Skip to Main Content
 

Global Search Box

 
 
 

ETD Abstract Container

Abstract Header

INHIBITION OF FREE RADICAL CURED THERMOSETTING ACRYLIC COATINGS

Lin, Che-Kuan
http://rave.ohiolink.edu/etdc/view?acc_num=akron1648073691546637

Abstract Details

2022, Doctor of Philosophy, University of Akron, Polymer Engineering.
For industrial applications, curing coatings in an air atmosphere is the simplest method at the job field. Free radical polymerization (FRP) is a well-known and widely used method to cure thermosetting acrylic coatings. Considering curing coatings by free radical polymerization (FRP), quenching of free radicals by oxygen (O2) is a huge problem in the open-air condition. This phenomenon is known as oxygen inhibition. It can result in a coating that cures beneath the surface but remains tacky or even sticky at the air-coating interface, where it is exposed to oxygen-rich air. Various chemical or physical strategies were proposed to reduce oxygen inhibition. Among those physical strategies, the oldest strategy to eliminate oxygen inhibition is to cure the coating in an inert atmosphere. In this case, coating is prevented from contacting with oxygen molecules because of the inert gas blanketing; as a consequence, oxygen inhibition won’t occur. However, the downside of this approach is the cost. Replacing air with nitrogen or other inert gases increases the cost of applying the coating. In addition, the industrial curing line is not easy to be made totally airtight. Losses of nitrogen gas or other inert gases would be another issue for industrial applications. The addition of paraffin wax floating on the top of the coating is an alternative method to eliminate oxygen inhibition. It is a common approach to solving oxygen inhibition in industrial applications. However, this approach is not perfect and still has to overcome some limitations. The properties of wax, for example, the phase behavior of wax or wax density, are critical in this approach. The wax thermal history and wax content on the curing behavior of coatings were further investigated in this study. To build up an effective barrier, the phase behavior of wax is critical. Considering paraffin wax is a semicrystalline material, it has crystalline and amorphous domains by nature. The polymer chains pack more regularly and tightly in the crystalline domain than in the amorphous domain. In addition, gases are generally impermeable to crystalline domains. These facts would cause an uneven protection on the coating top surface. A model formulation of MMA thermosetting acrylic coatings was developed to study the coating's wax distribution and curing behavior. This model formulation is a redox free-radical polymerization (RFRP) system carried out at room temperature without additional energy consumption. In the first part, paraffin wax was either annealed or quenched in order to make waxes with various levels of crystallinity. The wax distribution and curing behavior of acrylic coatings adding annealed and quenched waxes were studied. The amount of residual acrylate monomer in a cured sample was evaluated by DSC. Surface topography and roughness of cured coating samples were evaluated by the profilometer. The wax distribution along the coating cross-section and coating top/bottom surfaces was characterized by infrared spectra through ATR-FTIR. DSC characterized wax crystallinity. In the second part, reactive diluents with different polarities were selected to study the influence of the phase behavior of paraffin wax on the curing behavior of the coating. (Hydroxyethyl)methacrylate (HEMA) and Lauryl methacrylate (LM) were selected for this study. In the third part, the influence of wax blends on the coating curing behavior was studied. Waxes with different melting points were selected for this study. Free radical polymerization can be initiated through many ways, for example, thermal initiation, photoinitiation, or redox reaction. Unlike the redox free-radical polymerization (RFRP) system used in the first three chapters, the curing behavior of visible light curable thermoset acrylic coatings was studied in the last chapter. A model formulation of visible light curable thermoset acrylic coatings was developed for this study. The result shows that the visible light curable thermoset acrylic coating system has a high double bond conversion rate, close to the conventional UV light curable system, and has great potential in industrial applications, e.g., floor coating systems.
Mark Soucek (Advisor)
Kevin Cavicchi (Committee Chair)
Nicole Zacharia (Committee Member)
Chrys Wesdemiotis (Committee Member)
Qixin Zhou (Committee Member)
170 p.
Materials Science; Plastics; Polymer Chemistry; Polymers
Thermoset coating, Oxygen inhibition, Additive

Recommended Citations

Citations

  • Lin, C.-K. (2022). INHIBITION OF FREE RADICAL CURED THERMOSETTING ACRYLIC COATINGS [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1648073691546637

    APA Style (7th edition)

  • Lin, Che-Kuan. INHIBITION OF FREE RADICAL CURED THERMOSETTING ACRYLIC COATINGS. 2022. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1648073691546637.

    MLA Style (8th edition)

  • Lin, Che-Kuan. "INHIBITION OF FREE RADICAL CURED THERMOSETTING ACRYLIC COATINGS." Doctoral dissertation, University of Akron, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=akron1648073691546637

    Chicago Manual of Style (17th edition)

akron1648073691546637
373
© 2022, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.