HEAT-SENSITISATION OF AMMONIA-PRESERVED CENTRIFUBED NATURAL RUBBER LATEX CONCENTRATE BY POLYVINYLMETHYL ETHER. II. EFFECTS OF ADDITION OF INORGANIC ELECTRQLYTE5, UREA, CARBOXYLATE SOAPS AND FATTY-ALCOHOL ETHOXYLATES

ABSTRACT

Results are presented and discussed for the effects of addition of inarganic electrolytes, urea, carboxylate soaps and fatty-alcohol ethoxylates upon the heat_sensitisation of natural rubber (NR) latex by polyvinylmethyl ether (PUME). These results and those given in the previous paper are consistent with the heat-sensitisation of NR latex by PUME occurring by adsorption of PUME at the surface of the rubber particles. The effects of several types of additive are consistent uith these additives affecting either the availability of sites at the rubbei-aqueous phase interface at which PVME can be adsorbed, or the facility with which PUME can be adsorbed. The results are not generally consistent with heat-sensitisation being a consequence of precipitation of PUME in the aqueous phase of the latex as the temperature is raised. Some results also suggest a mechanism in which interparticle bridging of latex particles by adsorbed PUME occurs as the temperature of the latex is raised. Lack of effect of urea upon heat-sensltlsatlon by PVME Indicates that It does not directly involve the breaking of hydrogen bonds.