skip to main content


The NSF Public Access Repository (NSF-PAR) system and access will be unavailable from 11:00 PM ET on Thursday, June 13 until 2:00 AM ET on Friday, June 14 due to maintenance. We apologize for the inconvenience.

Search for: All records

Creators/Authors contains: "Hegde, Maruti"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. null (Ed.)
  2. null (Ed.)
  3. Melt acidolysis polymerization of hydroquinone with a kinked monomer, biphenyl 3,4′-bibenzoate, afforded a novel liquid crystalline polymer (LCP), poly( p -phenylene 3,4′-bibenzoate) (poly(HQ-3,4′BB)). Selection of hydroquinone diacetate (HQ a ) or hydroquinone dipivilate (HQ p ) facilitated either a tan or white final polymer, respectively. 1 H NMR spectroscopy confirmed consistent polymer backbone structure for polymers synthesized with either derivative of hydroquinone. Poly(HQ-3,4′BB) exhibited the onset of weight loss at about 480 °C, similar to commercially available Vectra® LCP. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) revealed a glass transition temperature ( T g ) of 190 °C and an isotropic temperature ( T i ) near 330 °C. The observation of a melting temperature ( T m ) depended upon the thermal history of the polymer. Wide-angle X-ray scattering (WAXS) and polarized optical microscopy (POM) confirmed the formation of a nematic glass morphology after quench-cooling from the isotropic state. Subsequent annealing at 280 °C or mechanical deformation induced crystallization of the polymer. Rheological studies demonstrated similar shear thinning behavior for poly(HQ-3,4′BB) and Vectra® RD501 in the power law region at 340 °C. Zero-shear viscosity measurements indicated that HQ a afforded higher melt viscosities after identical polymerization conditions relative to HQ p , suggesting higher molecular weights. 
    more » « less