The Challenge of Plastic Deformulation
Product failure, competitor claims, patent infringement, or pricing issues are all reasons companies look for polymer deformulation. The deformulation of plastics presents special challenges to the analytical chemist due to the unique nature of polymers and polymer families. Chemir Analytical Services understands the difficulty associated with identifying and quantifying product components. We have developed special expertise in the reverse engineering of plastics and have successfully deformulated many polymer products.
In most cases, our clients are interested in determining the additives in commercial polymeric products. Raw polymers are generally unsuitable for engineering applications and must be upgraded and customized. Numerous additives are on the market, and each enhances one or several specific properties. The most common additives are antioxidants, heat and light stabilizers, plasticizers, flame-retardants, processing aids, impact modifiers and fillers.
For extractive organic additives, we use a customized solvent extraction to isolate the additives from the base polymers. The necessary analytical techniques are then selected depending on the type of additives present. Gas Chromatography/Mass Spectroscopy (GC/MS) is often used for identification and quantitation of the volatile and semi-volatile organic additives. High Performance Liquid Chromatography (HPLC) may be used to analyze non-volatile and heat-unstable additives. Fourier Transform Infrared Spectroscopy (FT-IR), Nuclear Magnetic Resonance (NMR) Spectroscopy (NMR), Gel Permeation Chromatography (GPC) and UV-Vis spectroscopy are used to analyze polymeric additives such as impact modifiers, polymeric processing aids or plasticizers, and some polymeric UV stabilizers.
Inorganic additives such as pigments, fillers, reinforcement materials or some flame suppressants can be isolated from the polymer and organic additives by customized solvent extraction or by ashing. FT-IR, Thermogravimetric Analysis (TGA), Scanning Electron Microscope/Energy Dispersive X Ray Spectroscopy (SEM/EDXA), X-Ray Diffraction Spectroscopy (XRD) and Inductively Coupled Plasma Spectroscopy (ICP) may be used depending on the type and level of the targeted materials.
Metal stabilizers and organo-metallic catalysts, such as tin heat stabilizer in PVC or organo-metallic catalyst in polyurethanes or silicone based adhesives and sealants are difficult to separate from other organic additives. These can be identified by ICP trace metal analysis.
In addition, a number of our clients like to know the co-monomer contents or ratios in some special copolymer plastics such as Pebax (copolymer of tetramethlyene glycol with nylon 12), different types of Elvaloy (Dupont), ASA (acrylic-styrene-acrylonitrile), SEBS (styrene-ethylene-butylene-styrene) copolymer, etc. FT-IR and NMR are most useful in these instances. Sometimes, Pyrolysis GC/MS may be used depending on the sample property to be analyzed.
The most difficult plastics to deformulate are polyvinyl chloride (PVC), polypropylene (PP) and polyurethane (PU). Among the three, PVC, especially rigid formulations are the most complex. Rigid PVC has been in widespread use for several decades and a wealth of technology has been developed concerning its formulating, compounding, processing and applications. With many thermoplastic polymers it is necessary to add only small amounts of a few additives in order to obtain satisfactory properties. However, rigid PVC generally requires a significant number of additives in relatively large concentrations. The challenge lies not only in the number of additives, but in the separation of several polymeric additives such as the cross-linked impact modifiers, processing aids and lubricants from the PVC polymer and inorganic fillers for identification and quantitation. Also difficult is the identification and quantitative analysis of metal heat stabilizers, in particular the identification of the type of tin heat stabilizer in PVC.
In conclusion, no routine project exists in deformulation studies. People come to Chemir Analytical Services because of they need answers to difficult questions. A successful deformulation requires extensive knowledge, chemical experience as well as expertise at data interpretation. Every deformulation is a challenging learning opportunity for the scientists as Chemir.
Case study: Chemir Analytical Services recently examined two rigid PVC products for window profiles which contained about 9-10 components. In addition to the PVC base polymer, the additives in the formulation included a butyl acrylate rubber as the impact modifier, high molecular weight polymethyl methacrylate (PMMA) and polyethylene (PE) wax as the processing aids, calcium stearate and EBS (ethylene bisstearamide) present as the lubricant, and dibutyltin di (dodecyl mercaptide) as a heat stabilizer. The filler and pigment system was titanium dioxide and calcium carbonate. Another similar product contained a different tin stabilizer (alkyl tin mercaptoacetate) and silicone oils in addition to seven other similar additives. It was extremely challenging to separate, identify and quantify each additive in such a complicated formulation.
For more information about our deformulation services, or to request a project quotation, please visit www.chemir.com or call (800) 659-7659 and ask to speak with a Director of Technical Services.