City Research Online

Abstract

A comparison of the photoinitiating efficiency of acylphosphine oxides, in particular 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,2-dimethoxy-2-phenylacetophenone, acylphosphonates, 2-chlorothioxanthone and other commercial photoinitiators for the polymerisation of UV curable formulations was made. The formulations investigated included a non-pigmented epoxy
acrylate, a pigmented epoxy-acrylate and an unsaturated poly ester. During these investigations it was found necessary to add tertiary amines to all the photoinitiator formulations in order to obtain efficient cure speeds. Experimental evidence is provided showing the role of amines to be that of efficient oxygen scavengers. The acylphosphine oxides were found to be more efficient photoinitiators for the curing of thin films than the acylphosphonates, but were no better than the other commercial photoinitiators. Laser nephelometry and bulk polymerisation techniques were investigated as possible photoinitiator screening methods. Their limitiations are reported. The efficiency of an acylphosphine oxide and a commercial photoinitiator were compared for the polymerisation of a difunctional acrylate. The residual unsaturation in the thin polymer film was measured using Fourier
transform infrared spectroscopy in conjunction with transmission and ATR measurements. The photodecomposition products of the acylphosphine oxides were characterised and mechanisms for their formation suggested. The shelf-life stability of an acylphosphine oxide and a commercial photoinitiator were investigated using a typical UV curable formulation. The photocleavage mechanism of the acylphophine oxides was elucidated by CIDEP and chemical radical trapping techniques.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QD Chemistry
Departments:	School of Science & Technology School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

Export

Downloads