Characterization of Polymers and Plastics (pellets, powders and films) by the Thermo Scientific FLASH 2000 Elemental Analyzer

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1 Characterization of Polymers and Plastics (pellets, powders and films) by the Thermo Scientific FLASH 000 Elemental Analyzer Dr. Liliana Krotz and Dr. Guido Giazzi Thermo Fisher Scientific, Milan, Italy Application Note 0 Key Words CHNS/O, Dumas method, Polymers, Plastics Goal Samples of polymers and plastics, raw materials and additives were analyzed, considering the different content and aspect (pellets and films), to demonstrate the performance and reliability of the Thermo Scientific FLASH 000 Elemental Analyzer. Introduction The development and production of polymers and plastics requires rigorous quality control of raw materials, additives, stabilizers, intermediate and finished products. The analysis of their behaviour during moulding and the product lifetime evaluation is essential to ensure the quality of plastics. The chemical composition of plastics and polymers is tightly connected with their specific characteristics and their chemical/physical/mechanical properties. One of the required analyses is the quantification of nitrogen, carbon, hydrogen, sulfur and oxygen. Nitrogen determination is crucial, but the importance of sulfur evaluation has increased in recent years, as many of the classical methods are no longer suitable for routine analysis. Nitrogen containing compounds are used in the production process as a polymerization reaction. It can also act as termination agent and additive in order to provide the final product with specific properties. As an additive, nitrogen containing compounds can be used as: Stabilizing emulsion polymers. Chain transfer agents and other polymerization modifiers to control molecular weight. Plasticizers to increase flexibility. Stabilizers to prevent polymer degradation. Crosslinkers used to modify polymer networks. As the specification of the element content is sometimes very limited, an accurate measurement is required in order to maximize sample throughput, reduce operational costs and minimize human errors. Therefore, a simple and automated technique, which enables fast analysis combined with excellent accuracy and reproducibility is essential.

2 The Thermo Scientific FLASH 000 CHNS/O Elemental Analyzer (Figure ) requires no sample digestion or toxic chemicals, while providing important advantages in terms of time, automation and quantitative determination of nitrogen, carbon, hydrogen, sulfur and oxygen across a large range of concentrations, till trace content. The system provides automated and simultaneous CHNS determination in a single analysis run and oxygen determination by pyrolysis in a second run. The modularity of the system allows configuring the instrument for a single nitrogen determination, or for trace sulfur analysis when coupled to the Flame Photometric Detector (FPD). Methods For CHNS or CHN determination the FLASH 000 Elemental Analyzer operates with dynamic flash combustion of the sample. Samples are weighed in tin containers and introduced into the combustion reactor via the Thermo Scientific MAS 00R Autosampler with oxygen. After combustion, the produced gases are carried by a helium flow to a layer containing copper, then swept through a GC column, which provides the separation of the combustion gases. Finally it is measured by a thermal conductivity detector (TCD). Total run time is 8-0 minutes (Figure ). For trace sulfur determination, the gases produced by combustion are carried by a helium flow to a layer containing copper, Figure. FLASH 000 Elemental Analyzer. then swept through a water trap, a short GC column and finally the sulfur is measured by the flame photometric detector (FPD). Total run time is 5 minutes (Figure ). For oxygen determination, the system operates in pyrolysis mode. Samples are weighed in silver containers and introduced into the pyrolysis chamber via the MAS 00R Autosampler. The reactor contains nickel coated carbon at a temperature of 060 C. The oxygen in the sample, combined with the carbon, forms carbon monoxide which is chromatographically separated from other products and detected by the TCD detector (Figure ). Figure. CHNS/O configuration. Figure. Sulfur configuration by FPD detector.

3 For nitrogen determination, the Elemental Analyzer operates by dynamic flash combustion of the sample. Samples are weighed in tin containers and introduced into the combustion reactor via the MAS 00R Autosampler with oxygen. After combustion, the produced gases are carried by a helium flow to a second reactor containing copper, then swept through CO and H O traps, and a GC column. They are then detected by a thermal conductivity detector. Total run time less than five minutes (Figure ). A complete report is automatically generated by the Thermo Scientific Eager Xperience Data Handling Software. Results Different types of polymers and plastics, raw materials and additives were analyzed, considering the different content and aspect (pellets, powders and films), in order to demonstrate the performance of the FLASH 000 Elemental Analyzer, and to show the repeatability of results. Table shows the repeatability of CHNS/O determination in polyimide sample and Table shows the repeatability of NCS determination in polymers powders. For CHNS and NCS analysis, the system was calibrated with - mg of BBOT* standard using K factor as calibration method. The sample were weighed at - mg. For oxygen determination, - mg of benzoic acid was analyzed as standard using K factor. The sample were weighed at - mg. Table shows the CHN/O data of polyacrilonitriles. The calibration was performed with - mg of acetanilide using K factor as calibration method, and sample was weighed at - mg. Acrilonitrile (monomer) is the main component of many types of compounds (polyacrylonitriles) such as plastics. *BBOT:,5-Bis (5-tert-butyl-benzoxazol--yl) thiophene Figure. Nitrogen configuration. Table. CHNS/O data of polyimide. Element N% C% H% S% O% Average % RSD % Table. NCS data of polymers powders. Sample N% RSD % C% RSD % S% RSD % Table. CHN/O data of polyacrilonitriles. Sample N% RSD % C% RSD % H% RSD % O% RSD % A B C

4 Table shows the nitrogen data of polymers in pellets. The system was calibrated with 0- mg atropine standard using K factor as calibration method. Samples and were weighed at mg. For samples to 5 the calibration was performed with 5-6 mg atropine and samples were weighed at 0-0 mg. Table 5 shows the nitrogen data of polycarbonate polymers in pellets analyzed in duplicate. The system was calibrated with 5-0 mg atropine using K factor as calibration method. Sample was weighed at mg. Table. Nitrogen data of polymers (pellets). Sample N (ppm) RSD % Table 5. Nitrogen data of polycarbonate polymers (pellets). Sample 5 N % RSD % Table 6 shows nitrogen data of polyethylene films. As standard, - mg atropine was analyzed using K factor as calibration method. Samples were weighed at 0-5 mg. Table 7 shows the nitrogen data of plastics additives. The calibration was performed with 5-0 mg of atropine using K factor as calibration method. Samples were weighed at 5-0 mg. Table 6. Nitrogen data of polyethylene films. Sample N (ppm) RSD % Table 7. Nitrogen data of plastics additives Sample N % RSD % Raw Material Raw Material Raw Material Raw Material Raw Material (Dimeric Benzotriazole) Polycarbonate Dimeric Benzotriazole 0.69 Raw Material (Hindered Amine Light Stabilizer) 5.70 White Polystyrene Granules (Contains Hindered Amine Light Stabilizer) For trace sulfur determination by FPD detector, the system was calibrated with Thermo Scientific Pasta and Soil Reference Materials with 0.5 %S and 0.0 %S, respectively using quadratic fit as calibration method.

5 Table 8 shows the sulfur data of a polyethylene film sample. Table 9 shows the sulfur data of plastic powders while Table 0 shows the sulfur data of polymers. The samples were cut into small pieces and the samples were weighed 0.5- mg. Table 8. Sulfur data of polyethylene film sample. S (ppm) RSD % Table 9. Sulfur data of plastic powders. Sample S (ppm) RSD % Conclusions The Thermo Scientific FLASH 000 Elemental Analyzer, based on the Dumas combustion method has proved to be a valuable solution for the elemental analysis in polymers and plastics in terms of accuracy, repeatability and sensitivity of results. Its automation, high speed of analysis and the elimination of sample preparation process allow efficient analysis and help to reduce overall operational costs. The analysis was performed without matrix effect when changing the sample and element content indicating the complete combustion of the samples. With an upgrade, the FLASH 000 Elemental Analyzer can determine nitrogen only, simultaneous CHNS, NCS, CHN and oxygen. Trace sulfur determination is achieved when the system is coupled with the FPD detector. Table 0. Sulfur data of polymers. Sample S (ppm) Av. S (ppm) RSD % A B C D E F G H I J Application Note Thermo Fisher Scientific Inc. All rights reserved. ISO is a trademark of the International Standards Organization. All other trademarks are the property of Thermo Fisher Scientific and its subsidiaries. This information is presented as an example of the capabilities of Thermo Fisher Scientific products. It is not intended to encourage use of these products in any manners that might infringe the intellectual property rights of others. Specifications, terms and pricing are subject to change. Not all products are available in all countries. Please consult your local sales representative for details. Thermo Fisher Scientific S.p.A. Milan, Italy is ISO 900:008 Certified. Africa Australia Austria Belgium Canada China (free call domestic) AN0-EN 05S Denmark Europe-Other Finland France Germany India Italy Japan Korea Latin America Middle East Netherlands New Zealand Norway Russia/CIS Singapore Spain Sweden Switzerland UK USA