Rheology and Quality Control for Packaging

FSP600 Film Scanning System

The rheology of a packaging material impacts on production processes (e.g. thermoforming, blown and cast film, injection moulding (IM)) through its impact on flow.

Quality Control/Quality Assurance (QC/QA) for the material is possible through:

Implementation of small scale extrusion, and blown/cast film or IM operations

Extrusion systems with rheology dies, to assess the performance of the material in a processing scenario

Optical monitoring of the raw materials and finished products, to detect impurities and defects in the final product

Rheology of packaging materials:

The efficiency of many packaging processes, like flow-wrapping with flexible packaging or stacking/filling rigid, thermoformed or injection moulded packaging can be influenced by many parameters. Foremost amongst these is the molecular architecture of the polymer(s) used in the packaging material. This may be even more critical for recycled or reprocessed materials. These properties dictate the flow behaviour (rheology) of the polymer and may be measured using the rheological parameters of the polymeric material. They impact on the film-forming, mould–filling and thermoforming (possibility of thin spots) capability of a polymer, as well as many other flow-dependent performance properties. The flow properties of materials may be tested in the laboratory, using high-temperature rheometry.

QC/QA with small scale process equipment:

The processing and packaging performance of the polymeric packaging materials may be tested on a laboratory scale using instrumented laboratory extrusion systems, with small-scale post-ex assets (like small scale blown-film towers, or injection moulders) for example. In this way properly graded packaging base ingredients can be released for full-scale processing, and quality assurance/fault-tracing is facilitated during pre- or post-processing. Some laboratory extruders may also be fitted with rheology dies, to measure rheological parameters, as well as service the scaled-down post-ex plant.

QC/QA with optical monitoring:

During the manufacture of flexible or rigid packaging, optical techniques can be invaluable for improving the final quality of these packaging materials. At the source (the polymer resin) optical scanning techniques can detect, qualify and quantify impurities, such as black-spots, before the resin is processed. Post-ex, scanning techniques can detect, quantify, qualify impurities (e.g. fish-eyes) and therefore accurately grade product, indicating the likelihood of failure (tearing during flow-wrapping, holes or weak spots during thermo-forming, visible imperfections for moulded components) during packaging operations later.

Rheology Solutions offers a range of equipment and technical literature tailored to the Packaging and Polymer industries