Tomlins, P E; Richardson, M J*; Shenton, M J*; Janimak, J J* (2000) The influence of pigments on the crystallisation behaviour, morphology and dimensional stability of plates injection moulded from HDPE. NPL Report. CMMT(A)217

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Abstract

Certain organic pigments such as phthalocyanine blue are renounced within the moulding industry for causing problems of dimensional instability. In this study we examine how phthalocyanine blue and other organic pigments affect the crystallization behaviour of high density polyethylene through isothermal calorimetric measurements. These data are interpreted using a two stage parallel model based on coupled Avrami functions.
All of the pigments considered in this investigation affect the morphology of melt crystallized high density polyethylene to some extent as revealed by transmission electron micrographs of microtomed permanganically etched specimens. These morphological differences can arise from a combination of the processing conditions used to mould the material and or the nucleating effect of the pigments themselves. To distinguish between these two influences the morphology of samples melt crystallized under controlled cooling conditions are compared with those cut from injection moulded plates. These comparisons allow us to not only assess the relative importance that processing and pigments have on morphology and to identify the driving forces that are probably responsible for causing excessive shrinkage and warpage.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	CMMT(A)217
Subjects:	Advanced Materials Advanced Materials > Polymers
Last Modified:	02 Feb 2018 13:17
URI:	http://eprintspublications.npl.co.uk/id/eprint/1547

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