Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


osu1149020480.pdf (3.02 MB)

ETD Abstract Container

Abstract Header

Thermodynamic and glass transition behavior in CO2-Polymer systems emphasizing the surface region

Liu, Dehua
http://rave.ohiolink.edu/etdc/view?acc_num=osu1149020480

Abstract Details

2006, Doctor of Philosophy, Ohio State University, Chemical Engineering.
Application of carbon dioxide in polymer processing is a very attractive and innovative research area, driven by its significant impacts on environmental concerns, scientific and technological advancement and challenge. In this work, the interaction between CO2 and polymer, including both bulk phase and thin film, has been addressed and modeled in order to guide the product and process development with the aid of CO22. An Axisymmetric Drop Shape Analysis (ADSA) method was developed to determine the CO2-induced polymer dilation over a wide range of temperature and pressure. The experimental CO2 sorption, polymer swelling and glass transition temperature (Tg) depression, have been successfully integrated with a single model, i.e., Sanchez-Lacombe Equation of State (SLEOS). Moreover, the benefits of CO2 were demonstrated in the manufacturing of drug/polymer composite by reducing the operation temperature up to 35°C. Meanwhile, the anomalous polymer surface property, particularly Tg, was revealed in the development of CO2-assisted polymer interfacial bonding technique. It is believed that the polymer surface has a lower Tg relative to its regular bulk value. An Atomic Force Microscopy (AFM)–based visualization method was developed to explore this surface phenomenon. The results demonstrated that CO2 is able to further enhance the chain mobility near the surface region and allow the surface manipulation at lower temperatures. It has been hypothesized that shifts in the glass transition temperature in a polymer thin film or near a polymer surface is the result of liquid-like layer in that special region. We report here the first attempt to confirm this liquid-like layer theoretically by applying an inhomogeneous fluid theory combined with a chain molecule equation of state. Calculated entropy gradients in the surface region of a polymer reveal a liquid-like layer on the order of 1 nm at temperatures below the bulk Tg. This simple model provides a robust starting point for exploring the relation between experimentally observed anomalous properties and the inhomogeneities present near the surface.
David Tomasko (Advisor)
301 p.
Engineering, Chemical
Carbon dioxide; Polymer; Glass transition temperature(Tg); Swelling; Sanchez-Lacombe Equation of State; Surface Tg; Entropy density model

Recommended Citations

Citations

  • Liu, D. (2006). Thermodynamic and glass transition behavior in CO2-Polymer systems emphasizing the surface region [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1149020480

    APA Style (7th edition)

  • Liu, Dehua. Thermodynamic and glass transition behavior in CO2-Polymer systems emphasizing the surface region. 2006. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1149020480.

    MLA Style (8th edition)

  • Liu, Dehua. "Thermodynamic and glass transition behavior in CO2-Polymer systems emphasizing the surface region." Doctoral dissertation, Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1149020480

    Chicago Manual of Style (17th edition)

osu1149020480
4,077
© 2006, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.