How To Select A High Temperature Rubber Material-Nr NR
NR has no definite melting point, heat slowly softening, in 130 ¡æ ~140 ¡æ completely softened, ~ 150 ℃ ℃ viscosity very viscous fluids, 200 ¡æ began to break down, 270 c began to break down. Room temperature, NR elastic, temperature decreases gradually hardens, as low as 0 ° c flexible greatly reduced to-70 ℃ below becoming brittle. The frozen natural rubber is heated to room temperature can restore elasticity
NR of elastic modulus of about 3~6MPa, elongated 1000% without breaking.
NR Crystal under external tension crystalline, strong self-complementary; NR big molecular weight, high mechanical strength. Pure gum vulcanizate fracture strength for 16.7~28.4MPa, black carbon reinforced up to 24.5~34.3MPa after. NR multiple deformation and low heat of youth, with good resistance to Flex fatigue.
NR of double bonds, easy to absorb oxygen, ultraviolet light can decompose, and cracking.
NR does not contain polar groups, non-polar rubber, only some polar solvents. Insoluble in ethyl acetate, ethanol and acetone. In non-polar solvents such as gasoline, benzene is swelling. Solvent resistance oil resistance poor, alkaline resistance is good, but is not resistant to concentrated strong acids.
NR broad molecular weight distribution, with good processing properties. Good dispersibility and solubility of NR and compounding. Machined, has suitable plasticity and viscosity, the easier to calender roller.
6NR has better breathability, water resistance, cold resistance and electrical insulation. Excellent flexibility and tolerance.