Matthews, Alice (2010)
M.Res. thesis, University of Birmingham.
The following investigation presents the melting, polymerisation and crystallisation kinetics of XB2-CA4, an oligomer powder of cyclic butylene terephthalate with a stannoxane catalyst, which polymerises into cyclic poly(butylene terephthalate) (cPBT). When heated this material undergoes very rapid concurrent polymerisation and crystallisation. These processes were separated using a combination of two different techniques in the DSC, and Avrami analyses on the data produced. As reported in previous literature it was thought that Stannoxane catalyst degradation above 220°C caused production of linear polymer. However, FTIR and GPC experiments on samples heated to 230°C and 250°C, do not show production of linear polymer, but rather an increased production of cylcic polymer, but of a slightly lower molecular weight than that produced at 170°C and 190°C. It was initially thought that XB2-CA4 did not melt below 170°C, however, GPC experiments showed that some heavier molecules were produced in samples that were held at 150°C for more than 5 minutes. The molecular weight distributions from the GPC showed some significant findings with regard to the potential degradation of the samples above 220°C.
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