ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The nascent crystal structure and morphology of poly(oxymethylene) (POM) obtained from 1,3,5-trioxane crystals, induced by gaseous chemical initiators, was studied in order to clarify the solid-state polymerization mechanisms of this monomer. The polymerization starts at the surface of the monomer crystals and propagates towards its interior. The polymerization rate, therefore, depends on the size of the crystals and not on the initiator amount. Hexagonal fibrous crystals without a main orientation were obtained on the surface of the monomer crystal. These crystals orientated themselves along the c-axis of the monomer, due to the polymerization propagation inside the crystals by simultaneous solid-gas polymerization and crystallization mechanisms. The orientation depended on the reactivity of the initiator, the order being: BF3-O(C2H5)2 〉 SnCl4 〉 H2SO4-paraformaldehyde. The orientation was also improved by increasing the polymerization temperature, obtaining POM crystals similar to those found by radiation induced polymerization. At low polymerization temperature folded chain crystals were obtained similar to those encountered by solution polymerization according to crystallization succeeding polymerization mechanisms.
Additional Material:
13 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1978.021791016
