- Polybutene
A liquid
oligomer , polybutene is widely used as aplasticizer for high molecular weightpolymer s, such aspolyethylene .Properties
The liquid is clear and colourless, and is sold in many different grades. The grades are determined mainly by
molecular weight , the higher grades showing increasingviscosity . The oligomer degrades at high temperature (upwards of 350 C) to form monomerisobutene by chains unzipping from the chain ends.tructure
The
repeat unit is the same as that ofbutyl rubber orpolyisobutylene :- [-CH2-C(CH3)2-] n-
One of the end units in each chain is double bonded, so further derivatives can be synthesised owing to the reactivity of the bond. But the same
double bond makes the molecule sensitive tooxidation when hot liquid is exposed to air. Its structure should not be confused withpolybutylene , a high molecular weight polymer with a different chain repeat unit.Applications
It is used as an additive for
engine oil s andgrease s, and as an extender in putties used for sealing roofs and windows. In hydrogenated form, it is also used in a wide variety ofcosmetic preparations, such aslipstick . It is used inadhesive s owing to itstack iness.Bibliography
* Decroocq, S and Casserino, M, "Polybutenes", Chapter 17 in Rudnick (Ed), "Engine Oils and Bio-based Lubricants", CRC Press (2006).
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