Poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), poly(ethylene isophthalate) (PEI), and poly(trimethylene isophthalate) (PTI) were synthesized in a Parr reactor and melt-spun. Thermal and physical properties of the as-synthesized polymers and melt-spun fibers were determined. As-synthesized PEI and PTI were amorphous polymers and did not show any melting peaks by DSC analysis. All the polymers were thermally stable (TGA analysis). Amorphous films were made by a melt-press method with PET and PEI for determination of CO2 gas barrier properties. PEI, which has the meta-linkage of ester groups on the phenyl ring, had much lower CO2 gas permeability around one tenth that of PET, which has the para-linkage of ester groups on the phenyl ring. This is because in PET the phenyl rings are substituted in the para (1,4) positions, which allows for their facile flipping, effectively permitting gases to pass through. However, the meta-substituted phenyl rings in PEI do not permit such ring flipping, and thus PEI may be more suitable for barrier applications. The coalesced PEI was prepared from the inclusion compound of PEI with ?×-cyclodextrin. The coalesced PEI may have retained partially highly extended and parallel chains from the narrow channels of the inclusion compound, resulting in better/tighter packing among the PEI chains and exhibited a higher glass-transition temperature. Cyclic oligoesters of PET, PTT, PEI, and PTI were prepared by cyclo-depolymerization of these polyesters. The cyclic oligoesters were mixtures of different sized cyclic oligomers. PET cyclic oligomers showed four melting peaks at 59, 122, 194, and 276 o C. The cyclic oligomers of PTT, PEI, and PTI showed single melting peaks at 241, 335o C and 147o C, respectively. The cyclic oligoesters could be converted to linear polyesters by ring-opening polymerization. PTT was also prepared by ring-opening polymerization of its cyclic dimer obtained as a by-product in the conventional manufacturing plant. Antimony, tin, and titanium catalysts were used with various concentrations. The highest molecular weight, 40,000 g/mol was obtained when 0.25 mol% of titanium(IV) butoxide was used.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-12272004-133333 |
| Date | 29 December 2004 |
| Creators | Pang, Kyeong |
| Contributors | C MAURICE BALIK, Alan Tonelli, Richard Kotek, Samuel Hudson |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-12272004-133333/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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