CRYSTALLINITIES OF POLY(CHLOROTRIFLUOROETHYLENE) AND ITS COPOLYMERS BY DIFFERENTIAL SCANNING CALORIMETRY, X-RAY-DIFFRACTION, AND DENSITY-MEASUREMENTS

Crystallinities of films of copolymers of chlorotrifluoroethylene with 0 to 4% vinylidene fluoride, different molecular weights and thermal histories were calculated from differential scanning calorimetry (DSC) , X-ray diffraction (XRD), and density measurements. The crystalliniti es for these films range between 16 to 58%, 11 to 71%, and 13 to 77% a s determined by DSC, XRD, and density, respectively. Although the nume rical value of the DSC, XRD, and density crystallinities obtained by e ach of the techniques are different, they correlate well with each oth er. The primary source of error in DSC is the uncertainty in drawing t he baseline for separating the heat of fusion and heat of crystallizat ion. In XRD, the ambiguities in the separation of the amorphous and cr ystalline peaks reduce the precision of the results. Calculation of cr ystallinity from density values requires that the distribution of the VF2 between the amorphous and crystalline regions be known. In additio n, the density technique is not sensitive to variations in the crystal line and amorphous densities.