Contract No. W-31-109 Eng"-52 LEGAL NOTICEpvvpuwl aa aa accooitt at Oovammaat aponaorwl work. Naltbar tha Uoltod CaamUaloa, aor aar paraoa actlof M bahalf of tha Coaunlsaloii: aagrwarnHrtr»'rapr»aantatlott,ex^«aa«dor impUad. with raapoct to tha accuor naaMaaaa (rf tha Infemutloa coolaload la Ihla raport. or Oat tha uaa apvaraiu. Batfeed, or procaaa dlaeloawl la tUa rapert aiay oat li>£rii«a iteior a«)r UaMUtloa wHk raapaet to tha u»a of. or tor daiaacaa raaolttnc from tha ' taferaatUa. spparatua, nathod, or procaaa dlaeloaad In thla raport. M« t> tha abon. "parwn acUag on bahalf of tha Conmtaakm-(Acludaa aaj meoatractor at Oa Coaunlaatoa, or am^oyaa of auch contractor, to tha axtont that OT of tha OoauaiaaloB. or aatiAoyaa of auch coatractor preparaa. or provldaa acoaaa to, any talariBatloa poraaaat to hla amployuant or contract OoMMtaaton. or hla amplayaMat with a«icb extractor.

Latex, like many other colloidal systems, owes its stability to a large extent to the electrical charge carried by each particle in suspension. One possible explanation of how the particles become charged is that the protein adsorbed on the rubber hydrocarbon is capable of ionizing to a slight extent, both as an acid and as a base, much in the same manner as do amino acids. In a highly basic solution the rubber particle acquires a negative charge; whereas in an acid solution the charge is positive. At some stage between strongly acid and strongly basic solutions, the ionization of the adsorbed protein layer would be as much acidic as basic, and the particle would have no net charge. This is known as the isoelectric point, and has been found to be at a pH of 4.2. At or near the isoelectric point, the latex is very unstable, and coagulates rapidly. The charge carried by the particle may, of course, be due also to adsorption of ions from solution. The latex particles are normally negatively charged, but the sign of the charge can be reversed by the addition of acid, by the presence of polyvalent cations, and more recently it has been shown that cationic soaps may reverse the charge. In a cationic soap the positive ion is a long chain, and the negative ion is a halide, sulfate, etc. The hydrophilic group attached to the long chain of carbon atoms is a quaternary ammonium, sulfonium, or phosphonium group. The authors felt that, because positively charged latex seems to have some commercial possibilities, it would be of interest to attempt to prepare latex suspensions of reversed charge of higher concentrations than those used by Blow, which were apparently around 5 per cent.

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