Search results
Results from the WOW.Com Content Network
The molecular weight (MW) of the resulting polymer determines the applications. Low MW polyisobutene, a mixture of oligomers with M n s of about 500, is used as plasticizers. Medium and high MW polyisobutenes, with M n ≥ 20,000, are components of commercial adhesives. [2]
PIB homopolymers of high molecular weight (100,000–400,000 or more) are polyolefin elastomers: tough extensible rubber-like materials over a wide temperature range; with low density (0.913–0.920), low permeability and excellent electrical properties.
Polybutene is an organic polymer made from a mixture of 1-butene, 2-butene, and isobutylene.Ethylene steam cracker C4s are also used as supplemental feed for polybutene. It is similar to polyisobutylene (PIB), which is produced from essentially pure isobutylene made in a C4 complex of a major refinery.
These low molecular weight polyisobutylene polymers are used for caulking and as sealants. [2] High molecular weight PIBs are synthesized at much lower temperatures of −100 to −90 °C and in a polar medium of methylene chloride. [5] These polymers are used to make uncrosslinked rubber products and are additives for certain thermoplastics.
Low molecular weight poly-alpha-olefins are useful as synthetic lubricants such as synthetic motor oils for vehicles and can be used over a wide temperature range. [ 8 ] [ 10 ] Even polyethylenes copolymerized with a small amount of alpha-olefins (such as 1-hexene , 1-octene , or longer) are more flexible than simple straight-chain high-density ...
High molecular weight and crosslinking are desirable for the same reason. Strong dipole-dipole, hydrogen bond interactions and crystallinity also improve heat resistance. To obtain desired mechanical strength, sufficiently high molecular weights are necessary, however, decreased solubility is a problem.
PB-1 is a high molecular weight, linear, isotactic, and semi-crystalline polymer. PB-1 combines typical characteristics of conventional polyolefins with certain properties of technical polymers. PB-1, when applied as a pure or reinforced resin, can replace materials like metal, rubber and engineering polymers.
Isobutylene can also be produced in high purities by "back-cracking" MTBE or ETBE at high temperatures and then separating the isobutylene by distillation from methanol. Isobutylene is a byproduct in the ethenolysis of diisobutene to prepare neohexene : [ 5 ]