Polymers and Plastics Series: Integrated Analytical Approaches

04 Jun 2019

Solving Complex Polymer Packaging Problems

Flexible polymer packaging materials are widely used for a variety of products, including food, chemicals, and medical devices. Polymer films can bring unique barrier properties and allow for efficient packing and transport. A variety of advanced analytical techniques can be used to evaluate performance, evaluate claims and investigate compatibility issues of these films. Here are three case studies that demonstrate the value of an integrated analytical approach and in solving tough polymer and packaging problems.

Green Polymers for Medical Devices

For a polymer made from natural products to be used in an implantable medical device, it was important to understand the basic chemical properties of the polymer and any issues around the processing of the polymer. Chemical structure analysis included residual monomer (initially 10 times the competition) molecular weight distribution and copolymer structure (random distribution with a 53/47 split between two monomers). Examining processing properties included swelling profiles in water, thermal expansion and swelling/softening. Heating and aging properties continued to change over six months and the transition between polymorphs was relatively sharp, with one form dominating the first few microns of the fiber surface.

Thin Film Laminates for Food Packaging

For thin film laminates used in food packaging, imaging Raman spectroscopy on a microscope stage can be useful to analyze the composition of the laminates within the thin film and to measure the size of each component of the laminate. This specific case showed six discrete layers made up of polypropylene, polyethene, EVOH and a polyester copolymer, each with its own distinct properties. This in turn helps analyze the packaging to ensure the manufacturer of its performance and quality.

Failure Analysis for Food Shipping Containers 

Plastic shipping bags used for shipping a variety of liquid products (mostly foods) have shown strange failures in transoceanic shipping. Analytical approaches can be used to explore why bags may have a higher failure rate for a single product based on chemical and physical aspects. Failure analysis showed a fatigue crack mechanism, chemical analysis by gas chromatography mass spectrometry (GC-MS), gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) showed that the polymers were essentially identical. Low level low molecular weight differences were explored but were not causal. The fatigue cracking failure mechanism was consistent with repetitive forces, showing no real degradation of the polymer, no significant contamination and no significant difference in polymer performance.  Instead, the failures occurred with a liquid of higher density, but low viscosity. Sloshing during shipment exerted extra force on the bags causing failures.

Integrated analytical approaches provide multiple data points and clues, allowing us to solve new and different problems on a regular basis.  With both chemical and performance data, we can analyze structure and property. Innovative new polymeric materials require innovative characterization, teamwork and collaboration. For more insights on these case studies and integrated analysis, download our webinar recording.