Re: Thermal degradation of polymers?

From: Michael Priest (
Date: Mon Jul 30 2001 - 05:56:12 EEST

Hi all,

Bearing in mind that rapid tooling mould cycle times are often longer than
conventional tooling, a molten polymer will remain static in the barrel of
an injection moulding machine for a greater length of time than in a
production environment. Has anyone established any links between the
prolonged heating of a molten semi-crystalline polymer in the machines
barrel and the mechanical properties or shrinkage that results in the
mouldings? I would assume that after a period of time the polymers molecules
would degrade and the properties and shrinkage of the moulding would be
affected. Any suggestions?

Mick Priest

Engineering Dept.
Warwickshire College
Leamington Spa

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