Polymer Contamination

A chelant—polymer combination is an effective approach to controlling iron oxide. Adequate chelant is fed to complex hardness and soluble iron, with a slight excess to solubilize iron contamination. Polymers are then added to condition and disperse any remaining iron oxide contamination. 

Birch, C.J., and Sinclair, C.S., Blow-Fill-Seal Extrusion of Spore Contaminated Polymer An exploratory study, BPS News, BFS Operators Association, Sept. 1998. 

Figure 22 ESCA spectra for clean and contaminated polymer films.

A number of integrated circuit (IC) failure mechanisms are related to the presence of water and impurities at device surfaces. The most catastrophic failures are open or short circuits resulting from electrochemical attack on substrate metallization. Other, more subtle maladies include increased capacitive coupling between conductors (1.), reduced bipolar current gain (2), shifted MOS threshold voltages (3.4), and parasitic MOS devices (5.6). These problems arise from spurious electrical conduction processes in the presence of moisture and ionic contaminants. Polymer encapsulants, such as silicone rubber, provide barriers that prevent the formation of conductive water films on IC surfaces. 

Nature of the contamination Polymer dispersions [I, 5.7.] are mainly contaminated with fungi. The fungicide property of the biocide is essential and MBT or Isothiazolinones are typically used for this application. 

Suitable waste plastics feedstocks are single contaminated polymers with high selectivity to monomers or commingled waste plastics. Some mixed polymer waste streams and their estimated volume, (US 1993 statistics), amenable to recovery/recycling by thermolytic processes are shown in Table [1]. 

Thermal evolution analysis is an excellent tool for polymer studies complementary to other thermal techniques such as DTA, TG and pyrolysis. Its applications include thermal degradation studies, determination of additives and contaminants, polymer composition and structure identifications. With small variations, the apparatus can also be used for vapour pressure measurements, and for determination of odorous materials in polymer systems. Coupling of TEA to GC for the identification of effluents is practicable and useful. TEA-CT-GC was used for the analysis of volatiles from ABS 10 ppb of styrene but negligible acrylonitrile was detected in the headspace of a typical ABS resin [42]. 

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