夜激无码av毛片不卡_一级欧美做片免费观看_中文av乱片在线播放_2022自拍偷在线精品自拍偷

What is styrene butadiene rubber

Styrene butadiene rubber (SBR), also known as polystyrene butadiene copolymer. Its physical mechanism performance, processing performance and performance close to the natural rubber, the use of some properties such as wear resistance, heat resistance, ageing resistance and curing rate is more excellent natural rubber, but with a variety of natural rubber and synthetic rubber and, widely used in tires, tape, rubber hose, wire and cable, medical instruments and various rubber products production and other fields, It is the largest universal synthetic rubber variety and one of the earliest rubber varieties to achieve industrial production.

Advantages of styrene butadiene rubber

1) not easy to burn and oversulfur, good vulcanization flat.

2) Wear resistance, heat resistance, oil resistance and aging resistance are better than natural rubber. Good wear resistance at high temperature, suitable for passenger tyres.

3) the molecular weight in the processing to a certain extent is no longer reduced, so it is not easy to refining, uniform plastic degree. The hardness of vulcanized rubber changes little.

4) High packing can be achieved by increasing the molecular weight. Oil - filled styrene butadiene rubber has good processing performance.

5) styrene butadiene rubber has good ozone resistance. Excellent elasticity and strength, resistance to flexion, cracking and tearing

The production method of styrene butadiene rubber

1. Latex polystyrene butadiene rubber, by butadiene, styrene as the main monomer, with other auxiliary chemical raw materials, under certain technological conditions, the emulsion polymerization of the first Mr. Into styrene butadiene slurry, remove the untransformed monomer in the slurry, and then through condensation, drying and other processes to produce product glue.

2. Lysodic styrene butadiene rubber, by butadiene, styrene as the main monomer, in the hydrocarbon solvent, using lithium organic compounds as initiator, lead to anionic polymerization of polymer glue liquid, adding antioxidants and other additives, after condensation, drying and other processes to produce product glue.

Classification of styrene butadiene rubber

1. High temperature copolymer styrene butadiene rubber

High temperature copolymerization of styrene-butadiene rubber is the oldest variety of Styrene-butadiene rubber, polymerization temperature is 50℃, due to a relatively high conversion rate in the polymerization process, polymer latex particles crosslinking to form gel, branched chain more, low molecular weight copolymer content is large, physical and mechanical properties are poor. Since the use of low temperature copolymerization, copolymerization in the reduction of branching reaction and crosslinking degree, so that its molecular weight is higher and the distribution of molecular weight is narrower, greatly improved quality, resulting in high temperature copolymerization gradually eliminated, now only as some special purpose products used.

2. Low temperature copolymerized styrene butadiene rubber

Low temperature copolymerized styrene butadiene rubber is one of the largest synthetic rubber varieties in the world. It is widely used in tires and other rubber products. With the continuous improvement of the polymerization method, the variety and quality of styrene butadiene rubber are increasing. These varieties also have different characteristics.

3. Oil-filled styrene butadiene smelter

In order to improve the processing performance of styrene butadiene rubber and reduce the cost, in the process of polymerization, mineral oil (such as naphthenic oil, aromatic oil) is added to the latex, latex condensation absorbs a large amount of mineral oil and oil filled styrene butadiene base rubber. Compared with non-oil-filled styrene butadiene rubber, it has good technological performance, small shrinkage of rubber material, smooth surface, no coke burning phenomenon in the processing process, rubber in the deformation of the heat is less, so the service life of rubber products is correspondingly extended.

4. Carbon black styrene butadiene smelter

Before SBR latex condenses, a certain amount of carbon black is added to evenly disperse it into latex, and the carbon black base rubber is condensed by precipitation. The characteristics of this master rubber are: the physical and mechanical properties are more stable, good process performance, thus shortening the mixing cycle, easy to apply, but it is only suitable for making black rubber products.

5. Oil filled carbon black styrene butadiene smelter

In emulsion polymerization, adding oil and carbon black in latex, through condensation of styrene butadiene rubber. Its characteristics are that it can shorten the mixing time by 25% ~ 30%, and the mixing temperature is low, the coke burning risk is small, and it is convenient for continuous mixing; Improved working conditions, simplified process operation; Carbon black is evenly dispersed and has good reinforcing performance. Good calendering and pressing performance; The strength, thermal aging, wear resistance and fatigue resistance of vulcanized rubber were improved and the heat generation was small.

6. Dissolved polystyrene butadiene rubber

Sobr is a solution polymer using alkyl lithium as catalyst. According to different polymerization conditions and catalysts, polymers can be divided into random, partially block and symmetric block types. The random type has the characteristics of general styrene butadiene rubber, which can be used as tires and other rubber industrial products; Block copolymers have certain thermoplasticity and are mostly used in injection molding and extrusion products.

7. Alkene rubber

Alkene rubber is a new type of lysodic styrene butadiene rubber. It is the product of copolymerization of butadiene/styrene or butadiene/isoprene with alkene as catalyst. Its performance is similar to that of latex polystyrene butadiene rubber, and some properties are superior to latex polystyrene butadiene rubber, such as raw rubber strength, good processing performance, and uniform molecular weight distribution. It can be used to make tires and other products.

Field of use of styrene butadiene rubber

1. It is mainly used for tread, body and side of tire.

2. Because the butyl rubber has good touch, weather resistance, good resilience and small permanent deformation, can be used to make raincoat, blanket cloth, windbreaker and air mattress, etc., can also make uniform foaming, dense structure of sponge materials, but also widely used in shoe industry and a variety of light color rubber products.