Peptising Agents

The process for manufacture of a chloroprene sulfur copolymer, Du Pont type GN, illustrates the principles of the batch process (77,78). In this case, sulfur is used to control polymer molecular weight. The copolymer formed initially is carried to fairly high conversion, gelled, and must be treated with a peptising agent to provide a final product of the proper viscosity. Key control parameters are the temperature of polymerisation, the conversion of monomer and the amount/type of modifier used. 

In preparing the membrane, a clear sol was obtained by the addition of acid into the aluminum sec-butoxide sol to peptise the sol and obtain a stable colloid solution. Aluminum monohydroxides formed by the hydrolysis of aluminum alkoxides, which are peptisable to a clear sol. Peptisation was performed by the addition of acid and heat treatment for a sufficient time. It was found that stable sols cannot be obtained when the concentration of the peptisation acid is too low. The critical range for inorganic acids such as nitric, hydrochloric and perchloric acids is 0.03-0.1 mole/mole of hydroxide. In this study, nitric acid was used as the peptising agent. The resulting sols are poured into Petri dishes and dried in an oven at a controlled drying rate to obtain a gel layer. The molar ratio of zirconia salt... 

Natural rubber which has been reduced to an easy flowing consistency by prolonged mastication in the presence of peptising agents. Suitably compounded, DPR may be cast into moulds and vulcanised ebonite products from DPR are also possible. 

Natural rubber to which has been added on the plantation a quantity of a peptising agent. Such pre-softened and easily-softened rubbers... 

Compounding ingredients added to elastomers (2-5 phr) to increase plasticity and facilitate processing. In larger proportions (20-50 phr) certain oil softeners are classed as extenders. See Peptising Agent. 

An efficient peptising agent for natural rubber it is also used as a bleaching agent in the preparation of pale crepe rubber. 

It is the converse of coagulation or in other words, it is the re-dispersion of a coagulated sol. Substances like FeCl3 and HC1 which bring about peptisation are known as peptising agents. 

In the first series of experiments alumina support was formed with nitric acid as peptising agent. The support samples were calcined at three different temperatures (550, 750, and 800 °C, DN-650, DN-750 and DN-800). These alumina samples were submitted to the hydrothermal treatment (in water steam media) also at three different temperatures (150, 200 and 225 °C, Table 1 and Figs. 2 and 3). The results presented in Fig 2. clearly indicate that the alumina support calcined at 550 "C is not resistant against hydrothermal treatment in the applied temperature range. 

The further results given in Table 1 also indicate that some influence on supports structure transformation under hydrothermal conditions exerts type of used peptising agent. It was found that supports formed with using of nitric acid solution are more hydrothermally stable than alumina material formed with using of Culminal (DN-800 and DC-800 supports). The average pore radius in the case of DC-800 sample after hydrothermal treatment was two times larger than for DN-800 sample after the same treatment. 

The solutions thus formed behave in every way like other colloidal systems. The particles have a diameter of about 75 mm and iiaay be precipitated by the action of acids. It has not been possible from the literature to decide whether the tannin employed to deflocculate the graphite is a true peptising agent, or only a protective colloid. 

Zoltai, T., and M. J. Buerger, 1960. The relative energies of rings of tetrahedra. Z. Krist. 114 1. Zsigmondy, R., 1914. Influence of the quantity of peptising agent on the properties of hydrosols. Hydrosols of stannic acid. Z. Anorg. Chem. 89 210. 

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