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Thesis (M.S.)--University of Alabama at Birmingham, 2008. / Description based on contents viewed July 9, 2009; title from PDF t.p. Includes bibliographical references (p. 69-76).

Thesis (M.S.)--Michigan State University. Packaging, 2008. / Title from PDF t.p. (Proquest, viewed on Aug. 11, 2009) Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 255-263). Available also in a digital version from Dissertation Abstracts.

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.

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Results of an experimental test program are presented to determine the bursting strength of polyethylene terephthalate film and fabric cylinders containing axial silts of various lengths. The results demonstrate that the fabric material is superior to the film material as regards residual strength in the presence of a slit. It is shown that the strength-weight ratio of the fabric cylinders is approximately twice that of the film cylinders, largely due to the strength advantage of fiber over film. The results are compared with the predicted bursting strength obtained from two different semiempirical analyses, one based on notch strength analysis and the other employing fracture mechanics concepts. The comparison demonstrates that large errors can result from the application of the notch-strength analysis yields a scatter band which is consistent with the data scatter and follows the trend of the data. / Master of Science