Deformulation

Many polymer companies have not maintained a cadre of experts on the analysis of additives in polymers. Consequently, there is a need to train a new generation of people about additives and methods of deformulating them. Outsourcing of polymer/additive... 

J.W. Gooch, Analysis and Deformulation of Polymeric Materials, Paints, Plastics, Adhesives and Inks, Plenum Press, New York, NY (1997). 

There are thousands of commercially available additives of diverse chemical classes and with masses ranging from a few hundred to several thousand Daltons (cf. also Appendix II). Deformulation means reverse engineering, with subsequent analysis of each separated component. Product deformulation may hint towards the process of origin. Deformulation will combine several... 

It is of interest to examine the development of the analytical toolbox for rubber deformulation over the last two decades and the role of emerging technologies (Table 2.9). Bayer technology (1981) for the qualitative and quantitative analysis of rubbers and elastomers consisted of a multitechnique approach comprising extraction (Soxhlet, DIN 53 553), wet chemistry (colour reactions, photometry), electrochemistry (polarography, conductometry), various forms of chromatography (PC, GC, off-line PyGC, TLC), spectroscopy (UV, IR, off-line PylR), and microscopy (OM, SEM, TEM, fluorescence) [10]. Reported applications concerned the identification of plasticisers, fatty acids, stabilisers, antioxidants, vulcanisation accelerators, free/total/bound sulfur, minerals and CB. Monsanto (1983) used direct-probe MS for in situ quantitative analysis of additives and rubber and made use of 31P NMR [69]. 

Deformulation of vulcanised rubbers and rubber compounds at Dunlop (1988) is given in Scheme 2.3. Schnecko and Angerer [72] have reviewed the effectiveness of NMR, MS, TG and DSC for the analysis of rubber and rubber compounds containing curing agents, fillers, accelerators and other additives. PyGC has been widely used for the analysis of elastomers, e.g. in the determination of the vulcanisation mode (peroxide or sulfur) of natural rubbers. 

Scheme 2.3 Dunlop s deformulation of vulcanised rubbers. After Schnecko and Angerer [72]. Reproduced by permission of Hiithig GmbH...

Scheme 2.6 Rubber deformulation. After Coz and Baranwal [80]. Reproduced by permission of Rubber World Magazine (Lippincott)...

Gooch [4] has reported general deformulation schemes for solid paints and coatings, liquid paints, solid plastics, liquid plastic specimens, solid and liquid adhesives, in which preliminary examination (by OM, SEM, EDXRA) is followed by separation of the individual components and their subsequent identification (Scheme 2.9). Gooch employs different deformulation schemes for solid and liquid specimens, but essentially identical approaches for plastics, paints, adhesives and inks (Scheme 2.10). 

Scheme 2.9 General deformulation for paints, plastics, adhesives and inks. After Gooch [4]. Reproduced from J.W. Gooch, Analysis and Deformulation of Polymeric Materials, Paints, Plastics, Adhesives and Intes, Plenum Press, New York, NY (1997), by permission of Kluwer Academic/Plenum Publishers...

The increase in scientific production on polymer deformulation is considerably higher than the inflation in scientific papers (3.4% as from 1989). Bourgeois [111] has recently described reverse engineering of polyolefins and polyolefin blends. 

The first step in destructive polymer/additive deformulation is usually transfer of the additives into the... 

Table 3.4 compares the performance of dissolution and various extraction procedures. Chapter 9 addresses in more detail direct methods of deformulation of polymer/additive dissolutions, i.e. without separation... 

Although polymers in-service are required to be resistant toward hydrolysis and solar degradation, for polymer deformulation purposes hydrolysis is an asset. Highly crystalline materials such as compounded polyamides are difficult to extract. For such materials hydrolysis or other forms of chemolysis render additives accessible for analysis. Polymers, which may profitably be depolymerised into their monomers by hydrolysis include PET, PBT, PC, PU, PES, POM, PA and others. Hydrolysis occurs when moisture causes chain scissions to occur within the molecule. In polyesters, chain scissions take place at the ester linkages (R-CO-O-R ), which causes a reduction in molecular weight as well as in mechanical properties. Polyesters show their susceptibility to hydrolysis with dramatic shifts in molecular weight distribution. Apart from access to the additives fraction, hydrolysis also facilitates molecular characterisation of the polymer. In this context, it is noticed that condensation polymers (polyesters, -amides, -ethers, -carbonates, -urethanes) have also been studied much... 

Major applications of modern TLC comprise various sample types biomedical, pharmaceutical, forensic, clinical, biological, environmental and industrial (product uniformity, impurity determination, surfactants, synthetic dyes) the technique is also frequently used in food science (some 10% of published papers) [446], Although polymer/additive analysis takes up a small share, it is apparent from deformulation schemes presented in Chapter 2 that (HP)TLC plays an appreciable role in industrial problem solving even though this is not reflected in a flood of scientific papers. TLC is not only useful for polymer additive extracts but in particular for direct separations based on dissolutions. 

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