The addition of a capillary viscometer as well as special IR sensor, for ethylene content determination, to the CRYSTEX instrument creates a very powerful tool for the analysis of polypropylene copolymers. A schematic diagram of such an instrument is presented in Figure 1, together with the parameters being measured directly: Whole sample at high temperature after dissolution cycle and amorphous fraction (rubber) at low temperature after crystallization. All information available from a single experiment is summarized in Table 1 for a series of different samples.
ResultsThe capillary viscometer implemented into the CRYSTEX makes it possible to obtain the intrinsic viscosity [η] of the original sample as well as of the amorphous and crystalline components. Polymers in a very broad range of viscosity can be measured providing good precision better than 0.7% RSD.
A precise and robust apparatus has been made available to fully characterize PP copolymers. The intrinsic viscosity and ethylene contents of the whole polymer and its amorphous and crystalline fractions can be determined, as well as the soluble fraction percentage, which directly relates to xylene solubles, in a single analysis using a fully automated instrument under computer control. Thus a very comprehensive characterization of PP is achieved with a single instrument requiring very little operator interaction.