slowly decreases further with additional epimerization. The temperature dependence of the Young's modulus differs for trans-containing versus all-cis polymers, while the temperature dependence of the yield stress is set by the polymorph type (rotationally ordered vs. disordered).     

Reply to comment on “Limitation of uranium and thorium traces in charnockite matrix‐PIXE analyses at 3 MeV with Si (Li) detector”

Journal of Radioanalytical and Nuclear Chemistry -     

Chemical Composition and Antioxidant Activity of Essential Oil from Fruit of Schisandra perulata

Chemistry of Natural Compounds -     

Multi-analyte HPLC–DAD Method for Concurrent Analysis of Six Antimicrobials and Three Proton Pump Inhibitors Frequently used in Management of Helicobacter pylori Infection: Application to Simulated Intestinal Fluid Samples

Chromatographia - The present work deals with the optimization, validation and application of a versatile HPLC–DAD method for concurrent estimation of nine antimicrobials and proton pump...     

QUANTUM CHEMICAL STUDY OF TIN–SUBSTITUENT BONDS IN TRICOORDINATED TIN COMPOUNDS

Journal of Structural Chemistry - A quantum chemical study of tin–substituent bonds in tricoordinated tin compounds is conducted using the PC GAMESS-Firefly package. The structures of the...     

Structural,Computational and 3D Interaction Energy Calculations of the Compound 2-chloro-3-(1-napthyl)-5,5-dimethyl-2-cyclohexenone

Crystallography Reports - The molecular structure of 2-chloro-3-(1'-napthyl)-5,5-dimethyl-2- cyclohexenone was determined by single crystal X-ray diffraction. The compound crystallized in a...     

INFLUENCE OF THE INITIAL ROUGHNESS OF INTERFACES ON THE INSTABILITY DEVELOPMENT AFTER SHOCK-WAVE PASSAGE

Journal of Applied Mechanics and Technical Physics - Turbulent mixing at interfaces of three-layer gas systems after shock-wave passage has been studied. The influence of the initial roughness of...     

Ray Statement of the Acoustic Tomography Problem

Doklady Mathematics - The ray statement of the inverse problem of determining three unknown variable coefficients in the linear acoustic equation is studied. These coefficients are assumed to...     

The Software System LingvoDoc and the Possibilities It Offers for Documentation and Analysis of Ob-Ugric Languages

Doklady Mathematics - The LingvoDoc system ( http://lingvodoc.ispras.ru ) provides a service for collaborative language documentation and computations on the collected data. This software system...