WIDE-ANGLE X-RAY-SCATTERING STUDY OF CRYSTALLINE ORIENTATION IN RETICULATE-DOPED POLYMER COMPOSITES

Reticulate doping consists of casting a composite film from a solution containing both a polymer and a charge-transfer complex (CTC) and all owing the conductive free radical salt to recrystallize as the solvent is removed from the polymer. In this study, a highly branched, low mo lecular weight polyethylene (PE) was doped with the CTC tetrathiafulva lene-tetracyanoquinodimethane (TTF-TCNQ). Wide-angle X-ray scattering (WAXS), conductivity, optical microscopy, stress relaxation, and diffe rential scanning calorimetry (DSC) measurements were used to show the effect of the addition of filler and uniaxial orientation on the mecha nical and electrical properties of the composites. It has been shown t hat increasing TTF-TCNQ concentration shifts the preferential orientat ion 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 degrees C and cooled t o room temperature. These experiments showed a smaller incremental inc rease in crystalline orientation with increasing TTF-TCNQ. This observ ation was consistent with a drop in initial relaxation times calculate d from room temperature stress relaxation experiments. In the unorient ed composites, increasing TTF-TCNQ loading had no effect on PE crystal linity; however, the increase in crystallinity caused by uniaxial stre tching was decreased by the presence of TTF-TCNQ. (C) 1998 John Wiley & Sons, Inc.