Photodegradation and Microencapsulation of Organic Thermochromic Material for Application as Building Coating Envelope

Graduation Year

2024

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Electrical Engineering

Major Professor

Arash Takshi, Ph.D.

Co-Major Professor

Sesha Srinivasan, Ph.D.

Committee Member

Elias Stefanakos, Ph.D.

Committee Member

Andrew Hoff, Ph.D.

Committee Member

Ashok Kumar, Ph.D.

Keywords

Characterization, Encapsulation, Metal Oxides

Abstract

Due to exponential urbanization, residential building electrical loads have increased over the past decades. Also, deforestation has led to increased urban heat island effects, due to which summer has been scorching and winter has become freezing. This further increases the load on generation due to the extensive use of heating and cooling systems. New techniques, such as cool building materials and green building concepts, compensate for the load. The building can be coated with a material that has heat reflectivity capability for summer and heat-trapping capability for winter. One such material is thermochromic, which turns white upon heating and black upon cooling.

Thermochromic material can be used as building coating material, road coating material, and battery heating indicator.Thermochromic materials are organic and inorganic. Organic thermochromic materials are affected due to exposure to the environment. The properties of organic matter are influenced by sunlight, humidity, temperature, and other environmental parameters of thermochromic material (TCM). Hence, the need for research is imminent due to the limitations of organic thermochromic material. Previous photodegradation studies for organic thermochromic material suggested that the visible wavelength spectrum plays a significant role. Microencapsulation of organic with metal oxide to resist material degradation shows promising results. Microencapsulation influences the particles' thermal properties, chemical degradation, structure, and size. When exposed to environmental changes, titanium oxide shows the most promising results against photodegradation. Titanium oxide resistance against ultraviolet sunlight has the highest effect on photodegradation.

Titanium oxide is also sustainable as it can be recycled easily and is more environmentally friendly than other metal oxide. This dissertation focuses on using organic thermochromic commercial black dye as building coating material to reduce heating and cooling system loads. To use as external coating material, the organic material characteristics are firstly studied using techniques such as differential scanning calorimetry for thermal transition changes, scanning electron microscopy to study structural analysis, energy dispersive technique, and Fourier transform infrared spectroscopy for composition analysis. The same methods were utilized when the organic thermochromic material was microencapsulated. A solar simulator system of one sun wavelength spectrum was used to illustrate the effect of sunlight. The dissertation mainly focuses on the photodegradation of plain and encapsulated organic thermochromic material and studies their characteristics using ultraviolet-visible spectrophotometry to determine absorption peaks. A CIE laboratory analysis was also conducted to study the chromatic nature of the sample before and after exposure to the solar simulator. Color filters like sky blue, dark blue, green, and red were used to study the effect of different visible wavelength spectrums on the material.

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