Tomlins, P E; Smith, I; Bartlett, P* (2001) The influence of nucleating agents on the dimensional stability of pigmented mouldings. NPL Report. MATC(A)63

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Abstract

Certain organic pigments are known to cause dimensional instability problems, particularly in semi-crystalline polymers such as polypropylene and high density polyethylene. This may be attributable to the polymers crystallizing at higher temperatures than normal as a result of necleation by the pigments causing shrinkage stresses that are different to those observed in virgin polymer. Adding a second more effective nucleating agent to both pigmented and virgin feedstocks to control crystallization and hence the shrinkage behaviour of mouldings may provide a solution to this problem.
Whilst adding either sodium benzoate or palmerol in one or two concentrations dose have an affect on the dimensional stability of mouldings, the changes that occur depend on the type of pigment present. It is possible to tailor the shrinkage and/or warpage of differently pigmented mouldings for a particular application by identifying particularly active or benign pigments or by adding an additional nucleating agent.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	MATC(A)63
Subjects:	Advanced Materials
Last Modified:	02 Feb 2018 13:17
URI:	http://eprintspublications.npl.co.uk/id/eprint/2200

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