Editor’s Note: Do you need to analyze polymers for product quality assurance and quality control verification, failure analysis, deformulation, or product development? There are a variety of molecular spectroscopy techniques and applications that can help in your analysis — from Near Infrared (NIR) technology, Fourier Transform Infrared Spectroscopy (FTIR) and Fluorescence, to Raman and Ultraviolet-Visible and Visible Spectrometry. But if your sample is especially challenging, your first step might be to analyze the problem itself.
We’ll spend every Tuesday in February identifying three plastic and polymer problems, suggesting how to analyze the sample, and then recommending some spectroscopy solutions to help your analysis. Here are the first three problems:
Symptom 1: Bloom
Bloom refers to discolorations on polymers from phase separation of the material’s components and is caused by the incompatibility of certain additives with the polymer or other ingredients such as the migration of solid or liquid compounding materials which have a limited solubility in the polymer matrix. The best way to test this type of sample is to scrape material from the surface, then measure by single-bounce Attenuated Total Reflectance (ATR) sampling. Attenuated total reflection (ATR) is now the most common sampling technique in FT-IR spectroscopy. It allows you to quickly analyze polymer samples directly for identification or verification of bulk properties such as blend ratio. Your data analysis plan should include searching libraries for identifying the unknown material and adjusting the formulation based on identified material. An FT-IR Spectrometer — fitted with an Attenuated Total Reflectance (ATR) sampling accessory designed for use with a single bounce diamond crystal – is an appropriate instrument for this kind of analysis. Make sure the instrument utilizes software composed of spectral identification tools, interpretation algorithms, and scientific documentation that indexes the information.
Symptom 2: Hazing, Streaking, Incorrect Color
Improper formulation of additives or fillers, contamination, or poor mixing can result in hazing, streaking, or incorrect color. Make sure you measure directly or excise outer or inner material from sample. For best measurement, use a diamond ATR Mid-IR or Far-IR for inorganic fillers. To identify the problem, your data analysis plan should include comparisons to reference part data and search of libraries to identify differences. You should also change formulation if appropriate. We would recommend using an FT-IR Spectrometer – with built-in diamond ATR accessory, a solid-substrate beamsplitter, and the appropriate software with spectral identification tools, interpretation algorithms, and scientific documentation that indexes the information.
Symptom 3: Oily, Tacky Surface
Improper additive formulation or contamination could cause an oily or tacky surface. In order to measure the sample, you should wipe or scrape the surface to isolate material or direct analysis. Then you can measure the residue or sample surface on single bounce ATR as well as measure a reference part or sample with surface cut off. To identify the problem, your data analysis plan should include searching libraries to identify the material and adjusting the formulation or changing the process to avoid contamination. Like the Bloom problem, an FT-IR Spectrometer — fitted with an Attenuated Total Reflectance (ATR) sampling accessory– is an appropriate instrument for this kind of analysis. A monolithic diamond ATR crystal and high-efficiency, all-reflective optics in combination with a variety of interchangeable crystal plates is recommended. As with all the above instruments, make sure the software is composed of spectral identification tools, interpretation algorithms, and scientific documentation that indexes the information.
Visit our online polymer spectroscopy resource center to learn how you can analyze these and other polymer problems.