Linear Structure: The General Structure Of Unvulcanized Rubber. Due To The Large Molecular Weight, The Macromolecular Chain Is In The Shape Of A Random Coil Without External Force. When The External Force Is Applied And The External Force Is Removed, The Entanglement Degree Of The Coil Changes, The Molecular Chain Rebounds, And A Strong Recovery Tendency Occurs, Which Is The Origin Of The High Elasticity Of Rubber.
Branched Chain Structure: The Aggregation Of The Branches Of The Rubber Macromolecular Chain To Form A Gel. Gels Are Detrimental To Rubber Properties And Processing. During Rubber Mixing, Various Compounding Agents Often Cannot Enter The Gel Area, Forming A Local Blank, Unable To Form Reinforcement And Cross-linking, And Become A Weak Part Of The Product.
Cross-linked Structure: Linear Molecules Are Connected To Each Other Through The Bridging Of Some Atoms Or Atomic Groups To Form A Three-dimensional Network Structure. This Structure Continues To Strengthen As The Vulcanization Process Progresses. In This Way, The Free Mobility Of The Segment Decreases, The Plasticity And Elongation Decrease, The Strength, Elasticity And Hardness Increase, And The Compression Set And Swelling Degree Decrease.
The Source And Application Characteristics Of General-purpose Rubber
General-purpose Rubber Has Better Comprehensive Properties And Is Widely Used. Mainly:
① Natural Rubber, Obtained From The Latex Of Hevea, The Basic Chemical Composition Is Cis-polyisoprene. Good Elasticity, High Strength And Good Overall Performance.
②isoprene Rubber, The Full Name Of Which Is Cis-1,4-polyisoprene Rubber, Is A High-cis Synthetic Rubber Made From Isoprene. Because Its Structure And Properties Are Similar To Natural Rubber, It Is Also Called Synthetic Natural Rubber.
Rubber.
③ Styrene-butadiene Rubber, Referred To As Sbr, Is Obtained By The Copolymerization Of Butadiene And Styrene. According To The Production Method, It Is Divided Into Emulsion Polymerized Styrene-butadiene Rubber And Solution-polymerized Styrene-butadiene Rubber. Its Comprehensive Performance And Chemical Stability Are Good.
④cis-butadiene Rubber, The Full Name Is Cis-1,4-polybutadiene Rubber, Referred To As Br, Which Is Obtained By The Polymerization Of Butadiene. Compared With Other General-purpose Rubbers, The Vulcanized Butadiene Rubber Has Excellent Cold Resistance, Wear Resistance And Elasticity, Less Heat Generation Under Dynamic Load, And Good Aging Resistance. It Is Easy To Be Used With Natural Rubber, Neoprene, Nitrile Rubber, Etc. .
⑤ Neoprene Rubber, Referred To As Cr, Is Obtained By The
Polymerization Of Chloroprene. It Has Good Comprehensive Performance, Oil Resistance, Flame Resistance, Oxidation Resistance And Ozone Resistance. However, Its Density Is High, It Is Easy To Crystallize And Harden At Room Temperature, Its Storage Property Is Not Good, And Its Cold Resistance Is Poor.
The Source And Application Characteristics Of Special Rubber
Special Rubber Refers To Rubber With Some Special Properties.
The Main Ones Are:
①nitrile-butadiene Rubber, Referred To As Nbr, Is Obtained By The Copolymerization Of Butadiene And Acrylonitrile. It Has Good Oil Resistance And Aging Resistance, And Can Be Used For A Long Time In Air At 120°c Or In Oil At 150°c. In Addition, It Also Has Water Resistance, Air Tightness And Excellent Bonding Properties.
②silicone Rubber, The Main Chain Is Composed Of Alternating Silicon And Oxygen Atoms, With Organic Groups On The Silicon Atoms. High And Low Temperature Resistance, Ozone Resistance, Good Electrical Insulation.
③ Fluorine Rubber, A Synthetic Rubber Containing Fluorine Atoms In Its Molecular Structure. It Is Usually Expressed By The Number Of Fluorine Atoms Of Fluorine-containing Units In The Copolymer, Such As Fluororubber 23, Which Is A Copolymer Of Vinylidene Fluoride And Chlorotrifluoroethylene. Fluorine Rubber Is Resistant To High Temperature, Oil And Chemical Corrosion.
④ Polysulfide Rubber, Which Is Formed By Polycondensation Of Dihaloalkanes And Polysulfides Of Alkali Metals Or Alkaline Earth Metals. It Has Excellent Oil Resistance And Solvent Resistance, But The Strength Is Not High, The Aging Resistance And Processability Are Not Good, And It Has A Bad Smell. It Is Often Used In Combination With Nitrile Rubber. In Addition, There Are Polyurethane Rubber, Chlorohydrin Rubber, Acrylate Rubber And The Like.
The Effect Of Rubber Structure
The Effect Of Rubber Reinforcing Properties Is Mainly On Tensile Strength And Tear Strength. The General Rule Is: When The Particle Size Is The Same, High-structure Carbon Black Has A Great Reinforcing Effect On Amorphous Rubber, And Generally Has Higher Tensile Strength. And Tear Strength. The Structure Of The Rubber Is Also The Most Important Factor Affecting The Electrical Conductivity. The Branched Structure Is Easy To Form An Interwoven Conductive Path In The Rubber, Which Will Improve The Electrical Conductivity.
