The molecular structure, molecular weight and its distribution, P0, PRI, Mooney viscosity, processibility of raw natural rubber, curing characteristics of compounds and mechanical properties of vulcanites were studied by hot air aging. The results show that for raw natural rubber after heating at 70°C for 20 days, C = C bond of molecular chains was broken, the numbers of the C = C bond decreased, methyl oxidized, and –OH and –COOH formed. The number-average molecular weight, weight-average molecular weight and viscosity-average molecular weight decreased, the molecular weight distribution became wide. P0, PRI, Mooney viscosity, rubber elastic torque S ', viscous torque S ", elastic modulus G', viscous modulus G" and complex viscosity η* decreased, loss factor tanδ increased. The curing rate of compound reduced and curing characteristics were inferior. The elongation at break and tensile strength decreased, and tensile stress at 300% modulus and 500% modulus did not change obvious. Anti-aging property became deteriorate.

The effective storage time (i.e. storage life) of constant viscosity natural rubbers prepared with hydroxylamine hydrochloride, hydroxylammonium sulphate, hydrazine hydrate, aniline and semicarbazide hydrochloride respectively were investigated with heat accelerated storage aging combined with differential scanning calorimeter(DSC) method as well as the heat aging life equation. The results show that the effective storage time of constant viscosity natural rubber prepared with hydroxylamine hydrochloride is 19.2 years at 30°C, 39.4 years at 25°C and 82.9 years at 20°C. The effective storage time of constant viscosity natural rubber prepared with hydroxylammonium sulphate is 16.3 years at 30°C, 32.6 years at 25°C and 66.5 years at 20°C. The effective storage time of constant viscosity natural rubber prepared with hydrazine hydrate is 42.5 years at 30°C, 85.9 years at 25°C and 177.9 years at 20°C. The effective storage time of constant viscosity natural rubber prepared with aniline is 30.4 years at 30°C, 66.7 years at 25°C and 150.2 years at 20°C. The effective storage time of constant viscosity natural rubber prepared with semicarbazide hydrochloride is 13.5 years at 30°C, 27.4 years at 25°C and 57.1 years at 20°C.

The effect of constant viscosity natural rubber (CVNR) prepared with hydrazine dihydrochloride was studied, The results showed that the relation of dependence of tC10 and tC90 on temperature followed the rule below: CVNR > NR a;the sensitivity of tC10 increment to tC90 increment due to increasing of cure temperature followed the rule below: NR>CVNR; The relation of MH0 were as follows: NR>CVNR.

The properties of raw constant viscosity natural rubber were measured using a rubber processing analyzer. The results show that the rubber processing analyzer can characterize well the effect of viscosity stabilizer on the dynamic mechanical properties of raw constant viscosity rubber by applied strain sweep or frequency sweep. In linear viscoelastic region, the increment of the dynamic torque S’ of the constant viscosity natural rubber prepared with hydroxylamine hydrochloride decreases with the increase in the level of hydroxylamine hydrochloride . In the range of low frequency, the increment of the dynamic modulus G’ of constant viscosity natural rubber prepared with hydroxylamine hydrochloride is obvious lower than those of natural rubber and constant viscosity natural rubber prepared with aniline. G’ of the constant viscosity natural rubber prepared with aniline is just only a little higher than that of natural rubber. Hydroxylamine hydrochloride and aniline can decrease the molecular weight of rubber, and change the molecular weight distribution. The dynamical properties of constant viscosity natural rubber are dependent on the molecular weight and the molecular weight distribution.