Browsing by Author "Samuel Hudson, Committee Member"

Now showing 1 - 6 of 6

Fibrous Scaffolds for Tissue Engineering Applications.
(2010-07-27) Chung, Sangwon; Martin King, Committee Chair; Michael Gamcsik, Committee Chair; Nancy Monteiro, Committee Member; Samuel Hudson, Committee Member; Stephen Michielsen, Committee Member; Phillip Russell, Committee Member
Nonwovens Containing Novel Polymer Fillers.
(2010-06-14) Jung, Kyung Hye; Behnam Pourdeyhimi, Committee Chair; Xiangwu Zhang, Committee Chair; Saad Khan, Committee Member; Samuel Hudson, Committee Member
Novel Manufacturing, Spinning, and Characterization of Polyesters Based on 1,2-Ethanediol and 1,3-Propanediol
(2005-12-29) Pang, Kyeong; C MAURICE BALIK, Committee Member; Alan Tonelli, Committee Co-Chair; Richard Kotek, Committee Co-Chair; Samuel Hudson, Committee Member
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 γ-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.
Plasma Aided Finishing of Textile Materials
(2005-07-08) Matthews, Suzanne Rodden; Marian G. McCord, Committee Chair; Mohamed A. Bourham, Committee Member; Peter J. Hauser, Committee Member; Samuel Hudson, Committee Member
Surface modification of textile materials extends over a wide range of alterations to provide desired single or multi-features for various applications. It is a highly focused area of research in which alterations to physical and/or chemical properties lead to new textile products that provide new applications or satisfy specific needs. These processes, however, can involve numerous chemicals, some of which are toxic to humans and hazardous to the environment. In an effort to eliminate these harmful chemicals and waste products, surface modification and finishing via plasma treatment has become an attractive alternative, and is the focus of this work. Through analyzing and understanding plasma-substrate interactions, new and novel finishing applications have been developed. These processes include plasma-aided desizing of polyvinyl alcohol, and plasma-aided grafting of antimicrobial agents onto polypropylene nonwoven fabrics. Plasma treatment of PVA films has shown a significant amount of size removal through sputtering mechanisms, as well as increased solubility via chain scission, which further aids in ease of removal. Plasma treatment of PP fabrics has shown a viable pretreatment for free radical grafting of antimicrobial agents without the use of chemical etchants. In addition to new processing methods, this work has also provided an investigation into the development of a generalized solubility model for plasma exposed materials.
Processing Polymers with Cyclodextrins.
(2010-06-21) Williamson, Brandon; Alan Tonelli, Committee Chair; Samuel Hudson, Committee Member; Wendy Krause, Committee Member; Hasan Jameel, Committee Member; Charles Balik, Committee Member
The Role of Water in the Formation and Structure of Oligomer/alpha-Cyclodextrin Inclusion Complexes
(2007-07-05) Hunt, Marcus Andrew; Samuel Hudson, Committee Member; Alan E. Tonelli, Committee Co-Chair; C. Maurice Balik, Committee Co-Chair; Keith Dawes, Committee Member; Saad Khan, Committee Member
α-Cyclodextrin (α-CD), a cyclic oligosaccharide, can form inclusion complexes (ICs) with polymer molecules in the columnar crystal in which α-CD molecules stack to form a molecular tube. As-received α-CD in the cage crystal structure can form an IC with neat poly(ethylene glycol) (PEG). The transformation of α-CD from cage to columnar structure as a result of IC formation is tracked with wide-angle X-ray diffraction as a function of temperature, atmospheric water vapor content and guest molecular weight and hydrophobicity. A first-order kinetic model is used to describe the kinetics of the complexation. The time required to complex PEG(200) (MW = 200 g⁄mol) at low water activities is greater than 300 hours whereas a few hours are necessary at high water activities. Additionally, the complexation kinetics of the linear alkane, hexatriacontane (HTC), mixed with solid α-CD are slower than PEG(600) (MW = 600 g⁄mol), which has a similar molecular weight and all-trans end-to-end length as HTC. Complementary water vapor sorption and wide-angle X-ray diffractomery (WAXD) were performed on oligomer⁄α-CD ICs to determine their structures and stabilities. To discern the effect of guest molecule hydrophobicity on water adsorption isotherms, PEG(600) and HTC guests were used. Sorption isotherms for PEG(600)⁄α-CD IC are similar to those obtained for pure α-CD and PEG(600), suggesting the presence of dethreaded PEG(600) in the sample. WAXD collected before and after water vapor sorption of PEG(600)⁄α-CD IC indicated a partial conversion from columnar to cage crystal structure, the thermodynamically preferred structure for pure α-CD, due to dethreading of PEG600. This behavior does not occur for HTC⁄α-CD IC. Sorption isotherms collected at 20, 30, 40 and 50 °C allowed the calculation of the isosteric heats of adsorption and the integral entropies of adsorbed water which are characterized by minima that indicate the monolayer concentration of water in the ICs. Solid-state 13C NMR suggests a dramatic increase in HTC and α-CD molecular motion upon complexation.