Fully Automated Quality Control Solutions for Polypropylene and Polyethylene Production

Polymer Char, focused on polyolefin characterisation techniques, has available a platform of four automated analytical techniques for quality and process control in PP and PE production plants. CRYSTEX^® QC is an instrument that measures the soluble fraction, ethylene content, and intrinsic viscosity in polypropylene and polyethylene resins. It overcomes all the difficulties of the gravimetric methods based on xylene solubility and traditional wet chemistry, by eliminating sample weighing, external filtration or extraction devices, and all the associated tedious manual operations. No handling of solvent by the operators is required either. CRYSTEX^® QC analyses one large sample (up to 4 grams of polymer) at-a-time in and delivers the amorphous fraction %, ethylene content and intrinsic viscosity in approximately two hours. A similar, but high-throughput system of capacity for 42 consecutive samples is CRYSTEX^® 42, also offered for obtaining the soluble fraction %, ethylene content and intrinsic viscosity but in more homogeneous (pelletized) polypropylene and copolymers.

Both instruments are based on the TREF separation concept in which the sample is loaded into a TREF column for measuring the soluble and crystalline fractions of the polymer. Results are very precise due to the automation and the integration of an infrared detector (IR4), which accurately measures the amount of sample analysed.

Next is GPC-QC, a fast GPC/SEC for molar mass distribution in production and plant environments. This compact, high-temperature GPC/SEC instrument designed for manufacturing lines, delivers the complete Molar Mass Distribution for one sample through a simplified and fully-automated workflow that lasts approximately 30 minutes, including dissolution. The IR detection implemented in the instrument is highly stable, contributing to the overall reliability whilst providing chemical composition information at the same time. Such information is critical for controlling production of heterogeneous resins. This is particularly relevant in the case of copolymers that account for a large proportion of polyolefins produced, such as LLDPE, some HDPE, and the important group of EP copolymers as well. The information generated by the IR detector can be translated to either co-monomer weight fraction or to density units for a given product range.

Last in Polymer Char’s QC platform is a fully-automated Intrinsic Viscosity Analyser for determination of viscosity in polymeric materials. The whole process is performed without user intervention or handling any solvents including filling of vials and dissolution of the samples, thanks to an autosampler with capacity of up to 42 samples. IVA is compatible with the typically used organic solvents such as decalin, tetralin, tri-chlorobenzene (TCB) and orthodichlorobenzene, among many others. Dissolution temperature and analysis temperature can be programmed independently from ambient to 200oC, meaning that a wide range of polymers, even most crystalline ones, can be analysed with convenience and safety.

The analysis of polyolefins and other polymers containing significant C-H content can be further expanded by the incorporation of the optional Infrared detector IR4 to accurately quantify the injected polymer mass, which results in improved precision and accuracy of viscosity results.