Beschreibung:
AbstractThe morphology of poly(oxymethylene) appearing in the polymerization system of 1,3,5‐trioxane in cyclohexane using BF3 [or BF3O(C2H5)2] and water catalysis was studied in parallel with the kinetic behaviour of the reaction. Feather‐shaped crystals, whose poor reproducibility was a problem, were found to be formed in a limited range of catalytic conditions. As a function of the mole ratio H2O/BF3, the change of morphology was ordered as follows: needle‐like crystals (H2O/BF3<0,05), heterogeneous products (H2O/BF3=0,05 to 3), feather‐shaped crystals (H2O/BF3=3 to 10). and amorphous products (H2O/BF3>10). A new type of single‐crystal, tapered hexagonal rod, was found in the same catalytic region where feathershaped crystals were formed. The results of older preliminary work in a polar solvent, where a hexagonal, plate‐like crystal had been obtained, are also briefly reconsidered in the discussion.