Lists
Lists
Barrutia, Esther (1984) Synthesis and performance of novel azo initiators with special reference to emulsion polymerisation. Doctoral thesis, Polytechnic of North London.
Derivatives of 4,4'-azobis-4-cyanopentanoic acid were prepared using its diacid chloride and various hydroxyl and amino compounds. The objective was to obtain substances that would act both as initiators for different modes of free-radical polymerisation and also as stabilisers for emulsion polymerisation reactions carried out in the absence of added conventional surfactant. During the preparation of the above compounds, it was discovered that 4,4'-azobis-4-cyanopentanoyl chloride appears to exist in two different forms called I and II. These forms yielded two different forms of esters when reacted with straight-chain aliphatic alcohols. These esters are called 'esters A' and 'esters B', respectively. Surprisingly, the esters A were found to act as effective initiator/stabilisers for the emulsion polymerisation of styrene in the absence of conventional surfactant. Unfortunately, during the course of the investigation, it was suddenly found to be impossible to prepare further batches of acid chloride I, and most subsequent attempts to prepare acid chloride I met with failure. The efforts which had been made to try to prepare acid chloride I and to elucidate possible structural differences between I and II that might account for the observed phenomena are described in detail.
The rest of this work is concerned with the study of the behaviour of esters derived from acid chloride II and a range of fatty-alcohol ethoxylates. Results are given for the use of these derivatives as both initiators and stabilisers for the emulsion polymerisation of styrene in the absence of added conventional surfactant. The effects of temperature, initiator concentration and the total volume of water upon the rate of polymerisation were studied. Also, the effects of these variables upon the shapes of the conversion-versus-time curves obtained when the esters were used as initiator/stabilisers were investigated. The surfactant properties of some of the initiator/stabilisers have also been investigated. The kinetics of the decomposition of these initiator/stabilisers is also included.
 |
View Item |