(1) Strength of neoprene
Its raw rubber has high tensile strength and elongation at break, and it belongs to self-reinforcing rubber. The molecular structure of chloroprene rubber is regular, and the molecular chain contains polar chlorine atoms. groups that increase the intermolecular forces. Therefore, under the action of external force, it is easy to stretch and crystallize (self-reinforcing), and the molecules are not easy to slip off. In addition, the molecular weight is larger (20,000 to 200,000), so the tensile strength is larger.
(2) Excellent aging resistance
The chlorine atom connected to the double bond of the chloroprene rubber molecular chain makes both the double bond and the chlorine atom inactive, so the storage stability of the vulcanizate is good; Excellent aging resistance (weather resistance, ozone resistance and heat resistance) performance. Its aging resistance, especially weather resistance and ozone resistance, is second only to ethylene-propylene rubber and butyl rubber among general-purpose rubbers, and far superior to natural rubber; its heat resistance is better than that of natural rubber, styrene-butadiene rubber, and nitrile-butadiene rubber. Similarly, it can be used for a short period of time at 150 ℃, and can be used for 4 months at 90-110 ℃.
(3) Excellent flame resistance
The flame resistance of neoprene rubber is the best among general-purpose rubbers. It has the characteristics of non-spontaneous combustion. It can burn when exposed to flame, but the flame will be extinguished by itself. This is because when neoprene is burned, it can be decomposed under the action of high temperature. hydrogen chloride gas to extinguish the fire.
(4) Excellent oil resistance and solvent resistance
Neoprene’s oil resistance is second only to NBR and better than other general-purpose rubbers. This is because the neoprene molecule contains polar chlorine atoms, which increases the polarity of the molecule.
The chemical resistance of neoprene rubber is also very good. Except for strong oxidizing acids, other acids and alkalis have little effect on it. Neoprene also has better water resistance than other synthetic rubbers.
Due to the regularity and polarity of the molecular structure of neoprene, the large cohesion restricts the thermal movement of the molecules, especially at low temperatures. It is also difficult to restore the original state after tensile deformation, that is, crystallization occurs, the rubber loses its elasticity, and even brittle fracture occurs, so the cold resistance of neoprene rubber is not good.
Neoprene rubber has a greater tendency to crystallize than natural, styrene-butadiene, butyl rubber, etc. This is because the molecule of neoprene rubber is dominated by 1,4 addition trans structure, and the molecules are in a regular linear arrangement structure, which determines The crystallinity of the neoprene rubber is determined, and the higher the content, the stronger the crystallinity of the corresponding neoprene rubber. Unvulcanized rubber and vulcanized rubber will slowly harden and lose adhesion after long-term storage, that is, crystallization occurs. The temperature decreases, the crystallization speed increases, and the rubber becomes hard after crystallization, and the hardness and tensile stress increase.
The relative density of neoprene rubber is between 1.15 and 1.25, generally 1.23. When manufacturing the same volume of products, the dosage is larger than that of general general-purpose rubber.