Handwheel Materials: Bakelite, Plastic, etc.
Main Applications of Natural Rubber Handwheels: Natural rubber handwheels are widely used in industry, agriculture, defense, transportation, machinery manufacturing, medicine, and daily life due to their strong elasticity, excellent insulation, plasticity, water and air barrier properties, tensile strength, and wear resistance. These include tires for transportation; conveyor belts, transmission belts, and various seals for industrial use; medical gloves and blood transfusion tubes; and everyday items like rubber shoes, raincoats, and hot water bottles. Defense aircraft, artillery, and tanks, as well as cutting-edge technology such as rockets, satellites, spacecraft, and space shuttles, all require a large number of rubber handwheel components.
Other Properties
Natural rubber handwheels have high elasticity, particularly in raw rubber and vulcanized rubber with a low crosslink density. For example, within the temperature range of 0-100°C, the rebound resilience is between 50-85°C, and its elastic modulus is only 1/3000 of that of steel. Its elongation can reach 1000%, and after stretching to 350%, its permanent set after retraction is only 15%. Natural rubber handwheels have high elasticity, second only to butadiene rubber handwheels among general-purpose rubber handwheels.
Natural rubber handwheels have relatively high strength among elastic materials, including raw rubber, compounded rubber, and vulcanized rubber. The tensile strength of unvulcanized rubber handwheels is called Green's strength, and can reach 1.4-2.5 MPa. Adequate Green's strength is essential for rubber handwheel processing and molding. Natural rubber handwheels also have high tear strength, reaching 98 kN/m, and good wear resistance. The high mechanical strength of natural rubber handwheels is due to their self-reinforcing nature. When stretched, the macromolecular chains align along the stress direction, forming crystals.
Electrical Properties of Natural Rubber Handwheels: Natural rubber handwheels are non-polar and are a good insulating material. When natural rubber handwheels are vulcanized, polar elements such as sulfur and accelerators are introduced, which degrades their insulation properties.
Natural rubber handwheels are non-polar and soluble in non-polar solvents and oils. Natural rubber handwheels are not resistant to media such as cyclohexane, gasoline, and benzene. Unvulcanized rubber dissolves in these media, while vulcanized rubber handwheels swell. Natural rubber handwheels are insoluble in polar acetone and ethanol, and even less so in water. They are resistant to 10% and 20% hydrochloric acid, 30% sulfuric acid, and 50% sodium hydroxide.
The glass transition temperature of the raw rubber of natural rubber handwheels is -72°C, the flow temperature is 130°C, the decomposition temperature is 200°C, and the intense decomposition temperature is 270°C. After vulcanization, the Tg of natural rubber handwheels increases, and stick flow no longer occurs.
