1964 Volume 37 Issue 2 Pages 81-87
The present authors have investigated various combinations of factors such as presence or absence of activator, roll-temperature, relative humidity, content of added water and standing time. (1) Mooney viscosity tends to decrease with the increase of water content in compound, irrespective of presence or absence of activator and roll-temperature. (2) Scorch time and cure time for a compound containing no activator become repidly shorter with the increase in water content. For compounds containing an activator, it is observed that they tend to become shorter with the increase in water content at any roll-temperature.(3)As for the relationship between humidity and weight-change during storage, compounds containing no activator represent larger amount of moisture absorption than those containing an activator at any relative humidity. (4) Change of Mooney viscosity in the lapse of time, represents different tendency according to roll-temperature, humidity during storage and activator. Mooney scorch time is longer for a sample with more water content at any rolltemperature; the tendency becomes more pronounced in the absence of an activator. (5) Transparency is distinctly observed in samples with water content of more than 2.5%. (6) Tensile strength tends to reach the maximum at water content of about 2%. The modulus represents a somewhat larger value in the presence of an activator than in the absence.
