MATERIALS | TESTING
to safeguard consumer health by assuring the quality of polymers. This is evidenced by the number of areas that are tested for quality assurance, from impurity testing of raw materials to examining final products and packaging for leachates, volatile emissions and toxins. The other significant influence is the increasing global awareness of our environmental footprint, says Wita. To assure the highest possible quality of recycled polymers, it is important to pre-sort plastics. This means testing and analysis is critical and may often take place before the recycling process even begins. This allows for classification of plastic types, measurement of the crystallinity of semi-crystalline polymers and material characterisation, all of which are vital in assuring the quality of the material output. At present, PerkinElmer says that there are two primary problems that the industry is working to solve. “Firstly, there is the need to support the move towards a circular economy and to improve the recyclability of polymers,” says Wita. “To do so, we need to improve the speed at which the sorting and analysis of recyclable waste materials can be performed, in addition to improving our understanding of how specialist analysis improves the quality of the final materials, allowing for them to be put to the best possible use as they return into the cycle. FT-IR deployed through systems such as the Spectrum Two is presently the most common choice for analysis of polymers for quality assurance and control due to its high-speed, ease-of-use and ability to perform non-destructive analysis.” The second problem the industry is working to tackle is how to simulate accurately the thermal conditions a polymer may experience when it is implemented in a product, such as when it is used in injection moulding. Wita says the solution usually offered for determination of thermal properties such as melting point and glass transition temperature (Tg
) is differential scanning calorimetry
Right: The Spotlight IR infrared microscope from PerkinElmer allows detailed exploration of a polymer sample’s structural composition
28 COMPOUNDING WORLD | January 2022
(DSC). However, the most common type of DSC, heat flux DSC, typically uses heating rates below
50℃/min. Considering the injection moulding process often takes place in less than 30 seconds, she says this does not accurately simulate the conditions a polymer will experience. Perkin Elmer argues that Hyper DSC analysis using instruments such as PerkinElmer’s DSC 8000/8500 allows for controlled heating rates up to
750℃/min, providing a more accurate simulation of the process. Hyphenated options
Wita says another way the company is aiming to meet the expanding needs of industry is through its expansion of hyphenated solutions. For example, hyphenated Thermogravimetric – Infrared Analysis (TG-IR) provides powerful insight by pairing a thermogravimetric analyser with an infrared spectrometer for evolved gas analysis. When further hyphenated to TG-IR-GC/MS, this can present a very powerful combination that provides separation, identification and trace-level quantification all within a single workflow. Using hyphenated workflows such as these provides more information in less time. “The future of polymer testing lies in the development of solutions that allow for great speed and ease-of-use, helping labs to keep pace with the growing demand for high-quality polymer solutions,” says Wita. “I believe that through hyphenated analysis and software which is consistent across instruments, labs of the future will be better optimised to run the barrage of tests to meet their needs, making the ease of recycling and innovating in the polymer industry easier than ever before.”
Seeking answers IMAGE: PERKINELMER
Analytical polymer testing equipment touches every aspect of the plastics process chain, from resin polymerisation to compounding and conversion. “At each step, scientists and engineers in R&D and Quality Control need answers to understand and control key parameters such as melting point, crystallinity, melt stability, processability and blend compatibility, for example,” says Dr Bharath Rajaram, Senior Market Development Manager, Chemical & Materials Science at TA Instruments, a division of Waters Corporation. “Analytical testing provides these answers, allowing them to make time-sensitive decisions
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