The relevant properties of butyl rubber are supplemented. These properties also exist in butyl adhesive
(1) Air permeability
The dispersion speed of the gas in the polymer is related to the thermal activity of the polymer molecules. The side methyl groups in the butyl rubber molecular chain are densely arranged, which limits the thermal activity of the polymer molecules. Therefore, the gas permeability is low and the gas tightness is good.
(2) Thermal invariance
Butyl rubber vulcanizates have excellent heat resistance and invariability. Sulfur vulcanized butyl rubber can be used in the air for a long time at 100 ℃ or slightly lower temperature. The application temperature of resin vulcanized butyl rubber can reach 150 ℃ - 200 ℃. The thermal oxygen aging of butyl rubber belongs to degradation type, and the aging trend is softening.
(3) Energy absorption
The molecular structure of butyl rubber is short of double bonds, and the dispersion density of side chain methyl groups is large, so it has excellent characteristics of receiving vibration and impact energy. The rebound characteristics of butyl rubber are not more than 20% within a wide temperature range (- 30-50 ℃), which clearly indicates that the ability of butyl rubber to receive mechanical functions is superior to other rubbers. The damping property of butyl rubber at high deformation speed is inherent in the polyisobutylene segment. To a large extent, it is not affected by the application temperature, degree of unsaturation, vulcanization shape and formula change. Therefore, butyl rubber was an ideal material for sound insulation and vibration reduction at that time.
(4) Low temperature property
The space structure of butyl rubber molecular chain is spiral. Although there are many methyl groups, each pair of methyl groups scattered on both sides of the spiral are staggered by an angle. Therefore, the butyl rubber molecular chain is still quite gentle, with low glass transition temperature and good elasticity.
(5) Ozone and aging resistance
The high saturation of butyl rubber molecular chain makes it have high ozone resistance and weather aging resistance. The ozone resistance is about 10 times higher than that of natural rubber.
(6) Chemical invariance
The high saturated structure of butyl rubber makes it have high chemical invariance. Butyl rubber has excellent corrosion resistance to most inorganic acids and organic acids. Although it is not resistant to concentrated oxidizing acids, such as nitric acid and sulfuric acid, it can resist non oxidizing acids and medium concentration oxidizing acids, as well as alkali solutions and oxidation recovery solutions. After soaking in 70% sulfuric acid for 13 weeks, the strength and elongation of butyl rubber were hardly lost, while the functions of natural rubber and styrene butadiene rubber were severely reduced.
(7) Electric function
The electrical insulation and corona resistance of butyl rubber are better than that of simple rubber. The volume resistivity is 10-100 times higher than that of simple rubber. The dielectric constant (1kHz) is 2-3 and the power factor (100Hz) is 0.0026.
(8) Water absorption
The water penetration rate of butyl rubber is extremely low, and the water absorption rate at normal temperature is lower than that of other rubber, only 1 / 10-1 / 15 of the latter.
