Browsing by Author "Sheen, YC"

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Low-surface-free-energy materials based on polybenzoxazines
(2006)
Wang, CF
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Su, YC
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Kuo, SW
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Huang, CF
;
Sheen, YC
Synthesis, characterization and electrostatic dissipating ability of poly(oxyethylene) block polyesteramides
(1999-10-01)
Lin, JJ
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Sheen, YC
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Tseng, FP
;
Chang, FC
;
應用化學系
Poly(oxyethylene)diamines were included in the copolymerization of ethylene glycol and dicarboxylic acids, such as terephthalic, adipic and sebacic acid, to produce a series of hydrophilic polyether-ester-amides. With the addition of poly(oxyethylene)diamines (average molecular weight of 2,000) to PET in the amounts of 3.2, 6.6, 12 and 16 wt%, melting points of these polymers dropped accordingly, from 240 degrees C to around 227 degrees C, and the electronic resistivity decreased from 1x10(13) to approximately 8x10(8) ohm/sq. For comparison, the introduction of hydrophilic PEG-2000 or a low molecular weight diamine, such as triethyleneglycol diamine, has less effect on electronic resistivity. Molecular weight. polymer rigidity and ageing are other factors affecting the surface resistivity. The degree of hydrophilicity was measured by the moisture absorption of the fibers made from these polyether-ester-amides. A weight gain of 0.96% was observed for 12 wt% Poly(oxyethylene)diamine modified polyether-ester-amides in comparison with 0.40% for the unmodified poly(ethylene terephthalate), These results are explained by a mechanism involving moisture absorption on the polymer surface through the formation of hydrogen bonding with amide and -(OCH2CH2)-functionalities on the polymer surface.
The thermal degradation of phosphorus-containing copolyesters
(1996)
Chang, SJ
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Sheen, YC
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Chang, RS
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Chang, FC
;
交大名義發表
Two series of phosphorus-containing copolyesters were synthesized by polycondensation of phosphorus-containing monomers: poly(ethylene terephthalate)-co-poly(ethylene phenylphosphonate)s [PET-co-PEPPs] and poly(ethylene terephathalate)-co-poly(ethylene DDP)s [PET-co-PEDDPs]. Both series are considered as flame retardants in polyester fibers and polyester plastics. The phosphorus-containing polymers were characterized by NMR, IR, TGA and acid titration. Experimental results indicated that for the PET-co-PEPP higher phosphorus content results in lower thermal stability. However, an insignificant effect on thermal stability was observed in the case of PET-co-PEDDPs. Thus, the incorporation of the phosphorus linkage into the main chain results in less thermal stability than that having the phosphorus linkage as a pendant group, i.e. PET-co-PEDDPs are more stable than PET-co-PEPPs. (C) 1996 Elsevier Science Limited