1. Natural Properties
   Natural rubber is a milky latex secreted by cultivated rubber trees. It is processed and solidified to obtain the final product, which is composed mainly of polyisoprene, with a content of over 90%. It also contains small amounts of proteins, fats, acids, sugars, and ash.

2. Classification and Quality Standards
   Natural rubber is classified into smoked sheet rubber, latex, crepe rubber, and granulated rubber, based on manufacturing processes and appearance. Smoked sheet rubber and granulated rubber are the main types in the market.

Smoked sheet rubber is obtained through processes such as coagulation, drying, and smoking. Imported natural rubber in China is mostly smoked sheet rubber.

Granulated rubber is obtained through processes such as coagulation, granulation, and drying. Domestically produced natural rubber in China is mostly granulated rubber, also known as standard rubber.

Smoked sheet rubber is generally graded based on appearance, with six grades: special, first, second, third, fourth, and fifth. Rubber that does not meet the fifth-grade standard is classified as off-grade.

Granulated rubber is generally graded based on internationally standardized physical and chemical properties, including impurity content, initial plasticity, plasticity retention, nitrogen content, volatile content, ash content, and color index. Impurity content is the primary indicator, and it is categorized into five levels: 5L, 5, 10, 20, and 50.

3. Main Applications
   Due to its strong elasticity and good insulation, plasticity, water and gas resistance, tensile strength, and wear resistance, natural rubber is widely used in various industries, including industrial, agricultural, defense, transportation, machinery manufacturing, medical, and daily life sectors. It is commonly used in the production of tires for transportation.

Industrial applications include conveyor belts, transmission belts, and various sealing rings. Medical applications include gloves and transfusion tubes. Daily life products such as rubber shoes, raincoats, and hot water bags are also made primarily from rubber.