Wide-angle X-ray scattering study of crystalline orientation in reticulate-doped polymer composites

✍ Scribed by W. B. Genetti; R. J. Lamirand; B. P. Grady

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 240 KB
• Volume: 70
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19981128)70:9<1785::aid-app17>3.0.co;2-8

✦ Synopsis

Reticulate doping consists of casting a composite film from a solution containing both a polymer and a charge-transfer complex (CTC) and allowing the conductive free radical salt to recrystallize as the solvent is removed from the polymer. In this study, a highly branched, low molecular weight polyethylene (PE) was doped with the CTC tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ). Wide-angle X-ray scattering (WAXS), conductivity, optical microscopy, stress relaxation, and differential scanning calorimetry (DSC) measurements were used to show the effect of the addition of filler and uniaxial orientation on the mechanical and electrical properties of the composites. It has been shown that increasing TTF-TCNQ concentration shifts the preferential orientation of the crystalline phase of the PE from slightly perpendicular to slightly parallel to the casting surface. WAXS measurements were made on samples that were uniaxially stretched at 80°C and cooled to room temperature. These experiments showed a smaller incremental increase in crystalline orientation with increasing TTF-TCNQ. This observation was consistent with a drop in initial relaxation times calculated from room temperature stress relaxation experiments. In the unoriented composites, increasing TTF-TCNQ loading had no effect on PE crystallinity; however, the increase in crystallinity caused by uniaxial stretching was decreased by the presence of TTF-TCNQ.