| 摘要 |
<p>Finely-divided polyethylene terephthalate is made from fibre waste by treating the fibres either by a continuous or a non-continuous process in countercurrent with superheated steam at a temperature which is at least 3 DEG C. below their melting point until the relative viscosity of the polymer has fallen to less than 1,4, and thereafter mechanically comminuting the material thus formed while it is still hot in powder form. Comminution may be effected during the discharge from the treatment chamber with a worm having a progressively decreasing pitch height, which is coupled to a percussive instrument or to a rotating blade. Alternatively it may be effected in a cross-beater mill. The comminuted material may be reacted with methanol to form dimethyl terephthalate. Specification 839,371 is referred to.</p> |
