The effect of various inorganic and organic additives as possible
nucleating agents on the crystallisation behaviour of P. E. T. and the
suosequent influence on the morphological and mechanical properties
has been examined. Various methods of mixing(: the polymer and
additive were investigated and a method involving the screw-Extrusion
of the polymer and the additive was ultimately adopted. Crystallisation
studies were carried out using differential scanning calorimetry under
dynamic and isothermal modes. The results produced under conditions
of isothermal crystallisation were analysed by means of a computer.
Despite differences between batches of polymer all the additives
with the exception of indigo produced a nucleating effect in the polymer
as indicated by an increase in the rate of crystallisation compared
with that of the base polymer. Two organo-metallic substances
(sodium benzoate and sodium stearate) proved to be the most effective
in this respect by decreasing the degree of supercooling of the polymer
by 20 [degrees].
Morphological studies were carried out on isothermally crystallised
samples, after etching and replication using a transmission electron
microscope. A nodular structure whose dimensions were sensitive to
both the nucleating agent and the temperature of crystallisation was
observed.
Mechanical testing of samples direct from the D. S. C. was carried
out using a compression method. The breaking loads were found to
vary with both the type of nucleating agent used and the
crystallisation temperature chosen. A separate study involving the
exanination of the resulting fracture surfaces by scanning electron
microscopy revealed that a, high breaking load was associated with a
fine discontinuous structure whereas lower breaking loads were
characterised by a more continuous linear appearance. This implies
a higher energy of fracture due to the increased surface area of
the fracture surface of the former.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/4002 |
| Date | January 1976 |
| Creators | Ibbotson, C. |
| Contributors | Sheldon, R.P. |
| Publisher | University of Bradford, School of Polymer Science |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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