Explore polymer characterization (Part 1) : Techniques and their impact

by Taco van der Maten, Tuesday, 28th May 2024

transparent colored polymers plastic resins in test glasses in laboratory

Polymers are materials made up of a chain of repeating small monomers and they are found almost everywhere. There are natural polymers, such as wool and cellulose, but most people will be more familiar with the largest group of synthetic polymers: plastics. But with growing concerns about the impact of plastics on sustainability, polymer characterization techniques are becoming increasingly important.

These techniques can provide a wide range of measurements and insights into the properties of polymers. You can take a plastic bottle and find out exactly what polymers it’s made of, including the additives that enhance or change its properties. Or you can start with isolated polymers, investigate their molecular structure, such as whether it’s arranged in a crystalline or amorphous phase, and use that information to design new generations of plastic bottles.

So, innovations in polymer characterization can help design new materials with desired properties. How has our increased understanding of polymers and related analytical technologies improved our ability to design materials that are more functional and sustainable?

The broad range of polymer characterization techniques

Polymer characterization includes many chemical analysis techniques that examine the chemical properties of the polymer, such as its elemental, molecular composition, or molecular phases.

For example, X-ray fluorescence (XRF) analyzes the elemental composition of polymers. This information can help at the design stage by ensuring that the composition of a plastic is within the expected parameters. But it’s also essential for recycling: XRF can measure the elemental composition in a plastic to indicate how recyclable it is and identify the types of additives it contains, such as light stabilizers, anti-statics, colorants, and fillers.

XRF is also useful in polymer manufacturing because it can determine the catalysts and their concentrations for making polymers. These polymerization catalysts are expensive: quantifying them helps manufacturers understand how effective a catalyst is, ensuring that manufacturers use the optimal amount of catalyst for production cost.

Polymers structure

X-ray diffraction (XRD) focuses on the polymer structure or phases. It helps to tailor polymers to a specific property by analyzing their crystalline/amorphous ratio. This ratio is critical to a polymer’s properties: tensile strength, impact strength, and opacity are all affected by the particular crystalline/amorphous ratio.

For example, when a polymer is stretched it may crystallize, making it harder but also more brittle. So, tuning the molecular parameters may change this crystallization behavior under strain to fit the application.

Differential scanning calorimetry (DSC) measures heat flow during heating or cooling, which helps analyze thermal transitions like melting points and glass transitions. DSC helps improve manufacturing processes by identifying a polymer’s melting trajectory “fingerprint”, allowing manufacturers to figure out the optimal mixing of additives, as well as how to process the polymer at scale and how to extrude it.

What a better understanding of polymers can achieve

The control over design and production processes that these technologies provide leads to many improvements in polymer function and sustainability. For example, when colorants are added incrementally until the desired color is achieved, XRF can then indicate the ideal ratio of colorants to polymer, which saves on the cost of expensive colorants. Since colorants are often more expensive than the polymer itself, it pays to check with XRF.

Another benefit is more stable plastics. When the longevity and durability of the plastic are important properties, manufacturers can add UV stabilizers to prevent the polymer from becoming brittle in sunlight. Additives such as these are useful in the right proportions but can weaken the plastic if too much or too little is added – polymer characterization helps manufacturers strike a balance.

Polymer characterization is also important for compliance with international regulations. A challenge for characterization technologies in this context is being able to provide chemical analysis that’s up to date with the latest regulatory standards. Malvern Panalytical liaises with standard development organizations, such as ISO and ASTM International, and regulatory bodies, such as one of the EU Joint Research Centres (the Institute for Reference Materials and Measurements), to ensure its instruments always meet the highest expectations.

By combining innovation with regulation and technical support for our customers, we aim to put the very best polymer characterization techniques in the hands of researchers and manufacturers. 

Make sure you’re getting the most from the latest polymer characterization innovations – read our polymer recycling page to find out more.

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