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.

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The influences of kind and methed of additien of activater, and accelerator have been investigated on compounds containing fine powdered calcium silicate synthesized from acid clay. As a result, the following informations have been obtained:-
(1) Method of addition of activator: The comparison was made with fine powdered silica which had been obtained from acid clay. It was found more effective to add at preparation of the powder than mix to rubber; this tendency was more pronounced with fine powdered calcium silicate.
(2) As activator, an amine (Acting B) and a polyalcohol (diethylene glycol) indicated a good activating effect on silica and calcium silicate, respectively.
(3) The mixed system of thiazol and thiuram compounds was excellent as accelerator; it was characteristically found that sulfenamide (CM) had shown no delayed effect.

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The premier position of rubber conditioned by its excellent elasticity is being threatened by the apparition of various high resistant synthetic elastiomeric materials e.g. polyurethane.
Comparison of test results of spandex Lycra, a sort of commercialized products of polyurethane with those of rubber thread shows the distinguished superiority of the former to the latter in regard to tensile strength and resistance to many deteriorating agents. Of course, spandex has some defects e.g. at wet heat resistance and resistance to chlorine etc. but unless vulcanized rubber has its strength much increased and its life several times extended, rubber will turn out to be unable to oppose new enemies.
We, engaging in research of latex rubber many years, succeeded in increasing the strength of latex rubber one and a half times greater by improving the structure of latex coagulum at the same composition and extending the life of vulcanized rubber several times by improving its light-stability i.e. by compounding photodegradation-inhibitors which have not hitherto been on market but have been newly invented by us.
By these two processes, rubber will be able to hold its ever existing throne against new coming foes.

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