about_rubber

YC-Rubberabout_us products about_rubber contact_us links

Characteristics 、Application and Introduction of Basic Rubber

◎Excellent    ○Good △Fair  XPoor 　 　 　 　 　 　 　 　 　 　 　
Abbreviations of RUBBER by ISO 1629:1987E NR IR SBR BR NBR EPDM IIR CR CSM ACM MQ FKM
Characteristics of Pure Rubber Density 0.91 0.91 0.93 0.9 0.98 0.87 0.92 1.23 1.18 1.13 0.98 1.82
Ｔg(。C) -75 -75 -55 -85 -40 -55 -65 -50 -50 -30 -110 -30
Highest service Temp(。C) 70 70 70 70 100 125 100 100 125 150 225 250
Hardness （shore A) 30~90 30~90 40~90 40~80 40~90 40~90 40~80 40~90 40~90 60~90 40~80 55~90
Highest Tensile（ｋｇｆ／ｃｍ２） 35 30 25 20 25 20 20 25 30 20 15 20
Characteristics and Chemical Resistance of Elastomer Types Rebound resilience ◎ ◎ ○ ◎ ○~X ○ △~X ◎ △~X △~X ◎ △~X
Elongation at break% 800 800 800 800 700 500 800 800 500 350 400 300
Ozone resistance X X X X X ◎ ◎ ○ ◎ ◎ ◎ ◎
Flame resistance X X X X X X X ○ ○ X ○ ◎
Petroleum resistance X X X X ◎ X X ○ ○ ◎ ○ ◎
Sulphuric Acid 10% △ △ △ △ △ ◎ △ △ ◎ X X ◎
Benzine X X X X X X X X X X X ◎
Alcohol ○ ○ ○ ○ ◎ ◎ ◎ ○ ○ X X ◎
Ethyl Ether X X X X △ X X △ △ X X X
Oliver Oil X X X X ◎ △ ○ ○ ○ ◎ ◎ ◎
Methyl Ethyl Ketone △ △ △ △ X ◎ ◎ X X X X X

　

Rubber are  high-molecular-weight polymers which can stretch twice of their length and recover to almost their original shape after release of the applied force. Polymers, generally, can be divided into nature rubber and synthetic rubber. Nature rubber is the only one elastomer found in the nature; others all are man made. In order to improve products physical properties、 operating requirement、 optimum  density、 cost down and processibility, compounders usually put different kinds of additives into each their ingredients. The main additives are fillers、 plasticizers、 activators、 accelerators、 curing agents、 age resistors and other additives. In general, all ingredients are mixed in the mixer or two roll mill, and then, cured by different producing methods, such as compression molding、 transfer molding、 injection molding、 continuing cure、 steam cure, etc...

 

Fillers:

Carbon blacks and nonblack fillers can increase hardness、 tensile strength、 abrasion and tear strength of rubber products. Affecting the physical properties of rubber products are basically in particle size and surface area of fillers. the nonblack fillers include clays, calcium carbonate, silicates and precipitated and fumes silicates.

 

Plasticizers:

Add into the rubber compound to help mixing, processing, and increasing elasticity, such as petroleum oils or DOP, etc,,,

 

Activators:

The combination of activators, accelerators and curing agents could increase the rate of vulcanization. Zinc oxide and  stearic acid are the main activators.

 

Accelerators:

Accelerators could increase the curing rate and improve the physical properties of products, such as DM, M, CM, TMTD, TMTM, etc...

 

Curing Agents:

Curing agents could insert cross-linking between the polymer chains, such as sulphur and peroxide.

 

Age Resistors:

Age resistors are organic substances usually added in small amounts to retard deterioration caused by aging, such as antioxidant D, C, etc...

 

Other additives:

Other additives are ingredients for special purposes, such as blowing agents, retarders, pigments, and odorants, etc...

  

NR:

NR is the only one found in the nature which has characteristics of excellent elasticity, abrasion resistance and tensile strength. However, NR is almost 100% unsaturated elastomer, it lacks good resistance to oxidation and ozone. So, adding antioxidants and antiozonants is necessary. NR is almost used in tires, vibration mounts, shoes, and rollers.

 

IR:

IR is synthetic NR, which has two types, high cis and low cis. It doesn't tend to crystallize as easily as NR, and physical properties are as not excellent as NR. It can be mixed with NR to improve physical properties.。

 

SBR:

SBR can be compounded using the same ingredients for NR. However, SBR cures more slowly than NR. It can be mixed with NR, IR, and BR. SBR can be used in many applications as a replacement for NR.

 

BR:

BR has excellent characteristics of lowest Tg. It is more difficult to process than NR and SBR, but it can be blend with NR, IR, and BR to improve physical properties and abilities of process.

 

NBR:

NBR is the oil resistance elastomer. The resistance of oil depends on the proportion of acrylonitrile in the rubber. It has excellent resistance to heat and abrasion. NBR elastomers are the most widely used for oil and fuel resistant components such as seals, gaskets, o-rings, rollers. HNBR has better resistance used to higher temperature service and XNBR has better abrasion resistance.

 

EPDM:

EPDM has excellent resistance to weather, oxidation, aqueous solutions and high temperature. It is almost used for a wide rang of products, including door seals, cable insulations,belts, hoses and roof.

 

IIR: IIR has very low gas and moisture permeability. It has excellent resistance to  aqueous solutions, heat, and pharmaceuticals. But it has low cure rate and is not compatible with NR and SBR. BIIR and CIIR have better processing and mixing abilities.

 

CR:

CR is the elastomer which has distinctive properties of good resistance to  pharmaceuticals, heat, weather, flame, oil. It widely used in adhesives, hose, seals, and gaskets.

 

CSM:

CSM is also named Hypalon. It is a synthetic rubber and resistance to ozone, heat, weather, oil and chemical. It is used in electrical applications as protective jacketing where resistance to flame, heat, oil and chemical.

 

ACM:

The useful properties of ACM are excellent heat resistance, weather resistance, and ozone resistance. It can be a replacement for FKM.

 

MQ:

Silicon rubber has two types, liquid and solid. It has wide rang of service temperature and excellent resistance to weather. It is odorless and usually used in medical treatment applications and packing in cars.

 

FKM:

FKM has excellent resistance to chemical, oil, aqueous solutions, weather and heat. It is widely used in critical application requiring high resistance to heat, oil, fuel, flame and chemical, such as o-rings, seals, and gaskets.