Ammonium peroxydisulphate

Ammonium peroxydisulphate [7727-54-0] M 228.2. Recrystd at room temperature from EtOH/water. 

The first method, although effective, was soon abandoned for safety reasons, while the use of chromic acid has been largely discontinued. The other two have remained the most widely used pre-treatments, not only for LDPE but also for high-density polyethylene (HDPE) and polypropylene (PP). Other methods have been found to be effective, but for reasons of cost, safety or convenience, they have not been widely used. The pre-treatments include fuming nitric acid, potassium permanganate, ammonium peroxydisulphate, ozone, fluorine, peroxides, UV radiation, grafting of polar monomers, plasmas (see Plasma pretreatment), electrochemical oxidation (see Electrochemical pre-treatment of polymers) and the use of solvent vapours. The corona, flame and plasma methods and the use of trichloroethylene are now discussed briefly the latter is included because it involves a different mechanism. 

A variety of oxidants have been used to elfect chemical polymerization of aniline under acidic conditions, pH 1-3. It is very strange to note that there is no relationship between the oxidation potential of the reagent and the polymer yield however, our experience in polyaniline synthesis suggests that a simple oxidizing agent like ammonium peroxydisulphate yields a polymer of better quality than oxidizing agents contain-... 

Figure 4.7 Effect of pretreatment time and temperature on the joint strength of low-density polyethylene treated with 0.26 M solution of ammonium peroxydisulphate [50,51].

The chemical oxidative polymerization of aniline in aqueous HCl solution by ammonium peroxydisulphate, (NH4)2S203 is a modification of previously-published methods [2]. Elemental analyses for hydrogen are not sufficiently accurate to determine the extent of protonation, ("doping level) of the polymer. However, it can be safely assumed that each chloride ion found in the polymer will be accompanied by one proton. 

Anodic oxidation in aqueous solution often provides the best method of obtaining an element in its highest oxidation state. Ammonium and potassium persulphates (peroxydisulphate) are prepared by electrolysing concentrated solutions of the corresponding sulphates with cathodes usually of lead and smooth platinum anodes (at which the oxygen overpotential is high). The over-all reaction is... 

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