ISSN:
0449-2951
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The preparation of polyoxymethylene of high molecular weight by polymerization of trioxane, starting from concentrated solutions in hydrocarbon solvents (cyclohexane) initiated by addition of a cationic catalyst (BF3 etherate) and inducing the crystallization of trioxane by cooling the system from the initial to room temperature, is investigated. The success of the method depends largely on the time of permanence of the solution at the initial temperature after the induction period (activation time) the initial solution, which can be controlled by following the temperature variations of the system during this stage. The cooling of the activated solution may be performed either continuously, in which case it may be varied from 15 to 200°C./hr., or in two stages: quenching from the initial temperature to the precipitation point followed by controlled cooling at a lower rate from this point to room temperature. The latter method is preferable when initial temperatures higher than the melting point of the pure trioxane are chosen. Products having inherent viscosities ranging from 2.0 to 3.0 dl./g. (in 0.5% solutions in p-chlorophenol at 60°C.) are obtained.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1965.100030704
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