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Barnatt, Allen (1965) Studies in the polymerisation of higher terminal olefins. Doctoral thesis, Northern Polytechnic.
A short section of this thesis outlines some of the methods available for the synthesis of higher terminal olefins, and gives details of the special pyrolysis technique devised to prepare n-octadec-1-ene for use in polymerisations.
A review of some relevant theories concerning Ziegler catalysts is included.
For the polymerisation of n-octadec-1-ene with catalysts derived from titanium tetrachloride and triethyl aluminium, the dependence of polymer yield, intrinsic viscosity, melting point, density and hexane solubility on Al:Ti mole ratio, catalyst concentration end reaction temperature is reported. It is shown that results are in the main similar to those obtained for the polymerisation of lower terminal olefins under similar conditions.
By-products of low molecular weight included trans-n-octadec-2-ene, the formation of which is favoured by an increase in Al:Ti mole ratio, catalyst concentration or reaction temperature. Titanium tetrachloride, triethyl aluminium, and aluminium trichloride did not alone cause monomer isomerisation.
The effects of trans-n-octadec-2-ene and trans-n-octadec-7-ene on the polymerisation of n-octadec-1-ene were studied, and results show that the 2-isomer has the more pronounced effect. Possible explanations for this are put forward, end it is suggested that monomer isomerisation is a significant factor in determining polymer yield and molecular weight.
Refractive index and density measurements, together with differential thermal analysis, indicated that polyoctadecene has first order transitions st 41° and 68°, The two crystalline phases are separable by their differing solubilities in hexane at 25°, and it is proposed that the lower melting fraction is an atactic polymer containing only side-chain crystallisation.
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